What is svt in medical terms: Supraventricular tachycardia – Symptoms and causes

19.09.202319.07.2023 by alexxlab

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Supraventricular tachycardia (SVT) – NHS

Supraventricular tachycardia (SVT) is a condition where your heart suddenly beats much faster than normal. It’s not usually serious, but some people may need treatment.

Causes of supraventricular tachycardia (SVT)

SVT happens when the electrical system that controls your heart rhythm is not working properly.

This causes your heart to suddenly beat much faster. It can then slow down abruptly.

A normal resting heart rate is 60 to 100 beats per minute (bpm). But with SVT your heart rate suddenly goes above 100bpm. This can happen when you’re resting or doing exercise.

Symptoms of supraventricular tachycardia (SVT)

Having SVT means your heart suddenly beats faster.

This:

usually lasts for a few minutes, but can sometimes last for several hours
can happen several times a day or once a year – it varies
can be triggered by tiredness, caffeine, alcohol or drugs – but often there’s no obvious trigger
can happen at any age, but often starts for the first time in children and young adults – many people have their first symptoms between 25 and 40

You may get no other symptoms, but sometimes people also:

have chest pain
feel weak, breathless or lightheaded
feel tired
feel sick or are sick

Non-urgent advice: See a GP if you keep getting a fast heartbeat

It’s important to get it checked out. You might need a test, such as an electrocardiogram (ECG), to find out what’s going on.

Immediate action required: Call 999 or go to A&E if:

you have been diagnosed with SVT and your episode has lasted longer than 30 minutes
you have sudden shortness of breath with chest pain

You need to go to hospital for treatment immediately.

Things you can do to help with supraventricular tachycardia (SVT)

If your episodes of SVT only last a few minutes and do not bother you, you may not need treatment.

You can make changes to your lifestyle to reduce your chances of having episodes, such as:

cutting down on the amount of caffeine or alcohol you drink
stopping or cutting back on smoking
making sure you get enough rest

Your doctor may also be able to recommend some simple techniques to help stop episodes when they happen.

Treating supraventricular tachycardia (SVT) in hospital

SVT is rarely life threatening. But you may need treatment in hospital if you keep having long episodes.

This may include:

medicines to control the episodes of SVT – given as tablets or through a vein
cardioversion – a small electric shock to the heart to help it get back to a normal rhythm
catheter ablation – a treatment where thin tubes are placed through a vein or artery into your heart to correct the problem with the electrical system; this permanently cures the problem in most patients

Find out more about:

cardioversion: British Heart Foundation
catheter ablation: British Heart Foundation

Page last reviewed: 27 April 2021
Next review due: 27 April 2024

Types, Causes, & Risk Factors

Written by WebMD Editorial Contributors

How Your Heart Beats
What Is Supraventricular Tachycardia?
Causes
Symptoms
Diagnosis
Treatments
More

Sometimes, a problem with your heart’s electrical signals can make it speed up, even when you’re not anxious or exercising. One type of faster-than-normal heartbeat is called supraventricular tachycardia (SVT).

SVT is a group of heart conditions that all have a few things in common.

The term has Latin roots. Supraventricular means “above the ventricles,” which are the lower two sections of your heart. Tachycardia means “fast heart rate.”

Other conditions can cause your heart to beat too fast. Your doctor will need all the details of your symptoms. They’ll also do a physical exam and record your heartbeats to be sure of the diagnosis.

Most of the time, it doesn’t cause any serious health problems even though a racing heartbeat can be a scary feeling. Still, you should see your doctor about it. When your heart beats too quickly, it can’t pump out enough blood to meet your body’s needs.

Sometimes you might have a drop in blood pressure and feel dizzy or lightheaded. Other times, the only feeling is the rapid heartbeat.

Your doctor can try to bring your heart back into a regular rhythm with medicines and other treatments.

Your heart is a muscular organ that pumps about 100,000 times a day to send oxygen-rich blood out to your body. It has four pumping chambers to do the job. The left and right atria are at the top, and the left and right ventricles are on the bottom.

