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December 15, 1978

Genesis of Heart Sounds

JAMA. 1978;240(25):2732. doi:10.1001/jama.1978.03290250036011

To the Editor.—  I would like to make the following comments about the production of A2.Leatham1 recorded phonocardiograms and external carotid pulse tracings in ten healthy persons and concluded that the origin of the first component of S2 is associated with aortic valve closure by its relationship to the dicrotic notch. Although the foregoing hypothesis has been generally accepted, several investigators have reported that the first component of S2 precedes aortic valve closure by 5 to 30 ms.2-4To clarify this controversy regarding the relationship between the aortic valve closure and the first component of S2, we conducted a study on 20 subjects (Geriatrics 26: 372-374, 1978). Simultaneous phono-cardiograms, ECGs, and echocardiograms were recorded on a strip-chart recorder. The points of separation and closure of the echoes of the two cusps of the aortic valve were considered to be the aortic opening and closing points, respectively. The