Abstract

EKG records have been collected from humpback, blue and killer whales and smaller cetaceans, including harbour porpoise and bottlenose dolphins. Heart rate varies remarkably with animal size and condition. Rates range from 40 bpm in large whales to 165-180 bpm in harbour porpoise. Diving bradycardia is clearly exhibited.

EKG structure is typical of mammals. However, the PR interval (atrioventricular AV transmission time) and the QRS duration (ventricular excitation) are extremely short for very large animals and may not follow typical size/function predictions. No age effects on structure of the EKG have been found; pathological arrhythmias have been recorded.

Future work will concentrate on standardization of optimum electrode placement for clinical use and the establishment of a data bank of cetacean EKG recordings.