ENDOCARDIAC PRESSURE 



163 



In order to determine the endocardiac pressure communication must 

 be established with the cavities of the heart. This is accomplished by a 

 tube known as a sound, which is introduced into the left ventricle by passing 



FIG. 159. Simultaneous Registration of Curves of the Left Intraventricular Pressure (lower), 

 the Aortic Pressure (middle), and the Cardiac Impact (upper). Time o.oi of a second. (Hiirthle.) 



Systole 



Diastole/. 



FIG. 160. Schematic Cardiogram I, and Intraventricular Pressure Curves from the Dog. 

 (Hiirthle.) The ventricular pressure curve of the descending type is represented by the dotted line. 

 Pressure in millimeters of mercury, time in tenths of a second. 



it down the common carotid artery, or into the right auricle and ventricle 

 through the jugular vein. When such tubes are introduced and connected 

 with some form of pressure-recording apparatus, accurate tracings of the 

 variations in pressure during the heart-beat are obtained. 



