Original Article

Myocardial Preservation during Hypothermic Cardiopulmonary Bypass: A Team Endeavor

Emeritus Professor of Surgery, University of Colorado School of Medicine

^* Research institute for Biological Sciences Lakewood, Colorado 80227

Abstract

Myocardial failure is the primary cause of death following operation using hypothermic cardiopulmonary bypass. The mean mortality rate for coronary bypass in Medicare patients in the United States for 1984 was 5.5%.1njury to the heart is caused by aortic cross-clamping or total circulatory arrest. The lesion of hypoxia is characterized by progressive acidosis. The severity of acidosis correlates with the degree of post-operative myocardial dysfunction. In decision making concerning the management of perfusion or of operative technique, prevention and/or treatment of myocardial acidosis takes precedence over other considerations. Recent advances in understanding the effect of temperature on acidbase equilibria, and the recent introduction of online blood gas monitoring devices have given the perfusionist the necessary means to achieve perfusion which keeps the patient on the alkaline side of biological neutrality. Similarly, the surgeon should utilize the protective value of frequent coronary infusions with a cold, oxygenated, alkaline, buffered, anti-oxidant blood cardiopreservation solution. Figures and tables are presented which enable the perfusionist to understand hypothermic acidbase management, and to use appropriately hyperventilation and high flow perfusion, avoiding any use of CO₂ gas, while monitoring the patient’s course using venous blood samples which are uncorrected for temperature. With this team approach, improvement in operative mortality can be expected.