Supraventricular tachycardia (SVT) is a type of arrhythmia (abnormal heart rhythm) that causes your child's heart to beat very fast. SVT doesn't always cause symptoms. If it does cause symptoms, the most common are fussiness or poor feeding in babies and pounding or irregular heartbeats in older kids and teens.

Your child's cardiologist (heart specialist) may prescribe medicine to prevent another episode of SVT. Or they may teach you and other caregivers what to do if your child has another episode of SVT.

Most children with SVT have a normal heart. Sometimes SVT goes away on its own. In some kids, cardiologists can do a special procedure to stop the SVT.

Here's how to care for your child.

Follow your cardiologist's instructions for:

• Giving your child any recommended medicines. Be sure to ask if there are any side effects that you need to watch for.
• Whether you need to check your child's heart rate.
• What to do if your child has a very fast heart rate or has symptoms of SVT, such as poor feeding, tiredness, or fussiness (in babies) or a pounding or irregular heartbeat, shortness of breath, tiredness, dizziness, fainting, or chest pain (in older kids and teens).
• Making any follow-up appointments with the cardiologist for more testing.
• Getting trained in CPR. Ask your healthcare provider how to find a class.

If your older child or teen has supraventricular tachycardia, and you have been instructed by your cardiologist to try to treat it at home, have your child:

• Try to blow out against a pinched nose for 15–20 seconds.
• Blow into a straw while you cover the other end of it.
• Bend over (while seated) and put their head between their knees for 15–20 seconds.

If your child's heart rate doesn't come down after trying these treatments, or if your child becomes dizzy, weak, pale, or sleepy, call 911 right away or go to the ER.

Your older child or teen had SVT, but it got better after using the care instructions above. This way the specialist can make a note of it in your child's medical record. 

• Your baby has a high heart rate or symptoms of SVT, such as fussiness that is out of the ordinary for them, poor feeding, or tiredness.
• Your older child or teen:
  • Has a rapid heartbeat that's not corrected by using the care instructions above
  • Has a pounding or irregular heartbeat, shortness of breath, tiredness, dizziness, fainting, or chest pain

If your child stops breathing, call 911 first, then start CPR (cardiopulmonary resuscitation).

How does supraventricular tachycardia happen? The heart has electric signals that tell it to beat. These electric signals follow a path from the heart's top chambers (the atria) down to the bottom chambers (the ventricles). An area in the top chambers, called the sinus node, keeps the heart beating at a normal rate. Sometimes the signals can "short circuit," causing the heart to beat faster. This fast heartbeat is supraventricular tachycardia.

Who gets supraventricular tachycardia? Most kids with supraventricular tachycardia have normal hearts, but children born with heart disease are more likely to get SVT. Some causes of supraventricular tachycardia can run in families (such as Wolff-Parkinson-White syndrome, which happens when someone has an extra electrical pathway in the heart; that condition can lead to a fast heartbeat).

What other treatments are there for supraventricular tachycardia? Besides prescribing medicine, a cardiologist may be able to do an ablation, a procedure that uses energy to remove the abnormal electrical pathway that is causing SVT.