Your heart also has something of a natural pacemaker. It’s called the sinoatrial node, or SA node, for short. It’s at the top of the heart and sends out electrical signals that keep it beating the right way.

The electrical signal from the SA node makes the muscles of the atria contract to pull blood into the ventricles. Then the signal moves down and causes the muscles of the ventricles to squeeze. That causes blood to go out to the body.

The heart beats like this in a familiar lub-dub pattern some 50 to 99 times a minute if you’re at rest.

The heart normally increases and decreases in speed based on signals that get sent to the SA node. During a bout of SVT, these signals do not occur normally.

Tachycardia is a faster-than-normal heart rate at rest. If you have this condition, your heart beats too quickly — more than 100 times a minute. The “supra” in supraventricular means above the ventricles.

With this condition, the fast heartbeat starts in the top chambers of the heart, the atria. When electrical signals in the atria fire off early, the atria contract too soon. That interrupts the main electrical signal coming from the SA node. This results in the heart beating very quickly through an abnormal and separate pathway.

This condition is divided into three types:

Atrioventricular nodal reentrant tachycardia is the most common form. If you have it, there’s an extra pathway in your heart that causes an electrical signal to circle around and around instead of moving down to the ventricles. This can trigger the rapid heartbeat.

Atrioventricular reciprocating tachycardia happens when an abnormal pathway links the atria and ventricles, causing the signal to move around and around in a big loop.

If you have the inherited condition called Wolff-Parkinson-White syndrome, you have this extra pathway. This condition can be serious. If it is part of your family history, have it checked.

Atrial tachycardia happens when a short circuit in the right or left atrium triggers a faulty electrical signal.

Bouts of any of these can last from a few seconds to a few hours. When SVT only happens from time to time, it’s called paroxysmal supraventricular tachycardia.

Most of the time, SVT happens without any obvious reason. It often starts when you are in your teens or early 20s.

Sometimes you are born with abnormal pathways or electrical circuits in your heart. Faulty circuits can also form out of scar tissue left behind after surgery.

Your heart is more likely to race if you:

Drink a lot of caffeine and/or alcohol
Smoke
Are under a lot of stress or are very tired
Take certain medicines, such as asthma drugs, decongestants, and some herbal diet remedies
Take drugs such as cocaine or methamphetamine, also called crystal meth

When your heart beats too quickly, it doesn’t have time to fully refill with blood in between beats. That means it can’t send enough blood out to your body. That can cause:

Chest pain
Dizziness
Fatigue
Shortness of breath

If you have symptoms, your doctor will ask you detailed questions.

They’ll want to know how old you were when you first noticed a problem. They’ll also ask when and how your symptoms began. That includes whether you were exercising when you noticed things such as a rapid pulse, dizziness or a hard time breathing.

Other things they’ll ask you about:

Whether the symptoms came on suddenly or slowly
What they feel like to you and how long they tend to last
Whether you’ve noticed that you’ve had a fast heartbeat after caffeine or stress
Whether you or anyone in your family has had heart problems or procedures

During your exam, your doctor will listen to your heart and lungs with a stethoscope. They might also:

Feel your thyroid gland on your neck
Get your temperature and measure your blood pressure
Take a small blood sample with a thin needle

EKG test

If your doctor suspects supraventricular tachycardia after hearing about your symptoms, examining you and running some basic tests, they might ask you to get an EKG. You may hear them call it an “electrocardiogram” or an ECG.

This test records your heart’s rhythm over time, so if it’s not beating as it should, it can reveal what the problem is. If you’re getting one, there’s nothing special you need to do ahead of time to get ready.

To set up the test, a nurse or technician will attach six sticky patches called electrodes on your chest and others on your arms and legs. If you have a hairy chest, an aide may need to shave small areas so they stay put.

Each one will go with a wire that leads to a machine. During the test, which takes just a few minutes, you’ll be asked to lie still and breathe normally.

Home monitoring

You might have symptoms just once in a while, so a single EKG in the doctor’s office may not reveal an abnormal heart rate.

In these cases, you might need to wear a device for longer so doctors can record your heart while you’re having symptoms. You may be sent home with one of the following:

A Holter monitor is a small, battery-powered EKG that records your heart’s activity for 24 to 48 hours. The device is about the size of a small camera and has little electrodes placed on your chest while you wear it. You can do most of your daily activities, but you shouldn’t bathe or shower.

