How does the human heart work. What are the main components of the heart. How can we maintain a healthy heart. What modern medical interventions are available for heart conditions. How do diagnostic tools help in assessing heart health.

The Remarkable Structure and Function of the Human Heart

The human heart, though only slightly larger than a fist, is a powerhouse of the circulatory system. This muscular organ expands and contracts approximately 100,000 times daily, pumping nearly 2,000 gallons (7,571 liters) of blood throughout the body. Its tireless efforts ensure that every cell receives the oxygen and nutrients it needs to function optimally.

Anatomy of the Heart

The heart comprises four chambers: two upper chambers called atria and two lower chambers known as ventricles. These chambers work in harmony to receive and pump blood efficiently. At the heart’s apex sits the aorta, the largest artery in the body, responsible for carrying oxygenated blood from the left ventricle to the rest of the body.

Dividing the heart into right and left halves is a muscular wall called the septum. This partition ensures that oxygenated and deoxygenated blood do not mix within the heart. The heart’s intricate network of blood vessels includes two major veins—the superior vena cava and the inferior vena cava—which return deoxygenated blood to the right side of the heart.

The Coronary Arteries: Lifelines of the Heart

Coronary arteries play a crucial role in supplying blood to the heart muscle itself. However, these vital vessels can become compromised due to various factors. Can coronary arteries become blocked? Indeed, they can. Coronary arteries may become clogged as the heart attempts to repair damage caused by nicotine, natural minerals like calcium, and LDL cholesterol. This process leads to the buildup of plaque, resulting in a condition known as atherosclerosis.

Understanding Heart Disease and Its Consequences

Atherosclerosis, characterized by the hardening and narrowing of arteries, poses significant risks to heart health. The yellow mound visible on the bottom wall of a blood vessel in medical imaging often indicates this condition. In severe cases, a blood clot can form behind a blocked artery, potentially leading to a heart attack or stroke by abruptly cutting off blood flow to the heart or brain.

The Silent Threat of Cardiovascular Disease

Cardiovascular disease remains a leading cause of death worldwide. Why is heart disease so prevalent? Factors such as poor diet, lack of exercise, smoking, and genetic predisposition contribute to its high incidence. Recognizing the signs and symptoms of heart disease is crucial for early intervention and prevention of life-threatening events.

Cutting-Edge Interventions in Cardiac Care

Modern medicine offers various interventions to address heart conditions, from minimally invasive procedures to major surgeries. How do doctors treat severe heart conditions? Let’s explore some of the most advanced techniques in cardiac care.

Open-Heart Surgery and Bypass Operations

In cases where less invasive treatments are insufficient, open-heart surgery may be necessary. During this procedure, surgeons access the heart by opening the chest cavity. One common intervention is the coronary artery bypass graft (CABG), where a new blood vessel is sewn in to “bypass” a blockage, restoring blood flow to the heart muscle.

Heart Transplantation: A New Lease on Life

For patients with end-stage heart failure, a heart transplant may be the only option. This complex procedure involves replacing the diseased heart with a healthy one from a donor who is brain-dead but on life support. A successful heart transplant can significantly increase a patient’s life expectancy, often by 10 years or more.

Artificial Hearts: Bridging the Gap

When donor hearts are unavailable, artificial hearts serve as a life-saving alternative. The AbioCor, a self-contained artificial heart, has shown promising results, more than doubling patients’ life expectancy in some cases. The implantation of an artificial heart is an intricate procedure, taking approximately seven hours to complete and is reserved for individuals facing imminent mortality without intervention.

Innovative Technologies in Cardiac Support

Advancements in medical technology have led to the development of various devices to support or regulate heart function. These innovations have revolutionized the treatment of cardiac conditions, offering hope to patients with a wide range of heart problems.

Pacemakers: Regulating Heart Rhythm

Artificial pacemakers have become indispensable in treating certain heart rhythm disorders. How does a pacemaker work? This small device mimics the electrical impulses normally generated by the sinoatrial node, helping the heart maintain a regular and appropriate beating rate. Pacemakers are particularly beneficial for individuals whose hearts beat too slowly.

The implantation of a pacemaker is a relatively simple procedure, typically lasting about an hour. Surgeons make a small incision, usually on the left side of the chest, and place wires in the heart that connect to the pacemaker device. This minimally invasive approach allows for quick recovery and immediate improvement in heart function for many patients.

Diagnostic Tools for Heart Health Assessment

Accurate diagnosis is crucial for effective treatment of heart conditions. Modern medicine employs a variety of sophisticated tools to evaluate heart health and detect potential problems early.

Electrocardiogram (ECG/EKG): Tracking Electrical Activity

An electrocardiogram, commonly known as an ECG or EKG, provides a graphic record of the heart’s electrical activity. This non-invasive test can diagnose various heart conditions, including heart disease and rapid heartbeats such as atrial fibrillation. How has ECG technology evolved? The first electrocardiograph, introduced by Cambridge Scientific Instruments, required patients to sit with their hands and feet in salt water during the test.

Today’s ECG procedures are much more advanced and patient-friendly. A modern electrocardiogram takes only about five minutes to complete. Electrodes placed on the arms, legs, and chest measure the heart’s electrical impulses at rest, providing valuable data for cardiac assessment.

Pulse Monitoring: A Simple Yet Effective Tool

Monitoring pulse rate is a straightforward method to assess heart health. Pulse monitors can be attached to the body, or individuals can manually check their pulse by placing their index and middle fingers on the underside of the wrist. What is considered a normal resting heart rate? For adults, the average resting heart rate typically falls between 60 to 100 beats per minute.

Cardioversion: Restoring Normal Heart Rhythm

For patients with abnormal heart rhythms, cardioversion offers a way to restore a normal heartbeat. This can be achieved through electrical means, such as with a defibrillator, or through medication. Electrical cardioversion involves delivering a controlled electric shock to the heart, while pharmacological cardioversion uses specific drugs to regulate heart rhythm.

Pharmacological Approaches to Heart Health

Medication plays a crucial role in managing various heart conditions. Different classes of drugs target specific aspects of heart function to improve overall cardiovascular health.

Types of Heart Medications

• Diuretics: Help reduce fluid buildup in the body, easing the heart’s workload
• Inotropic drugs: Strengthen heart contractions
• Vasodilators: Relax blood vessels, improving blood flow
• Beta-blockers: Block the effects of adrenaline, reducing heart rate and blood pressure
• Anticoagulants: Thin the blood to prevent clot formation

These medications, when prescribed appropriately, can significantly improve heart function and reduce the risk of complications in patients with heart disease.

Ultrasound Imaging in Cardiac Assessment

Ultrasound technology provides another valuable tool for evaluating heart health. Doctors often use ultrasound to investigate unexplained chest pain, assess damage after a heart attack, or monitor patients with a history of heart disease. This non-invasive imaging technique offers real-time views of the heart’s structure and function, aiding in accurate diagnosis and treatment planning.

Lifestyle Choices for Optimal Heart Health

While medical interventions play a crucial role in treating heart conditions, maintaining a heart-healthy lifestyle is equally important for prevention and overall cardiovascular well-being.

Nutrition: Fueling Your Heart

A heart-healthy diet is fundamental to cardiovascular health. What foods promote heart health? Incorporating whole foods such as fruits, vegetables, nuts, legumes, whole grains, and fish rich in omega-3 fatty acids can significantly improve heart function and reduce the risk of heart disease.

Exercise: Strengthening Your Heart Muscle

Regular physical activity is essential for maintaining a healthy heart. How much exercise is needed for heart health? The American Heart Association recommends at least 150 minutes of moderate-intensity aerobic exercise or 75 minutes of vigorous aerobic activity per week. Activities such as brisk walking, swimming, cycling, or dancing can all contribute to improved cardiovascular fitness.

Stress Management: Protecting Your Heart

Chronic stress can have detrimental effects on heart health. Implementing stress-reduction techniques such as meditation, yoga, or deep breathing exercises can help mitigate the negative impact of stress on the cardiovascular system.

Smoking Cessation: A Critical Step

Quitting smoking is one of the most important steps individuals can take to improve heart health. Tobacco use is a major risk factor for heart disease, and cessation can lead to significant improvements in cardiovascular function and overall health.

By combining these lifestyle modifications with regular medical check-ups and adherence to prescribed treatments, individuals can significantly reduce their risk of heart disease and promote long-term cardiovascular health.

Emerging Technologies in Cardiac Care

The field of cardiology continues to evolve, with new technologies and treatments emerging to improve patient outcomes and quality of life. These innovations offer hope for more effective, less invasive interventions for a wide range of heart conditions.

Minimally Invasive Cardiac Procedures

Advancements in surgical techniques have led to the development of minimally invasive procedures that can address various heart conditions with reduced risk and faster recovery times. Transcatheter aortic valve replacement (TAVR), for instance, allows for the replacement of a diseased aortic valve without open-heart surgery, benefiting patients who may not be candidates for traditional surgical approaches.

Wearable Technology for Heart Monitoring

The rise of wearable devices has revolutionized personal health monitoring, including heart health. Smart watches and fitness trackers equipped with ECG capabilities allow individuals to track their heart rate and rhythm continuously, potentially detecting irregularities early. How accurate are these devices? While not a substitute for professional medical evaluation, many wearable devices provide valuable data that can prompt timely medical consultation.

Artificial Intelligence in Cardiac Diagnostics

Artificial intelligence (AI) is increasingly being integrated into cardiac care, enhancing diagnostic accuracy and treatment planning. AI algorithms can analyze medical images, such as echocardiograms and CT scans, with remarkable precision, often detecting subtle abnormalities that might be missed by the human eye. This technology holds promise for earlier detection of heart disease and more personalized treatment strategies.

The Future of Heart Health: Personalized Medicine

As our understanding of genetics and molecular biology advances, the field of cardiology is moving towards more personalized approaches to heart health. This paradigm shift promises tailored prevention strategies and treatments based on an individual’s unique genetic profile and risk factors.

Genetic Testing for Heart Disease Risk

Genetic testing is becoming an increasingly important tool in assessing an individual’s risk for certain heart conditions. By identifying specific genetic markers associated with cardiovascular disease, healthcare providers can implement targeted prevention strategies and interventions before symptoms arise.

Precision Medicine in Cardiac Care

Precision medicine aims to tailor medical treatment to the individual characteristics of each patient. In cardiology, this approach may involve analyzing a patient’s genetic makeup, lifestyle factors, and environmental exposures to determine the most effective treatment strategies. How does precision medicine improve cardiac care? By customizing treatments based on an individual’s unique profile, precision medicine has the potential to enhance treatment efficacy while minimizing side effects.

Regenerative Medicine: Repairing the Heart

The field of regenerative medicine holds promise for repairing damaged heart tissue. Stem cell therapy and tissue engineering techniques are being explored as potential methods to regenerate heart muscle and blood vessels. While still largely experimental, these approaches could revolutionize the treatment of heart failure and other cardiac conditions in the future.

As research continues and technology advances, the future of cardiac care looks increasingly bright. From improved diagnostic tools to more effective and personalized treatments, these innovations offer hope for better outcomes and enhanced quality of life for individuals with heart conditions.

In conclusion, maintaining heart health requires a multifaceted approach, combining preventive measures, early detection, and advanced medical interventions when necessary. By staying informed about the latest developments in cardiac care and adopting heart-healthy lifestyle habits, individuals can take proactive steps towards ensuring their cardiovascular well-being for years to come.

Heart Pictures | HowStuffWorks

Your heart may be only slightly larger than your fist, but it’s one tough muscle. Take an inside look at the heart, and learn interesting facts and tips for keeping it healthy.

You’ve seen plenty of diagrams, but this is the real thing. The average heart expands and contracts about 100,000 times each day, pumping close to 2,000 gallons (7,571 liters) of blood throughout the body.

Here, the parts of the heart are identified. The heart has four chambers; the upper two are called atria, and the lower two are called ventricles. At the top of the heart is the aorta, which carries oxygenated blood to the entire body from the left ventricle.

If you were to split your heart in half, you could see the muscular wall known as the septum, which divides the organ’s right and left sides.

Within the heart are also arteries that are responsible for supplying the blood. All blood enters the right side of the heart through two veins: the superior vena cava and the inferior vena cava.

A coronary artery can become clogged as the heart tries to repair damage caused by nicotine, natural minerals such as calcium and LDL cholesterol. Plaque builds up as a result, and this hardening of the arteries is known as atherosclerosis, indicated by the yellow mound on the bottom wall of the blood vessel.

A blood clot can also form behind a blocked artery, and within minutes it can shut down blood flow to your heart or brain and cause a heart attack or stroke. Surgery may be required to prevent these conditions. See the next page to learn more.

During open-heart surgery, the chest is cut open so that doctors can access the heart. A common procedure is to sew in a new piece of blood vessel to bridge over (bypass) the blockage. This procedure is called a heart bypass operation.

In some cases, a whole new heart is needed. Here, a heart sits in ice in an operating room. A healthy heart is obtained from a donor who is brain dead but on life-support. A transplant can increase patient survival by 10 years or more.

If there isn’t a donor heart available, artificial hearts are also an option. Barney Clark received the first artificial heart implant Dec. 2, 1982 in Salt Lake City, Utah. Take a closer look at an artificial heart on the next page.

The AbioCor is a self-contained artificial heart that is expected to more than double patients’ life expectancy, with one recipient surviving an additional 512 days.

The surgery to implant an AbioCor artificial heart is extremely delicate and takes around seven hours to complete. The procedure is only for individuals who are likely to die within two weeks without the transplant procedure.

Here you can see how the artificial heart looks inside the human body. Pacemakers are another tool to keep the heart functioning. Learn more about how they work next.

An artificial pacemaker mimics the electrical impulses normally created by the sinoatrial node. It helps the heart beat regularly at an appropriate rate and is usually for people whose heart beats too slow.

A pacemaker is implanted under the skin during a one-hour surgery. A small cut is made, usually on the left side of the chest, and wires are placed in the heart that connect to the device. Next, see the tools doctors use to determine the health of your heart.

An electrocardiogram, like the one above, is also called an ECG or EKG. It is a graphic record of the heart’s electrical activity and can be used to diagnosis heart disease or rapid heartbeats, such as atrial fibrillation.

The first electrocardiograph was introduced by Cambridge Scientific Instruments. A patient sat with hands and feet in salt water during the test.

Today’s electrocardiograms only take about five minutes. Electrodes are placed on the arms, legs and chest and measure the electrical impulses of the heart at rest.

Pulse monitors can also be attached to the body, or you can place your index and middle finger on the underside of the wrist to feel for your pulse, which is the number of heartbeats per minute. The average resting heart rate for adults is 60 to 100 beats per minute.

Abnormal heart rhythms can be treated with cardioversion by electric shock, such as with a defibrillator as shown here. Cardioversion is also accomplished through medicinal means, shown next.

Heart failure can be treated with several types of drugs — diuretics, inotropic and vasodilator drugs that do everything from thinning the blood and relaxing the blood vessels to blocking the effects of adrenaline.

Doctors can also use ultrasound to determine the condition of your heart, especially if you experience unexplained chest pain, have had a heart attack or a history of heart disease. Learn how to keep your heart healthy next.

Eating whole foods such as fruits, vegetables, nuts, legumes, whole grains and fish for omega-3 fatty acids can help improve your heart health.

Exercise is also great for your heart, since your heart is in fact a muscle. Doctors recommend 30 minutes of cardiovascular exercise three times a week at the bare minimum.

