Registration of Heart Sounds. 



13 



stitched to the heart, and a recording Frank capsule. The sound 

 receptor consists of a light segment capsule 2 cm. in diameter 

 and similar to the miniature myocardiograph recently described. 1 

 It differs in that it has only one arm connected with a trapezoidal 

 plate which pivots on the segment capsule. When stitched to 

 any portion of the heart this arm transmits the sound vibrations 

 to a tensely stretched, heavy rubber diaphragm covering the 

 segment capsule. The interior of the receptor communicates by 

 tubing with a Frank segment capsule covered by a light film of 

 dried rubber cement to which a tiny mirror is allowed to adhere. 

 By leaving a side-tube open to an adequate degree, as is customary 

 in sound registration, the gross mechanical changes are eliminated. 



In comparing the sounds thus derived from the ventricle and 

 the aorta essential differences were found, especially in the first 

 sound. The first ventricular sound consists of three elements: 



1. One or two initial vibrations which begin during auricular 

 relaxation and precede by a variable interval the rise of intra- 

 ventricular pressure. 



2. The main vibrations composed of 7 to 13 irregular vibrations 

 which begin with the onset of the intraventricular pressure rise. 



3. The final vibrations, variable in number, which occur during 

 the ejection period of the heart. 



The first aortic sound is also divisible into three components, 

 the second and third of which give the group a configuration 

 essentially different from that of the first ventricular sound. 

 They are: 



1. One or two initial vibrations, evidently corresponding to 

 the same vibrations in the ventricular sound. 



2. A first main component consisting of a group of irregular 

 oscillations beginning at the same time as the main vibrations of 

 the ventricular sound. 



3. A second main component occasionally consecutive with but 

 often disconnected from the first component so as to give a 

 reduplicated appearance to the sound. 



1 Wiggers, Amer. Jour. Physiol., 1916, XL, 218. 



