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Supraventricular tachycardia or SVT is an abnormally fast heart rhythm. This abnormal heart rhythm starts in the upper chambers, or the atria, of the heart.

“Ssupraventricular” means above the ventricles. “Tachy” means fast, and “cardia” means heart. Typically, the heart’s electrical system precisely controls the rhythm and rate at which the heart beats. In supraventricular tachycardia, abnormal electrical connections, or abnormal firing of the links cause the heart to beat too fast.

What is supraventricular tachycardia?

Typically, during supraventricular tachycardia episodes, the heart speeds up to rates of 150-200 beats per minute. Occasionally, the heart speeds up to a rate as high as 300 bpm. After some time, the heart returns to a normal rate, which is 60 to 100 beats per minute, on its own or after treatment, depending from patient to patient.[1]

Supraventricular tachycardia or paroxysmal supraventricular tachycardia, or paroxysmal atrial tachycardia are different names for the same condition.

If you're suffering from this condition, you're not alone. The incidence is 35 per 10,000 person-years or 2.29 per 1000 persons. Atrioventricular nodal reentrant tachycardia is the most common non-sinus tachydysrhythmia in young adults, and women have two times more likely to develop paroxysmal SVT in comparison to men. In addition, older individuals have five times higher chance of developing non-sinus tachydysrhythmia compared to younger individuals.[1]

What are the different types of supraventricular tachycardia?

Sometimes it is normal to have an increased heart rate, such as during exercise, with a high fever, or under stress. This fast heart rate is sinus tachycardia and noting abnormal that should worry you. Sinus tachycardia is a typical response to the stressors mentioned above and is not considered a medical problem. However, supraventricular tachycardias are abnormal, and there are few types:

  • Atrioventricular nodal reentrant tachycardia or AVNRT is the first one, which is the most common type, after atrial fibrillation.
  • Atrioventricular reciprocating tachycardia or AVRT, including Wolff-Parkinson-White syndrome, is another type.[1]

What causes supraventricular tachycardia?

Supraventricular tachycardia usually results from abnormal electrical connections in the heart that short-circuits the standard electrical system, but what causes these abnormal pathways is not clear.

In the case of Wolff-Parkinson-White syndrome, the condition is probably there as an inherited disorder. Overly high levels of the heart medication digoxin, such as Lanoxicaps or Lanoxin, can cause supraventricular tachycardia as well. Rarely, conditions that affect the lungs, such as chronic obstructive pulmonary disease, pneumonia, heart failure, and pulmonary embolism, can also cause a type of SVT called multifocal atrial tachycardia or MAT.[2]

There are other factors, besides age and sex, that contribute to the development of some types of supraventricular tachycardia, and they are coronary artery disease and many other heart-related problems, problems with your thyroid glands, either having an overactive or underactive thyroid gland, (illegal) drugs, supplements and even nicotine, anxiety or emotional stress, physical fatigue, diabetes, obstructive sleep apnea. 

What are the symptoms of supraventricular tachycardia?

With supraventricular tachycardia, you may have palpitations, an uncomfortable feeling that your heart is racing or pounding in your chest. You may also notice that your pulse is rapid or see or feel your pulse pounding, especially at the neck where large arteries are close to the skin. Additional symptoms include feeling dizzy or lightheaded, near-fainting or fainting as syncope, shortness of breath, chest pain, throat tightness, and sweating.[3]

How to diagnose supraventricular tachycardia

A description of your symptoms is one of the most important clues in diagnosing this disease. Your doctor will ask what, if anything triggers the episodes you experience. He will also wish to know how long do the episodes last, and whether anything stops them. Because supraventricular tachycardia is a problem with your heart’s electrical system, the most important test is the electrocardiogram. An ECG measures the heart’s electrical activity and can record any supraventricular tachycardia episodes you might experience. An ECG usually goes along with a medical history and physical examination, lab tests, and a chest X-ray. If you do not have an episode of supraventricular tachycardia while at the doctor’s office, your doctor will probably ask you to wear a portable ECG to record your heart rhythm on a continuous basis, which is a perfect solution if you're this type of patient. 

This portable ECG refers to by several names including ambulatory electrocardiogram, ambulatory ECG, Holter monitoring, 24-hour ECG, or cardiac event monitoring. Portable ECG will record your heart rhythm while you are having supraventricular tachycardia even when you are not at your doctor’s office.

