In the course of some work recently undertaken in Dr. Thayer's service to localize the third heart-sound by the use of simultaneous tracings, a remarkably constant, presytolic sound-representation was observed on the electrophonogram ; and its description will be the effort of this paper. The technic employed, the value of the Einthoven electrophonograph, and some of the factors concerned in the audibility of cardiac sounds have been previously discussed ;1 but attention may be recalled to the constancy and reliability of apex-tracings obtained in the left decubitus, and to the localization of the first sound by the foot of the ventricular rise of the apex cardiogram
In a reconsideration of the tracings of sixteen normal schoolboys, it may be said that the pulse-rate varied from 65 to 100, diastasis2 ranged from 0.12 to 0.50 second in the series, and from 0.21 to 0.39 second in an individual case, as
BRIDGMAN EW. NOTES ON A NORMAL, PRESYSTOLIC SOUND. Arch Intern Med (Chic). 1914;XIV(4):475–480. doi:10.1001/archinte.1914.00070160025002
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