Electrocardiogram of the Diving Seal

Abstract

During the normal dive, the seal has a reflex bradycardia that is not accompanied by inversion of P waves or T waves or by atrial or ventricular arrhythmias, although the seal does have an occasional block of conduction across the A-V node during normal diving. The reflex bradycardia during the dive appears to be mediated through vagal stimulus. The electrocardiograms of the seal during voluntary diving and during forced submersion with struggle are different.