Lastly, make sure you make time to chill out. If you’re always stressed, then your body thinks it’s in a constant state of threat, which increases blood pressure and your heart rate. If you lead a stressful life, try to relax with friends after work, take a walk or give meditation a try. The right amount of sleep also goes a long way toward combating your stress level. For more information, see 10 Ways to Avoid a Heart Attack and our Circulatory System articles.

A clear picture of your heart is worth a thousand words

Speaking of Health

Monday, February 2, 2015

Your heart is one of the most important parts of your body, pumping oxygen and blood throughout the body to sustain life. The fist-sized organ beats 100,000 times per day, pushing five or six quarts of blood each minute.

If your heart is not functioning properly because of narrowing blood vessels, valve damage, an infection or something else, it is important to get the best heart care. A comprehensive heart program includes doctors trained in cardiovascular diseases working in a multidisciplinary team with radiologists, rehabilitation specialists and other experts to provide care for common conditions to rare disorders. Top programs also actively research new diagnostic techniques and treatments. 

When evaluating a hospital’s heart program, ask about the imaging technology used to diagnose and treat heart diseases. You will want your team using techniques that are state-of-the-art. Superior imaging leads to rapid interpretation of test results, more accurate diagnosis, as well as better treatment outcomes.

Two state-of-the-art imaging techniques used by a number of Mayo Clinic Health System locations, including La Crosse, Eau Claire and Mankato, are 3D echocardiography and biplane angiography.  

• Three-dimensional echocardiography is an ultrasound of your heart that creates three-dimensional images of the heart and its various structures. With these images, cardiologists are better able to see the anatomy of your heart and how it’s functioning in order to make more informed decisions regarding diagnosis and treatment.
• Biplane angiography uses two X-ray cameras. These cameras take pictures simultaneously, employing only one contrast injection to reduce the amount of contrast agents — and also reduce the risk of potential kidney damage. The sharp, high-resolution images allow the cardiologist to see small blood vessels in great detail and clearly determine the degree of blockage. By inserting only a small amount of dye, the cardiologist can watch the path of blood flow through your vessels in real time. These images are extremely important during procedures that require exacting precision – such as stent placement, blood vessel interventions and other clinical procedures.

Heart disease is easier to treat when detected early. If you have a family history of heart disease and are concerned about developing heart disease, talk to your doctor about steps you can take to reduce your heart disease risk. You should seek medical care if you are experiencing chest pain, shortness of breath and/or fainting.

For the safety of our patients, staff and visitors, Mayo Clinic has strict masking policies in place. Anyone shown without a mask was either recorded prior to COVID-19 or recorded in a non-patient care area where social distancing and other safety protocols were followed.

How did the human heart become associated with love? And how did it turn into the shape we know today? |

Jehan de Grise and his workshop, “The Heart Offering,” 1338-1344. Illustration from The Romance of Alexander, Bodleian Library, Oxford, England.

We see the familiar symbol everywhere — in text messages, signs, cakes, clothing, and more. But we also know the real heart looks nothing like it. Historian Marilyn Yalom tells us how the anatomical organ became the symbol that we all know today.

In 2011, I went to the British Museum in London to see a collection of 15th-century artifacts, which included gold coins and jewelry that were part of the Fishpool Hoard found in England in 1966. I was particularly attracted to a heart-shaped brooch (below, one of the heart brooches from the hoard).

That day, I noticed the heart’s two upper lobes and its V-shaped bottom point as if I were seeing them for the first time. It quickly dawned on me that the symmetrical shape is a far cry from the ungainly lumpish organ inside us. From that moment on, the figure of the heart pursued me. I wanted to answer two questions: “How did the human heart become transformed into the iconic form we know today?” and “How long has the heart been associated with love?”

Artist unknown. Brooch from the Fishpool Hoard, 1400-1464, British Museum, London, England.

As far back as the ancient Greeks, lyric poetry identified the heart with love in verbal conceits. Among the earliest known Greek examples, the poet Sappho agonized over her own “mad heart” quaking with love. She lived during the 7th century BC on the island of Lesbos surrounded by female disciples for whom she wrote passionate poems, now known only in fragments, like the following: Love shook my heart, Like the wind on the mountain Troubling the oak-trees.

Greek philosophers agreed, more or less, that the heart was linked to our strongest emotions, including love. Plato argued for the dominant role of the chest in love and in negative emotions of fear, anger, rage and pain. Aristotle expanded the role of the heart even further, granting it supremacy in all human processes.

Artist unknown. Drachm depicting a silphium seed pod, ca. 510-490 BC. Sanctuary of Demeter and Persephone, Cyrene.

Among the ancient Romans, the association between the heart and love was commonplace. Venus, the goddess of love, was credited — or blamed — for setting hearts on fire with the aid of her son Cupid, whose darts aimed at the human heart were always overpowering.

In the ancient Roman city of Cyrene — near what is now Shahhat, Libya — the coin (above) was discovered. Dating back to 510-490 BC, it’s the oldest-known image of the heart shape. However, it’s what I call the non-heart heart, because it is stamped with the outline of the seed from the silphium plant, a now-extinct species of giant fennel. Why in the world would anyone have put that on a coin? Silphium was known for its contraceptive properties, and the ancient Libyans got rich from exporting it throughout the known world. They chose to honor it by putting it on a coin.

Illustration from the novel Manon Lescaut by Antoine François Prévost, iStock.

The ancient Romans held a curious belief about the heart — that there was a vein extending from the fourth finger of the left hand directly to the heart. They called it the vena amoris. Even though this idea was based upon incorrect knowledge of the human anatomy, it persisted. In the medieval period in Salisbury, England, during the church ceremony in the liturgy, the groom was told to place a ring on the bride’s fourth finger because of that vein. Wearing a wedding ring on that finger goes back all the way to the Romans.

Artist unknown, “Herr Alram von Gresten: Minne Gespräch,” from the Codex Manesse. Heidelberg University Library, Heidelberg, Germany.

During the 12th and 13th centuries, the heart found a home in the feudal courts of Europe. Minstrels in France celebrated a form of love that came to be known as “fin’ amor.” Fin’ amor is impossible to translate: today we call it courtly love, but its original meaning was closer to “extreme love,” “refined love” or “perfect love.” Courtly love required the troubadour to pledge his whole heart to only one woman, with the promise that he would be true to her forever. Accompanied by his lyre or harp, he’d sing his heart out in the presence of his lady and the members of the court to which she belonged.

This explosion of song and poetry that started in France spread to Spain, Portugal, Italy, Germany, Hungary and Scandinavia, each of which created its own variations. Through them, love staked out its place not only as a literary concept but also as an important social value and an intrinsic part of being human. A yearning for amorous love seeped into the Western consciousness and has remained there since. The illustration (above) is from the German Codex Manesse, a compilation of love poems which historians place sometime between 1300 to 1340. Between the couple, a fanciful tree rises to form the outline of a heart, which carries within it a coat of arms bearing the Latin word AMOR (love.)

Jehan de Grise and his workshop, “The Heart Offering,” 1338-1344. Illustration from The Romance of Alexander, Bodleian Library, Oxford, England.

In 1344, the first known image of the indubitable heart icon with two lobes and a point appeared. It made its debut in a manuscript titled The Romance of Alexander, written in the French dialect of Picardy by Lambert le Tor (and, after him, finished by Alexandre de Bernay). With hundreds of exquisitely ornamented pages, Alexander is one of the great medieval picture books.

The scene containing the heart image appears in the lower border of a page decorated with sprays of foliage, perched birds and other motifs characteristic of French and Flemish illumination. On the left-hand side (above), a woman raises a heart that she has presumably received from the man facing her. She accepts the gift, while he touches his breast to indicate the place from which it has come. From this moment on, there was an explosion of heart imagery, particularly in France.

Master of the Chronique scandaleuse, “Miniature of Two Women Trying to Catch Flying Hearts in a Net” (detail), ca. 1500. From Pierre Sala, Petit Livre d’Amour, British Library, London, England.

During the 15th century, the heart icon proliferated throughout Europe in a variety of unexpected ways. It was visible on the pages of manuscripts and on luxury items like brooches and pendants. The heart also turned up in coats of arms, playing cards, combs, wooden chests, sword handles, burial sites, woodcuts, engravings and printer’s marks. The heart icon was adapted to many practical and whimsical uses, with most — but not all — related to love.

Frenchman Pierre Sala contributed to the history of the amorous heart with a book titled Emblèmes et Devises d’amour, or Love Emblems and Mottos, prepared in Lyon around 1500. His collection of 12 love poems and illustrations was intended for Marguerite Bullioud, the love of his life, although she was married to another man. (She and Sala wed after her husband’s death.) Sala’s tiny book was meant to be held in the palm of one’s hand. In one of the illustrations (above), two women attempt to catch a bevy of flying hearts in a net stretched out between two trees. The winged heart, borrowing from angels, had already appeared in earlier illustrations as the sign of soaring love.

Artist unknown, Pensez à moi, ca. 1900. Paper valentine, image courtesy of Marilyn Yalom.

Though some people assume that Valentine’s Day is the creation of the modern greeting card industry, its history is much older — indeed, so old that its origins are clouded. Saint Valentine of Rome was added to the Catholic calendar by Pope Gelasius in 496, to be commemorated on February 14, the same day it still occupies. While there have been various theories of why St. Valentine became associated with love, it most likely developed during the late Middle Ages in the context of Anglo-French courtly love.

By the mid-17th century, the celebration of Valentine’s Day in England was customary for those who could afford its rituals. Affluent men drew lots with women’s names on them, and the man who picked a lady’s name was obliged to give her a gift. The earliest English, French and American valentines were little more than a few lines of verse handwritten on a sheet of paper, but over time, makers began embellishing them with drawings and paintings. These were folded, sealed with wax, and placed on their intended’s doorstep.

Then, the first commercial valentines appeared in England at the end of the 18th century. They were printed, engraved or made from woodcuts and sometimes colored by hand. They combined traditional symbols of love — flowers, hearts, cupids, birds — with doggerel verse of the “roses are red” variety. Thanks to the Industrial Revolution, mass-produced Valentine’s Day cards obliterated the handmade variety in England and the US. The French, too, began exploiting the commercial valentine, with cards featuring angel-like cupids surrounded by hearts (above, a French card, circa 1900).

Milton Glaser, I Love New York, 1977. Trademarked logo, New York State Department of Economic Development, New York, New York.

In 1977, the heart icon underwent yet another transformation when it became a verb. The “I ❤ NY” logo was created to boost morale for a city in crisis. Trash piled up on the streets, the crime rate spiked, and it was near bankruptcy. Hired to design an image that would increase tourism, graphic designer Milton Glaser created the famous logo (above) that has since become a cliché and a meme. With the logo, Glaser extended the heart’s meaning beyond romantic love to embrace the realm of civic feelings and thereby opened the gateway to new uses. Once it became a verb, ❤ could connect a person with any other person, place or thing.

Twenty-two years later, a new graphic form appeared that brought the heart into a whole new realm. In 1999, Japanese provider NTT DoCoMo released the first emojis made for mobile communication. In the original set of 176 symbols, there were five concerning the heart. One was colored completely red, one included white blank spots to suggest 3-D depth, another had jagged white blanks at its center signifying a broken heart, one looked as if it were in flight, and one had two small hearts sailing off together.

Now there are more 30 different emojis containing a heart, and I suspect the heart image will keep evolving in unknown ways for centuries to come. While the heart may be only a metaphor, it serves us well, for love itself is impossible to define. Throughout the ages, men and women have tried to put into words the various shades of love they’ve experienced — fondness, affection, infatuation, attachment, endearment, romance, desire or “true love.” But when words fail us, we fall back on signs. We add ❤ to our emails, texts and notes. We send valentines adorned with ❤ to those dear to us. We give gifts with❤ patterns. We make ❤ -shaped cookies for children. The continued global popularity of the heart as a symbol for love offers us a small dose of hope, serving as a reminder of the ageless assumption that love can save us.

This story was adapted from Marilyn Yalom’s TEDx talk and from her book The Amorous Heart: An Unconventional History of Love, with the permission of Basic Books, an imprint of Perseus Books LLC, a subsidiary of Hachette Book Group. Copyright © Marilyn Yalom 2018.

Watch her TEDxPaloAlto talk here:

Congenital Heart Defects – Facts about Hypoplastic Left Heart Syndrome

Hypoplastic (pronounced hi-puh-PLAS-tik) left heart syndrome or HLHS is a birth defect that affects normal blood flow through the heart.

What is Hypoplastic Left Heart Syndrome?

Hypoplastic left heart syndrome (HLHS) is a birth defect that affects normal blood flow through the heart. As the baby develops during pregnancy, the left side of the heart does not form correctly. Hypoplastic left heart syndrome is one type of congenital heart defect. Congenital means present at birth. Because a baby with this defect needs surgery or other procedures soon after birth, HLHS is considered a critical congenital heart defect (CCHD).

Hypoplastic left heart syndrome affects a number of structures on the left side of the heart that do not fully develop, for example:

• The left ventricle is underdeveloped and too small.
• The mitral valves is not formed or is very small.
• The aortic valve is not formed or is very small.
• The ascending portion of the aorta is underdeveloped or is too small.
• Often, babies with hypoplastic left heart syndrome also have an atrial septal defect, which is a hole between the left and right upper chambers (atria) of the heart.

In a baby without a congenital heart defect, the right side of the heart pumps oxygen-poor blood from the heart to the lungs. The left side of the heart pumps oxygen-rich blood to the rest of the body. When a baby is growing in a mother’s womb during pregnancy, there are two small openings between the left and right sides of the heart: the patent ductus arteriosus and the patent foramen ovale. Normally, these openings will close a few days after birth.

In babies with hypoplastic left heart syndrome, the left side of the heart cannot pump oxygen-rich blood to the body properly. During the first few days of life for a baby with hypoplastic left heart syndrome, the oxygen-rich blood bypasses the poorly functioning left side of the heart through the patent ductus arteriosus and the patent foramen ovale. The right side of the heart then pumps blood to both the lungs and the rest of the body. However, among babies with hypoplastic left heart syndrome, when these openings close, it becomes hard for oxygen-rich blood to get to the rest of the body.

Learn more about how the heart works »

Occurrence

The Centers for Disease Control and Prevention (CDC) estimates that each year about 1,025 babies in the United States are born with hypoplastic left heart syndrome.1 In other words, about 1 out of every 3,841 babies born in the United States each year is born with hypoplastic left heart syndrome.

Women can take steps before and during pregnancy to reduce the risk of having a baby born with birth defects. Such steps include taking a daily multivitamin with folic acid (400 micrograms), not smoking, and not drinking alcohol during pregnancy.

Learn more about how to prevent birth defects »

Causes and Risk Factors

The causes of heart defects such as hypoplastic left heart syndrome among most babies are unknown. Some babies have heart defects because of changes in their genes or chromosomes. These types of heart defects also are thought to be caused by a combination of genes and other risk factors, such as things the mother comes in contact with in the environment or what the mother eats or drinks or the medicines the mother uses.

Read more about CDC’s work on causes and risk factors »

Diagnosis

Hypoplastic left heart syndrome may be diagnosed during pregnancy or soon after the baby is born.

