How is PE Diagnosed? – Blood Clots

A number of different things may alert a physician that a person may be experiencing a pulmonary embolism, or blood clot in their lung.  When this is suspected, a number of crucial tests may be performed, including:

Pulse Oximetry

Often, the first test performed when PE is suspected is a blood oxygen level. The simplest way to measure the blood oxygen level is with a pulse oximeter. Pulse oximetry is a noninvasive way (does not involve a blood draw or needle stick) to monitor the percentage of hemoglobin that is saturated with oxygen. Hemoglobin is the unique molecule in red blood cells that has the ability to carry oxygen.

The pulse oximeter consists of a probe or sensor plus a computer. The probe, which looks like a padded clothespin, is placed on a relatively thin part of a person’s body, such as a finger or earlobe. Both red and infrared light are then transmitted through the tissue by the probe. Based on the absorption of the red and infrared light caused by the difference in color between hemoglobin that is saturated with oxygen (red) and unsaturated hemoglobin (blue), the computer can estimate the proportion of hemoglobin that is oxygenated. The pulse oximeter then displays this result as a percentage. A blood oxygen saturation level less than 95 percent is abnormal. It may be explained by a lung or heart problem already present, such as emphysema or pneumonia, or by PE (or both).

Arterial Blood Gas

A more precise measurement of blood oxygen level is obtained from a sample taken directly from an artery with a needle or a thin tube (catheter). An arterial blood gas (ABG) measures the levels of both oxygen and carbon dioxide in the blood to determine how well the lungs are working. While most blood tests are performed on samples taken from a vein, an ABG is performed on a sample taken from an artery. In most cases, the artery in the wrist is used for this purpose, but other arteries may be used. The levels of blood gases are measured as partial pressures in units of millimeters of mercury (mm Hg). A partial pressure of oxygen less than 80 mm Hg is abnormal.

Chest X-Ray

A chest x-ray cannot prove that PE is present or absent because clots do not show up on x-ray. Nevertheless, a chest x-ray is a useful test in the evaluation for PE because it can find other diseases, such as pneumonia or fluid in the lungs, that may explain a person’s symptoms. Occasionally, when pulmonary infarction occurs, the x-ray may suggest this diagnosis, although more testing is necessary to prove it with certainty. A normal or negative chest x-ray with a low, otherwise unexplained blood oxygen level, however, raises the suspicion for PE.

Ventilation-Perfusion Scan (VQ Scan)

A VQ lung scan may be a useful test to determine whether a person has experienced PE. This test evaluates both air flow (V = ventilation) and blood flow (Q = perfusion) in the lungs. About one hour before the test, a slightly radioactive version of the mineral technetium mixed with liquid protein is administered through a vein to identify areas of the lung that may have reduced blood flow. Multiple images are taken from different angles, using a special camera that detects radioactivity. For half of the images, the person breathes from a tube that contains a mixture of air, oxygen, and a slightly radioactive version of the gas xenon, which reveals air flow in different parts of the lung. For the other half of the images, the camera tracks the technetium, which reveals blood flow in different parts of the lung. PE is suspected in areas of the lung that have significant “mismatches”—that is, good air flow but poor blood flow.

Except for the minor discomfort from having an intravenous catheter placed, a VQ lung scan is painless and usually takes less than an hour. The exposure to radioactivity from the test is very minor and results in no side effects or complications.

A radiologist interprets the images from the VQ lung scan and decides whether the probability of a PE is high, low, or intermediate. If the probability is high, the diagnosis is made. If the probability is low or intermediate (that is, nondiagnostic), or if the VQ scan cannot be interpreted clearly, other testing must be considered. Even when PE is ultimately proven to be present, the VQ scan may be nondiagnostic. If clinical suspicion is low and the VQ scan reveals a low probability of PE, generally no further testing is needed. A normal VQ scan means PE is not present.

Spiral Computed Tomography of the Chest

An alternative to the VQ scan is a spiral computed tomography (CT) of the chest. A spiral CT of the chest uses special equipment to obtain multiple cross-sectional x-ray images of the organs and tissues of the chest. CT produces images that are far more detailed than those available with a conventional x-ray. Many different types of tissues—including the lungs, heart, bones, soft tissues, muscles, and blood vessels—can be seen.

