A Morphologic Study of Canine Hearts Subjected to Fibrillation, Electrical Defibrillation and Manual Compression

The pathologic effects on the heart of fibrillation, countershock and manual compression have been studied in canine hearts. Survival experiments have permitted evaluation of the permanence of the damage produced. Massage of the normally beating heart produced minimal nonspecific damage. Manual compression on the fibrillating heart was seen to elicit changes more severe than those observed after fibrillation alone, including occasional focal myocardial necrosis. Alternating-current countershock produced both epicardial and myocardial damage at the site of application of the electrodes. In view of their localization, these changes would not be expected to alter cardiac function appreciably. Comparable changes, but less severe in type, were found in the hearts of animals subjected to condenser discharge countershock. Padding of the electrodes with saline-soaked gauze did not appear to influence the degree of damage.