During Pregnancy

During pregnancy, there are screening tests (also called prenatal tests,) to check for birth defects and other conditions. Hypoplastic left heart syndrome may be diagnosed during pregnancy with an ultrasound, (which creates pictures of the body). Some findings from the ultrasound may make the health care provider suspect a baby may have hypoplastic left heart syndrome. If so, the health care provider can request a fetal echocardiogram, an ultrasound of the baby’s heart, to confirm the diagnosis.This test can show problems with the structure of the heart and how the heart is working with this defect.

After the Baby Is Born

Babies with hypoplastic left heart syndrome might not have trouble for the first few days of life while the patent ductus arteriosus and the patent foramen ovale (the normal openings in the heart) are open, but quickly develop signs after these openings are closed, including:

• Problems breathing,
• Pounding heart,
• Weak pulse, or
• Ashen or bluish skin color.

During a physical examination, a doctor can see these signs or might hear a heart murmur (an abnormal whooshing sound caused by blood not flowing properly). If a murmur is heard or other signs are present, the health care provider might request one or more tests to make a diagnosis, the most common being an echocardiogram. Echocardiography also is useful for helping the health care provider follow the child’s health over time.

HLHS is a defect that also can be detected with newborn pulse oximetry screening. Pulse oximetry is a simple bedside test to determine the amount of oxygen in a baby’s blood. Low levels of oxygen in the blood can be a sign of a CCHD. Newborn screening using pulse oximetry can identify some infants with a CCHD, like HLHS, before they show any symptoms.

Treatments

Treatments for some health problems associated with hypoplastic left heart syndrome might include:

Medicines

Some babies and children will need medicines to help strengthen the heart muscle, lower their blood pressure, and help the body get rid of extra fluid.

Nutrition

Some babies with hypoplastic left heart syndrome become tired while feeding and do not eat enough to gain weight. To make sure babies have a healthy weight gain, a special high-calorie formula might be prescribed. Some babies become extremely tired while feeding and might need to be fed through a feeding tube.

Surgery

Soon after a baby with hypoplastic left heart syndrome is born, multiple surgeries done in a particular order are needed to increase blood flow to the body and bypass the poorly functioning left side of the heart. The right ventricle becomes the main pumping chamber to the body. These surgeries do not cure hypoplastic left heart syndrome, but help restore heart function. Sometimes medicines are given to help treat symptoms of the defect before or after surgery. Surgery for hypoplastic left heart syndrome usually is done in three separate stages:

1. Norwood Procedure
   This surgery usually is done within the first 2 weeks of a baby’s life. Surgeons create a “new” aorta and connect it to the right ventricle. They also place a tube from either the aorta or the right ventricle to the vessels supplying the lungs (pulmonary arteries). Thus, the right ventricle can pump blood to both the lungs and the rest of the body. This can be a very challenging surgery. After this procedure, an infant’s skin still might look bluish because oxygen-rich and oxygen-poor blood still mix in the heart.
2. Bi-directional Glenn Shunt Procedure
   This usually is performed when an infant is 4 to 6 months of age. This procedure creates a direct connection between the pulmonary artery and the vessel (the superior vena cava) returning oxygen-poor blood from the upper part of the body to the heart. This reduces the work the right ventricle has to do by allowing blood returning from the body to flow directly to the lungs.
3. Fontan Procedure
   This procedure usually is done sometime during the period when an infant is 18 months to 3 years of age. Doctors connect the pulmonary artery and the vessel (the inferior vena cava) returning oxygen-poor blood from the lower part of the body to the heart, allowing the rest of the blood coming back from the body to go to the lungs. Once this procedure is complete, oxygen-rich and oxygen-poor blood no longer mix in the heart and an infant’s skin will no longer look bluish.

Infants who have these surgeries are not cured

Infants with hypoplastic left heart syndrome may have lifelong complications.  They will need regular follow-up visits with a cardiologist (a heart doctor) to monitor their progress. If the hypoplastic left heart syndrome defect is very complex, or the heart becomes weak after the surgeries, a heart transplant may be needed. Infants who receive a heart transplant will need to take medicines for the rest of their lives to prevent their body from rejecting the new heart.

References

1. Mai CT, Isenburg JL, Canfield MA, et al. for the National Birth Defects Prevention Network. National population-based estimates for major birth defects, 2010-2014. Birth Defects Res 2019; 1– 16. https://doi.org/10.1002/bdr2.1589.

The images are in the public domain and thus free of any copyright restrictions. As a matter of courtesy we request that the content provider (Centers for Disease Control and Prevention, National Center on Birth Defects and Developmental Disabilities) be credited and notified in any public or private usage of this image.

The images are in the public domain and thus free of any copyright restrictions. As a matter of courtesy we request that the content provider (Centers for Disease Control and Prevention, National Center on Birth Defects and Developmental Disabilities) be credited and notified in any public or private usage of this image.

An Image-Based Model of the Whole Human Heart with Detailed Anatomical Structure and Fiber Orientation

Many heart anatomy models have been developed to study the electrophysiological properties of the human heart. However, none of them includes the geometry of the whole human heart. In this study, an anatomically detailed mathematical model of the human heart was firstly reconstructed from the computed tomography images. In the reconstructed model, the atria consisted of atrial muscles, sinoatrial node, crista terminalis, pectinate muscles, Bachmann’s bundle, intercaval bundles, and limbus of the fossa ovalis. The atrioventricular junction included the atrioventricular node and atrioventricular ring, and the ventricles had ventricular muscles, His bundle, bundle branches, and Purkinje network. The epicardial and endocardial myofiber orientations of the ventricles and one layer of atrial myofiber orientation were then measured. They were calculated using linear interpolation technique and minimum distance algorithm, respectively. To the best of our knowledge, this is the first anatomically-detailed human heart model with corresponding experimentally measured fibers orientation. In addition, the whole heart excitation propagation was simulated using a monodomain model. The simulated normal activation sequence agreed well with the published experimental findings.

1. Introduction

Heart modeling can quantitatively study the physiological and pathological mechanism of the heart diseases, such as arrhythmias, atrial, and ventricular fibrillation, and hence to help improve their diagnosis and treatment. These developed models can also be used for medical teaching [1]. In the last several decades, a lot of research has been done on the heart modeling, from genes to the whole organ [2–4]. The hearts used for modeling were mainly from canines [5, 6], rabbits [7–9], mice [10], pigs [11], or humans [3, 12–17].

Mathematical modeling of the heart anatomy is a prerequisite for cardiac electro-mechanical simulations. Simulating the main cardiac features, including cardiac rhythms [18], mechanics [19–21], hemodynamics [22], fluid-structure interaction, energy metabolism [23], and neural control [24], can only be achieved with detailed heart structure information. It needs to be emphasized that these properties are interrelated so that any changes in one property may influence others, which makes the virtual heart modeling complicated. Therefore, giving full consideration to the anatomical structure of the heart is essential.

Several mathematical human heart models have been constructed to study its electrophysiological properties using the computed tomography and other modern medical imaging methods [25, 26]. However, the space resolution of these computed tomography-based heart models was not very high [12, 27]. It was 1 mm for the model developed by Lorange and Gulrajani, and the final model contained approximately 250, 000 points. The model developed by Weixue et al. [27] contained approximately 65,000 myocardial discrete units with a spatial resolution of 1.5 mm. Furthermore, neither of the two models included the conduction system. Later, human atrial models were constructed from the MRI images [16], and some of them included the atrial conduction system [14]. A human ventricular model with fiber orientations and laminar structure was constructed by Rohmer et al. [17] using the DT-MRI. In addition, the Visible Human Project provides a useful data source for detailed human heart anatomical modeling [15]. However, none of the above-mentioned models described the complete geometry of the human heart, including both the atria and the ventricles, the conduction system, and the fiber orientation.

The conduction system plays an important role in the electrical propagation. It contains SAN, interatrial pathways, AVN, and intraventricular conduction pathways. Conduction system abnormalities could lead to cardiac arrhythmias. However, it is practically difficult to distinguish the conduction system from the surrounding tissues based on the current computed tomographic or MRI images. The heart models in early days mainly focused on the geometry of the heart without considering its conduction system [28–30]. Recently, researchers have attempted to construct the atrial conduction system [14, 31] as well as the ventricular conduction system with the His-Purkinje system [32]. However, none of the previously published models contain both the atrial and ventricular conduction systems.

Myofiber orientation also plays an important role in the electrical conduction and mechanical contraction. Many experimental procedures have been developed to measure myofiber orientation. In early days, the measurement was usually restricted into small areas. After full thickness blocks were removed from different sites of the heart, they were cut into serial slices from epicardium to endocardium. The fiber orientation was measured from each slice [33–36]. In the early 90s, a quantitative method was developed to measure the whole ventricular fiber orientations [5], which has been widely used by other studies [6, 7, 11]. However, this method is still very timeconsuming. Advanced imaging technique, including the automated confocal microscopy, polarization microscopy and two-photon tissue cytometry, and DT-MRI, makes the measurement of fiber orientation and laminar structure possible [37–39]. However, most of these methods have been only applied to the measurement on the ventricle, not the atria.

In order to validate the function of the anatomic model, the cardiac action potential (AP) and the simulation of cardiac electrophysiology should be simulated and validated with experimental data. Until now, different AP models have been developed from different species. They were mainly based on the Hodgkin-Huxley (HH) equation, which could be used to calculate the flow of ions in the membrane and hence calculate the membrane potential changes. There are also a lot of human AP models, which include atrial working muscles [40–44], SAN [31, 45], Purkinje fibers [46, 47], and ventricle [48–51]. In our simulation, because the newly developed models are much more time-consuming and less robust in the three-dimensional simulation, the commonly used CRN model [41] and the ten Tusscher model [49] were applied to the atrial and ventricular cells.

Regarding the simulation of cardiac electrophysiology, the reaction-diffusion equations were commonly used in combination with the anatomic and AP models. Modeling of the electrical conduction in early days was usually based on the cellular automata [2, 3, 27, 52, 53]. Later, with the enhancement of computation capacity, ionic models have been gradually applied to small-scale simulation of excitation conduction. In 1978, Tung introduced the “bidomain model” to simulate the propagation of excitation [54], However, the bidomain model requires a major dimension of the matrix inversion, and very large computing capacity. Therefore, the monodomain model was often used [55–59] because only the changes of cell membrane potential are calculated. Studies have also shown that there were no obvious differences for the computed excitation sequence between the bidomain model and monodomain model [60].

The aim of this study is to construct a whole human heart model with detailed anatomical structure which contains atrial and ventricular conduction systems and fiber orientations. Based on the constructed heart model, the human AP models will be assigned to different parts of the heart. Finally, the normal electrical propagation will be simulated and compared with the experimental data.

2. Materials and Methods

2.1. Cardiome-CN Human Heart Anatomical Model

2.1.1. Data Acquisition

After the confirmation of brain death, the heart specimen (Figures 1(a), 1(b)) from a healthy male adult with a tragic accident was donated to Zhujiang Hospital, Southern Medical University, P. R. China, by his family members. They gave the written consent. The use of the heart for research purpose was approved by the Ethics Committee of the Southern Medical University. The National Rules and Regulations on Heart research were strictly followed. The pretreatment of the heart and image data collection were performed at the Southern Medical University, and the follow-up works including image processing, the three-dimensional (3D) heart anatomical reconstruction was completed at Zhejiang University.

Firstly, the pericardium was carefully stripped off and removed with the large blood vessels (aorta and pulmonary arteries) retained for perfusion. The lead oxide and gelatin solution (gelatin and water ratio was 5%; lead oxide solution and water ratio was 25%) were then injected into the chambers of the heart through the aorta [61]. After the solution was cooled down, the heart specimen was scanned using a spiral CT (Philips/Brilliance 64). The raw CT images had a resolution of 512 pixels by 512 pixels, and the total number of images was 531 with the spatial resolution of (Figure 1).

2.1.2. Image Processing Procedure for the Construction of Human Heart Model

The commercial software ScanIP (Simpleware Inc.) was used to segment and reconstruct the anatomy of the human heart with some manual intervention to achieve the maximum accuracy. The processing procedure is briefly summarized as follows.(1)Contrast adjustment: as can be seen in Figure 2(a), the contrast between myocardium and gelatin inside the heart cavity was not obvious in the original CT image. After the contrast adjustment, they could be distinguished obviously (Figure 2(b)). (2)Image cropping: since a large portion of the original CT image was from the background, they were cropped to define the area of interest and to reduce the image size to (Figure 2(c)). After image cropping, the required computer memory was reduced, and the reconstruction speed was improved.(3)Contour extraction: the threshold segmentation was firstly applied to the cropped images to obtain the myocardium (Figure 2(d)). Unfortunately, some nonmyocardial tissues were wrongly included. To overcome this limitation, manual check was performed to exclude these nonmyocardial tissues. The connective tissues linked with the endocardium, such as mastoid muscle, trabecula, and so forth, were also excluded. A regional growing method was then applied to generate a clear myocardial image, as shown in Figure 2(e).(4)Image reconstruction: the above image processing procedure was repeated to all the CT images to reconstruct the heart with a surface mesh (Figures 2(f) and 2(g)).

2.2. Construction of Conduction System of the Cardiome-CN Human Heart Model

Mimics software (Materialise Inc) was used to construct the cardiac conduction system based on prior knowledge of the human heart anatomy. The conduction system in our model contained sinoatrial node (SAN), crista terminalis, pectinate muscles (PM), Bachmann’s bundle (BB), intercaval bundles, atrioventricular node (AVN), atrioventricular ring (AVR), His bundle, bundle branches, and Purkinje network. As an example, the detailed process to construct crista terminalis is summarized as follows.(1)Reconstruct 3D heart model from the segmented CT images: after this step, the manipulation of the voxels in the 3D model directly reflected the corresponding pixels in 2D images. However, at this stage, the conduction system was not distinguished from the heart wall, as shown in Figure 3(a).(2)Edit the CT images interactively: to separate the conduction system, the reconstructed model was depicted based on prior knowledge of the anatomical structure of the human heart. The heart model was extended from the anteromedial wall on the right side of the entrance of the superior caval vein to the right side of the entrance of the inferior caval vein [62, 63]. The voxels from the right side of the superior caval vein and downwards to the right side of the inferior caval vein were then selected as shown in Figure 3(b). (3)Project to 2D image: after the voxels of crista terminalis were obtained, they were deleted from the 3D model (the white banding in Figure 3(c)). The corresponding 2D image pixels were also deleted as marked with the green rectangle in Figure 3(c). (4)Edit the 2D images: an image erosion operation was performed to locate crista terminalis under the epicardium, and a dilation operation was used to spread crista terminalis out of the endocardium. The final 3D model was obtained as shown in Figure 3(d). The blue pixels in the upper image of Figure 3(d) show a cross-sectional image of the crista terminalis.(5)Classification and visualization: the other conduction bundles were also obtained similarly by repeating the above 4 steps.

2.3. Construction of Fiber Orientation of the Cardiome-CN Human Heart Model

2.3.1. Fiber Orientation Acquisition

In order to obtain the fiber orientation, some atrial muscles were peeled off along the fiber orientation after the CT scan (Figure 4(a)). The heart was then scanned by a 3D laser scanner (RealScan USB Scanner model 200) with a spatial resolution of 0.01 mm. Geomagic software (Geomagic, Inc) was used to trace the fiber orientation [64]. As shown in Figure 4(b), different curves represent the fiber orientation with its coordinate information. A registration method was then applied to obtain three layers of fiber orientation at the same coordinate. The details of this method has been described in our previous publication [65].

