THE HEART SOUNDS. 



29 



4. The sudden collision of the ventricular contents with the column 

 of blood in the aorta and pulmonary artery. 



5. The sudden tension of the blood caused by a collision of the blood 

 particles in the ventricles. 



6. The rub of the heart against the pericardium. 



7. The vibration of the chest wall from the sudden rigidity and 

 pressure of the heart. 



8. The tension of the auriculo-ventricular valves. 



9. The sudden opening and consequent vibration of the semilunar 

 valves. 



The first sound. It was shown by C. J. B. Williams l and a com- 

 mittee of the British Association, that the first sound can be heard in 

 the excised heart, and this, even if the auriculo-ventricular valves be 

 held open with the fingers. 



Ludwig and Dogiel 2 listened to the heart, after tying in succession 

 the venae cavre, the pulmonary artery and vein, and the aorta. The 

 first sound continued, and seemed to be but slightly altered in character. 

 These experiments entirely overthrow the view that the first sound is 

 of simple valvular origin. The valves can be held back by hooks or by 

 the finger, and neither the papillary muscles, nor any other, suggested 

 mechanism, can throw the valves into tension, yet a systolic sound 

 continues. 3 



Sibson and Broadbent 4 listened to the exposed heart of the ass and 

 of the dog. They record that the first sound is apparently of equal 

 loudness over the whole ventricle, that it begins and continues with a 

 rumble, and that it ends with an accent or sharp sound, which is coin- 

 cident with the extreme contraction of the cavity, and with a faint 

 shock felt just then over the ventricle. If the blood be shut off 

 by tying the vena? cavae, the accent appears to be quite lost and the 

 rumble is materially weakened. The tone of the sound is undoubtedly 

 altered by removing the action of the auricular-ventricular valves, 

 and it has been determined that the sudden throwing into tension 

 of the auriculo-ventricular valves in the dead heart does produce 

 a tone. 



The first sound has been by Wintrich 5 resolved into two tones, one 

 deep and the other high. These are, doubtless, the rumble and the 

 accent described by Sibson. Haycraft 6 has found that the deeper tone 

 alone persists in the excised heart, while the higher tone can be pro- 

 duced in the dead heart by throwing the auriculo-ventricular valves 

 into tension. 



By some authors the first sound has been attributed to the 

 bursting open of the semilunar valves, but any vibration of these 

 valves must be entirely damped down in a fluid which is of almost 

 the same specific gravity as the valve itself. There is no evidence 

 in favour of the view that these valves are suddenly forced open. 

 On the contrary, it is highly probable that they quietly open at 



1 Rep. Brit. Ass. Adv. Sc., London, 1836, p. 269. 



2 Ber. d. k. sacks. Gesellsch. d. Wissensch., math.-nat. CL, Leipzig, 1868, Bd. xx. S. 89. 



3 Halford has denied the occurrence of any sound in the heart after ligation of the 

 venee cavre and pulmonary veins ("The Action and Sounds of the Heart," London, I860, 

 pp. 25-27). 



4 Sibson, " Medical Anatomy," 1869, p. 89. 



5 Sitzungsb. d. phys.-med. Soc. zu JZrlangen, 1875, Bd. vii. S. 51. 



6 Journ. fhysiol., Cambridge and London, 1890, vol. xi. p. 486. 