When PE is suspected, contrast dye (usually iodine dye) is administered through a vein to make the blood vessels stand out.

During the spiral CT, radiation is emitted from a rotating tube. Different tissues absorb this radiation differently. During each rotation, approximately 1,000 images are recorded, which a computer then reassembles to produce a detailed image of the interior of the chest. The x-ray rotates as the patient passes through the CT scanner in a spiral path—hence the term “spiral” CT. The amount of radiation exposure is relatively low, and the procedure is not invasive.

Pulmonary Angiogram

If the VQ scan interpretation is low, intermediate, or uncertain probability of PE, or if the spiral CT is normal yet the symptoms are still suspicious, then the definitive test is a pulmonary angiogram.  An angiogram is an invasive test that uses x-rays to reveal blockages or other abnormalities within the veins or arteries. Contrast dye (usually iodine dye) helps blood vessels show up clearly on x-rays. During an angiogram, contrast dye is injected into a blood vessel, and its path is tracked by a series of x-rays.

A pulmonary angiogram examines the arteries that carry blood from the heart to the lungs and is performed to see if PE is present. Using x-rays in real-time (fluoroscopy), the radiologist inserts a catheter into a vein and advances it until it reaches the vena cava (the very large vein that carries blood to the heart). Next, the radiologist advances the catheter still farther into the right side of the heart and finally into the pulmonary artery, the large artery that carries blood to the lungs. The radiologist directs the tip of the catheter into the different branches of the right and left pulmonary arteries and injects the contrast dye, which illuminates the arteries on x-ray. If PE is present, it will show up as a blockage.

Risks associated with a pulmonary angiogram include the possibility of damage caused by the catheter, bleeding, and an allergic reaction to the contrast dye. The amount of radiation from the x-rays is too small to cause any harm.

Echocardiogram

An echocardiogram is an ultrasound of the heart. Doppler ultrasound, B-mode ultrasound, and M-mode ultrasound (a rapid sequence of B-mode images that allows motion to be visualized) are combined to give information about the size of the heart, the function of the valves, and the strength of the heart muscle. (Duplex ultrasound is discussed in detail in Question 9. ) The echocardiogram can spot areas of the heart that are not working well. When patients with a PE have an echocardiogram, approximately 40 percent will be found to have abnormalities of the right side of the heart, particularly the right ventricle. While an echocardiogram is not actually used to diagnose a PE, it can identify strain on the right side of the heart caused by a large PE as well as certain heart problems that may imitate a PE.

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Diagnosing Blood Clots | Imaging Tests Overview

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Angiography of thoracic aorta

Doppler ultrasonography is the most widely available noninvasive test for deep vein thrombosis.  

Diagnosing deep vein thrombosis and pulmonary embolism may be difficult as the signs and symptoms associated with these disorders are not unique to these conditions. For example, leg pain and swelling or chest pain and shortness of breath may have other causes. As a result, testing is needed to confirm the diagnosis.

Venography and pulmonary angiography remain the gold standards for diagnosis of deep vein thrombosis and pulmonary embolism respectively; however, these tests are now being increasingly replaced by less invasive and less expensive procedures. Three types of imaging tests may be used to diagnose clots in veins.

RADIO LABEL TESTS

Radioactive fibrinogen leg scanning is moderately sensitive and specific for clots in the calf and popliteal veins, but less sensitive for superficial clots in the femoral or iliac veins.

The AcuTect venogram test is a synthetic radiochemical that binds to a protein found on activated platelets. The AcuTect venogram is used to diagnose acute venous clots in the lower extremities of patients with signs and symptoms of such clots. The AcuTect appears to detect acute, but not chronic, clots in the veins.

ULTRASOUND TESTS

The doppler-augmented ultrasound and impedance plethysmography technique are sensitive to proximal clots that cause blockages. Impedance plethysmography does not detect calf vein clots or proximal vein clots that do not block the blood vessel.

Doppler ultrasonography is the most widely available noninvasive test for deep vein thrombosis. Doppler ultrasonography has become the dominant test since the 1980s and has largely replaced impedance plethysmography for noninvasive testing.

X-RAY AND COMPUTED TOMOGRAPHY TESTS

Venography testing can detect clots in both calf and proximal veins.

