196 THE CIRCULATION OF THE BLOOD 



lation produced by a more moderate voltage to disappear. Unfortu- 

 nately, however, these stronger currents produce irreparable damage in 

 the central nervous system, so that the method of applying stronger cur- 

 rents, even were it feasible to do so quickly enough, would be of no 

 therapeutic value in removing fibrillation. 



The disappointing results that have followed the repeated attempts 

 to resuscitate persons killed accidentally by electric shocks is undoubt- 

 edly dependent upon the fact that in the heart of man it is impossible 

 to bring back the normal beat after the ventricles have been thrown into 

 fibrillation. Fibrillation of the ventricle is also the cause of the sudden 

 cardiac failure occurring when blood clots or emboli cause a blockage 

 of the coronary circulation (it is sometimes the cause of angina pec- 

 toris, for example). It must also be remembered in clinical practice 

 that mechanical stimulation of the ventricles may produce fibrillation, so 

 that in attempted resuscitation by cardiac massage care should be taken 

 not to apply this too vigorously. 



Auricles 



Although ventricular fibrillation is seldom recovered from, it has been 

 clearly shown in recent years that fibrillation of the auricles is relatively 

 common and that it is by no means immediately fatal. Indeed it is one 

 of the most common of the chronic cardiac disorders in man. Auricular 

 fibrillation can be produced experimentally by the application of a 

 strong electric stimulus to the auricles. If, however, a weaker stimulus 

 is applied, the auricles do not go into typical fibrillation, but come to 

 beat at a very rapid and regular rate, perhaps three or four hundred a 

 minute. This condition is called "auricular flutter," and is quite fre- 

 quently observed in the clinic. The cause of flutter might be either a 

 paroxysm of extrasystoles or a so-called circus movement. The latter 

 possibility was demonstrated by Mines 13 in rings of tissue cut from the 

 auricle of the ray fish; when a stimulus was applied at one point a con- 

 traction wave was set up which went round and round the ring, so that 

 a series of contractions were the result of one stimulus. If such circus 

 movements were associated with depressed conduction of the muscular 

 fibers the excitation wave would be irregularly transmitted and account 

 for fibrillation. Garrey 59 and Lewis both subscribe to these views. 



The influence of auricular fibrillation and flutter on the beat of the ven- 

 tricle is an extremely important one in connection with the irregular- 

 ities of the heart observed in man, and this influence in most cases is 

 explained by considering (1) the narrowness of the path (in the auric- 

 uloventricular bundle) along which the impulses have to travel, and (2) 



