Supraventricular Tachycardia

What is supraventricular tachycardia?

Supraventricular tachycardia (pronounced sue-prah-ven-TRIK-yu-lar tack-ih-CAR-dee-ah) is a problem with the heart’s electrical activity that causes an irregular heart rhythm. Tachycardia is a broad term used to describe fast heart rates and rhythms. (“Tachy” means fast and “cardia” means heart.)

There are 4 chambers in the heart — the top 2 are the atria, and the lower 2 are the ventricles. The heart uses an electrical system to make the muscle walls of the atria and ventricles pump blood, which you notice as your heartbeat.

The heartbeat is the squeezing and relaxing of the muscle walls at the right times in the right order. Normally, the heartbeat starts in the right atrium when a group of cells called the sinus node sends an electrical signal. This is the heart’s rhythm monitor (pacemaker).

There are many different types of tachycardia. Sinus tachycardia is a normal increase in heart rate in response to activity (running or playing), fear or excitement. Supraventricular tachycardia (SVT) is one type of tachycardia. In SVT, the heartbeat comes from either a faster beating (electrically overactive) area of the atria or a “short circuit” of electricity involving the atria. Each of these causes an overly fast heartbeat. SVT typically happens in distinct episodes. How often these episodes occur and how long they last are different from one person to another.

  • SVT is the most common heart rhythm problem in children. It occurs in as many as 1 in 250 otherwise healthy children.

    Sometimes, SVT goes away on its own early in life. If your child has SVT after age 1, the chance that it will go away on its own is low.

    Short episodes usually don’t bother the person much. But if the fast heartbeat continues too long, the heart can become fatigued, which can be dangerous.

    Tests for a heart rhythm problem usually happen after your child (or a caregiver) notices a fast heartbeat. There are many different causes of a fast heartbeat. It is important to have a heart doctor (cardiologist) confirm the diagnosis of SVT and discuss treatment options.

    Children with SVT don’t always need treatment. In general, those with SVT that doesn’t happen often and is well tolerated may simply need to be monitored. Those with more symptoms may take medicines that can decrease the frequency of episodes. There are also procedures that, in most cases, can cure the rhythm problem.

Supraventricular Tachycardia at Seattle Children’s


  • Our Heart Center is the top-ranked cardiology and cardiac surgery program in the Northwest and among the best in the nation, according to U.S. News & World Report. With more than 40 pediatric cardiologists, we have experience diagnosing and treating every kind of heart problem.

    Our heart team has treated many children with SVT. We have extensive experience providing the treatment these patients require through our Arrhythmia Program.

    Seattle Children’s has been treating children since 1907. Our team members are experts in their fields and in meeting the unique needs of children. For example, the doctors who give your child anesthesia (sedation) are board certified in pediatric anesthesiology. This means they have extra years of training in how to take care of kids. Our child life specialists know how to help children understand their illnesses and treatments in ways that make sense for their age.

  • When you come to Seattle Children’s, a team of people will take care of your child. Along with your child’s heart doctor (cardiologist), you are connected with heart rhythm specialists (pediatric electrophysiologists), child life specialists, social workers and others, if their expertise is needed.

    We work together to meet all of your child’s health needs and help your family through this experience. We’ll discuss treatments in ways you can understand and involve you in every decision.

    Read more about the supportive care we offer.

Symptoms of Supraventricular Tachycardia

Children with SVT may feel like their heart is racing or pounding. If their heart cannot pump enough blood and oxygen to their brain, they may feel lightheaded or dizzy. Rarely, children with SVT have no symptoms.

Infants and very young children may not be able to communicate symptoms of SVT. But, in some cases, a caregiver might notice a racing heartbeat.

Diagnosing Supraventricular Tachycardia

To diagnose this condition, your doctor will examine your child, check their heartbeat and use a stethoscope to listen to their heart. The doctor will ask for details about any symptoms your child has, their health history and your family health history.

To learn about the electrical activity (rhythm) in your child’s heart, the doctor will use an electrocardiogram (ECG). If an abnormal heartbeat does not happen during this test, your child may need to wear a portable rhythm-monitoring device at home. A device called a Holter monitor can record your child’s heart’s activity for 24 hours. Another device, called an event recorder, can be turned on by your child when they feel a problem with their heart rhythm. SVT that tends to happen only once in a while can be hard to diagnose.

To get more information about how your child’s heart looks and works, they may need other tests, like a chest X-rayexercise testing or an echocardiogram. A rhythm specialist (pediatric electrophysiologist) may also use electrophysiology studies to help detect the cause of a child’s abnormal rhythm (arrhythmia) and decide which treatment to use.

Treating Supraventricular Tachycardia

Your child may not need any treatment for SVT. Often, this type of fast heartbeat does not cause any problems. But sometimes, it keeps the heart from pumping the right amount of blood to the brain or other organs. This can be dangerous.

Symptoms of SVT can also get in the way of athletic activity and even everyday activities. It’s important to have your child’s heart checked by a doctor who can offer treatment, if your child needs it.

If diagnosed with rheumatic fever, your child will need follow-up care with a heart doctor (pediatric cardiologist) to check for long-term damage to the heart (rheumatic heart disease).

  • Your child may need treatment if they have SVT that causes symptoms, that happens often or that lasts for a while.

    In some cases, doctors treat SVT first with medicines that correct the heart rate, like beta-blockers. If medicine does not control SVT well enough or the patient doesn’t want to take medicine, doctors may perform an electrophysiology study to identify the exact type of SVT and perform an ablation. An ablation is a procedure that uses a spaghetti-like plastic tube (catheter) to destroy the tissue that causes the rapid heartbeat.

    Read more about the treatment options we offer through our Arrhythmia Program and in our Cardiac Catheterization Lab.

  • Doctors treat SVT by removing the heart tissue that is causing the irregular rhythm. This procedure is called ablation.

    Traditionally, ablation procedures have been performed with a small tube (catheter) that burned (cauterized) the abnormal tissue. This uses energy called radiofrequency energy.

    Now, a catheter that uses an energy called cryoablation is used. Cryoablation destroys the tissue by freezing it instead of burning it. This new technique may be safer. It also seems that the heart tissue is able to recover better after cryoablation. Talk with your heart doctor about which energy type is best for your child.

Contact Us 

Contact the Heart Center at 206-987-2515 to request an appointment, a second opinion or more information.

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