The Role of the Slow Inward Current in the Genesis of Ventricular Tachyarrhythmias in Man

Abstract

The mechanisms of cardiac arrhythmias are extremely difficult to evaluate in the intact human heart. This can only be accomplished under exceptional circumstances such as in the Wolff-Parkinson-White syndrome. Here an anatomically determined pathway can be identified in which propagation of an impulse leads to the typical circus movement tachycardia of the syndrome. Intracellular potentials cannot be obtained in the intact human heart at the present time, making discussions on the possible role of the slow response in the genesis of clinically occurring ventricular arrhythmias purely speculative. We want to stress therefore that we cannot draw any practical conclusions about consequences of the slow response concept in relation to the treatment of ventricular arrhythmias in man. In discussing the possible role of the slow response as mechanism of clinically occurring ventricular arrhythmias we have to rely heavily upon the notion that this mechanism can be blocked by verapamil [1].