This early anatomical study challenged the classical morphological descriptions of the cardiac conduction system across multiple mammalian species.
MORE THAN a decade ago one of us (D. J. G.)1encountered a case of right and a case of left bundle branch block. Being interested in the lesions within the branches of the His bundle, which are supposed to produce the bizarre electrocardiographic complexes characteristic of bundle branch block, he obtained the hearts at necropsy for a study of the blocking lesions. No difficulty in locating the bundle was anticipated because texts on the heart contain detailed descriptions of the two nodes and the bundle that comprise the so-called conduction system. A meticulous search of the hearts failed to reveal the bundle. This surprising result stimulated the Glomsets2to investigate the conduction system in various mammals. Adequate numbers of hearts from man, dog, monkey, horse, sheep, cattle, and swine were examined grossly and microscopically. They concluded that there does not exist in the hearts of any of
Daniel J. Glomset (Sun,) studied this question.