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.)

SVT is the most common heart rhythm problem in children. Sometimes, it goes away on its own early in life. However, if your child has SVT after age 1, the chance that it will go away on its own is low.

  • The heart has 4 chambers (spaces that hold blood): 2 atria at the top and 2 ventricles at the bottom. A complex electrical system makes these chambers squeeze and relax, at the right time and in the right order, to pump blood. A heartbeat starts in the right atrium when a group of cells (sinus node) sends an electrical signal.

  • In SVT, an overly fast heartbeat comes from a faster-beating (electrically overactive) area of the atria or from a “short circuit” of electricity involving the atria.

    SVT typically happens in distinct episodes. How often these episodes happen and how long they last are different from one person to another. Short episodes usually do not bother the person much. But if the fast heartbeat continues too long, the heart can become tired, which can be dangerous.

Supraventricular Tachycardia at Seattle Children’s

    • Seattle Children’s team of 40+ pediatric cardiologists diagnoses and treats SVT in children of all ages, from newborns to adolescents.
    • Our Arrhythmia Program includes 3 full-time pediatric electrophysiologists, more than anywhere else in the region. After their training in pediatric cardiology, they have further subspecialty training in dealing with cardiac arrhythmias, like SVT. The Arrhythmia Program is also supported by a team of specialty technicians and nurses who know how to deal with these conditions.
    • We offer a full range of diagnostic procedures and treatments. Along with using heart medicines, we have deep experience with radiofrequency ablation and cryoablation procedures in children who need them to correct an abnormal heart rhythm.
    • If your developing baby is diagnosed with SVT before birth, our Prenatal Diagnosis and Treatment team works closely with you and your family to plan and prepare for the care your baby will need.
    • Your child’s treatment plan is custom-made for them. Some children with SVT do not need treatment, and others do. We closely watch your child’s needs to make sure they get the care that is right for them at every age.
    • If your child was born with SVT, we have a special Adult Congenital Heart Disease Program to meet your child’s long-term healthcare needs. This program, shared with the University of Washington, transitions your child to adult care when they are ready.
    • We are committed to your child’s overall health and well-being and to helping your child live a full and active life.
    • Whatever types of care your child needs, we will help your family through this experience. We will discuss your child’s condition and treatment options in ways you understand and involve you in every decision.
    • Our nurses are experienced at supporting families with SVT. They help manage your child’s care and teach you and your child about this condition.
    • Our child life specialists know how to help children understand their illnesses and treatments in ways that make sense for their age.
    • Seattle Children’s has many resources, from financial to spiritual, to support your child and your family and make the journey as smooth as possible. We regularly see families who travel from other states and countries to come to our Arrhythmia Program.
    • Read more about the supportive care we offer.
    • Doctors at Seattle Children’s are working to advance treatment for SVT and enhance the quality of life for children with this condition.
    • We were the first institution in the region to routinely offer cryoablation for children, greatly increasing the safety of ablation for SVT.
    • Seattle Children’s is one of the few institutions in the region to offer “zero fluoro” or “minimal fluoro” ablation. This means we use techniques – many that we developed – to expose your child to little or no X-ray radiation. Most places use fluoroscopy during ablation.
    • Dr. Stephen Seslar has been part of creating international databases to track information about SVT ablation procedures. These databases help doctors learn more about which methods work best.
    • Dr. Terrence Chun has a special interest in developing techniques to improve the safety and accuracy of ablation procedures. He has been invited to lecture on unique aspects of SVT ablation in children.

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 child’s 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 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.

  • Holter monitor can record your child’s heart’s activity for 24 hours.
  • An event recorder can be turned on by your child when they feel a problem with their heart rhythm.

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

Treating Supraventricular Tachycardia

Children with SVT do not always need treatment. Often, this type of fast heartbeat does not cause any problems. If SVT does not happen to your child often and symptoms do not bother them, they may only need to have regular checkups in the clinic.

But sometimes SVT keeps the heart from pumping the right amount of blood to the brain or other organs. This can be dangerous. Also, symptoms of SVT can get in the way of athletic activity and even everyday activities. So, it is important to have your child’s heart checked by a doctor who can offer treatment if your child needs it.


Your child may need treatment if they have SVT that causes symptoms, happens often or lasts for a while. In some cases, doctors treat SVT first with medicines that correct the heart rate, like beta-blockers. This can decrease how often episodes happen.


If medicine does not control SVT well enough or your child does not want to take medicine, doctors may perform an electrophysiology study to figure out the exact type of SVT and perform an ablation.

An ablation is a procedure that uses a thin plastic tube (catheter) to destroy the abnormal tissue that causes the rapid heartbeat. Traditionally, doctors did this with a catheter that used radiofrequency energy to burn (cauterize) the abnormal tissue.

Now, doctors sometimes use cryoablation. This method destroys the tissue by freezing it. This newer 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 method is best for your child.

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

Contact Us 

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

Providers, see how to refer a patient.

Related Links

Paying for Care

Learn about paying for care at Seattle Children’s, including insurance coverage, billing and financial assistance.

For Healthcare Professionals