2.3.2. Construction of Ventricular Fiber Orientation

After the registration, the orientations of the endocardial and epicardial fibers had the same coordinate. Figure 5(b) shows all the measured points with the fiber orientation data. These data were used to construct the whole ventricular fiber orientation. The construction steps are summarized as follows.(1)Identify the center of gravity of the left and right ventricles (the red lines in Figure 5(a)).(2)Calculate the angle of each measured point: the center of gravity was set to be origin, with z axis on the right side and y axis on the upside. Figure 5(c) shows the angles of all the points on a single layer, with different colors representing different angels in degrees from 0°–360°. (3)Calculate the angle of each point on the direction from the apex to the base of the heart: for each layer, the points having fiber orientation at the endocardium and epicardium are marked, respectively, with yellow and green in Figure 5(d). The angle of each point was then calculated as described in step 2. (4)Match the endocardial and epicardial fiber angles with the corresponding CT data for each layer (Figure 5(e)): the linear interpolation was then used to calculate the fiber orientation of all the points on the epicardium and endocardium for each layer, as shown in Figure 5(f).(5)Calculate the fiber orientation between the epicardium and endocardium over the myocardial wall, as shown in Figure 5(g). (6)Follow steps 2–5, the fiber angles of all the layers were obtained. Figure 5(h) shows the fiber angles in a coronal plane (xz plane).

2.3.3. Construction of Atrial Fiber Orientation

Due to the complexity of atrial myoarchitecture, its fiber orientation has not been well quantified. The published qualitative studies concluded that right atrial fiber orientation is obliquely aligned and has different regularity at different layers.

In this study, only the epicardial myofiber orientation of the atria was measured. With the measured atrial fiber orientation data, the interpolation technique was applied to the whole atrial points. The construction steps are summarized as follows. (1)Calculate the inclination and transverse angles of each point with measured fiber orientation in the atria. (2)For the points without measured fiber orientation, the inclination and transverse angles from their closest point having measured fiber orientation were assigned.

2.4. Electrophysiological Cell Models

For the atrial SAN, the cell model developed by Chandler et al. was used [45]. For the crista terminalis, PM, BB, and atrial working muscles, the models developed by Courtemanche et al. [41] were used. The detailed description has been given in our recently published study [66].

Modeling of human AVN cells is difficult, partially because there is no published study and there is no physiological parameter of human AVN cells available. In this study, a modified AP model of the atria was used to represent the AVN cell model to have the conduction time in the AVN within the physiological range [41]. There are also no existing AP models of the His bundle and bundle branches. It has been reported that Purkinje cell is the principal cell in His bundle, particularly for the left bundle branch [67, 68]. Therefore, the human Purkinje cell AP model developed by [46] was used to represent the AP models of the His bundle, left and right bundle branches. For the ventricles, the cell model developed by ten Tusscher et al. was used [49, 69].

2.5. Numerical Simulation of Excitation Conduction

The monodomain equation was used to simulate the excitation conduction, which is expressed as [70]:

where is the surface volume ratio of cells (μm⁻¹), is the specific capacitance (pF), is the bulk intracellular conductivity (mS/cm), is the transmembrane potential (mV), is the transmembrane stimulating current density, and is the sum of all transmembrane ionic currents (pA/pF).

In this study, the finite difference method was used to calculate (1) because of its simplicity and suitability for the parallel computation. The time step was 0.01 ms, the anisotropy of the atrial working muscles was set as 1.3 : 1 [66], the conduction system was set as 9 : 1 [31], and the ventricular working muscles were set as 2 : 1 [55, 71].

The simulation was performed on a Dawning TC4000L server, which had symmetric multiprocessor shared memory and contained one management node and 10 computation nodes. Each computation node contained two Intel Xeon 5335 processors, 4 G memory, and 160 G hard disk. The total theoretical computing capacity was up to 184 Gflops. MPICh3 was used to implement the communication between the computational nodes [66].

3. Results

3.1. Reconstructed Anatomical Model of the Human Heart

The reconstructed human heart anatomical model, including both the ventricles and atria, is shown in Figure 6(b). From the segmented images (Figure 6(a)), it can be seen that the left ventricular wall is much thicker than that of the right ventricle (average value: 8–10 mm versus 2–4 mm), and different layers of the ventricle have different thicknesses. The wall thickness of the atria is slightly thinner than the right ventricle.

3.2. Reconstructed Conduction System of the Cardiome-CN Heart Model

The final conduction system contained the following. (1)SAN (Figure 7(b)): including the center and periphery part. It locates at the superior poster lateral wall of the right atrium with the size of about , which matches the published experimental data [56–59].(2)AVN (Figure 7(e)): including fast conduction region, slow conduction region, and central region [57, 72–78]. The slow conduction region was similar to the inferior nodal extension [78, 79], the fast conduction region was similar to the transitional tissue, and the central region was similar to the compact node. In our model, the size of the AVN was about .(3)Crista terminalis and PM (Figure 7(b)): There is little quantitative data about the crista terminalis and PM, in this study, they were reconstructed from the qualitative description of the position and anatomic structure [62, 63]. The crista terminalis was extended from the anteromedial wall on the left side of the entrance of the superior caval vein to the right of the entrance of the inferior caval vein. PM are parallel alignment of the muscle bulges on the appendage wall and the posterior wall of the right atria [62].(4)Intercaval bundles (Figure 7(b)): one bundle connects the origin of the crista terminalis and the anterosuperior rim of FO, and the other connects the origin of the crista terminalis and CS. The details have been reported in our previous publication [66].(5)BB (Figure 7(b)): the length of the BB is 14.7 mm, and the maximum diameters of the anteroposterior and superoinferior are 4.5 mm and 3.7 mm [62, 80–82]. (6)His bundle, left and right bundle brunches, and Purkinje fiber system (Figure 7(e)): they were constructed from the published data [68, 83–88]. Left bundle branch starts from the bifurcation of the atrioventricular bundle, descends along the interventricular septum about 1.5 cm, and is then divided into three branches. The right bundle branch starts from the end of the bifurcation of the atrioventricular bundle, moves downward along the membranous part of interventricular septum, and passes the papillary muscle of the conus to the moderator band. After reaching the root of prepapillary muscles, it is divided into three branches. The Purkinje fibers reach into the ventricular myocardial to form the subendocardial network. It is mainly located in the lower part of the interventricular septum, apex, papillary muscles, and free wall. In our model, the Purkinje fiber system, not the His bundle and left and right bundle brunches, conducts the excitation to the surrounding ventricular working muscles.

3.3. Reconstructed Fiber Orientation of the Cardiome-CN Heart Model

On the ventricular epicardium (see the first two images from the left in Figure 8(a)), fibers start from the atrioventricular junction and extend obliquely to the cardiac apex along the blunt edge. Near the atrioventricular junction area, longitudinally oriented fibers are observed. When crossing the blunt edge and close to the posterior sulcus, the fiber orientation is transverse. The fiber orientation of the diaphragmatic surface of the right ventricle is nearly circumferential until it crosses the sharp edge. When close to the outlet of the right ventricle, it is perpendicular to the plane. The fiber orientation in the anterior interventricular groove does not continue, but it forms an angle.

On the middle layer of the anterior and on the posterior and lateral walls of the left ventricle, the fibers are nearly circumferential (see the middle two images in Figure 8(a)), and the fiber in the diaphragmatic surface of the right ventricle middle layer is also circumferential. But when crossing the blunt edge, the fiber orientation is a little oblique, then changes to circumferential again in the anterior wall. When close to the outlet of the right ventricle, the fiber becomes steep and the orientation is longitudinal. Different with the ventricular epicardial junctional area, the fiber continues on the middle layer junctional area of the right and left ventricles.

On the endocardium (see the two images from the right in Figure 8(a)), the fiber orientation is more oblique on the anterior wall than the posterior wall. Overall, from the apex to the base of the heart, the epicardial fibers are arranged clockwise, and the endocardial fibers are counterclockwise. From the epicardium to endocardium, the fiber orientation changes continuously, but inconsistently at different parts.

Figure 8(b) gives the comparison between our results and these from other groups. The first row in Figure 8(b) is one cross-section of the fiber orientation from our model, the second row is the published human ventricular DTMRI data [8, 55, 89], and the third row is the data extracted from [55]. It clearly shows that our result was very similar with the DIMRI data. Figure 8(c) shows the constructed fiber orientation of the cross-sections of the ventricle, with the inclination and transverse angles given.

Figure 9 shows the atrial anatomical model with the fiber orientation. The atrial fiber orientation is much more complex than the ventricle. On the posterior and lateral wall of the right atrium, the main fiber direction is longitudinally aligned. The fibers begin in the junction area of the superior vena cava and extend to the atrioventricular junction. Because of the pulmonary veins in the left atrium, the fiber orientation is not as regular as the right atrium. On the posterior and upper posterior wall of the left atrium, fiber orientation is inclined, with a greater inclination on the upper posterior wall. On the lateral wall of left atrium from the left superior pulmonary vein to the apex of the left auricular appendage, it is also inclined. At the top of the left atrium, it is inclinable from the left and right pulmonary veins to the left atrial appendage and interatrial septum, respectively, and is fused on the anterior wall of the atrium. Figures 9(a) and 9(b) are the atrial anatomic model with the fiber orientation, and Figure 9(c) is the final atrial fiber orientation of some selected layers of the atrial model; each layer is represented by inclination and transverse angles.

3.4. Simulation Results of the Cardiac Electrical Propagation

The excitation sequence of the human heart is shown in Figure 10. The frequency of the pacemaker in our model was 1.19 Hz. The excitation starts from the SAN, reaches the BB and crista terminalis in right atrium after approximately 10 ms, and conducts to AV junction via the FP, SP, and crista terminalis. It then quickly conducts to the APG. After about 50 ms the left atrial septum close to the fossa ovalis is activated.

The current originated in the SAN also conducts excitation to the left atrium via the BB. In the left atrium, the excitation initiates from the region near the BB, then conducts to the APG via the right PM and to the posterior part of the right atrium, and ends at the posterior-inferior left atrium. The complete activation time is 30 ms for BB, 81 ms for the right atrium, 79 ms for left atrium, and 109 ms for the entire atrium. The conduction velocity is about 115 cm/s, 76 cm/s, 125 cm/s, and 107 cm/s in the crista terminalis, atrial muscles, PM, and BB, respectively.

When the excitation conducts to the AVN, with a delay of about 15 ms, it reaches the His bundle, left and right bundle, and then to the Purkinje network. The first breakthrough in the endocardium is at about 136 ms in the lower septum, and then the excitation conducts to the ventricular cells via Purkinje network. The first breakthrough point in the epicardium is at the anterior and posterior septal region, which is consistent with clinical measurements [90]. In the left and right ventricles, the last activated regions are the posterolateral area and the pulmonary conus and posterobasal area. It happens at about 228 ms. The conduction velocity varies at different parts, with the slowest speed of 40 cm/s at the apex, about 70 cm/s at the middle part of the heart and, about 80 cm/s at the upper part close to the base of the ventricle.

4. Discussion

4.1. Fiber Orientation Modeling

The fiber orientations of the ventricles and atria have been investigated in this study. The human ventricular fiber orientation has been widely studied with the range of +60° ~ −60°, depending on the different species used [5, 8, 91–93]. Our results agreed well with what has been published [17, 36, 94, 95]. Moreover, our results quantitatively showed that the fiber orientation is not homogeneous on the same layer and also varies at different parts of the heart. It is more inclined near the orifice of pulmonary trunk than the middle and bottom parts of the ventricles, and on the diaphragmatic surface of the epicardium, the left ventricular fiber has steeper angles than the right ventricle.

In this present study, the epicardial fiber orientation of the atrium was quantitatively measured, and the result shows that the atrial fiber orientation in general is less regular than that of the ventricle. On the right atrial epicardium, the fiber has some patterns, but in the left atrium, it is quite irregular because of the pulmonary veins. Our data was consistent with other experimental data [62, 96, 97].

4.2. Conduction System Modeling

A detailed cardiac conduction system has been constructed in this study. It is very difficult to distinguish different conduction pathways using the anatomic or morphological methods. In our model, it has been assumed that muscle bundles exist between the origin of crista terminalis and CS and FO, and they compose of normal atrial muscles, but have high anisotropy ratio. The geometry of the two pathways agreed the general description of the experimental data [96–98]. To the best of our knowledge, this is the first model containing the two pathways in biatrial conduction simulation. Due to the lack of accurate experimental data, the accurate geometry of the two pathways can not be obtained in our simulation, but our simulation showed that they could make the conduction pattern in the atria more close to the clinic data [66].

Recently, it has been reported that the SAN structure was functionally insulated from the atrium by the connective tissues, fat, and coronary arteries [99]. It has also been reported that the atrial myocardium was excited via the superior, middle, and/or inferior sinoatrial conduction pathways. Therefore, in our simulation the excitation from the periphery cell only conducts to the crista terminalis, and the two internodal bundles are supposed to be from near the SAN. In the other atrial simulations [14, 31], the SAN could conduct electricity to the surrounding atrial working muscles, because the SAN was considered not to be insulated from the surrounding tissues.

Due to the complexity of the AVN, its anatomy and morphology have not been fully understood. In our model, based on the theory of the dual AVN pathways [78, 100–102], the AVN is divided into three parts: fast and slow conduction regions, and central region. The fast conduction region receives the electrical excitation from the transitional cells, and the slow conduction region receives the electrical excitation from the isthmus. These settings may have some differences with the real anatomic structure, but it made the whole heart modeling become feasible.

Many models have been constructed to simulate the electrical conduction in the ventricle and they have different resolutions and the construction methods varies too, but the majority of them were artificially depicted based on the prior knowledge of the anatomical structure [103, 104] or special algorithms [105, 106]. The His-Purkinje system is important for the ventricular conduction, and there are many qualitative anatomical descriptions [84–88, 107–109]. In our model, the His-Purkinje system was artificially depicted based on the prior knowledge. The His and bundle branches are separated from the Purkinje network, and the Purkinje fibers are connected each other. Our model was also close to the recently constructed His-Purkinje system of a rabbit from macroscopic images [110].

4.3. Excitation Conduction Modeling

The simulated excitation sequences of the atria and ventricles in our model agreed well with the published experimental data [30, 111]. The conduction velocity in the right atrial wall is not homogenous; the velocity of the posterolateral wall with PM is 70 to 100 cm/s and the average velocity is close to 95 cm/s, which is within the range of 0.68–1.03 m/s [112]. The velocity of crista terminalis is 1.15 m/s, which is also consistent with the experimental data of 0.7–1.3 m/s [113]. Lemery et al. [111] reported that the total BB conduction time was  ms, our result of 16 ms is slightly shorter than the average value, but is within the range. The conduction speed of BB in our simulation is between 95 to 150 cm/s, and the average velocity is 113 cm/s; it is within the range reported by Dolber and Spach [114].

De et al. [115] reported that the duration of left atrial propagation and whole atria was and  ms, respectively. The experimental data in [111] showed the activation time of LA and whole atria were  ms and  ms, respectively, while the results of [116] were  ms and  ms, respectively. In our simulation, the total activation time of left atrial and whole atria are 79 ms and 109 ms, respectively, which is similar to these experimental data.

For the ventricle, the conduction time from the onset of His to the onset of ventricular working muscles is about 41 ms, which is within the range of  ms [117] and close to another simulation result [32]. After the excitation of lower septum in endocardium, the electricity spread to the epicardium and then upward to the base of ventricle; the whole conduction time of the ventricular working muscles is about 92 ms, which is close to the experimental data of about 100 ms [30, 117] and another model study [118]. The conduction speed of ventricular muscles is about 0.7 m/s, close to 0.6 m/s [119] and fall in the range of 0.3–1.0 m/s [120].

