Effect of Electric Shock on the Heart * 



By L. p. FERRIS, B. G. KING,t P. W. SPENCE and H. B. WILLIAMS f 



AS a basis for the development of protective measures and prac- 

 ^ tices, knowledge of the limits of dangerous electric shock is 

 obviously important and this joint investigation at the College of 

 Physicians and Surgeons of Columbia University was initiated in the 

 hope of obtaining some of the needed data. In seeking a value of 

 current which if exceeded would be dangerous to man, it is important 

 to consider for different practical conditions the effects which are 

 brought about as the current is increased. The threshold of sensa- 

 tion is reached at about one milliampere for a frequency of 60 cycles. 

 Other investigators have found that at about 15 milliamperes from 

 hand to hand the subject becomes unable to control the muscles 

 subjected to stimulation. 



Any currents that prevent voluntary control of the skeletal muscles 

 are dangerous because their pathway through the body might include 

 the respiratory muscles and stop breathing during the shock. If 

 prolonged, asphyxial death would result, but the time required is a 

 matter of minutes rather than seconds, so that opportunity may be 

 afforded for action to release the victim. No serious or permanent 

 after-effects are likely to appear merely from the cessation of respira- 

 tion, provided it is not continued beyond the point where the victim 

 can be resuscitated by artificial respiration. 



Currents somewhat greater than those just necessary to stop respi- 

 ration by action on the muscles may cause fatalities, even though the 

 duration of such shocks is but a few seconds or less — far too short to 

 be important from the standpoint of interruption of respiration and 

 obviously too short to give any opportunity for rescue before the end 

 of the shock. Death under such conditions is brought about by 

 ventricular fibrillation, which is a disruption of normal heart action. 

 This condition is an uncoordinated asynchronous contraction of the 



* Digest of a paper published in the May 1936 issue of Electrical Engineering and 

 presented at the A. I. E. E. Summer Convention, Pasadena, California, June 22-26, 

 1936. 



t Drs. H. B. Williams and B. G. King, joint authors of this paper, are of the staff 

 of the College of Physicians and Surgeons of Columbia University, New York. 

 Electrical facilities of the Bell Telephone Laboratories supplemented those of the 

 Physiology Laboratories of the Medical Center where most of the experimental 

 work was done. 



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