An event monitor is also a portable EKG but might be more practical if you have symptoms less than once a day. You can wear it for longer than a Holter and press a button on it when you’re having symptoms. The monitor will record details only for the few minutes you’re feeling the fast heartbeat.

Your doctor may ask you to wear it for days or weeks.

Further tests

If you’re diagnosed based on the results of an EKG, you may need more tests to figure out what type of SVT you have and what’s causing it.

Often, this can include what’s called an “electrophysiology study” so that doctors can learn in more detail how the different sections of your heart are sending electrical signals to each other.

For this test, you are sedated at a hospital or clinic and soft, flexible wires are passed through your veins into your heart. You will need someone to drive you to and from your appointment. Talk to your doctor about how to prepare because this test is more involved.

One treatment for SVT uses medicine to slow the heartbeat.

If that doesn’t fix the problem for you, another option is called ablation. In this procedure, a surgeon burns the pathway that causes the abnormal electrical signals.

If you feel like your heart is fluttering and you have any of the symptoms listed above, make an appointment with your doctor to be tested.

Top Picks

clinical death from the point of view of medicine – Moscow 24, 06/09/2015

Photo: M24. ru/Mikhail Sipko

Woland’s mouth, perfectly describe the feelings of most people. Probably, there is no person who would not be afraid of death. But along with the big death, there is a small death – clinical. What is it, why people who have experienced clinical death often see the divine light and is it not a delayed path to paradise – in the material M24.ru.

Clinical death from the point of view of medicine

The problems of studying clinical death as a borderline state between life and death remain among the most important in modern medicine. Unraveling many of its mysteries is also difficult because many people who have experienced clinical death do not fully recover, and more than half of patients with a similar condition cannot be resuscitated, and they die for real – biologically.

So, clinical death is a condition accompanied by cardiac arrest, or asystole (a condition in which various parts of the heart stop contracting first, and then cardiac arrest occurs), respiratory arrest and deep, or beyond, cerebral coma. With the first two points, everything is clear, but about whom it is worth explaining in more detail. Usually doctors in Russia use the so-called Glasgow scale. According to the 15-point system, the reaction of opening the eyes, as well as motor and speech reactions, is evaluated. 15 points on this scale correspond to clear consciousness, and the minimum score – 3, when the brain does not respond to any kind of external influence, corresponds to transcendental coma.

After stopping breathing and cardiac activity, a person does not die immediately. Almost instantly, consciousness is turned off, because the brain does not receive oxygen and its oxygen starvation sets in. But nevertheless, in a short period of time, from three to six minutes, he can still be saved. Approximately three minutes after breathing stops, cell death begins in the cerebral cortex, the so-called decortication. The cerebral cortex is responsible for higher nervous activity and, after decortication, resuscitation measures, although they can be successful, a person can be doomed to a vegetative existence.

Photo: TASS/Sergey Bobylev

A few minutes later, cells of other parts of the brain begin to die – in the thalamus, hippocampus, cerebral hemispheres. The state in which all parts of the brain have lost functional neurons is called decerebration and actually corresponds to the concept of biological death. That is, the revival of people after decerebration is in principle possible, but a person will be doomed for the rest of his life to be on artificial lung ventilation and other life-sustaining procedures for a long time.

The fact is that the vital (vital – M24.ru) centers are located in the medulla oblongata, which regulates breathing, heartbeat, cardiovascular tone, as well as unconditioned reflexes like sneezing. With oxygen starvation, the medulla oblongata, which is actually a continuation of the spinal cord, dies one of the last sections of the brain. However, although the vital centers may not be damaged, by then decortication will have set in, making it impossible to return to normal life.

Other human organs such as the heart, lungs, liver and kidneys can survive much longer without oxygen. Therefore, one should not be surprised at the transplantation, for example, of kidneys taken from a patient with an already brain dead. Despite the death of the brain, the kidneys are still in working condition for some time. And the muscles and cells of the intestine live without oxygen for six hours.