5. Limitation

Firstly, the mastoid muscles could not be clearly distinguished from the ventricular muscles. This is especially obvious in the right ventricle, therefore the mastoid muscles were not included in our heart model. Secondly, our model only contained the atrial epicardial fiber orientation, since the atrial wall is too thin and the endocardial fiber is complex. Thirdly, the AP model of the AVN was based on the human atrial model. It may not effectively represent the physiological parameters of human AVN cells and may influence the simulation accuracy. In addition, the anatomy of whole heart conduction system was constructed based on the priori knowledge of the heart anatomy, which may affect the simulation.

6. Conclusion

In conclusion, a human heart model with detailed anatomical structure, conduction system, and fiber orientations have been constructed. To the best of our knowledge, this is the first anatomically-detailed human heart model with corresponding experimentally measured fibers orientation. Different AP cell models have been assigned to different parts of the heart, and the simulated normal activation sequence agreed well with the published experimental data. Such detailed anatomical heart model could be very useful for future research on understating of the mechanisms influencing cardiovascular function and its physiological and pathological processes.

Acknowledgments

This project is supported by the 973 National Basic Research & Development Program (2007CB512100), the 863 High-tech Research & Development Program (2006AA02Z307), the National Natural Science Foundation of China (81171421), and the Nature Science Foundation of Zhejiang Province of China (Z1080300).

Newly born blood vessels win British Heart Foundation photography prize

The British Heart Foundation (BHF) has just announced the winner of its annual Reflections of Research science image competition. Where science and art collide, the competition challenges BHF-funded scientists to showcase their state-of-the-art heart and circulatory disease research through the generation of captivating images.

Dr Neil Dufton, Lecturer in Inflammatory Sciences at Queen Mary University of London, was this year’s guest judge. He said:

“All of the images shortlisted in this year’s competition offer a stunning glimpse into the cutting-edge work being carried out by BHF scientists. 

“The winning image is truly eye-catching. The chaotic mixture of different cells around the outside contrasts perfectly with a ‘through the looking glass’ moment where we see new, and exquisitely detailed, blood vessels forming in the centre.”

Here are the winners and the shortlisted images:

Judges’ winner – Recreating heart blood vessels

Although at first glance it appears to resemble a luminous jelly fish, this image shows new blood vessel-like structures (pictured in green) sprouting from a 3D gel. These structures were created using a mixture of two types of heart cell. Encouraging new blood vessels to form after a heart attack to replace those that have died could help to re-establish blood supply to damaged areas of the heart and aid recovery. Photo by Elisa Avolio/University of Bristol/British Heart Foundation Reflections of Research

Supporters’ Favourite – Biodegradable microspheres for healing hearts 

This image shows a microsphere, a tiny object (just quarter of a millimetre wide) made from biodegradable material. Researchers are using microspheres to grow cells and give them a better chance of surviving in the heart. Human stem cell-derived heart cells are cultured on the surface of the microspheres, where they stick to the surface and make connections with their neighbours. The microspheres can then be easily injected into the heart to deliver cells directly to damaged tissue. Photo by Annalisa Bettini/University College London/British Heart Foundation Reflections of Research

Shortlisted – A renal reflection

This is not actually a tree, but in fact blood vessels of the kidney captured using a CT scanner. The branching reflection was inspired by reflecting pools from around the world. The heart and the kidneys work closely with one another. Heart disease can impact the blood supply to the kidneys, which in turn can cause kidney disease. Similarly, kidney disease can alter hormone levels, which in turn can change blood pressure, causing heart disease. Photo by Natalie North and Joanna Koch-Paszkowski/University of Leeds/British Heart Foundation Reflections of Research

Shortlisted – All fat and bones

A vibrant network of blood vessels (red) and fat (green) within the bone marrow of a mouse with peripheral vascular disease has been expertly captured in this image. New blood cells (blue) are made in the bone marrow, a spongy tissue in the middle of your bones. However here the peripheral vascular disease has caused regions of the bone marrow dedicated to blood cell production to be replaced by fatty deposits. Photo by Lauren Eades/University of Leeds/British Heart Foundation Reflections of Research

Shortlisted – Texture of a heart

A developing heart of a mouse embryo has been captured using an electron microscope (left) and a laser microscope (right). In the black and white image we can see how cells in a developing heart don’t form a smooth surface. To capture the image on the right cells were stained with two coloured markers; red to visualise nuclei, and green to highlight cell boundaries. These red and green cell boundaries show how some cells huddle together in small structures and form strong connections with their neighbours. Other cells end up alone and will dive into the heart to find stronger connections as it continues to develop. Photo by Xin Sun/University of Oxford/British Heart Foundation Reflections of Research

Shortlisted – Stuck on you

The flower-like red shapes in this image are platelets, the smallest of our blood cells. Platelets stick together when they recognise a damaged blood vessel, forming a blood clot and helping to stop bleeding. However, if platelets become over-active they can cause excess clotting, which can cause conditions like heart attacks and strokes. Capturing images like this can help to identify changes in over-active platelets compared with healthy ones. Photo by Beth Webb/University of Leeds/British Heart Foundation Reflections of Research

Shortlisted – 

The way to the heart is through the stomach

The image shows a network of blood vessels in fat, which make a heart shaped impression within the network. Many of these blood vessels are thinner than a strand of hair. To create this image the researcher collected hundreds of images from thinly sliced mouse tissue sections then stitched these back together to generate a complete 3D image of all the blood vessels. Images of blood vessels can help researchers to visualise the damage caused by diabetes and see if new treatments are able to repair them. Photo by Michael Drozd/University of Leeds/British Heart Foundation Reflections of Research

Shortlisted – Fused together

Multiple lung cells are pictured having joined together to create large virus-infected cells. This abnormal cell fusion is triggered when the COVID-19 virus infects healthy cells, causing them to become infected and display the COVID-19 spike protein on their surface. This prompts a series of events that causes infected cells to reach out and fuse with neighbouring cells. Photo by Mauro Giacca/King’s College London/British Heart Foundation Reflections of Research

Check out some more of our great image galleries:

Shortlisted – Silent genes

This image shows egg-shaped nuclei in a thin slice of heart tissue from a mouse embryo. The nuclei contain the cell’s instruction manual, DNA, which includes instructions for making proteins. The speckled dots pictured are proteins that can bind to DNA to switch genes off and reduce their activity. Photo by Jacob Ross/King’s College London/British Heart Foundation Reflections of Research

Shortlisted – A storm is brewing in the broken heart

Lit up like the Earth viewed from space, this image shows a scar in the heart that forms after a heart attack. The body creates this scar, made of collagen, to repair damage to the heart sustained during the heart attack. Different types of collagen are seen in red, yellow and green, with the initial scar in red and yellow on the left of the image. Moving from left to right we see more green collagen, which represents the scar expanding into undamaged tissue. Photo by Victoria Reid and Kali Pandya/University of Edinburgh/British Heart Foundation Reflections of Research

Shortlisted – 

Atrial digital twins

The process of recreating a digital replica of the atria (the upper chambers of the heart) of three patients is captured in this fantastic image. This is used to visualise conditions where the heart beats irregularly, like atrial fibrillation. Starting with images captured from MRI scans (far-left column), more detailed information is added to the images as we move from left to right to look at different aspects of the structure and function of the heart. This allows the researchers to find critical regions to target (final column) during treatments to try to restore a normal heartbeat. Photo by Caroline Roney/King’s College London/British Heart Foundation Reflections of Research

An augmented reality system for image guidance of transcatheter procedures for structural heart disease

Abstract

The primary mode of visualization during transcatheter procedures for structrural heart disease is fluoroscopy, which suffers from low contrast and lacks any depth perception, thus limiting the ability of an interventionalist to position a catheter accurately. This paper describes a new image guidance system by utilizing augmented reality to provide a 3D visual environment and quantitative feedback of the catheter’s position within the heart of the patient. The real-time 3D position of the catheter is acquired via two fluoroscopic images taken at different angles, and a patient-specific 3D heart rendering is produced pre-operatively from a CT scan. The spine acts as a fiduciary land marker, allowing the position and orientation of the catheter within the heart to be fully registered. The automated registration method is based on Fourier transformation, and has a high success rate (100%), low registration error (0.42 mm), and clinically acceptable computational cost (1.22 second). The 3D renderings are displayed and updated on the augmented reality device (i.e., Microsoft HoloLens), which can provide pre-set views of various angles of the heart using voice-command. This new image-guidance system with augmented reality provides a better visualization to interventionalists and potentially assists them in understanding of complicated cases. Furthermore, this system coupled with the developed 3D printed models can serve as a training tool for the next generation of cardiac interventionalists.

Citation: Liu J, Al’Aref SJ, Singh G, Caprio A, Moghadam AAA, Jang S-J, et al. (2019) An augmented reality system for image guidance of transcatheter procedures for structural heart disease. PLoS ONE 14(7):
e0219174.

https://doi.org/10.1371/journal.pone.0219174

Editor: Yuanquan Wang,
Beijing University of Technology, CHINA

Received: March 5, 2019; Accepted: June 18, 2019; Published: July 1, 2019

Copyright: © 2019 Liu et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Data Availability: All relevant data are within the paper and its Supporting Information files.

Funding: The author(s) received no specific funding for this work.

Competing interests: The authors have declared that no competing interests exist.

Introduction

Transcatheter procedures are the predominant and increasingly favored treatment approach in a wide variety of structural heart disease, including atrial septal defect and patent foramen ovale closure, valvular repair/replacement, left atrial appendage closure and deployment of hemodynamic monitoring devices [1]. These procedures are typically performed under X-ray fluoroscopy since it is the most common imaging modality, provides real-time imaging, and can readily visualize radiopaque markers on transcatheter devices to help locate equipment position [2]. However, while one can identify the silhouette of the heart using fluoroscopy, the intracardiac structures are transparent, and therefore contrast agents, which transiently opacify the structure of interest, are used to visualize the relative position of the catheter to surrounding tissues. Furthermore, fluoroscopy only provides a 2D projection of the heart, catheter and other devices, and therefore no information of depth is provided (Fig 1A).

Fig 1. Imaging modalities in cardiovascular interventions.

A: The heart is transparent in real-time X-ray fluoroscopic images. B: Pre-operative CT scan images provide a high contrast for understanding heart anatomy with (C) the 3D reconstruction.

https://doi.org/10.1371/journal.pone.0219174.g001

Besides fluoroscopy imaging, echocardiography can directly image heart tissue and blood flow, and is often used as a complementary imaging modality [3]. Although recent literature reports that transesophageal echocardiography (TEE) has been used to provide intra-operative 2D and 3D visual feedback, this technology requires skilled operators, and uses TEE equipment not readily available in all hospitals [4]. The limitations of these imaging techniques increase the complexity and uncertainty of current procedures, requiring the interventionalist to estimate the 3D position and orientation of the catheter/device by analyzing images from multiple imaging angles and modalities.

Preoperative imaging modalities, such as computed tomography (CT) and magnetic resonance (MR) imaging, which provide detailed anatomical information in 3D (Fig 1B & 1C), can be displayed on separate screens or overlaid on real-time imaging modalities (i.e., fluoroscopy and echocardiography) to improve image-guided interventions. Moreover, the preoperative images can be processed by applying novel deep learning methods (e.g., CSRNet) to provide the quantification results for the segmentation of cardiovascular structures [5]. However, the method of displaying hybrid images provides little additional information and often obstructs the view of the real-time image during the procedure [6]. Furthermore, all of these images are displayed on 2D screens, which fundamentally mitigate any depth perception, thus limiting the ability to perceive the position and angle of a catheter within the 3D heart rendering.

Automated image registration of different modalities is a non-trivial endeavor but useful for a variety of applications, ranging from diagnostics and surgical planning, to image-guided surgery and post-procedural evaluation of therapeutic outcomes [7]. Literature survey on medical image registration indicates that a variety of algorithms have been developed, including intensity- [8], gradient- [9] and feature-based methods [10]. The intensity-based image registration has been applied for registering CT and MR images by maximizing the mutual information between two images [11]. However, pixel intensities may vary dramatically due to the inconsistent imaging parameters in different modalities. Compared to intensity, image gradients are more stable factors because the contrast between the target anatomy and surrounding regions (e.g., bone vs. soft tissues) remains similar across different imaging modalities. Therefore, other researchers proposed a novel method based on the differential total variation for registration of MR images [12]. Beyond gradient-based registration, feature descriptors (e.g., SIFT, SURF, and BRIEF) were also used for registration of medical images [13, 14]. These feature-based registration methods are preferred to intensity- or gradient-based registration methods, due to its broader applicability, but the challenge of accurately segmenting cardiac features from different image modalities has yet to be addressed. For example, the heart is visible in CT scans while it appears transparent or with low-contrast in fluoroscopic images due to the restricted X-ray energy used to ensure the safety of the patients and interventionalists.

Augmented reality, as an emerging technology for providing enhanced visualization, has attracted increasing interest in the medical community. For example, OpenSight is the first FDA cleared AR system to be used for pre-operative planning of surgeries. The pioneering AR systems for medical use are mainly focused on improving the visualization in orthopedic surgeries [15, 16] and neurosurgeries [17, 18]. These systems, however, cannot be used for cardiac interventions because they do not provide real-time monitoring or quantitative feedback, which is critical to instruct and/or aid physicians for positioning catheters and devices [19].

To address these limitations, we propose a novel approach for image guidance which displays, in real-time, high-resolution 3D holographic renderings of the catheter and patient’s heart using augmented reality devices. The overall procedure of the proposed AR assisted guidance system is shown in Fig 2. The geometry of the patient’s heart is generated (prior to the procedure) through the segmentation of cardiac CT scans. The real-time position and orientation of the catheter are automatically detected by processing fluoroscopic images that are captured from two angles. By registering the fluoroscopic images with the CT scans, the heart and catheter renderings are set into the same coordinate system and displayed on the AR device. The registration of the fluoroscopic images and CT scans is achieved by using the spine as a universal fiduciary marker because the spine is stationary and relatively clear in both imaging modalities.

This paper specifically reports the demonstration of the proposed AR image- guidance system on a 3D printed model of a heart and spine as segmented from a human CT scan. We demonstrate optimized methods for segmentation of the spine from fluoroscopic images, and registration of the two image modalities to provide a single coordinate system for rendering the catheter’s position in AR. Based on registration results, the detected catheter is rendered inside the heart model as 3D holograms using the AR devices to provide quantitative visual feedback for guiding the interventional procedure. Although the printed heart model is static, it serves as a proof of principle that the AR-guidance system may be used for both procedural and training purposes. Future work will focus on developing dynamic heart models that better recapitulate cardiac motion from both respiration and contraction.

Materials and methods

The use of the medical images in this study was approved by the institutional review board (IRB) at Weill Cornell Medicine. The informed consent requirement was waived as the patients’ information were de-identified prior to the study.

