Supraventricular Tachycardia (SVT) in Children
Supraventricular tachycardia, most commonly referred to as SVT, is the most common type of abnormal fast heart rhythms in children. Learn about Normal Conduction System. SVT is a broad term and includes many different forms all with similar type of symptoms.
The type of SVT is classified based on the path of electrical signal during the tachycardia. SVT begins in the upper chambers of the heart, (Atria), travels through an abnormal electrical circuit within the AV node (AV node reentrant tachycardia or AVNRT), or, through an extra abnormal pathway, called an accessory pathway or bypass tract (AV reentrant tachycardia or AVRT). An accessory pathway is an extra band of tissue/fibers that connect the atria to the ventricles.
Signs and Symptoms
Signs and symptoms of AVNRT include:
- Palpitations- the feeling of a rapid or erratic heart beat while sitting quietly or at rest or faster than normal heart rate with exercise
- Fainting (syncope)
- Chest pain
- Shortness of breath
- Heart pounding
- Feeling pulsations in your throat
- Sudden sense of a fast heart rate and a sudden end to the to the fast heart rate
- Toddlers and younger (when verbal) children may describe symptoms as their "heart beeping"
Infants cannot communicate their symptoms but they may exhibit signs of:
- Poor feeding
- Profuse sweating with feeding
- Being Listless/lethargic
- Appearing generally ill
- Breathing faster than normal
These symptoms can be brief but can also last for several hours.
Your doctor or health care team may refer you to a pediatric electrophysiologist (EP) or someone who specializes in children with heart rhythm disorders. Your EP team may use one or multiple tools to help diagnose AVNRT. A heart monitor during the symptoms is the best way to diagnose SVT and can include:
Your EP team may prescribe medication for treatment. Medication is not a cure but can decrease the number of episodes and help to control symptoms. In most cases, these medications are taken daily.
The vagus nerve is a nerve in the body that can affect the heart rate. When it is stimulated, the heart rate can slow down. Certain maneuvers, called vagal maneuvers, are designed to stop the SVT by stimulating the vagus nerve.
For older children, vagal maneuvers include:
- "Bearing down": pretending as if you are having a bowel movement - blowing on your thumb
- Doing a headstand, if you already know how to do one.
- Putting very cold water/ice on your face
For babies or young children who can't follow these directions, vagal maneuvers include:
- Place an ice pack over the eyes for 15-30 sec. A frozen bag of vegetables works really well. Avoid placing anything around the infant's nose.
- Pressing the infant's knees to the chest for 15-30 seconds
If the episode is lasts a long time, your child is ill or has fainted or you don't feel comfortable doing these maneuvers at home, you can call your doctor or go to an emergency room. If your child appears very ill, you should call 911. In the emergency room, your child may receive an intravenous (IV) medication to stop the SVT. If the medication is not successful and your child remains ill, a brief electrical shock (cardioversion), may be required. This is usually done while your child is sedated.
Typically, children and adolescents with AVNRT do not have activity restrictions but understanding what triggers an individual's SVT like exercise or strenuous activity can help avoid further episodes.