THE PUMPING ACTION OF THE HEART 



159 



lar pressure curve, the initial vibrations occur 0.01 second prior to the rise 

 in pressure, the main vibrations reaching their greatest amplitude before 

 the sphygniic period begins, and the final vibrations occurring during 

 the early part of the sphygmic period and therefore just before the aortic 



11 I f 



,5 -5 mm fir Mf. ; 







....: 



B. 



f, f 1 ** 



3 '/\ 



C. 



Fig. 37. Electrophonograms along with intraventricular pressure curves from three dif- 

 ferent experiments. In A the uppermost curve shows the pressure, the middle one the sounds 

 of the right ventricle, and the lowermost one those of the aorta. P indicates the relative posi- 

 tion of the curves. M is due to mechanical oscillations. $2 indicates the second sound, and 

 /, 2, 3, and 4 the corrected time relations of the first sounds. In B, the pressure and sound 

 curves are both from the left ventricle (letters same as in A). In C, the aortic and pulmonary 

 arterial sounds are shown (letters same as in A). (From Wiggers and Dean.) 



pressure has reached its height. The main vibrations therefore occur 

 during the descending limb of the R wave of the electrocardiogram (be- 

 ginning 0.01 second before its completion), the small preliminary vibra- 