Currently, methods have been developed that can increase the duration of clinical death up to two hours. This effect is achieved with the help of hypothermia, that is, artificial cooling of the body.

Photo: TASS/Vladimir Smirnov

As a rule (unless, of course, it happens in a clinic under the supervision of doctors), it is rather difficult to determine exactly when the cardiac arrest occurred. According to current regulations, doctors are required to carry out resuscitation measures: heart massage, artificial respiration for 30 minutes from the start. If during this time it was not possible to resuscitate the patient, then biological death is stated.

However, there are several signs of biological death that appear as early as 10–15 minutes after brain death. First, Beloglazov’s symptom appears (when pressing on the eyeball, the pupil becomes similar to a cat’s), and then the cornea of the eyes dries up. If these symptoms are present, resuscitation is not carried out.

How many people survive clinical death safely

It may seem that most people who find themselves in a state of near death come out of it safely. However, this is not the case, only three to four percent of patients can be resuscitated, after which they return to normal life and do not suffer from any mental disorders or loss of body functions.

Another six to seven percent of patients, being resuscitated, nevertheless do not fully recover, suffer from various brain lesions. The vast majority of patients die.

Such sad statistics are largely due to two reasons. The first of them – clinical death can occur not under the supervision of doctors, but, for example, in the country, from where the nearest hospital is at least half an hour away. In this case, the doctors will come when it will be impossible to save the person. Sometimes it is impossible to timely defibrillate when ventricular fibrillation occurs.

“Special Report”: Beyond the Boundaries

The second reason is the nature of the damage to the body during clinical death. When it comes to massive blood loss, resuscitation is almost always unsuccessful. The same applies to critical myocardial damage in a heart attack.

For example, if more than 40 percent of the myocardium is affected as a result of blockage of one of the coronary arteries, death is inevitable, because the body cannot live without heart muscles, no matter what resuscitation measures are taken.

Thus, it is possible to increase the survival rate in case of clinical death mainly by equipping crowded places with defibrillators, as well as by organizing flying ambulance crews in hard-to-reach areas.

Clinical death for patients

If clinical death for doctors is an emergency, in which it is necessary to urgently resort to resuscitation, then for patients it often seems like a path to the bright world. Many near-death survivors have reported seeing light at the end of a tunnel, some meeting their long-dead relatives, others looking at the earth from a bird’s eye view.

“I had a light (yes, I know how it sounds), and I seemed to see everything from the outside. It was bliss, or something. No pain for the first time in so much time. “someone else’s life and now I’m just slipping back into my skin, my life – the only one in which I’m comfortable. It’s a little tight, but it’s a pleasant tightness, like a frayed pair of jeans that you’ve been wearing for years,” says Lydia, one of the patients, who suffered clinical death.

Photo: M24.ru/Mikhail Sipko

It is this feature of clinical death, its ability to evoke vivid images, that is still the subject of much controversy. From a purely scientific point of view, what is happening is described quite simply: brain hypoxia occurs, which leads to hallucinations in the actual absence of consciousness. What kind of images arise in a person in this state is a strictly individual question. The mechanism of occurrence of hallucinations has not yet been fully elucidated.

At one time the endorphin theory was very popular. According to her, much of what people experience near death can be attributed to the release of endorphins due to extreme stress. Since endorphins are responsible for getting pleasure, and in particular even for orgasm, it is easy to guess that many people who survived clinical death considered ordinary life after it to be only a burdensome routine. However, in recent years, this theory has been debunked because researchers have found no evidence that endorphins are released during clinical death.

There is also a religious point of view. As, however, in any cases that are inexplicable from the standpoint of modern science. Many people (there are scientists among them) tend to believe that after death a person goes to heaven or hell, and the hallucinations that survivors of near-death experience saw are only proof that hell or heaven exists, like the afterlife in general. It is extremely difficult to give any assessment to these views.

Nevertheless, not all people experienced heavenly bliss at clinical death.

“I suffered clinical death twice in less than one month. I didn’t see anything. When they returned, I realized that I was nowhere, in non-existence. I didn’t have anything there. I concluded that there you get rid of everything by completely losing yourself , probably, together with the soul. Now death does not really bother me, but I enjoy life, “accountant Andrey cites his experience.

