Effect of Capacitor Discharges on the Heart [includes discussion]

This paper reports the results of the defibrillation of the dog´s heart by means of capacitor discharges. It was found that if the heart had been in fibrillation for a period not exceeding 30 seconds, a capacitor of suitable value charged to the proper voltage would arrest the fibrillation. In cases where the chest was open and the heart exposed, a discharge of 5 joules or more at a potential of not less than 500 volts would restore normal heart action. In cases where the chest was not opened, but the discharge was sent through electrodes on opposite sides of the chest, a discharge of 500 joules or more at several thousand volts was required. If the heart remained in ventricular fibrillation, without cardiac massage, for from 1 to 3 minutes, a capacitor discharge could not be relied upon to resuscitate the heart and restore normal rhythm. It was also found that capacitors charged to lower values would produce fibrillation when discharged through a normal heart.