Segmentation of 3D anatomical structure from CT images

The 3D anatomical structures were segmented from diagnostic CT scans to provide a direct visualization of the patient’s heart during the interventional procedure. The original CT images were first imported as a Dicom file format into a 3D medical image processing software (i.e., Materialise Mimics). Each slice of the CT images was then binarized by manually selecting an appropriate threshold value according to the target anatomical structure of interest (Fig 3A). The threshold processing typically generates a rough segmentation that contains many isolated 3D objects due to the low contrast and low resolution of the CT images (Fig 3B). To remove the noise, only the largest object is selected, and its inner holes are filled to generate the 3D model. The largest object was then modified by setting a 3D mask and further adding/removing target regions for each slice. The reconstructed 3D model was finally smoothed and exported as an STL file. Both the segmented heart volume and spine were combined in the 3-matics software to unify all meshes in the same coordinate system.

Fig 3. Segmentation of anatomical structures.

A: A slice of CT scans shows the segmented region after thresholding. B: 3D reconstruction of the heart and spine by selecting the largest object and filling inner holes. C: The 3D models are cleaned by deleting peripheral blood vessels and bones. D: 3D models are further modified and fabricated using a 3D printer. E&F: The 3D printed model is tested under the X-ray fluoroscopy machine.

https://doi.org/10.1371/journal.pone.0219174.g003

After the segmentation from the volumetric CT images, the 3D CADs (computer aided designs) were imported into another editing software (i.e., Geomagic Wrap, 3D Systems Corporation) to further trim away the undesired structures including ribs, chest bones, or small peripheral blood vessels (Fig 3C & 3D). These features are trimmed to produce models that are practical to 3D print and visualize in the AR environment. For specific percutaneous transcatheter procedures (e.g., transseptal puncture), a preplanned path and target rings were added to the CADs in order to provide visual guidance to the interventionalists.

Spine detection in fluoroscopic and CT images

In order to detect the catheter’s position and provide the 3D visual guidance in real time, the first step is to register the coordinate systems of the fluoroscopic images and CT scan. The spine was selected as a universal fiduciary marker because it is relatively clear in both imaging modalities with minimal or no movement and is stable between the time a preoperative CT is acquired and a transcatheter procedure is performed. Since the variations in positioning of the patients can affect the geometry and location of the spine, the patients are required to lie in supine position for both CT imaging and X-ray fluoroscopic procedures to ensure the consistency of spine appearance. Furthermore, our algorithm does not make any assumption regarding the orientation of the spine, and therefore it will minimize the sensitivity to changes due to patient positioning. However, this effect needs to be further studied in future work where images of a single patient with minor variation in positioning can be obtained.

In the experiments, five thoracic vertebrae (T4-T8) are selected as the fiduciary marker because they are close to the atriums of the heart and are visible during the transseptal puncture procedure. In addition, the vertebral bodies are selected as the intrinsic fiducial marker because they are the most visible in a fluoroscopic image, and thus minimizes the needed amount of radiation.

Spine detection in CT images was achieved by taking a projection view from the 3D segmented models, such that a 2D image of the spine with a similar outline as the fluoroscopic image was obtained (Fig 4A). The projection angle was set equivalent to the capturing angle of the c-arm as recorded in the meta-data of the fluoroscopic image. Fig 4C shows a projection view of the spine created at Right Anterior Oblique view 30 degree (i.e., RAO30). However, since the patient may not be perfectly flat on the table, the fluoroscopic image and projection image of the spines are registered using a Fourier-based method.

Fig 4. The Fourier based registration method.

A: A projectional view of the 3D model that is reconstructed from CT images. B: The original fluoroscopic image is taken at RAO30. C: Only the spine image is created from the 3D model. D: The spine image detected from the fluoroscopic image. E-F: The polar-logarithmic transformed Fourier images corresponding to C-D; the rotation and scale factors are converted to the translations in X and Y axis. G: The phase correlation plot shows the maximum point is located at the position corresponding to the rotation and scale shifts. H: The overlaid image shows the final registration result.

https://doi.org/10.1371/journal.pone.0219174.g004

To detect the spine from fluoroscopy, the noise of the original image (Fig 4B) was first reduced through the Gaussian smoothing method and binarized by applying Otsu’s adaptive thresholding. A bounding box calculated from the largest object was used to generate a region of interest for the refined binarization. A morphological close operation is then performed to remove noise and small particles that may be present in the region of interest. The segmented spine from a fluoroscopic image is shown in Fig 4D.

Image registration based on fourier transform

Since the spine is a rigid object and its relative position inside the patient is consistent, a rigid registration is used to determine the transformation matrix between the fluoroscopic images and the 3D heart model. A 2D projection image of the segmented 3D spine model is denoted as the fixed reference image (I_c), whereas the X-ray fluoroscopic images captured at the same angle is denoted as the moving image (I_f). The registration of the two image modalities enables to determine the transform matrix (T_f) such that the catheter and heart can be put into a single coordinate system with the scaling factor k, rotation angle θ, and translation (t_x, t_y),
(1)
where, P_c and P_f are the spine positions in CT and fluoroscopic images, respectively. In order to decouple the scale, rotation and translation factors, the spine images are first processed through 2D Fourier transformation. According to the properties of the Fourier transform, the transformed images F_c and F_f are related by
(2)
where Φ(u, v) is the spectral phase change depending on scaling, rotation and translation. However, the spectral magnitude is translation-invariant,
(3)
The spectral amplitude relationship in Eq (3) indicates that the rotation of the spine results in the same rotation by the same angle in the spectral amplitude images and the scaling by k scales the spectral amplitude by k⁻¹. The rotation and scaling can be further decoupled by defining the spectral amplitudes in the polar coordinates (θ, ρ). Accordingly, Eq (3) is then expressed as,
(4)
Therefore, the image rotation α is then converted as the shift along the angular axis (i.e., horizontal axis in Fig 4E and 4F). The scaling of the original image is converted to a scaling of the radial coordinate (i.e., ρ/k). By using a logarithmic scale for the radial coordinate, the scaling is then converted to a translation.
(5)
where, γ = log(ρ) and κ = log(k). Using the polar-logarithmic representation, both rotation and translation are converted to the translations, as shown in Fig 4E and 4F. By applying Fourier transform on the polar-logarithmic representations in Eq (5), one obtains,
(6)
where rotation and scaling are represented as phase correlations e^{−j2π(χα+ψκ)}. In the ideal case when two identical images are correlated only with the translation, the inverse Fourier transformation of the phase shifts is a Dirac δ-function at (α, κ). In real cases, the rotation and scaling factors are determined by finding the maximum location from the inverse Fourier transformation image (see Fig 4G). With the same scale and rotation, the phase correlation method is used again to determine the translation factor (t_x, t_y). The combination of the Fourier and polar-logarithmic transformation is also called Fourier-Mellin method.

Detection of catheter position and 3D visualization

After the two image modalities are registered into the same coordinate system, 3D rendering occurs in three steps: 1) The catheter was detected from fluoroscopic images that are captured at two different angles; 2) The third dimensional location (i.e., the depth information) is calculated from the pair of 2D locations with the known rotation angle; and 3) The catheter’s position and orientation within the heart is rendered in AR.

Detection of catheter from fluoroscopic images.

In this study, a 12-French catheter was used for demonstration of the transseptal puncture procedure. Since the catheter is relatively big (4 mm in diameter) and has a higher X-ray absorption rate than the soft tissue and bones, it appears darker than the surrounding area in fluoroscopic images. Therefore, a pixel intensity-based method is developed to determine the catheter’s position. The detection of the catheter starts from the bottom edge of the image with the direction initialized along the Y axis as the catheter is often inserted from the inferior vena cava in the case of a transseptal puncture procedure.

The ten rows of pixels at the bottom of the image are first binarized using an adaptive thresholding method. A 50×10 region of interest (ROI) is then extracted with the center located in the middle of the dark object (i.e., the catheter) in the bottom ten rows (Fig 5B). Within the ROI, the edges of the catheter are detected by calculating the derivatives along the direction that is perpendicular to the axial direction of the catheter (Fig 5C & 5D). The centerline of the catheter is then determined as the middle points between two edges. Following the centerline direction, a new ROI is updated on top of the previous ROI and the detection of the catheter centerline is repeated in the updated ROI (Fig 5E). The final results of the detected centerline of the catheter are shown in Fig 5F.

Fig 5. The catheter is detected from the fluoroscopic image.

A: Original image. B: The ROI is first extracted at the bottom of the image. C: The gradient of the ROI reveals the edge of the catheter. D: The derivatives of the pixel intensity along the X-axis shows the two edge points are located at the two global peaks. E: An updated ROI is created on top of the previous ROI along the center line of the catheter. F: The final detection results are overlaid to the original image.

https://doi.org/10.1371/journal.pone.0219174.g005

Calculation of the 3D position from two fluoroscopic images.

The catheter’s position in 3D space is determined by processing the fluoroscopic images captured from two distinct angles. In the experiment, the C-arm was rotated in the axial plane (i.e., around the main axis of the body). Fig 6A–6C show three example images captured with the C-arm oriented at Left Anterior Oblique view 30 degree (LAO30), Anterior-Posterior (AP), and RAO30. Since these three orientations are rotated around the Y axis, the positions of the catheter in the two images have the relationship,
(7)
where P₁ and P₂ are the catheter’s position in the two images, and θ is the rotation angle. With the detected position of the catheter (x₁, y₁ and x₂, y₂) and the known rotation angle, the third dimensional positions (z₁, z₂) are solved from Eq (7). Fig 6D and 6E shows the 3D positions of the catheter that are determined from the fluoroscopic images (Fig 6A–6C).

Fig 6. Localization of catheter in 3D space.

A, B&C: The catheter is detected from fluoroscopic images that are captured at LAO30, AP, and RAO30 angles. The centerline of the catheter is displayed in red. D&E: The 3D locations of the catheter are determined by using three pairs of images (i.e., AP+LAO, AP+RAO, and LAO+RAO).

https://doi.org/10.1371/journal.pone.0219174.g006

Enhanced visualization on augmented reality device.

To provide enhanced visualization, the patient’s heart, spine, and catheter are rendered as holograms and displayed on the augmented reality device (Fig 7). In the proposed system, we select the HoloLens (Microsoft Corporation) as the AR device for three reasons: (i) The HoloLens is a pair of video see-through goggles that do not block the surgical view of the medical practitioners and therefore do not disturb the normal interventional procedures. (ii) The HoloLens is able to simultaneously project the results onto the wearable goggles to generate the true stereo holograms for 3D AR visualization. (iii) The HoloLens is integrated with a wireless communication module that can be used to seamlessly receive the processed results from the server computer via a shared Wifi network.

Fig 7. The enhanced visualization on the augmented reality device.

A: The 3D rendering of the heart and spine are displayed as holograms on the HoloLens. B: The preprocedural planning is shown as red lines crossing the ideal transseptal puncture site (shown as target rings). C: The catheter is rendered in the 3D space and its position is determined by processing the fluoroscopic images. D-F: A virtual camera is attached to the endpoint of the catheter to provide the first-person view of the catheter when inserting through the inferior vena cava (D), entering the right atrium (E), and approaching the transseptal puncture target (F).

https://doi.org/10.1371/journal.pone.0219174.g007

In the first step, the 3D model of the heart and spine are imported into the HoloLens system. The movement trajectory of the catheter was planned by experienced interventionalists and plotted as a virtual path in the 3D model (red lines in Fig 7A & 7B). The target transseptal puncture site was modified as concentric rings to provide additional references.

In addition to the rendering of heart and spine, the catheter position (detected off-line) from nine sets of fluoroscopic images are rendered on the HoloLens. In order to save on computational time, only ten key points are selected and rendered as spherical objects with a diameter of 4 mm (shown as red spheres in Fig 7C). A blue virtual catheter is rendered along the trajectory of the red spherical objects. To assist the operator for a better understanding of the catheter’s location relative to the heart, a virtual camera is also generated at the distal tip of the catheter, with the view angle aligned with the orientation of the catheter’s tip (Fig 7D, 7E & 7F).

The system was also embedded with voice recognition and hand gesture detection. The system allows the operator to use two fingers to grab the 3D renderings and reposition or rotate them to any desired locations or orientations. The 3D renderings can be changed by voice command. When the operator says ‘open’, the system creates a cross sectional view to provide more detailed information about the inner geometry of the heart anatomy (Fig 7B). In addition, several standard views/orientations, such as AP, LAO30 and RAO30, are preloaded in the system and can be easily accessed by voice command (see supplementary video S1 File).

Results and discussion

The 3D anatomical model of the heart and spine was segmented from the de-identified images from a patient, provided by the Dalio Institute of Cardiovascular Imaging. Using the segmented anatomical models, a phantom model was created by 3D printing (Connex3 Object260, Stratasys Ltd. MN, US) and imaged under X-ray fluoroscopy (Fig 3E and 3F). A thin layer of metal coating was applied to the spine to simulate the contrast of the bone in fluoroscopic images. The use of all medical images was approved by the institutional review board (IRB) at Weill Cornell Medicine.

A catheter (Destino Reach 12 Fr, Oscor Inc. FL, US) was inserted into the 3D-printed model to simulate the transseptal puncture procedure. The experimental setup with varied catheter positions was imaged at 15 fps using an interventional X-ray system (Allura Clarity, Philips Healthcare, US) at the cardiac catheterization laboratories in New York Presbyterian Hospital—Weill Cornell Medicine campus. After image registration and detection of the catheter from the fluoroscopic images, the catheter’s position relative to the phantom heart model was displayed on the HoloLens to provide an augmented visualization.

Performance of Fourier-based registration

Average registration errors.

The image registration algorithm is evaluated by quantifying the registration errors between the fluoroscopy images and the projectional images derived from the CT model. The registration error is defined as the distance between the centroid of the same vertebrae in the two registered image modalities (Fig 8A). The registration method was tested in five different groups depending on the imaging angles that are anterior-posterior (AP), left anterior oblique view 30 and 60 degree (LAO30, LAO60), and right anterior oblique view 30 and 60 degree (RAO30, RAO60). The experimental results summarized in Fig 8B indicate that the misalignment errors are consistently below one millimeter for all five groups.

Fig 8. Performance of image registration.

A: The misalignment error is defined as the distance between the centroid of the paired vertebrae detected from the fluoroscopic image (in gray color) and projectional CT image (in yellow color). B: The results show that the misalignment errors are consistently below 1 mm for the five experimental groups when capturing the fluoroscopic images at different angles.

https://doi.org/10.1371/journal.pone.0219174.g008

Comparison with other registration methods.

The Fourier based registration algorithm was also evaluated by comparing with other feature-based registration methods. As presented in previous research, the SIFT (scale-invariant feature transform) method was proven effective for registration of medical images of the same modality. Similarly, the SURF (speed up robust feature) method was also applied to extract local features for image registration. Since the SURF method uses an integer approximation of the determinant of the Hessian detector, its computational time is significantly reduced compared to the SIFT descriptor.

In this study, the same fluoroscopic images and CT images were processed for matching local features using the SIFT and SURF methods. The paired feature points were then used to determine an optimal transform matrix. The performance of the two feature-based methods and the present Fourier-based method were first evaluated by measuring the registration success rate. After the two images were registered with the optimal transform matrix, the overlaid images were carefully examined by skilled operators. If there was a significant misalignment (e.g., Fig 8A), the registration was considered a failed case. In total, 35 pairs of fluoroscopic images and projectional CT images were registered by SIFT, SURF, and Fourier based methods. The registration success rate is summarized in Table 1. The results show that the Fourier based method has the highest success rate (100%). While both feature-based methods reveal a lower success rate than the Fourier method, the SURF method performed slightly better than SIFT, which confirms the improved robustness of the SURF detectors and descriptors [20].

