Propagation of impulses in the His-Purkinje-ventricle system

¹ Department of Physiology of the Instituto Nacional de Cardiología, Mexico, D. F.

In isolated and perfused hearts of dogs, electrical activities of the A-V node, bundle of His and ventricular fibers were recorded simultaneously. The activity of the Purkinje tissue was also recorded from an exposed false tendon of the right ventricle. When the auricle was stimulated with rates from 1 to 3/sec., the average latency between the activation of the bundle of His and the Purkinje fibers (H-P) was 21 msec. If these structures were stimulated either through the auricle or through the ventricle, a latency was recorded between the activation of the Purkinje tissue and the endocardial ventricular fibers (P-V and V-P). These average latencies were 30 msec. When the ventricle was stimulated with progressively increasing frequencies, the bundle of His could not follow frequencies above 6.5/sec., while the ventricular and Purkinje fibers followed up to 7.8/sec. During fibrillation, the average maximal frequency of the responses of the bundle of His was 6/sec.