370 SUDDEN STOPPAGE OF HEART. [BOOK i. 



the best which the heart can make at the moment, the accom- 

 plishment of each beat is, so to speak, a hurdle which has to be 

 leapt, one of the long series of hurdles which make up the steeple- 

 chase of life. At any one leap failure may occur; so long as 

 failure does not occur, so long as the beat is made, and a fair 

 proportion of the ventricular contents are discharged into the 

 great vessels, the chief end is gained, and whether the leap is 

 made clumsily or well is, relatively considered, of secondary 

 importance. But if the beat be not made, everything almost 

 (provided that the miss be due not to vagus inhibition but to 

 intrinsic events) is unfavourable for a succeeding beat r the mys- 

 terious molecular changes,Hby which the actual occurrence of one 

 beat prepares the way for the next, are missing, the favourable 

 influences of the extra rush of blood through the coronary arteries 

 due to a preceding beat are missing also, and even the distension 

 of the cardiac cavities resulting from the continued venous inflow, 

 at first favourable, speedily passes the limit and becomes un- 

 favourable. And these untoward influences accumulate rapidly 

 as the first miss is followed by a second, and by a third. In this 

 way a heart, which has been brought into a state of unstable 

 equilibrium by disordered nutrition (as for instance by imperfect 

 coronary circulation, such as seems to accompany diseases of 

 the aortic valves leading to regurgitation from the aorta into the 

 ventricle, in which cases sudden death is not uncommon), which 

 is able just to accomplish each beat, but no more, which has a 

 scanty if any saving store of energy, under some strain or other 

 untoward influence, misses a leap, falls, and is no more able to rise. 

 Doubtless in such cases could adequate artificial aid be promptly 

 applied in time, could the fallen heart be stirred to even a 

 single good beat, the favourable reaction of that beat might 

 bring a successor, and so once more start the series ; but such 

 a period of grace, of potential recovery, is a brief one. Even 

 a coarse skeletal muscle, when cut off from the circulation, soon 

 loses its irritability beyond all recovery, and the heart cut off from 

 its own influence on itself runs down so rapidly, that the period 

 of possible recovery is measured chiefly by seconds. 



We made an exception just now in favour of vagus inhibitory 

 action. We may repeat that the effect of inhibitory action is to 

 lessen the expenditure of energy and so to assist the heart for 

 future efforts ; it saves the heart at the expense of the rest of the 

 economy. The heart, so far as we know, cannot in the working of 

 the living economy be brought to a final arrest by the simple 

 action of the vagus. The effect of the augmentor action on the 

 other hand is to increase the expenditure of energy ; it saves the 

 rest of the economy at the expense of the heart. And probably 

 in some cases augmentor action may bring about the cessation 

 of the heart beat. Disordered cardiac nutrition shews itself 

 frequently in a dilated condition of the ventricles ; the systole 



