Overview

Supraventricular tachycardia (SVT) is a type of irregular heartbeat, also called an arrhythmia. It's a very fast or erratic heartbeat that affects the heart's upper chambers. SVT also is called paroxysmal supraventricular tachycardia.

The typical heart beats about 60 to 100 times a minute. During SVT, the heart beats about 150 to 220 times a minute. Sometimes it beats faster or slower.

Most people with supraventricular tachycardia don't need treatment. If you do, options may include specific actions or movements that a healthcare professional recommends, and medicines. Some people need treatment to reset the heart rhythm or block faulty signals that cause the irregular heartbeat. Others need a device to control the heartbeat.

Types

Supraventricular tachycardia (SVT) falls into three main groups:

  • Atrioventricular nodal reentrant tachycardia (AVNRT). This is the most common type of supraventricular tachycardia.
  • Atrioventricular reciprocating tachycardia (AVRT). This is the second most common type of supraventricular tachycardia. Most often, it's seen in younger people.
  • Atrial tachycardia. This type of SVT appears to be more common in people who have heart disease. Atrial tachycardia doesn't involve the atrioventricular AV node, which is a small amount of tissue between the upper and lower chambers of the heart.

Other types of supraventricular tachycardia include:

  • Sinus nodal reentrant tachycardia (SNRT).
  • Inappropriate sinus tachycardia (IST).
  • Multifocal atrial tachycardia (MAT).
  • Junctional ectopic tachycardia (JET).
  • Nonparoxysmal junctional tachycardia (NPJT).

Symptoms

The main symptom of supraventricular tachycardia (SVT) is a very fast heartbeat. It may last for a few minutes to a few days. With SVT, the heart beats more than 100 times a minute. It may beat 150 to 220 times a minute. The fast heartbeat may come and go quickly.

Symptoms of supraventricular tachycardia may include:

  • Pounding or fluttering feelings in the chest, called palpitations.
  • A pounding feeling in the neck.
  • Chest pain.
  • Fainting or almost fainting.
  • A lightheaded or dizzy feeling.
  • Shortness of breath.
  • Sweating.
  • Weakness or extreme tiredness.

Some people with SVT don't notice any symptoms.

In infants and very young children, symptoms of SVT may be vague. The symptoms can include sweating, poor feeding, a change in skin color and a fast pulse. If your infant or young child has any of these symptoms, talk with a healthcare professional.

When to see a doctor

Supraventricular tachycardia (SVT) is usually not life-threatening unless you have heart damage or another heart condition. But if SVT is severe, the irregular heartbeat may cause the sudden loss of all heart activity. This is called sudden cardiac arrest.

Call a healthcare professional if you have a very fast heartbeat for the first time. Also call if an irregular heartbeat lasts longer than a few seconds.

Symptoms of SVT may be linked to a serious health condition. Call 911 or your local emergency number if you have a very fast heartbeat that lasts for more than a few minutes. Or call if a fast heartbeat occurs with these symptoms:

  • Chest pain.
  • Dizziness or near fainting.
  • Shortness of breath.
  • Weakness.

Causes

Supraventricular tachycardia (SVT) is caused by faulty signaling in the heart. Electrical signals in the heart control the heartbeat.

In SVT, a change in these signals causes the heartbeat to start too early in the heart's upper chambers. When this happens, the heartbeat speeds up. The heart can't fill with blood properly. Symptoms such as lightheadedness or dizziness can happen.

How does the heart beat?

To understand the cause of supraventricular tachycardia (SVT), it might help to know how the heart usually works.

The heart has four chambers:

  • The two upper chambers are called the atria.
  • The two lower chambers are called the ventricles.

Inside the upper right heart chamber is a group of cells called the sinus node. The sinus node makes the signals that start each heartbeat.

The signals move across the upper heart chambers. Then the signals arrive at a group of cells called the AV node, where they usually slow down. The signals then go to the lower heart chambers.

In a healthy heart, this heart signaling process usually goes smoothly. Most often, the heart beats about 60 to 100 times a minute at rest. But in SVT, the heart beats faster than 100 beats a minute. The heart may beat 150 to 220 times a minute.

Risk factors

Supraventricular tachycardia (SVT) is the most common type of irregular heartbeat in infants and children. It also tends to happen more often in women, especially during pregnancy.

Health conditions or treatments that may raise the risk of SVT include:

  • Coronary artery disease, heart valve disease, heart failure and other heart diseases.
  • Long-term conditions that affect the lungs and airways.
  • A heart condition present at birth, also called a congenital heart defect.
  • Past heart surgery.
  • A sleep disorder called obstructive sleep apnea.
  • Thyroid disease.
  • Diabetes in which blood sugar levels stay too high.
  • Some medicines, including those used to treat asthma, allergies and colds.

Other things that may raise the risk of SVT include:

  • Stress.
  • Too much caffeine.
  • Too much alcohol use. That's 15 or more drinks a week for men and eight or more drinks a week for women. It also can mean five drinks on any given day for men and four drinks on any day for women.
  • Family members with SVT.
  • Smoking and nicotine use.
  • Stimulant drugs, including cocaine and methamphetamine.

Complications

Without treatment, frequent bouts of supraventricular tachycardia (SVT) over time may weaken the heart and lead to complications such as heart failure. The risk of this goes up for people who also have other health conditions.

When the heart beats too fast, it may not send enough blood to the body. As a result, the organs and tissues may not get enough oxygen.

A serious bout of SVT may cause fainting or a sudden loss of all heart activity, called sudden cardiac arrest.

Prevention

The same lifestyle changes used to manage supraventricular tachycardia (SVT) also may help prevent it. Try these tips.

  • Follow a heart-healthy lifestyle. Eat a nutritious diet, don't smoke, get regular exercise and manage stress. Also, aim to get 7 to 9 hours of sleep each night if you're an adult. Children and babies need more sleep depending on their age.
  • Don't use a lot of caffeine. Stay away from having lots of caffeine. For most people with supraventricular tachycardia, moderate amounts of caffeine do not trigger bouts of SVT.
  • Keep a notebook or journal of when symptoms happen. Include the symptoms, your heart rate and what you were doing at the time of the fast heartbeat. This information can help you learn the things that trigger the very fast heartbeat.
  • Use medicines carefully. Some medicines may have stimulants in them that can trigger SVT. These include some medicines bought without a prescription.
  • Work with your healthcare team. Manage any health concerns you have, including high blood sugar, cholesterol or blood pressure.
By Mayo Clinic Staff