The experimental observations on dogs' heart sounds here described were intended to cast further light on the relative importance of muscular and of valvular elements in the production of the first heart sound. The theory based on these observations seemed to conflict with the views of recent workers, particularly with those of Wolferth and Margolies in their excellent study of the variations of intensity of the first sound in heart block. The relation between auricular systole and the first sound is therefore described in some detail. It is believed that the theory offered gives a coherent explanation of all the phenomena noted in the study of the first heart sound.1
Dogs anesthetized with a brand of chlorbutanol were subjected to midline thoracotomy, and respiration was artificially maintained. The heart sounds were recorded by a collodion Frank capsule from small tambours attached to the ventricular surface by short rigid
DOCK W. MODE OF PRODUCTION OF THE FIRST HEART SOUND. Arch Intern Med (Chic). 1933;51(5):737–746. doi:https://doi.org/10.1001/archinte.1933.00150240096007
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