Tissue reaction to extracorporeal circulation and elective cardiac arrest

Tissue reaction to extracorporeal circulation and elective cardiac arrest by cross clamping of the aorta was studied in dogs with normal hearts by a combination of pathological methods (including histopathology and histochemistry of frozen and dried serial biopsies) as well as physiological and biochemical methods. Thirty dogs had biopsies of the left ventricle wall and the liver prior to extracorporeal circulation, after resuscitation from extracorporeal circulation with and without elective arrest and after a 6 hour recovery period. At the end of the experiments a complete autopsy was done. After 30 minutes arrest at 37°C, the hearts could be easily resuscitated. In spite of focal glycogen losses, they were able to support the circulation during the recovery period. After 45 minutes arrest at 37°C, the response was unpredictable. Greater amounts of glycogen lost from the myocardium indicated eventual failure of the heart. The failure of the resuscitated heart to support the circulation was attributed to a lack of substrate (glycogen). It was not due to structural alteration or changes in the local enzyme capacity as measured histochemically. The correlative patterns which appeared for all three modes of evaluation form the baseline for the application of the developed systemic analysis to experiments with longer recovery periods and to dogs with abnormal hearts.