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January 1965

Square-Wave 250 Cycle Cardiac DefibrillatorUse in Cardiac Surgery

Author Affiliations

From the Department of Surgery, Division of Thoracic Surgery, University of Maryland School of Medicine.

Arch Surg. 1965;90(1):29-34. doi:10.1001/archsurg.1965.01320070031006

CARDIAC DEFIBRILLATION has become an established method of resuscitation in ventricular fibrillation occurring in the operating room, or after coronary occlusion. Defibrillation in the past has been accomplished by the use of a defibrillator which provided a 60 cycle alternating current of about 1½ to 3 amp, with voltages varying from 150 to 250 volts, for 0.10 to 0.50 seconds applied across large electrodes to the heart.6 For an average sized human heart, a current of 1 ampere applied for 0.1 second is optimal. If it does not defibrillate, the duration can be increased to 0.2 seconds; if it proves ineffective, the amperage can be increased gradually to 5 amp. The inherent dangers in the indiscriminate use of higher pulses with longer duration are burns to the myocardium and irreversible myocardial damage leading to cardiac arrest.

With the rapid progress of cardiac surgery, more complicated cardiac lesions become amenable

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