Peripheral Ramification of the Cardiac Conducting System

The study of the peripheral distribution of the right bundle branch in bovine, dog's, goat's, lamb's, and human hearts demonstrates an anatomical basis for the production of varying degrees of right bundle-branch block on operative incision of the anterior wall of the right ventricle. The left branch of the cardiac conducting system, with its transventricular cavity conducting bundles to the papillary muscles and the ventricular wall in bovine, dog's, goat's, lamb's, and human hearts, offers an anatomical basis for varying degrees of disturbance in left ventricular conduction due to operative incision or instrumentation in the left ventricle. Comparative anatomical studies in man and animals show conducting fibers which traverse the ventricular cavities in structures previously termed pseudotendons or false chords. In man, the existence of these transventricular cavity conducting bundles has not been emphasized, probably because of the traditional methods of opening the heart at autopsy. The combined electrocardiographic and anatomical concepts provide a useful background for caution in open-heart operation, lest stretching during manipulative procedures or cutting these peripheral conducting bundles produces irrevocable conduction-damage.