In general, studies have shown that at the time of human death, the body loses little in weight (literally a few grams). Adherents of religions hastened to assure mankind that at this moment the soul is separated from the human body. However, the scientific approach says that the weight of the human body changes due to chemical processes occurring in the brain at the time of death.

Physician’s opinion

Current standards require resuscitation within 30 minutes of the last heartbeat. Resuscitation stops when the human brain dies, namely on registration on the EEG. I have personally resuscitated a patient once who went into cardiac arrest. In my opinion, the stories of people who have experienced clinical death are, in most cases, a myth or fiction. I have never heard such stories from patients of our medical institution. As well as there were no such stories from colleagues.

Moreover, people tend to call clinical death completely different conditions. It is possible that the people who allegedly had it did not actually die, they just had a syncopal state, that is, fainting.

Cardiovascular diseases remain the main cause that leads to clinical death (as well as to death in general). Generally speaking, such statistics are not kept, but it must be clearly understood that clinical death occurs first, and then biological. Since the first place in mortality in Russia is occupied by diseases of the heart and blood vessels, it is logical to assume that they most often lead to clinical death.

Dmitry Yeletskov

anesthesiologist-resuscitator, Volgograd

One way or another, the phenomenon of near-death experience deserves careful study. And it is quite difficult for scientists, because in addition to the fact that it is necessary to establish which chemical processes in the brain lead to the appearance of certain hallucinations, it is also necessary to distinguish truth from fiction.

science coma patients scientific issues clinical death

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How light and darkness control our biological rhythms 3

Soyuz

Fresh number

Society

30.11.2020 17:45

Magazine “Schrödinger’s Cat” (Polina Ogorodnikova)

Domestic cats for some reason ask to eat from early morning, while office workers get hungry in the afternoon. Owls get food at night, and many residents of St. Petersburg dislike white nights because of insomnia. In each of us, the biological clock is ticking, but what exactly are the processes behind the movement of their arrows?

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Where the clock is hidden

The biological clock is one of the body’s systems, like the immune system or the cardiovascular system. All living beings need these clocks to synchronize with the rhythms of nature – to adapt to the change of day and night or the change of seasons. Many functions of the body are subject to the biological clock, including thermoregulation, blood pressure, and hormone production.

The clock that controls our body works on three levels. The first is a tiny clockwork hidden in every cage. For its discovery, American researchers Jeffrey Hall, Michael Rosbash and Michael Young received the 2017 Nobel Prize in Physiology or Medicine.

The main role in it is played by special clock proteins, which are synthesized in all cells with a nucleus – in animals, plants, and fungi. Part of the clock proteins is formed in the morning, activating the metabolism in the cell, the other – in the evening, inhibiting metabolism. This is how the daily, or circadian (from the Latin circa – about and dies – day), the rhythm of the work of an individual cell is set. And if one of the genes that synthesize clock proteins mutates, various rhythms of the body can be disturbed: sleep and wakefulness, motor activity, digestion. All these rhythms are connected – if a person does not sleep at night, this can lead not only to insomnia or depression, but also to diabetes, even to cancer.

Clocks are needed not only for every cell, but also for the organism as a whole. The rhythms of all cells are synchronized by a special hormonal gland of the brain called the pineal gland, or the pineal gland, which produces melatonin and serotonin – hormones that regulate our sleep and wakefulness, as well as appetite and mood. During daylight hours, the pineal gland produces the “happiness hormone” serotonin, and during the dark, serotonin is converted into the “sleep hormone” melatonin – it makes sleep deeper and more fulfilling.

In sufficient quantities, melatonin is produced only in the dark, even dim light reduces its production – turn off all the lamps and curtain the windows! And serotonin, on the contrary, needs light: the more light, the better the mood and the higher the performance.

Now let’s move on to the third level. The highest control center for all the rhythmic functions of the body is the suprachiasmatic nuclei of the hypothalamus. It is this group of nerve cells that receives a direct signal from the retina of the eye, which tells the clock what is now on the street: day or night. This small area in the diencephalon is the main generator of circadian rhythms, its neurons adjust to external light signals and control the pineal gland.

