SVT (Supra + ventricular + tachycardia) in Babies

What is SVT?

SVT is an abnormal heart rhythm. In this case, the heart suddenly beats much faster than normal. It is the most common cause of too fast heart rhythms in babies and young children.

When the heart beats much faster because of SVT, we call this an episode of SVT. Episodes of SVT often only last for a short time (maybe a few minutes). Sometimes they last longer.

SVT often seen in very young babies, usually with otherwise normal hearts, and the heart rate is usually more than 220 beats per minute. This is caused by extra electrical signals in your baby’s heart.

Most babies stop having episodes of SVT by the time they are 1 year old. But they may come back as they get older.

How serious is SVT?

It is not often a life-threatening problem. If an episode goes on for a long time, your baby’s heart muscle may get tired. This means the heart won’t pump as well as normal. Your child may get sick if no one sees that SVT is going on for a long time (usually hours).

If an episode of SVT last for a long time and your baby is not acting well, you must take your baby to the emergency room. Your baby may need an IV medicine or a treatment called electrical cardioversion to help stop the SVT.

How is SVT diagnosed?

We use electrocardiogram (ECG or EKG) to check for SVT. This is a painless test that records the rhythm and electrical activity of your baby’s heart. It will show SVT during an episode of rapid heart rate.

How can I tell if my baby’s heart is racing?

If your baby:

• Looks pale, feels cool to the touch

• Is tired or hard to wake up

• Is feeding poorly

• Is very irritable, fussy, and breathing faster or harder than normal

Your doctor or nurse may show you how to check your baby’s pulse. If so, count your baby’s heart rate with a stethoscope or feel your child’s chest or pulse for 1 minute. If your baby’s heart is beating too fast, you may not be able to count the heart rate.

How can I slow my baby’s racing heart?

Vagal maneuvers. These attempt to stimulate the vagus nerve to help stop an episode of heart racing. They work by interrupting the electrical signals that are causing SVT.

• Put a bag of frozen food (such as peas or corn) or a cold, wet wash cloth or paper towel over most of your baby’s face. Do not do this for more than 10-15 seconds. 

• Do not cover your baby’s nostrils or mouth.  Only do this if you have been taught by a medical provider.

When do I follow up with the doctor?

Yes. You should follow up with a Pediatric Cardiologist in a clinic until cleared by that doctor.