CAUSES OF ARREST OF THE ACTION OF THE HEART. 63 



pulsations will continue for a long time. The following experiment illustrating this 

 point was performed upon the heart of an alligator six feet in length: 



The animal was poisoned with woorara, and twenty-eight hours after death tin- 

 heart, which had been exposed and left in situ, was pulsating regularly. It was then 

 removed from the body, and, after some experiments on the comparative force, etc., of 

 the pulsations when empty and when filled with blood, was filled with water, tne 

 valves having been destroyed so as to allow free passage of the fluid through the cavi- 

 ties, and the vessels ligated. The ventricles, still filled with water confined in their 

 cavity, were then firmly compressed with the hand, so as to subject the muscular fibres 

 to powerful compression. From that time, the heart entirely ceased its contractions 

 and became hard like a muscle in a state of cadaveric rigidity. This experiment shows 

 how completely and promptly the heart, even of a cold-blooded animal, may be ar- 

 rested in its action by mechanical injury. 



Cases of death from distention of the heart are not infrequent in practice. It is well 

 established that the form of organic disease which most frequently leads to sudden 

 death is that in which the heart is liable to great distention. We refer to disease at the 

 aortic orifice. In other lesions there is not this tendency ; but, when the aortic orifice 

 is contracted or the valves are insufficient, any great disturbance of the circulation will 

 cause the heart to become engorged, which is liable to produce a fatal result; 



Most persons are practically familiar with the distressing sense of suffocation which 

 frequently follows a blow upon the epigastrium ; and a few cases are on record of in- 

 stantaneous death following a comparatively slight concussion in this region. We had an 

 opportunity, in the winter of 1854-'5, of witnessing an autopsy in a case of this kind. A 

 young mulatto man, employed as a waiter at the Louisville Hotel, received a blow in the 

 epigastrium while frolicking, which produced instantaneous death. On post-mortem ex- 

 amination, no lesion was discovered. Although these cases are rare, they are well recog- 

 nized, and the eifects are generally attributed to injury of the solar plexus. The dis- 

 tress is precisely what would occur from sudden arrest of the heart's action ; for it is 

 the blood charged with oxygen and sent by the heart to the system, which supplies the 

 wants of the tissues, and not the simple entrance of air into the lungs ; and arrest of 

 the circulation of arterial blood, from any cause, produces suffocation as completely 

 as though the trachea were ligated. This fact we have clearly proven by experiments. 

 It is a question whether the arrest of the heart, if this be the pathological condition, be 

 due to concussion of the nervous centre or to the direct effects of the blow upon the 

 organ itself. Our present data do not enable us to answer this question definitely, but 

 they rather incline us to the opinion that in such accidents the symptoms are due to 

 direct injury of the heart. An additional argument in favor of this view is founded on 

 our knowledge of the mode of operation of the sympathetic system. The effects of 

 stimulation or irritation of this system are not instantaneously manifested, as is the case 

 in the cerebro-spinal system, but are developed slowly and gradually. 



As far as we have been able to learn by experiment, the nervous influences which 

 arrest the action of the heart operate through the pneumogastrics and are derived from 

 the spinal accessory nerves. As we have just seen, we can closely imitate this action by 

 galvanism. The causes of arrest in this way are numerous. Among them may be men- 

 tioned, sudden and severe bodily pain and severe mental emotions. With the exception 

 of arrest of the heart from loss of blood and from distention, from whatever cause it 

 may occur, stoppage of the heart takes place from influences operating through the 

 nervous system. It may be temporary, as in syncope, or it may be permanent ; and ex- 

 amples of the latter, though rare, are sufficiently well authenticated. 