Everything has its time

02:00 – Deepest sleep

03:00 – Lowest blood pressure

04:30 – Lowest body temperature

06:45 – Most dramatic increase in blood pressure

07:30 – Stops secretion of melatonin

08:30 – Possible urge to defecate

10:00 – Highest readiness for action

14:30 – Maximum coordination

15:30 – Fastest reaction time

17:00 – Most active blood circulation and maximum muscle strength

18:30 – Highest blood pressure

19:00 – Highest body temperature

21:00 – Melatonin secretion begins

22:30 – Intestinal motility is suppressed

The source of this “schedule” is a book “Biohacking. A Guide to Unleashing the Body’s Full Potential” by Finnish researchers Sovijärvi Olli, Teemu Arin and Halmetoja Jaakko. But the time here is approximate – do not be discouraged if your “highest readiness for action” comes much later than ten in the morning!

How not to break your watch

What about owls and larks – do they have clocks set differently? Actually we don’t know. Maybe there are also “pigeons” – people who are active during the day, but sleepy in the morning and evening. But it is known for sure that, no matter what bird you are, you need to sleep at night and stay awake during the day. This is how we are genetically programmed, to live differently means to shorten life.

It is especially harmful to constantly change your routine. For example, scientists from the University of Michigan studied the database of the Nurses Health Study project – a long-term study of the health of more than 120,000 American nurses – and found that shift work (either day or night) increases the risk of ischemic stroke by 4% every five years. Other studies based on the same data have shown that working night shifts at least three nights a month for 15 years or more can increase the risk of colorectal cancer as well as breast cancer.

The reason is desynchronosis, that is, a mismatch of biological rhythms, which is a risk factor for the development of cardiovascular and oncological diseases. Desynchronosis is accompanied by prolonged increased fatigue, decreased performance and sleep disturbances.

One-time desynchronosis is known to anyone who has experienced jet lag – a syndrome that occurs when a person changes time zones abruptly, when a person crosses more than three or four time zones. After it comes the stage of resynchronization – when the biological rhythms of the body adjust to the new conditions. Interestingly, if the flight was from east to west, the average recovery speed will be 92 minutes a day, and if from west to east – it will be one and a half times lower, 57 minutes a day. It turns out that it is more difficult to adapt when flying to the east.

Our body also feels out of sync when we while away the time with a smartphone. It is the blue, short-wavelength part of the color spectrum that suppresses the production of melatonin. The melanopsin photopigment in the cells of the retina of the eye reacts to blue light – the opinion of the brain about whether it is night or day depends on it. When the light is red, the brain does not understand that it is daytime outside. But the screens of gadgets just emit a bright and cold blue light, in vain cheering the brain in the middle of the night.

For biohackers: mobile applications for taking care of circadian rhythms

Name: My circadian clock

What it works on: Android and IOS

What it can: helps norms analyze the rhythms of sleep, eating and physical activity

How it works. The course of the biological clock depends not only on light, but also on the time of training and eating. Moreover, the more predictable the daily routine is, the more successfully biorhythms will regulate important processes in the body: digestion, immune response, sleep, and much more. View your schedule in graph form, get recommendations, and help scientists at the Salk Institute for Biological Research in the United States learn more about the circadian rhythms of different people using the mobile application. For the first two weeks, it will carefully collect information about the subject, and then it will begin to instill good habits – for example, do not skip lunch at work and go to bed on time.

What is it called: Twilight

What it works on: Android

What it can do: prevents gadgets from spoiling sleep

How it works. From a medical point of view, life in pink glasses can be quite useful. But it is even better to build a red or orange filter between the eyes and gadget screens. It is useful to observe such a regimen in the evenings so that the blue spectrum does not once again lead to the production of melanopsin, which signals the biological clock that it is daytime – time to be awake. To reduce the harmful effects of blue screens, a mobile application will help, which will make the colors of the display warmer in the evening. By the way, in many modern smartphones this function is included in the standard settings.

What it’s called: Lux Light Meter Free