EFFECT OF ELECTRIC SHOCK ON HEART 465 



Recovery of Heart from Ventricular Fibrillation 



Recovery of the heart from ventricular fibrillation by the application 

 of a short intense shock was reported first by Prevost and Battelli in 

 1899. Kouwenhoven, Langworthy and Hooker also have reported 

 the recovery of dogs from fibrillation by the application of what has 

 recently been termed a "counter-shock." The opportunity to experi- 

 ment on recovery from ventricular fibrillation with large animals arose 

 with the use of sheep and other large species in 1932. Currents up to 

 25 or 30 amperes were applied through large electrodes placed near 

 the heart. 



After some preliminary tests all counter-shocks were given with 

 electrodes outside the skin on both sides of the chest so as to include 

 the heart between them. Such counter-shocks were found to be effec- 

 tive in recovering coordinate heart action in about 60 per cent of the 

 cases. 



Figure 7 is an electrocardiographic record of heart action before and 

 after a shock that caused fibrillation and at different stages after the 

 application of a counter-shock that arrested the fibrillation and allowed 

 the heart to resume its coordinate beating. The current and voltage 

 of the fibrillating shock and the counter-shock are shown also to the 

 same scale for comparison. The fibrillating shock of 6 amperes and 

 0.03 second duration occurred during the sensitive phase of the 

 cardiac cycle. The counter-shock which followed \]/2 minutes later 

 was of 26 amperes for 0.1 second duration. Times marked on the 

 different sections are referred to the beginning of the record. It may 

 be observed that the last electrocardiogram is practically identical 

 with the pre-shock electrocardiogram. Many sheep have been ob- 

 served for periods of months after recovery from fibrillation, with no 

 evidence of abnormalities. Several have given birth to normal 

 lambs, and in many instances the recovered sheep have been used in 

 subsequent tests and again recovered. 



The possibilities of counter-shock have not been fully explored to 

 determine the optimum conditions for its application, particularly as 

 regards magnitude and character of current, its duration, and points 

 of application. In regard to the latter, however, it would seem that 

 some short path embracing the heart would be best. Any technique 

 of recovery of the heart must be applied promptly so as not to permit 

 deterioration of the brain which might result in impairing the com- 

 petency of the victim if recovered. While the time limit would depend 

 on many factors, it is a matter of minutes rather than seconds. The 

 prompt application of artificial respiration ventilates the lungs and is 

 believed also to maintain a small circulation of blood, sufficient to delay 



