THE SYSTOLIC OUTPUT OF THE HEART. 



FIG. 33. Curves illustrating the effect of a rise of 

 aortic pressure (a 7 ) upon the pressure in the right (a"} 

 auricles ; to be read from right to left. Kauders. 



output then becomes imperfect, the residual blood increases, the left 



auricular pressure rises, 



and the blood is congested 



back upon the venous 



system. 



A greater rise of 



arterial pressure can be 



produced by excitation of 



the splanchnic nerves than 



by closure of the thoracic 



aorta with a clip. 1 This 



difference in result is to 



be explained by the follow- 

 ing facts : 



1. On closing the aorta 



with a clip, the driving 



power of the heart is cut off from the lower parts of the vascular system, 



the blood stagnates therein, and thus the return of the venous blood to 



the heart is impeded. This is not so in the case of splanchnic constriction. 



2. The power 

 of the heart to 

 empty itself in 

 systole is greatly 

 lessened by the 

 closure of the 

 aorta, for the 

 elastic reservoir 

 formed by the 

 arteries into 

 which the blood 



FIG. 34. Aortic pressure. A, vertical feet-down position ; B C, is thrown in Sys- 

 effect of abdominal compression ; D, horizontal position. tole is enorm- 



ously diminished. 



Whenever the left ventricle fails to maintain its output, the pressure 

 rises in the left auricle. Subsequently, in consequence of the back effect 

 through the lungs, it rises in the right auricle. 2 Figure 33 illustrates 

 the effect on auricular 

 pressures of a rise in 

 aortic pressure. The 

 points marked a, a', a", 

 give the corresponding 

 moments in time on the 

 three curves. 



The dependence of 



the arterial pressure and FIG. 35. Aortic pressure, 

 the systolic output on the 

 diastolic filling of the 

 heart is shown by the experimental results obtained on compressing 

 the abdomen or thorax. 



A, horizontal position ; B C, 

 abdomen compressed ; D, vertical feet-up position ; 

 EF, abdomen compressed ; G, horizontal. Hill. 



1 v. Basch, Ber. d. k. sacks. Gesellsch. d. Wissensch. math.-pkys. CL, Leipzig, 1875, 

 S. 383 ; S. Mayer, SUzungsb. d. k. Akad. d. Wissensch, math.-naturw. CL, Wien, 1879, 

 Bd. Ixxix. Abth. 3, S. 19. 



2 Kauders, Ztsc.hr. f. klin. Med., Berlin, 1892, Bd. xxi. S. 68. 



