What is supraventricular tachycardia (SVT)?

Supraventricular tachycardia (SVT) is a type of abnormal heart rhythm, or arrhythmia. The heart’s rhythm (heartbeat) is regulated by natural electrical impulses that travel through the heart muscle. These impulses tell the heart’s chambers when to contract.

SVT refers to a fast arrhythmia that is generated from somewhere in the top filling chambers of the heart (supraventricular means above the ventricles). This is the most common type of fast arrhythmia in children. It can present during pregnancy or in infancy as well as later in childhood. In this abnormal heart rhythm, the body’s natural electrical impulses stimulating the heart do not come from the sinus node within the heart as they should. Instead, electrical activity may be carried through additional pathways through the heart, which as commonly referred to as “accessory pathways.” Other forms of SVT may be created from additional areas in the atria or near the atrioventricular (AV) node. Electrical impulses can be generated at a rapid rate, which may result in up to 230 to 280 heartbeats per minute. It may seem surprising, but children typically are able to tolerate these fast heart rates well. Sometimes, SVT can be stopped by using vagal maneuvers, but sometimes medicines are required to restore the normal sinus rhythm.

Treatment for SVT is possible with the valsalva/vagal maneuver, in which the patient is asked to strain, or bear down, in order to slow the heart rate. In babies and younger children, SVT may be stopped with application of a large bag of ice to the face. If this is not effective, medications can be used to slow the heart rate. For those with severe SVT, cardioversion may be recommended. In cardioversion, an electrical shock is delivered to the heart to change an abnormal heart rhythm back to a normal rhythm.

Dr. Imran A. Niazi, MD
Cardiac Electrophysiologist

Supraventricular tachycardia (SVT) is a term used to describe an abnormally rapid heartbeat that occurs in some people. The heart seems to palpitate and race out of control. Sometimes, it lasts for a few seconds or minutes. At other times, the patient has to go to the ER and have the condition controlled by IV medication.

Rapid heartbeat is usually accompanied by shortness of breath, chest discomfort and lightheadedness. It is usually not a dangerous or fatal condition.

SVT may be present from birth. As we grow older, fast heart rates become more perceptible because the aging heart may not be able to withstand a fast heart rate as well as a youthful one can.

This condition can be controlled by medications, but most people opt for an ablation procedure. This is a nonsurgical way of correcting the electrical shortcut that causes the problem. It usually takes a few hours, but is very safe and effective.

Arrhythmias that begin above the ventricles are called supraventricular tachycardia (SVT). In this condition a series of early beats in the atria speeds up the heart rate. There are two main types of supraventricular tachycardia:

  • Sinus tachycardia is a normal increase in the heart rate. It is caused when the sinus node sends out signals faster than usual. It often occurs with fever, excitement and exercise. No treatment is needed. Rarely, a disease such as anemia (low blood counts) or increased thyroid activity can cause this fast heart rate. In these cases, when the disease is treated, the tachycardia goes away.
  • In Wolff-Parkinson-White (WPW) syndrome, an abnormal path between the atria and ventricles cause the electrical signal to arrive at the ventricles too soon to be sent back into the atria. Very fast heart rates may begin as the electrical signal bounces between the atria and ventricles. Many people with WPW syndrome do not have noticeable symptoms.

Heart rhythm disturbances that originate in the upper heart chambers are referred to as supraventricular tachycardias or SVT, and as a group are the most common type of arrhythmia. These arrhythmias are generally considered benign and are not life threatening.

There are five major types of rhythm disturbances that arise in the upper heart chambers:

  1. Atrioventricular (AV) nodal reentrant tachycardia
  2. AV reentrant tachycardia
  3. Atrial tachycardia
  4. Atrial flutter
  5. Atrial fibrillation

Your physician and/or nurse will review with you the suspected mechanism of your SVT.

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Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.