V/Q scanning may be used as a one-step method to diagnose pulmonary embolism in patients with a normal chest radiograph. In patients with an abnormal chest radiograph, V/Q scanning should be used in combination with helical spiral computed tomography testing. V/Q scans tend to be used mainly to exclude rather than confirm pulmonary embolism. V/Q scanning is able to show small clots–and this ability is enhanced by single photon emission computed tomography.

The helical spiral computed tomography technique is very effective in diagnosing clinically important pulmonary embolism and a large number of alternative diagnoses in patients with symptoms who have undergone a V/Q scan. This is an accurate method for detecting and excluding most types of pulmonary embolism.

Laboratory testing is another method of diagnosis

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Intracardiac thrombi. Diagnosis and treatment

Blood clots can form not only in veins, but also in heart cavities and arteries.

Blood clots are a natural reaction of the body. They contribute to the restoration of damaged blood vessels. A blood clot is a blood clot that contains fibrin (a protein needed for blood clotting). But blood clots in the cavities of the heart is a completely different matter.

The most dangerous thing is that there are no symptoms by which one can suspect the presence of intracardiac thrombi. It is possible to detect a thrombus in the cavities of the heart only during diagnostics (echocardiography, etc.). And any symptoms (shortness of breath or suffocation) a person can only feel with pulmonary embolism.

Thrombi can be in the left or right cavities of the heart, in the atria or ventricles (more often these are parietal thrombi).

What are blood clots:

• Floating. These are partially attached thrombi. The danger is that the floating part of the thrombus may come off;
• Parietal, when the clot is completely attached to the wall of the chamber of the heart;
• Occlusive. The most dangerous! These clots cut off blood flow.

Thrombi in the left side of the heart

Most often, blood clots in the left cavities of the heart occur against the background of three diseases.

People at risk are:

• with mitral valve stenosis;
• with atrial fibrillation (atrial fibrillation):
• with postinfarction aneurysm of the left ventricle.

Blood clots in the left side of the heart – the risk of arterial thromboembolism, ischemic attacks or cerebral infarction! With the localization of blood clots in the left cavities of the heart, the arteries of the kidneys, upper and lower extremities, and the arteries of the intestine can also be affected.

Heart attacks and strokes

In arterial atherosclerosis and plaque rupture, a blood clot forms in the artery. As a result, myocardial infarction (necrosis of the organ tissue) can occur. If a thrombus located in the cavity of the left ventricle breaks off, then, spreading through the blood stream, it can clog the arteries of the brain (as a result, cerebral infarction occurs – ischemic stroke), kidneys (kidney infarction), intestines (intestinal infarction, mesenteric thrombosis), limbs (gangrene).

If a clot breaks off, it can spread with the bloodstream and close the vessel lumen! When the vessel is blocked, blood circulation is disturbed, which leads to oxygen starvation and tissue necrosis. This can cause complications such as myocardial infarction, PE, and even death.

If there is an open oval window in the intercardiac septum, blood clots from the veins of the lower extremities, the pelvis can move from the right atrium to the left and then enter the brain with the blood flow. The result is also a stroke.

Blood clots resulting from an aneurysm of the heart

After a heart attack, parietal thrombi may form in the left ventricle. They are seen by specialists with the help of echocardiography. This is the main type of diagnostic for the detection of blood clots in the cavities of the heart. If they are detected, a specialist may prescribe anticoagulants (in the absence of contraindications).

Thrombi formed during mitral valve stenosis

There is a special variety – a spherical thrombus in the left atrium. Such a thrombus is formed during mitral valve stenosis, in which outflow from the left atrium into the left ventricle is disturbed.

Thrombi formed during atrial fibrillation (atrial fibrillation)

In atrial fibrillation, blood clots are usually localized in the left atrial appendages. The ear is a protrusion of the atrium (it looks like a sac). Thrombi of the left atrial appendage can be detected most often only with transesophageal echocardiography. They are very difficult to detect with echocardiography.

Blood clots in the right side of the heart

The presence of a blood clot in the right side of the heart is fraught with complications in the form of thromboembolism of the branches of the pulmonary artery (a disease in which the arteries of the lungs are affected). PE is one of the most dangerous complications.

