Mechanisms of supraventricular tachycardia.

One of several mechanisms may be responsible for the arrhythmia in patients with attacks of SVT. When conventional therapy is ineffective in preventing the attacks and when the attacks occur frequently, then electrophysiologic studies should be performed. These studies help determine the mechanism of the arrhythmia and provide the means for testing antiarrhythmic drugs for prophylactic use. When drugs fail, sophisticated, specially designed antiarrhythmic pacemakers can be used when the electrophysiologic mechanisms are known.