74 



In more recent times the view that ventricular fibrillation 

 is a cause of sudden death in man has been accepted by- 

 numerous observers. Sir James Mackenzie^ writes of sudden 

 death in auricular fibrillation: "It has appeared to me 

 probable that in these cases the ventricle has passed into 

 fibrillation as MacWilliam suggested." Again, referring to 

 sudden death from heart failure: " The cause of sudden 

 death is almost certainly due to the onset of an abnormal 

 rhythm, probably ventricular fibrillation." Sir Thomas 

 Lewis* states that " We have now the strongest a priori 

 reasons for believing that sudden and unexpected death 

 comes to many patients in a manner suggested by 

 MacWilliam in 1889." The causation of death in this way 

 has also been recognized by Hering* and many other 

 observers. 



Direct electrocardiographic curves indicative of ven- 

 tricular fibrillation at the moment of death have been 

 recorded, notably by an American observer, Halsey.* Oppor- 

 tunities for the gaining of such direct evidence are naturally 

 scanty, but the indirect evidence that has accumulated is 

 sufficient to show that this is, in all probability, not only a 

 common cause but the usual cause of sudden and unexpected 

 death of cardiac origin. 



Relation of Death from Fibrillation to Ordinary 

 Myocardial Failure. 



The mode of death described in this article is a failure 

 of the heart's action essentially different from cardiac (or 

 myocardial) failure in the sense of exhaustion of the con- 

 tractile power of the cardiac muscle ; a verdict in the latter 

 sense would usually be, in cases of sudden death, fallacious. 

 While such exhaustion of contractility is, of course, of 

 common occurrence in disease, it is a gradual process, 

 leading to more and more marked impairment of the 

 pumping power necessary to maintain a good circulation and 

 to respond to the increased demands of muscular exercise, 

 etc. There is no ground for the assumption that a sudden 

 loss of power can occur — that is, that muscular fibres 

 endowed with contractility adequate for a tolerably good 

 blood pressure and blood flow should abruptly become 

 enfeebled or paralysed, apart, of course, from the sudden 

 action of violent poisons or such gross causes as asphyxia, 

 obstruction of coronary supply, haemorrhage, etc. What 

 really happens in the supervention of ventricular fibrillation 

 is a misapplication of contractile energy thrown away in a 

 turmoil of fruitless activity, a disastrous change occurring 

 in muscle that may be already more or less limited in power, 

 or that may, on the other hand, be possessed of vigour more 

 than siifficient for the ordinary needs of the circulation. 

 This often occurs in a heart showing no failure of 

 rhythmicity, excitability, or contractility. 



The inadequacy of former explanations of sudden death 

 by failure of the heart to contract and expel its contents, 