A thrombus may first form in the deep veins of the lower extremities. If a floating thrombus breaks off, then with the blood flow it first enters the right heart, and then into the pulmonary artery. This can lead to sudden death!

Diagnosis

The main method for diagnosing intracardiac thrombi in MedicCity is echocardiography.

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Echo-KG (ultrasound of the heart)

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Echo-KG (ultrasound of the heart)

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Echo-KG (ultrasound of the heart)

If you need to diagnose blood clots in the veins, a duplex scan of the veins of the lower limbs, etc.

Treatment

To prevent blood clots, your specialist may prescribe you anticoagulants or antiplatelet agents (if there are no contraindications).

Patients with mitral valve stenosis, atrial fibrillation or postinfarction aneurysm need regular echocardiographic monitoring! Especially in the presence of prosthetic valves. In this case, ECHO-KG should be done every year.

After a myocardial infarction, it is necessary to check whether a blood clot has formed in the cavity of the heart.

Those who take hormonal contraception are also at risk. They increase the risk of thrombosis, as well as myocardial infarction. You may find a warning in the instructions for the side effects.

Intracardiac clots can lead to serious complications! If necessary, consult a doctor and follow all recommendations.

The material was prepared with the participation of a specialist:

• Zakharov Stanislav Yurievich

  Cardiologist, doctor of functional diagnostics

  Highest qualification category, Doctor of Medicine, Member of the European Society of Cardiology and the Russian Society of Cardiology

Thrombus: why is it dangerous separation, who is at risk, how to avoid the formation of a blood clot – January 16, 2023

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Where do blood clots come from?

A thrombus itself is an accumulation of “glued” platelets that can attach to the vessel wall due to inflammation, microtrauma, or atherosclerotic plaque. Blood clots form due to increased blood clotting.

Generally, blood clots form in large vessels. Under the influence of mechanical and biochemical processes, a thrombus can break away from the wall to which it was attached.

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2

Why is a blood clot detachment dangerous?

Having broken off, blood clots move into smaller vessels. Due to the size of a blood clot, it can completely clog a small vessel. After blockage, blood supply stops, that is, the delivery of oxygen and nutrients to the organ or part of it. This leads to heart attack, stroke, thromboembolism and even death.

– Lack of oxygen leads to ischemia. There are organs most sensitive to lack of oxygen. If this happens in the heart muscle, then a heart attack, if in the pulmonary, then thromboembolism. If a larger vessel, a large focus of ischemia, then this can lead to death. For example, if a blood clot cuts off the blood supply to such important vascular centers in the brain as the trunk, where both the center of respiration and the center of cardiac activity, explains doctor Olga Molchanova.

Olga Molchanova — cardiologist, leading researcher at the Federal State Budgetary Institution National Medical Research Center for Therapy and Preventive Medicine of the Ministry of Health of Russia, expert at the NGO League of Health of the Nation.

In a separate article, we talked about how ischemic stroke is treated in Russia today, which develops due to blockage of a vessel, and the most common cause of this is a detached blood clot.

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3

Who is at risk?

Thrombus formation is facilitated by increased blood clotting due to a sedentary lifestyle, dehydration, high levels of cholesterol, sugar. But there are other factors as well.

“The risk group includes people after surgery, with heart rhythm disturbances, obese people, varicose veins of the lower extremities, including pregnancy complications, smokers, the elderly,” says cardiologist Mehman Mammadov.

Mehman Mammadov – cardiologist, doctor of medical sciences, professor, expert of the public organization “League of Nation’s Health”.

Most patients with thrombosis are over 40 years of age. With age, the blood coagulation system begins to work differently, and diseases appear that can lead to thrombophlebitis, for example, oncology . Thrombosis of deep and superficial veins often hides the debut of oncological diseases. According to doctors, every fourth patient who develops deep vein thrombosis is a cancer patient.

A dangerous period is considered childbearing and 40 days after childbirth : the female body is preparing for childbirth and blood loss, there is an imbalance in the coagulation and anticoagulation systems.

Another risk factor is taking hormonal drugs . Women who have relatives with deep vein thrombosis or pulmonary embolism should see a vascular surgeon before starting hormone medication.

