Supraventricular tachycardia (SVT) is a fast heart rate that begins in the upper part of the heart (atria), above the ventricles. Normally, the heart's electrical system precisely controls the heart's rhythm; in this condition, abnormal electrical connections cause the heart to beat too fast.
Most supraventricular tachycardias result from abnormal electrical connections (bypass tracts) in the heart that short-circuit the normal electrical system and cause an increase in electrical activity.
Supraventricular tachycardia may cause an uncomfortable feeling that the heart is racing, pounding, and/or beating irregularly (palpitations). Additional symptoms include feeling dizzy or lightheaded, near-fainting or fainting (syncope), shortness of breath, chest pain, throat tightness, and sweating.
Some supraventricular tachycardias do not cause symptoms and may not need treatment. But if supraventricular tachycardia recurs, medicines or a procedure called catheter ablation may be needed to correct the abnormal heartbeat.
WebMD Medical Reference from Healthwise