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Types of Supraventricular Tachycardia - Topic Overview

Supraventricular tachycardia (SVT) is a fast heart rate that begins in the upper chambers of the heart (atria). With SVT, abnormal electrical connections in the heart cause it to beat too fast.

There are many types of SVT. Each type causes the abnormal fast heart rate in a slightly different way.

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Treatment depends on the type of SVT and what is causing it, if known. Treatment might include medicines that slow the heart rate or a procedure called catheter ablation that stops the rhythm problem.

Atrial fibrillation or flutter

Atrial fibrillation is the most common type of SVT. It means that the heart's upper chambers (atria) beat irregularly.

Atrial flutter is like atrial fibrillation, because the electrical problem is in the atria. But with atrial flutter, the heart beats very fast in a regular rhythm. Atrial flutter is less common than atrial fibrillation.

Atrioventricular nodal reentrant tachycardia

Atrioventricular nodal reentrant tachycardia (AVNRT) is a common type of supraventricular tachycardia. It accounts for many of the fast heart rates that start in the upper part of the heart (excluding atrial fibrillation). Atrioventricular (AV) nodal reentrant tachycardia can cause symptoms at any age. It typically is not a result of other forms of heart disease.

AVNRT is caused by an abnormal or extra electrical pathway in the heart, a kind of "short circuit." Electrical pathways in the heart consist of microscopic muscle fibers that conduct electrical impulses. Normally, a single electrical pathway allows impulses to travel from the upper to the lower chambers. An extra electrical pathway in the AV node allows those impulses to travel backward at the same time, starting another heartbeat. During AVNRT the electrical impulses continuously go around the two pathways. This is known as "reentry" and can lead to a very fast heart rate.

Atrioventricular reciprocating tachycardia

Atrioventricular reciprocating tachycardia (AVRT) occurs when there is an extra electrical pathway linking the upper (atria) and lower (ventricles) chambers of the heart.

AVRT includes Wolff-Parkinson-White (WPW) syndrome.

Normally, the AV node is the only tissue that conducts electrical impulses between the upper and lower chambers of the heart. All electrical impulses must go through the AV node to reach the lower chambers of the heart. In an atrioventricular reciprocating tachycardia, electrical impulses travel one direction in the normal manner, down the AV node to the lower chambers (ventricles), but they then travel back up to the upper chambers (atria) through an abnormal, extra electrical pathway (accessory pathway) located outside the AV node.

Symptoms may start during the teen or young adult years.

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