Find A Physician

Return to Supraventricular Tachycardia Overview

More on Supraventricular Tachycardia

Hospital News

Return to Supraventricular Tachycardia Overview

More on Supraventricular Tachycardia


Health Library

Return to Supraventricular Tachycardia Overview

More on Supraventricular Tachycardia

Research and Clinical Trials

Return to Supraventricular Tachycardia Overview

More on Supraventricular Tachycardia

Clinical Services

Return to Supraventricular Tachycardia Overview

More on Supraventricular Tachycardia

Supraventricular Tachycardia

How does a normal heart beat?

The heart is a hollow muscular organ – approximately the size of your clenched fist – that beats 40 million times per year (between 60 and 100 beats per minute).  The heart’s pumping action is controlled by its electrical system, which gives rise to the heart rhythm.

Normal cardiac rhythm results from electrical impulses that begin in a special group of cells that form the sinoatrial (SA) node, also called the sinus node. Located in the right upper chamber of the heart, sinus node cells act as the heart's natural pacemaker.  Impulses spread from the sinus node to the right and left atria (the upper chambers of the heart), causing them to contract at the same time. The impulses then travel to the AV (atrioventricular) node, the region that manages impulse traffic from the atria to the ventricles (the lower chambers of the heart). Here, impulses are slowed slightly to give the atria time to contract before the signal reaches the ventricles.

From the AV node, the impulses travel through a system of specialized heart tissue. Located in the wall that separates the two ventricles, this conducting system splits to form the right and left bundle branches that travel to the respective ventricles. Via this conducting pathway, powerful electrical "jump-start" signals are delivered to the ventricular muscle of the heart. In the healthy heart, these impulses travel at the same speed so that the two ventricles contract at the same time, and oxygen-rich blood from the lungs is pumped throughout the body.

What is supraventricular tachycardia (SVT)?

Tachycardia is the term describing an abnormally rapid heart rate of more than 100 beats per minute. Supraventricular tachycardia refers to a rapid, regular heart rhythm that begins in the atria and may or may not involve ventricular tissue. Many cases of SVT are caused by the presence of a second pathway for electrical conduction. In these cases, electrical impulses do not follow the normal conduction pathway, but rather travel in "circles" called reentry circuits. The heart beats with each cycle, resulting in rapid heart rates typically between 150 and 250 beats per minute.

The two most common forms of SVT are atrioventricular nodal reentrant tachycardia (AVNRT) and atrioventricular reentrant tachycardia (AVRT). Atrioventricular nodal reentrant tachycardia arises when a second pathway for electrical conductance exists within the AV node. Under certain circumstances, an electrical impulse will conduct down one pathway within the AV node, then back toward the atria over the second pathway, forming an endless loop. The heart beats with each cycle, resulting in a rapid heart rate.

Atrioventricular reentrant tachycardia (AVRT) arises when an abnormal bridge of tissue connects the atria and ventricles. This tissue forms an "accessory pathway" that provides a second route (in addition to the AV node) by which electrical impulses can reach the ventricles. Electrical impulses can travel to the ventricles, then back toward the atria, forming a circular pattern that, like AVNRT, results in a rapid heart rate.

A third form of SVT, known as atrial tachycardia, arises from a circuit in the upper chambers (atria) of the heart.

What are the symptoms of SVT?

These can include:

  • palpitations (the feeling of the heart beating rapidly)
  • light-headedness
  • dizziness
  • shortness of breath
  • chest pain
How is SVT treated?

Treatment can include medication (beta blockers and calcium channel blockers can be effective) or catheter ablation – treating the problematic heart tissue with radiofrequency energy or freezing temperatures – to disrupt the aberrant pathways.

  • Bookmark
  • Print

    Find a Doctor

Click the button above or call
1 877 NYP WELL


eNewsletters

Hospital News


Clinical Services


Top of page