Anatomy of the Cardiac Conduction System in the Rabbit

Abstract

Anatomy of the cardiac conduction system was studied in 15 rabbits with serial histologic sectioning of 4. The rabbit's sinus node is a simple and distinct structure located at the junction of the crista terminalis with the sinus intercavarum nearly midway between the two cavae; it contains an unusually large percentage of P cells but is not organized about a large central artery. The AV node and His bundle are relatively small and are displaced anteriorly by the large coronary sinus normally present in the rabbit because of its persisting left superior vena cava. The AV node is organized with input system and bypass tracts similar to those of man and the dog. Doth the AV node and His bundle contain many conspicuously large nerve trunks. The blood supply of the sinus node is from terminal small branches of both the right and left coronary arteries and that to the AV node and His bundle is from similar terminal branches of the septal artery only. The possible functional significance of some of these anatomic features is discussed.