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Types of Supraventricular Tachycardia (SVT)

Treatment Can Vary Among the Various Types of SVT

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Updated November 12, 2011

Written or reviewed by a board-certified physician. See About.com's Medical Review Board.

Supraventricular tachycardia (SVT) is the name given to a category of rapid cardiac arrhythmias that originate in the atrial chambers of the heart. While the symptoms caused by all these types of SVT are the pretty much the same, when it comes to treatment, there are important differences among them. The SVTs are split into two broad categories: "reentrant" and "automatic" SVT.

Reentrant SVT

Most people who have SVT have been born with an extra electrical connection in their heart. These extra electrical connections can intermittently disrupt the heart's normal electrical system, producing SVT. The kind of tachycardia produced by these extra connections is called reentrant tachycardia.

The names given to the various types of reentrant SVT can be confusing, but the key is that the names indicate where the extra connection is located within the heart.

The Most Common Types of Reentrant SVTs

While the treatment options for all these types of reentrant SVT include both ablation procedures and medications, the "best" treatment depends to a large extent on the specific type. (You can learn more about the recommended treatments by clicking on each specific type of SVT listed above.)

Automatic Tachycardias

One type of SVT is not caused by extra electrical connections in the heart. This type of SVT is called automatic SVT.

Normally, the heart rhythm is controlled by electrical impulses produced by the "pacemaker" cells of the heart, located in the sinus node.

But in automatic SVT, cells in some other location within the atria begin producing their own electrical impulses, more rapidly than the sinus node does, thus taking over the rhythm of the heart and producing an automatic SVT. Automatic SVTs are much less common than reentrant SVTs. They usually occur only in people who have a significant medical illness - especially severe lung disease, uncontrolled hyperthyroidism, or many acute illnesses severe enough to require intensive hospital care.

Automatic SVTs are usually quite difficult to treat directly, since there is no extra electrical connection that can be ablated, and since antiarrhythmic drugs often do not work very well in suppressing these arrhythmias. So the real treatment of automatic SVT is an indirect form of therapy, namely, treating the underlying medical illness. Almost invariably, once a patient with automatic SVT has recovered enough to be discharged from the intensive care unit, the arrhythmia will have disappeared.

One special variety of automatic SVT is not due to an acute illness, and tends to be chronic and difficult to manage: Inappropriate sinus tachycardia (IST), which merits a discussion of its own.

Sources

Blomström-Lundqvist C, Scheinman MM, Aliot EM, et al. ACC/AHA/ESC guidelines for the management of patients with supraventricular arrhythmias--executive summary: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines and the European Society of Cardiology Committee for Practice Guidelines (Writing Committee to Develop Guidelines for the Management of Patients With Supraventricular Arrhythmias). Circulation 2003; 108:1871.

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