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associated with ventricular tachycardia. The myocardial 

 conditions underlying tachycardia are closely related to 

 those on which fibrillation is dependent, and there is abun- 

 dant evidence that the former may develop into the latter. 

 The excessive rate of beat — whatever be the origin of the 

 tachycardia — is in itself favourable to this development, 

 since it involves shortening of the refractory period and 

 lengthening of the conduction time. The rapidity of 

 succession of contractions — whether arising in the ventricles 

 themselves or transmitted with abnormal frequency from the 

 auricles as in auricular flutter — that the ventricles can stand 

 without fibrillating varies much in different conditions; 

 when the conductivity is already depressed and the con- 

 duction time long, a much lower grade of acceleration 

 natiirally suffices to establish fibrillation, as can be demon- 

 strated experimentally. 



From the work of many observers we know that in certain 

 hearts (for instance, after coronary ligation, etc.) there is 

 often a characteristic sequence of events illustrative of the 

 close relations of tachycardia and fibrillation — extra-systoles, 

 first singly, then in irregular runs, more or less continuous 

 tachycardia, and finally fibrillation. Apart from the super- 

 vention of fibrillation it is known that the fall of blood 

 pressure attendant on tachycardia is compatible with life 

 for very considerable periods ; there have been recoveries 

 after periods of excessively low blood pressure attended by 

 unconsciousness, etc., for hours. It remains to be seen 

 whether the fall of blood pressure is often or ever sufficient 

 per se to kill, or whether the fatal issue is always deter- 

 mined by the occurrence of fibrillation. There are no 

 grounds for accepting vagus inhibition as a mode of sudden 

 death during tachycardia. The vagus is known to lose 

 effectiveness in this condition. Auricular flutter, etc., may 

 induce unconsciousness lasting for hours without causing 

 death; a very small blood supply can suffice to keep the 

 nerve centres alive, as Leonard Hill showed many years ago. 

 The absence of fibrillation is an essential feature in the 

 recovery from ordinary cases of fainting due to temporary 

 vascular relaxation due to vasomotor failure or to vagal 

 inhibition, etc. 



Status Lymphaticus, Electrical Shock, Digitalis. 



A possible development of the mechanism of fibrillation is 

 worthy of consideration in connexion with the sudden and 

 unexplained deaths of the status lymphaticus, occurring, as 

 they often do, in the absence of any recognized causation. 

 The features of some recorded examples would fit in with 

 the known phenomena of fibrillation — for example, such 

 cases as have shown an abrupt abolition of the signs of 

 heart action while the respiratory movements persisted for 

 some little time, in marked contrast to the order of events 

 in death by asphyxia. 



Fibrillation is one of the modes of death in electrical 



