INFLUENCE OF THE RESPIRATORY MOVEMENTS. 149 



its development than the second. The anterior (A) is the anacrotic auricular 

 wave, the second (V) the ventricular wave. 



Fig. 55, II, represents a sphygmographic tracing from the subclavian artery 

 of the same individual. It is recognized at once by the peculiarity that the 

 anacrotic notch (a) occupies approximately the junction of the lower and middle 

 thirds of the ascending limb. The recoil-elevation (R) in this curve also is rela- 

 tively small, for the same reason as in the carotid curve. Below the recoil-eleva- 

 tion are seen feebly developed elasticity-elevations. 



Tracings from the femoral artery made with a minimum of friction on the 

 part of the writing stylus exhibit an indentation (Fig. 55, III, a) immediately 

 preceding the ascending limb of the curve, which is blurred in coarse curves. A 

 comparison of this indentation with the anacrotic notch at the lower portion of 

 the ascending limb of the curve from the subclavian artery (Fig. II) will convince 

 the observer that the anacrotic auricular notch must be sought in this well-marked 

 elevation. 



It should be mentioned at this point that sphygmographic tracings from cases 

 of aortic insufficiency are characterized further by the following peculiarities: 



FIG. 55. I, II, III, Curves Exhibiting Anacrotic Elevation, a, in Association withflnsufficiency of the 



Aortic Valves. 



i , the great height of the curve ; 2 , the rapid fall of the writing lever from the apex. 

 Both of these peculiarities are due to the fact that a large quantity of blood is 

 thrown into the arteries by the enlarged and hypertrophied ventricle, a considerable 

 portion of which flows back into the ventricle after the completion of the systole. 

 In accordance with observations i and 2 the pulse is therefore a quick one. 3, A 

 distinct notch is not rarely found at the apex representing an elastic vibration of 

 the greatly distended arterial wall. 4, In tracings taken from cases of aortic 

 insufficiency, as, for example, in that shown in Fig. 55, I, the recoil-elevation (R) 

 is moderate as compared with the size of the curve, because, owing to the lesion 

 of the aortic valves, the pulse-wave in its recoil does not impinge upon a suffi- 

 ciently large surface. When the destruction of the semilunar valves is considerable, 

 the recoil-elevation must be produced by the impact of the recurrent wave against 

 the opposite ventricular wall. Below the recoil-elevation the curve presents two 

 or three faintly marked elasticity-oscillations (i, 2, 3). The enormous height of 

 the entire curve is sufficiently explained by the massive column of blood injected 

 into the arterial system by the greatly hypertrophied and dilated ventricle. 



INFLUENCE OF THE RESPIRATORY MOVEMENTS ON SPHYG- 

 MOGRAPHIC TRACINGS. 



The respiratory movements exert a distinct influence on the move- 

 ments of the pulse by virtue of two different factors: (i) the purely 

 physical diminution of arterial pressure that accompanies each inspira- 

 tion, and the increase attendant upon each expiration; (2) the variations 

 in blood-pressure, due to excitation of the vasomotor nerve centers, 

 which attend the respiratory movements. 