Much higher risk of thrombosis after surgery and injury . Due to injury, the blood coagulation system is activated. The immobility of the patient during the operation and in the postoperative period also plays a role. Fully blood flows from the legs only when a person walks. In all surgical departments, prevention of thromboembolic complications is carried out.

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4

Can a person who has a blood clot come off be saved?

To avoid the severe consequences of a blood clot detachment, you should immediately call a doctor at the first symptoms. It is worth paying attention to the fact that the person turned pale, covered with sweat, there were pains behind the sternum, in the back of the head, in the chest.

— For pulmonary embolism, the main symptom is an acute sudden onset of shortness of breath. The patient may be disturbed by coughing, hemoptysis, frequent and sharp pain in the chest. Among other things, thromboembolism can be accompanied by loss of consciousness for a long or short period of time,” Artem Gavrilko, an X-ray surgeon from the OKB No. 1 of Tyumen, told us earlier. – These conditions and symptoms require an emergency call for an ambulance. When they appear, in no case should a person himself get to the hospital. He can threaten not only himself, but also everyone around him. <...> If, for example, we are talking about pulmonary embolism, then the symptoms of this process develop very, very quickly. But these symptoms may be preceded by thrombosis of the lower extremities. In simple words, in such a patient, the leg swells and becomes very blue. The thrombus in this case has not yet come off and has not flown away, but the risk that this will happen soon is quite large. In such cases, you should immediately consult an emergency doctor, because there is a high risk of death. Similar symptoms can occur within a fairly short time – two days. With the worst course of the disease and the influence of negative factors, a person may die.

Infographics: Vitaly Kalistratov / City Portals

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5

How quickly does a blood clot come off?

– This is about two or three seconds. The fact is that our blood circulates very quickly throughout the body. It is impossible to catch and notice the process of separation of a blood clot. Usually, doctors already see in fact that a thromboembolism has occurred, that is, that a blood clot has flown away and arrived in some place. Tracking how it travels through the body is unrealistic, – notes Artem Gavrilko.

Most often, the phrase “clot came off” refers to pulmonary embolism (PE). The lumen of a large vessel is clogged with a thrombus or blood clots, and this causes disturbances in the entire cardiovascular and respiratory systems. PE is a complication of venous thrombosis and thrombophlebitis. Not every detached blood clot and not every PE leads to death. Most often, a fatal outcome occurs with massive thromboembolism, when not one thrombus, but many, came off and “flew away”.

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6

What should be done for prevention?

The formation of blood clots can be prevented – for this you need to monitor the level of sugar and cholesterol in the blood, blood clotting in order to start treating the identified diseases as early as possible. You also need to avoid injuries and prolonged stress, follow a diet, exercise regimen and drinking regimen. At the same time, it is not necessary to follow an active lifestyle strenuously – 30 minutes of walking a day is enough to reduce the risk of thrombosis. In addition, if there are special prescriptions of doctors, they must be followed.

No fancy diet required, just healthy eating recommended by dieticians and other doctors.

– Food should be enriched with vegetarian food: berries, vegetables. It is better to avoid fatty animal food, replace it with fish with a minimum amount of animal fat. You should also avoid refined sugar and products with it, advises cardiologist Olga Molchanova.

Separate attention should be paid to water. You need to drink at least one and a half liters a day – and that’s not counting coffee, tea, soup and juices. Especially it is necessary to pay attention to the elderly and their relatives. According to Molchanova, in old age, the feeling of thirst may weaken, so you need to remind loved ones to drink clean water.

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7

What else to read on the topic?

Doctors always advise you to pay attention to your own blood pressure and, if it is higher or lower than normal, contact them. But what is actually fraught with increased or decreased pressure, and how does the upper indicator differ from the lower one? We figured out these details together with cardiologists.

By the way, how do you need to measure pressure correctly in order to avoid the most common mistakes? In fact, there are not so many of them, but they can significantly affect the final result of the measurement. For example, you should not measure pressure while running, and any stress (not only physical, but also psycho-emotional) can affect the accuracy of the numbers.

Heart problems can strike at any time – for example, after recovering from covid. Postcovid syndrome has already been included in the International Classification of Diseases, and some complications can also affect the functioning of the heart.