The registration precision was also evaluated by measuring the average registration errors for all three methods. The summarized results in Table 1 indicate that the Fourier method has the lowest misalignment error (0.425 vs. 0.883 for SIFT and 0.875 for SURF). The computational time was also measured for the three methods by using a computer running Microsoft Windows Operation System with CPU at 3.10 GHz. The results in Table 1 show that the SIFT and SURF methods have similar performance and consume more computational time than the Fourier based method.

Detection of catheter and 3D rendering

In the experiment, the catheter was inserted into the phantom heart model at fixed positions and imaged from three different angles (i.e., AP, LAO30, and RAO30), as shown in Fig 9A–9C. Although only two different views are needed, the additional view was captured to evaluate/confirm the precision of the determined 3D positions. The paired images captured from two angles were used to calculate the 3D position of the catheter’s endpoint (Fig 9D). The precision of the localization of the catheter in 3D space was quantified by using a mean standard error (MSE),
(8)
where, P_i is the calculated 3D position from each paired images and is the mean value of all 3D positions. The evaluation experiment was conducted by placing the catheter at five different locations.

Fig 9. The evaluation results on the determined 3D position of the catheter.

A: The mean standard errors for 1000 points on the catheter are all below 2 pixels (i.e., 0.5 mm). B: A histogram indicates the majority of mean standard errors are below 0.5 pixel.

https://doi.org/10.1371/journal.pone.0219174.g009

The experimental results on the catheter at an example location indicate that the MSE for 1000 points on the catheter are all below 2 pixels (i.e., 0.5 mm) (Fig 9A). The histogram plot (Fig 9B) demonstrates that the majority of MSE is below 0.5 pixels (i.e., 0.125 mm). The evaluation results for all five locations in Table 2 show that the calculated 3D position has an average MSE of 0.298 mm. To provide context, during a transseptal puncture procedure for an adult patient, an interventionalist expects the catheter to be placed within a ∼5 mm safe region centered at the ideal puncture site [21, 22]. Although the experimental results indicate a high precision on the static phantom model, the effectiveness of using the AR guidance for real-time procedure requires further investigation by using more realistic patient data that involves cardiac and respiratory motion.

Discussion

In the present AR image-guidance system, the 3D position of the catheter is determined by processing two fluoroscopic images. Using the spine as the fiduciary marker, the image registration method is able to set the 3D heart rendering (segmented from CT images) and the catheter rendering (determined from fluoroscopic images) in the same coordinate system.

The visualization of the patient’s anatomic models has been adopted in clinics for the diagnosis of diseases, planning of surgical procedure, and intraoperative guidance. However, the visualizations are typically displayed on 2D computer screens. In order to obtain an intuitive perception of the 3D models, the operator needs to frequently rotate the models by using a computer mouse. The development of AR and VR technologies enables a more intuitive solution for 3D visualization and provides a transformative human-machine interface. The smart AR glasses used in the present system allow the user to use both eyes to directly view the 3D models instead of looking at a 2D screen while constantly rotating the models. Moreover, the virtual 3D heart models can be rendered at any position/orientation that is comfortable to the interventionalists. Compared to the conventional 2D visualization system that requires the user to frequently switch back and forth between the display monitor and surgical sites, the direct projection/rendering enabled by AR technology allows for an improved hand-eye coordination.

The limitations of the proposed system are the following: (i) The 3D printed heart model is static, and therefore does not recapitulate the dynamic geometry and lcoation of the heart due to contractions and respiration. Future work will need to overcome these challenges by gating the CT model with multiple phased CT scans with an ECG signal. Furthermore, other real-time changes in cardiac phase, heart rate, volume status/loading conditions can affect the true cardiac position and geometry. Previous literature has shown that real-time phase matching between 2D fluoroscopic images and 3D CT images is achievable and can compensate for respiratory motion [23]. Similarly, we can generate the pseudo 4D CT images of the heart by analyzing motion vector fields [24]. The pseudo 4D images can facilitate the rendering of a dynamic heart model that well reflects the real-time geometry and position of the heart. Another solution could incorporate ultrasound that can directly image the heart tissue. These future improvements will directly dictate the accuracy of this image-guidance system, which currently is unknown, since only the precision of catheter localization has been characterized for the proposed system. (ii)Updates for renderings can only be taken as quickly as a C-arm can switch between the two fluoroscopic angles. This precludes the rendering of continuous motion of the catheter. However, continuous tracking is possible for hospitals that have bi-plane C-arms. (iii) Difficulty of automated segmentation of spine exists in processing real patient fluoroscopic images. Currently we tested our proposed system on a 3D-printed model that admittedly has greater contrast of the spine features compared to real patient images that have more complex tissue structures. More advanced image processing and potentially machine learning algorithms will be needed to effectively segment spines in real-time on patient images.

Conclusion

This paper reports a novel AR-assisted 3D visualization system for image guided percutaneous cardiac interventional procedures. The 3D model of the patient’s heart was segmented from CT images for planning the surgical procedures. A Fourier based method was capable of registering the intraoperative fluoroscopic images with the 3D heart model. Compared to other feature-based methods, the registration algorithm based on the polar-logarithmic transform of the frequency domain showed a significantly increased registration success rate (100% vs. 85.7-91.4%) and improved registration accuracy (0.42 vs. 0.88 mm). The 3D positions of the catheter were calculated by processing the fluoroscopic images captured at different angles. The detected catheter was precisely rendered as holograms on the AR device in 3D space with an MSE of 0.30 mm.

Compared to standard interventional technology, the AR system enables the 3D visualization and more user-friendly interface for interventionalists to better understand the heart anatomy. Therefore, it may assist the development of new therapeutic procedures and lower the learning curve for existing procedures. Furthermore, the developed guidance system and benchtop models can be used for pre-procedural planning and practicing complicated procedures. The new system can also work as a new teaching/training tool for residents and fellows and provides a quantitative platform for comparing methods for different PCI procedures amongst interventionalists.

Supporting information

S1 File. AR guidance system for percutaneous cardiac intervention.

The supplementary video demonstrates the use of the AR system to guide the catheter insertion for the transeptal puncturing procedure. The 3D rendering of the heart is dynamically changed according to the user input via gesture or voice command. A virtual display is also created to provide a first-person view to assist the navigation of the catheter inside the heart.

https://doi.org/10.1371/journal.pone.0219174.s001

(MP4)

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Heart: five versions of the origin of the symbol of love

When a tired but happy young mother looks out of the window of the maternity hospital with two parcels in her arms to show them to her husband, she […]

When a tired but happy young mother looks out of the window of the hospital with two parcels in her arms to show them to her husband, she becomes even happier … Why? Because he sees below her husband with flowers and a giant glowing heart – a symbol of love lined with candles.

This symbol is understandable to everyone, in any country, on any continent.Perhaps, in terms of frequency of use, it is second only to the Christian cross.

However, it has long been noticed that the recognizable heart, consisting of two adjacent semicircles, connected by one edge, and the other gradually tapering downward to form an acute angle, bears little resemblance to a real human heart from an anatomy textbook. How did we come to the conclusion that it is with this sign ♥ that we designate not only our love for a person dear to us, but also the center of the circulatory system on children’s medical posters or, for example, heart balm?

After reading quite a few articles on the topic, as well as familiarizing himself with various accompanying legends, your humble servant was able to find five main versions of the origin of the heart symbol, which seem to be the most plausible.

Version one – “curly”

It is associated with ivy, which in ancient Greece was often used to represent the vine, personifying the god of winemaking Dionysus. Already many thousands of years ago, a symbol similar to ♥ was found in Hellenic mosaics, as well as in their pottery and in the form of festive ritual wreaths, which the priests of Dionysus covered their heads with.

Despite the fact that the symbol somewhat compromised itself in the 5th-4th centuries BC.e., when it began to be used as the emblem of brothels (found, for example, in Pompeii), it also had a positive meaning.

Ivy was also considered a symbol of loyalty and procreation, and was often presented to the bride and groom during wedding ceremonies. Widowers and widows also often decorated the tombstones of their deceased spouses with the ivy symbol, since they wanted to be as inseparable with them as ivy twisted around the stem of another plant.

Second version – “curly”

It cannot be attributed to any particular author, but it was most lucidly formulated by Galdino Pranzarone, a professor of psychology from Virginia (USA), who analyzed various literary, mythological and other sources.In it, the origin of the heart is associated not with the inner (heart), but with the outer parts of the human body.

The professor found that it was very common for ancient civilization, with its cult of the human body, to chant the female figure. As a whole, and its individual parts. For example, in Syracuse, they even built a temple in honor of the goddess Aphrodite Callipiga (literally, Aphrodite the Beautiful Pop).

“A real heart is never such a bright scarlet color, and in its shape there is no depression at the top and a sharpness at the bottom.But this is exactly the outline of a beautiful female butt, ”the scientist wrote. Simply put, the inhabitants of the ancient world were inspired by the beauty of the female figure and it is to the lines of the body that the ♥ symbol owes its origin.

Version three – “immoral”

Here it could be without quotes. In ancient times, on the northern coast of the Mediterranean Sea in Cyrenaica (modern Libya), the plant silphium from the Umbrella family was widespread. Already by the III-IV centuries after the Nativity of Christ, it is considered to have disappeared due to climate change and predatory harvesting.

The trade in this plant was such a lucrative business that coins were even issued in the city of Kyrenia with the image of the opened sylphium seeds. Sylphius was the only tribute paid to Rome by the conquered Cyrene.

Why was this plant needed? Sylphium has been used to make spices, as an antidote for snake and insect bites, and has helped in many ailments: indigestion, cough, sore throat, tachycardia, and fever.

But the Roman patricians especially valued him not for this, but for his abortive properties.Sylphium seeds were with them both a kind of currency and an invitation to intimate relationships without obligations. The day after the intimacy happened, the woman used sylphium so as not to get pregnant, and sometimes even later to get rid of the unwanted child.

It is believed that the image of the sylph from the coins of Kyrenia could have become the prototype of our ♥.

Fourth version – “lyric”

Lyric, because it is associated with the lyre – an ancient musical instrument, just made in the shape of ♥, almost correct, but only inverted.

Some kind of calm melodies were often played on this instrument, its music calmed and bewitched. Noble citizens invited a musician with a lyre and a singer to the house to sing an ode to their beloved woman.

In addition, this version is associated with the legend of the love of the musician Orpheus and the beautiful Eurydice. When she died, Orpheus descended into the kingdom of the dead and, with his lyre playing, mesmerized Charon, and then so amazed Hades and Persephone that they let go of the human soul from their kingdom for the first and last time.

Version 5 – “swan”

Finally, a final noteworthy version says that the ♥ symbol is associated with swans. Swan loyalty and beauty have become proverbs. Since ancient times, the swan was considered a royal bird.

It is well known that once formed a pair of swans remains inseparable until the end of their lives. Such examples are quite rare in the animal kingdom. It is because of this that swans are considered a symbol of family and a happy marriage.

In addition, swans are extremely beautiful creatures.Their bent necks at the moment of “kissing”, when the birds swim very close to each other, form a semblance of a heart. Therefore, one of the hypotheses of the origin of the symbol of love is associated with them.

How the heart symbol became popular

Already at the beginning of the Middle Ages, the symbol of the heart began to be used in iconography to depict the Passion of Christ and the loving heart of the Lord.

Starting from the middle of the XIII century, the ♥ symbol began to appear in works of art, depicting no longer ivy leaves, but the human heart and the very feeling of love.

The first known case of such use was found in the French manuscript “Le roman de la poire” – “A novel about a pear” (1250), where a lover gives his lady a heart as a symbol of his feelings.

Further, the ♥ symbol is used more and more often on the pages of books and in painting, until finally, in the 19th century, the era of printed materials begins and one enterprising lady from the United States, Esther Howlen, does not dare to print scarlet “valentines” in cyclopean editions. It is thanks to the tradition of depicting a heart on postcards that the familiar symbol of love has become finally popular and recognizable.

And now, when TV and the Internet have connected to the popularization of the heart, probably only in the most remote corners of the world they will not be able to understand what this symbol means.

Conclusion

What would you like to say in the end? By and large, it doesn’t matter how our dear ♥ appeared. The main thing is what meaning we will put into this symbol now, as well as into the very concept of “love”.

The main thing is how we can show, actualize our love for people close to us and for God, how much we value our relationships with them and with Him.In this sense, actions and constancy speak for us more than some symbols, although a simple display of attention will be pleasant and not superfluous.

P.S. For the discerning reader who wants to read something else about symbols, I can offer article “Angels and Demons of the Roads” about the symbols that can be found on cars today.

You can applaud the author (at least 10 times) 113

90,000 Beautiful images of hearts. 240 high-quality photos for free

Wide heart in high quality on a transparent background.

Classic red heart on a white background. High resolution picture

Heart on fire

This heart is made up of a huge variety of multi-colored roses. A couple in love walking at the bottom of image

Just a cute red ribbon on a gray background

A gray bear with a blue nose gives you a heart

Bright pink splash of love

A brilliant heart filled with love magic. The background is transparent

Beautiful summer nature, heart-shaped tree

Insert a photo of a loved one into a transparent heart

A very beautiful heart that stands out among the night lights

Two perfect hearts on a white background

Two glowing hearts on a dark background

Love chained in ice

Eight hearts blazing in love fire

Heart drawn with a paint brush.Transparent background

Beautiful heart made of red threads

Stunning natural landscape and tree with a heart-shaped crown

Our hearts will love, despite the fragments of a million broken hearts below us

Perfect heart and red ribbon. High Resolution Wallpaper

I will find the right key to your heart when Cupid impales him with his arrow

Heart for your girlfriend who loves to read books

Heart flame reflected in sea water

Beautiful heart for a musical girl

Roses and a heart on a green background

One big heart made up of many small pieces

Mosaic consisting of hundreds of hearts.Great background for your words

A heart filled with love can fly

Two fiery outlines on a black background. For your fiery speech

Two small hearts lie on the bark

A girl with dark hair expresses her love

Two rubies inside a gold frame on a black background

Two lovely heart-shaped candles

A girl holding a paper heart in the light

Very beautiful red heart-shaped crystals

Glass heart filled with many chocolates

Just one spark and love will flare up very brightly

Two heart-shaped lollipops

Space portal leading to the love universe

Two loving hearts in a million are cold as stone

An excellent background for your holiday wishes.Write something inside the heart

Red roses and a pink heart on a wooden floor

Mechanical heart for steam punk fans

Two glossy heart-shaped balloons

When love flows in your veins. Great template for your greeting lettering

Metal forms for love baking

Two red hearts lie on luxurious silk

Dew covered four hearts

Many heart-shaped chocolates are packed in colorful foil.Great background for greeting card

Stone heart as a gift

Beautiful heart made of rose petals. The perfect way to express your love

When you are happy to be together

High-res square background

One red heart-shaped candle on a wooden table

If your girlfriend is in love with chocolate

Purple sparkling heart on a black background

Vertical stripes, flowers and hearts

Two fire snakes intertwined with each other and got two hearts

Delicate pink heart.Very beautiful color

Two sharp hearts polished to a shine

Lightning breaks hearts

Red and blue hearts in the snow

Another beautiful classic heart on a transparent background

If you want to express your love for a girl from Canada

Autumn nature and heart-shaped tree

A weapon that brings love and happiness

A small gift for your girlfriend. Vintage Wood Background

Incense surrounds a white heart on a string

Heart painted with careless strokes of various colors

Pink heart in green grass

A heart-shaped clasp attached to a rope

Purple splashes on a gray background

Red heart painted on a white brick wall

Neat pink heart on a white background

Glass heart on a white background

Two beautiful hearts with keyholes and angel wings

Pink heart painted on wet glass

A small heart almost fell into a hole in the floor

Fiery heart shows the direction of movement

Red heart and its reflection on a blue background

Beautiful beach and a heart of petals

Heart made by waves of water

Sweet heart-shaped sweets

Heart surrounded by white flowers and wings

Pink heart on a yellow background.Fire, wings, sun rays and climbing plant

Wind and white heart on a pink background

Love is like music in our heart

You will recognize this light among thousands of others

Two small hearts under an umbrella

Pink love crystal

Let’s create our love together

Classic heart for any purpose on a transparent background

Background image for your love speech

The guy hugs a huge heart

Heart next to the shop

Beautiful drawing of two heart-shaped balloons

Many brilliant hearts joined into one piece

Beautiful brooch in the shape of a heart with precious stones

Beautiful roses create a frame around the heart

Simple heart on a black background.Is this what you were looking for?