Your doctor may also recommend an electrophysiology study, where he will insert flexible wires into a vein, usually in the groin, and thread into the heart. Electrodes at the end of the wires send information about your heart’s electrical activity. In this way, the EP study can map any abnormal electrical activity. It is also possible to identify the type of supraventricular tachycardia you have, and guide treatment.

Treatment of supraventricular tachycardia

Some supraventricular tachycardias do not cause symptoms and may not need any treatment at all. However, when symptoms do occur, the doctor will probably recommend a treatment. 

Your doctor may teach you how to perform vagal maneuvers, such as the Valsalva maneuver or coughing. You could learn this to slow your heart rate. If vagal maneuvers do not work, you could take a fast-acting intravenous medication such as adenosine or verapamil. If the arrhythmia does not stop and symptoms are severe, electrical cardioversion, with a brief electric shock to the heart to reset the heart rhythm, may be the only solution. If supraventricular tachycardia recurs, you may need long-term treatment, including beta-blocker or other antiarrhythmic medications, to slow the heart rate. Catheter ablation is common during an electrophysiology study. Radio waves should go directly through the catheter to the specific heart tissue that is generating abnormal electrical impulses. The radio waves cause the area of the heart muscle to heat and selectively destroyed, eliminating the SVT.[1, 4]

Important precautions

Avoid consuming alcohol, coffee, and chocolate, as substances in these products can provoke episodes of supraventricular tachycardia.

Besides, nonprescription decongestants, herbal remedies, and diet pills often contain stimulants, so avoid those as well. 

Illegal drugs, such as cocaine, ecstasy, or methamphetamine, also can trigger episodes of supraventricular tachycardia. It is essential to be aware of which substances affect you and to avoid them to prevent incidents of irregular heartbeats.

What increases the risk supraventricular tachycardia and long-term side effects?

Some lifestyle factors can increase your risk of having an episode of supraventricular tachycardia, so you need to avoid them throughout your life. These risk factors are overuse of caffeine, nicotine, alcohol, or use of illegal drugs, such as cocaine or methamphetamine. Doctors also warn against using nonprescription diet pills because many contain caffeine, ephedra, ephedrine, the herb ma huang, or other stimulants that can cause you to have episodes of supraventricular tachycardia.[1,2] 

You should immediately call 911 or seek emergency services immediately if you have a fast heart rate and you faint or feel as though you are going to faint.

If you have severe shortness of breath, chest pain, symptoms of a heart attack or stroke, you should also report it. 

Call your health professional if you are having fluttering in your chest that persists and does not go away quickly or if you have frequent palpitations.

Read More: Supraventricular Tachycardia: Diagnosis & Therapy

Living with supraventricular tachycardia

Home care for people who suffer from supraventricular tachycardia includes monitoring this condition and trying to slow the heart when a fast heart rate occurs. To control your condition, you may find it helpful to keep a diary of your heart rate and your symptoms during the day. Check your pulse when you experience the symptoms, and record the information in your journal to show it to your doctor during the exam. Be aware that if your heart is beating rapidly, it may be difficult to feel the pulse and get an accurate count of the actual heart rate.

By keeping a diary of your heart rate and symptoms, you may be able to identify stressors that might trigger your attacks. Common triggers are lack of sleep, drinking alcohol, or overeating, so try to tell what in your case most commonly triggers your episodes. Avoiding anything that might harm you, you will be able to control this condition. For people who are especially sensitive, even decaffeinated teas or coffee can cause supraventricular tachycardia episodes as well. [1,2]

You should also avoid decongestants that contain stimulants, including oxymetazoline, such as Afrin and other brands, and pseudoephedrine, such as Sudafed, Actifed, and other brands as well. 

To live all your life with a diagnosis of supraventricular tachycardia, you must follow suggested instructions and prevent supraventricular  tachycardia episodes whenever possible.

Also, if you have these symptoms you might need medications to treat supraventricular tachycardia. Beta-blockers are the first choice, followed by calcium channel blockers, and an electrophysiologist can often correct this problem. An electrophysiologist performs a procedure whereby a catheter is inserted into the heart; the area responsible for the tachycardia is stimulated and found. After this, the area is bombarded by radio frequency waves from the catheter changing the SVT. There are risks, and the procedure is expensive, but it helps in 80-90% of all cases. For some patients Atenolol works very well, and there do not appear to be any long-term side effects of beta-blockers that differ from the short-term ones.

If supraventricular tachycardia is untreated, over time it may weaken your heart and can lead to heart failure. This is particularly true, if you have other coexisting medical conditions. In extreme cases, an episode of supraventricular tachycardia may cause unconsciousness or cardiac arrest.