Differentiation of supraventricular and ventricular tachycardias

Abstract

Summary o 1. Problems encountered in the differential diagnosis of supraventricular and ventricular tachycardias are reviewed and exemplified by representative electrocardiograms. 2. In supraventricular, as well as in ventricular, types of rapid ectopic rhythms, the action of the ventricles may be very rapid or only moderately accelerated, regular or irregular, the QRS duration may be normal or prolonged, and the atria may beat independently or follow the action of the ventricles. Clinical and electrocardiographic criteria based on one or several of these aspects are, therefore, inconclusive and deceptive. 3. When an ectopic tachycardia presents abnormal and/or prolonged QRS complexes, its supraventricular or ventricular origin can be established, though not in every instance, on the basis of: (a) a comparison with single conducted (supraventricular) impulses, or single premature beats, recorded before, after, or during the tachycardia; (b) the occurrence of ventricular fusion beats and (c) a consideration of the type of QRS widening and the mode of its onset and/or disappearance.