Hearts cut from colored paper

Magic heart made from neon smoke

For those who are in love with the sea

Just a heart on paper

Dark heart with diamonds

Couple in love, two silhouettes inside a beautiful heart

Heart made of many small stones, red roses and yellow lights

Stone heart with three black stripes

Chocolate heart as a gift

Two hearts surrounded by intricate patterns

Red heart lies on the fur

These dice always show the heart

Beautiful collage to create your unique greeting card

Black cat surrounded by love

Huge bouquet of red roses in the shape of a heart

Two empty hearts

Red heart in a white frame and its reflection

When I saw you, I pressed this particular key

90,000 Heart symbol.The history of images. 14-16 centuries .: philologist – LiveJournal

“Love magic” Liebeszauber (Love Spell) (1470s), artist unknown.

Lucas Cranach the Elder .1505

Hearts are now rather a symbol of vulgarity. They appeared en masse in the 19th century, in the Victorian era. But the story of their image is completely different.
Here are rare pictures and miniatures, which were not found in search engines, from the National Library of France and the British Museum.

————– Versions of the origin of the emblem —-
========================== =============== ====
Ivy leaf:

was used in ancient times as a decorative element in ceramics by the Greeks, and later by the Etruscans and Romans.
On a Greek vase, she can be like a stylized grape, often together with the god of the vine, Dionysus, the patron saint of passion and sensuality.

Ivy had many meanings – including obscene ones: the Greek “houses of tolerance” in the IV century. BC NS. used ivy leaf as a logo.

Another version:
North Africa, in the city of Cyrene, in the 7th century BC. produced special spices from the Silphium plant. It was a contraceptive and was used practically throughout the ancient world.

Cyrenecoin

On the coins of the city of Cyrene, the seed of this plant was depicted, in its shape resembling a heart. In ancient Rome, these spices were widely recognized. Patricians, inviting a person they liked on a date, sent her this symbol.

More versions:
============

A pair of swans, swimming towards each other, form a heart shape at the moment of touch.

Swans are a symbol of love, loyalty and devotion, since a formed couple stays together for life, which is extremely rare in the animal world.

Le Livre des échecs amoureux 1495 g

Oysters – a symbol of carnal love:

Prayer book of Catherine of Cleves, 1440 g

——————— ——- Miniatures — —–

————– le symbole du coeur-NBF —
======= ================================= ==
————- –White heart ————

Français 22545, fol. 186v, Machaut et la statue de l’Amour
14ème siècle

Français 239, fol.112v, Ghismonda recevant le coeur
15ème siècle

le fragment de Metz: Metz Bibliothèque Municipale Ms 1486 Miniatures de Jean Colombe copié sur Barthelemy d’Eyck.

—————- Red Heart ————–
=============== ========================= ==

Book of Hours, Bruges; c. 1500-1510

Red symbolized blood.

Français 12399, fol. 104, Ratio accusant Satan
1495

1495

—————- Graphics ———-
========= =============================== =

————- “Flaming heart: ———-
The heart was depicted like this:

Print made by Anonymous (Monogrammist CG)
Date
1500-1550
Venus, a full length naked figure, holding a burning heart in her right hand, an arrow in her left, a bull (sign of the zodiac) lower left, encircled by clouds

School of / style of Lucas Cranach the Younger
1550-1570
Plate 5: Venus

The Seven Planets / Venus
Print made by Monogrammist IB
1528

Giulio Bonasone
People lighting torches from a concave mirror reflecting the sun and worshipers offering their hearts; from a series of 150 engravings.
1555

Giulio Bonasone
1555
Hermocrates kneeling by an altar upon which is an eagle taking the heart out of a dog; from a series of 150 engravings. 1555

—————— Graphics ————

The Five wounds of Christ; the bleeding heart at center, the hands and feet with stigmata in the corners; illustration to the German edition of the ‘Devotissimae Mediationes’, ‘Gebet und betrachtungen des lebens des mitlers gotes Jesu Christi’, Augsburg: Grimm and Wirsung, 1521.
Woodcut

Print made by Anonymous (Monogrammist)
Date
1500-1525
The Sacred Heart with IHS; these letters open with scene of the crucifixion and Mary Magdalene, the Virgin Mary, St John, and instruments of the torture of Christ; above is the Holy Trinity and at the four corners the symbols of the Evangelists

Albrecht Dürer
1528 (circa)
Emblematical design; allegory with three female figures, Misfortune at an altar beats a heart held in tongs by Envy

Print made by Wolf Traut
1500-1520

Description
The Adoration of the Sacred Heart

Lucas Cranach the Elder
Date
1505
Four saints adoring Christ crucified upon the Sacred Heart; Christ appears on the cross with a banderole, within a bleeding heart at upper center; the heart is displayed by a shield, which is held by four angels; in the landscape below kneel St Sebastian, the Virgin, St John and St Roch

Pierre Choque, Commémoration de la mort d’Anne, reine de France, duchesse de Bretagne, Paris; c.1514-1515

————– Miniatures ——–
——— National Library of France —
—– ———— Heart Games —————-
================== ====================== ======

Tenture de Recueil et Déport Joyeux

Tenture de Manière et Chère Aimable

Tenture de Fol Cuidier et Espérance

Tenture de Deuil et Tristesse

Tenture de Rogier Bon Temps

———— Jewelry —————
===================================

West Iran, Hamadan (province), Nihavand)
Date
1stC-3rdC (between)
Period / Culture
Parthian
Gold belt-buckle or clasp

Finger-ring (fede-ring)

—————- – Dishes ————

Gradually the origin of the symbol was forgotten, but the emblem has already spread throughout the world.

Polychrome painted plate with the monograms of a European couple.
The date 1763
====================

If we talk about other accompanying symbols, then it has no less ancient history. For example, an arrow piercing the heart is an emblem known since the days of Ancient Rome.

The arrow belongs to Cupid – the god of love. Actually, the angels that are painted on postcards are also the image of Cupid or Cupid. A characteristic image of a heart pierced by an arrow is found in the ruins of Greek and Roman temples and in the Egyptian pyramids, and even in the ruins of the Aztec cities.

Teller (tondino), radial geteilt, in der Mitte ein Arm mit einem von Amors Liebespfeil durchbohrten Herzen; Anfang 16. Jh.
Kunstgewerbemuseum Berlin

—————————————- –

“Love Magic” Liebeszauber (Love Spell) (1470s), artist unknown.
witchcraft at its most attractive. The young witch has woven the magic of love in scrolls that float in the air. The magic worked, and now the desired young man stands at the door of her house.

More on the topic:

Lovers on miniatures of the 15th century HERE

LOVE, all posts HERE

—————– ——
http://www.britishmuseum.org/
http://www.bnf.fr/fr/
http://en.wikipedia.org/wiki/Heart_%28symbol%29
http : //ru.wikipedia.org/wiki/%D0%A1%D0%B8%D0%BC%D0%B2%D0%BE%D0%BB_%D1%81%D0%B5%D1%80%D0% B4% D1% 86% D0% B0
http://en.wikipedia.org/wiki/Wilton_Diptych
http: // nends.tumblr.com/
http://zikzag.ru/eto_intirestno/3819-istoriya-serdechka.html
http://www.liveinternet.ru/users/1583508/post145559731

The heart symbol is … What is the Symbol hearts?

Heart symbol

Heart symbol (♥) – a symbol in the form (shape) of a heart. The symbol is often used to represent love.

Versions of the origin of the symbol

1. A pair of swans swimming towards each other, at the moment of touching, form a heart shape. Swans are a symbol of love, loyalty and devotion, as a formed couple stays together for life ^[1] , which is extremely rare in the animal kingdom. ^[2]
2. The sign depicts the area of ​​the female pelvis. Psychologist Galdino Pranzarone from Roanoke College in the US state of Virginia believes that the heart symbol is derived from a feature of female anatomy, indicating that ancient people associated female beauty primarily with female body shapes from the back: ^[3]
   

   … were so prized by the ancient Greeks that they even built a special temple to Aphrodite Kallipigos … […] This temple, apparently, was the only religious building in the world dedicated to the worship of female buttocks.

   – ^[4]

3. The image resembles a schematic outline of the heart of an amphibian ^[5] .
4. The heart symbol can also be traced in the shape of the heads of kissing people.

   Heads of kissing people form a heart shape

5. The shape of the symbolic heart is nothing more than an ivy leaf ^[6] . In Hellenistic culture, ivy was considered a symbol of the god of winemaking and the passion of Dionysus.On Greek amphoras, the ivy symbol was often used for decoration. ^[7] Ivy had many meanings – including obscene ones: the Greek “houses of tolerance” in the 4th century. BC NS. used ivy leaf as a logo.

Using symbol

Valentine greeting card, 1950

1. to visually indicate the word “love”. The symbol is depicted on gift products: postcards, toys, chocolates, etc. When celebrating Valentine’s Day, it is customary to give cards in the shape of a heart – “valentines”.It is also customary to give gifts in the form of a heart to loved ones for birthday and other holidays.
2. In computer games, hearts symbolize “life”.
3. on playing cards, the heart symbol denotes the suit “Hearts”.

On playing cards, the heart symbol denotes the suit “hearts”

Computer code

The heart is usually indicated by a smiley face <3 ^[8] . Unicode has several characters to represent it:

Mathematical description

There are several mathematical formulas that lead to curves that look like a heart symbol.The most famous of them is the cardioid, which is a special case of Pascal’s cochlea, the epicycloid, and the sinusoidal helix ^[9] . Other curves, such as (x ² + y ² −1) ³ −x ² y ³ = 0, can better approximate the shape of the heart. ^[10] .

Literature

• Ole Martin Høistad. The history of the heart in world culture from antiquity to the present. M., Text, 2010.

Notes

90,000 Pencil drawings a human heart (56 photos) 🔥 Funny pictures and humor

The heart means a lot to a person.The real heart is the basis of our body, which is responsible for our life. Also, our heart allows us to show us such valuable feelings as warmth, love and tender feelings for a person. In order to draw a human heart, you first need to know well the anatomy of the heart, but if you are not a doctor, then this is not an easy task, and therefore you need the following things – any picture of a human heart or an atlas of human anatomy, white plain paper and a pencil. To begin with, start with the outline of the heart and blood vessel, then draw the ventricles and atria, then draw the valves, and then you can paint the result.the volume you can already color the received. Next, we suggest looking at pencil drawings for sketching a human heart.

Drawing with colored pencils a human heart.

Pencil drawing of a human heart.

Drawing for a sketch of a heart.

Black and white drawing of a heart.

Color drawing heart.

Drawing human heart.

Color drawing heart.

Drawing heart, flowers, butterflies.

Black and white drawing of a human heart.

Color drawing of a human heart.

Drawing with colored pencils heart.

Pencil drawing heart.

Drawing for a sketch of a human heart.

Pencil drawing heart.

Drawing for a sketch of a heart.

Black and white picture of a heart.

Drawing mechanical heart.

Drawing antistress heart.

Pencil drawing heart in flowers.

Color drawing heart.

Black and white picture of a heart.

Pen drawing a human heart.

Drawing for a sketch of a human heart.

Drawing heart, bird.

Black and white picture of a human heart.

Color picture of a human heart.

Pencil drawing.

Heart in a cut.

Simple drawing of an internal organ.

Powerful heart valves.

Drawing of an internal organ.

Pencil drawing.

Drawing in color.

An important human organ.

Small heart.

Professional drawing.

Drawing for sketching.

Neat drawing.

Heart in pencil.

Nice drawing.

Drawing of a strong heart.

Pencil drawing.

With drops of blood.

Drawing with colored pencils.

Drawing for sketching.

Colored heart.

Drawing of a heart.

Heart in hands.

An important organ.

Black pencil drawing.

Realistic drawing.

Drawing for sketching.

Beautiful drawing of a heart.

I like not like

About the shape of the heart – Journal of observations and reflections – LJ

If we compare the real human heart

with the accepted graphic symbol,

, then a skeptic (this is me 🙂 will have doubts about the roots of the established image.Below are some fundamental views on heart shape.

1. Romantic
According to the most beautiful legend, this symbol originates from the image of two swans swimming towards each other against the background of a scarlet sunset:

2. Greek
According to cultural researchers and psychologists, the image came to us from ancient Greece: the ancient Greeks associated female beauty primarily with the forms of the female body from the back.To be quite accurate and frank, beauty for them was in the shape of the female buttocks as the personification of the reproductive function. They (buttocks) were so valued by the ancient Greeks that they even built a special temple to Aphrodite Kallipigos: the Goddess of Beauty must have a standard of ass, a fact.

3. Roman
The image resembles a schematic outline of an amphibian heart or the head of a male penis. According to one version, the heart symbol appeared in ancient Rome.Perverted patricians sent it to beloved or longed-for persons

4. IT-shnoe
Geeks don’t care about their origins.
In emoticons, the heart is written as <3, in Unicode and HTML layout, you should use the plate:

5.2 = 1

Don’t believe me? Get here:

P.S. I apologize for the awful design of the post – I can’t cope with the layout on the iPad.

Posted via LiveJournal app for iPad.

How do I crop a heart-shaped image in Silverlight?

I am working on an imaging application in Silverlight. I am currently stuck on one.

The problem is that I want to crop the image in the shape of a heart. How do I crop a heart-shaped image in Silverlight?

silverlight-4.0

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vishal

July 27, 2011 at 13:24

2 answers

• draw heart shape android canvas

  Hi i want to draw a heart shape i know how to use drawCircle () and some other canvas classes but how to draw a heart shape i have an equation that creates a heart shape polar r = (sin (t) * sqrt (abs (cos (t)) )) / (sin (t) + 7/5) -2 * sin (t) + 2 is a heart-shaped reference wherever you can…

• How do I crop an image to a circle in Titanium?

  You can crop the image by setting it to the background of the label and then setting the label to the size you want, but is there a way to crop it into a circle? Thanks!

1

You can use a clipping path – something like this:

(you will need to change the exact path according to your image).

Alternatively you can use a heart-shaped opacity mask.

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Richard Inglis

July 27, 2011 at 14:14

0

I would recommend just creating a heart in Photoshop or something with a transparent center and a solid color on the outside. Then just draw a heart in your image.This way you don’t have to deal with cropping and you have better control over the shape.

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Chris Haas

July 27, 2011 at 13:53

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