Factors Effecting Survival in Excision and Replacement of the Canine Heart

¹ Hahnemann Medical College, Philadelphia, Holzer Clinic, Gallipolis, Ohio
² 7 Bramhall Street, Portland, Maine 04102

Forty-two dogs were subjected to excision and replacement of the heart, through utilization of heart-lung bypass, localized cooling of the heart and chemical pacing of the heart in the postoperative period. Factors effecting mortality were analyzed. In seven of 42 animals surviving over 24 hours, the average duration of ischemia of the heart was 78 minutes. In 35 animals dying within the first 24 hours, ischemia time was 87 minutes. In both groups, the duration of heart-lung bypass was constant. Whereas it has been contended that the safe period of extracorporeal circulation is more restrictive of what can be accomplished than the duration of "reversible anoxic cardiac arrest," this evidence suggests that within the limitation of heart-lung bypass the duration of ischemia of the heart is dominant. Therefore, a method by which the heart could be perfused should be superior to the one employed in these experiments.