THE PULSE. 527 



begins in the jugular before a pulse wave appears in the carotid at 

 the same level, as is shown, for example, in the tracings reproduced 

 in Fig. 218. The more sensitive and probablj^ more reliable optical 

 methods of recording indicate, however, that the c wave appears 

 exactly at the time of the pulse in the subclavian artery,* a fact 

 which would justify Mackenzie's view that this wave is due to im- 

 pact from the neighboring arteries. Measurements made in the 

 auricle itself reveal a positive wave occurring at the beginning of 



Fig. 218. — Simultaneous tracings of the jugular pulse, the carotid pulse, and the 

 apex beat. (Bachmann.) At the bottom of the tracing the time is given in fiftieths of 

 a second. The vertical lines 0, 1, 2, 3, etc., mark synchronous points on the curves. 

 .4, The auricular wave; s, the so-called c wave caused by the systole of the ventricle; v, the 

 stagnation wave caused by the filling of the auricle. It will be noticed that the c wave 

 (marked s in the tracing) occurs at the beginning of the ventricular systole as marked on 

 the apex beat, and shortly before the puise in the carotid artery. The height of the v wave 

 is reached just after the occurrence of the dicrotic notch on "the carotid wave, and coin- 

 cides with the opening of the auriculoventricular valves; Aj, the negative wave caused by 

 the effect of the ventricular systole; Vf, the negative wave following the opening of the 

 auriculoventricular valves. 



ventricular systole and explained as due to a protrusion of the 

 closed auriculoventricular valves toward the auricle as the pressure 

 rises in the contracting ventricle. If this auricular positive wave 

 is transmitted back to the jugular vein it may enter as a factor in 

 the production of the c wave as usually recorded. Following the 

 c wave is a second negative wave, usuallj^ quite marked, which 

 occurs during the period of systolic output of blood from the ven- 

 tricles. It has been explained as due to the shortening of the 

 ventricle from base to apex, resulting in a downward movement of 

 the closed auriculoventricular valves. The sudden forcible pulling 

 * Wiggers, Loc. cil. 



