Alterations in regional contractility following cardiopulmonary bypass with intraoperative ischemia

Coronary occlusion during cardiopulmonary bypass has been used in place of aortic occlusion to perform coronary artery anastomoses, but this procedure on distal myocardial function has not been evaluated. Regional myocardial function was examined with the use of ultrasonic crystals in 20 dogs subjected to this technique to compare normothermic and hypothermic (30 degrees C) bypass in both beating and fibrillating hearts. We found a significant decline in the velocity of contraction of the distal segment in fibrillating compared to bearing hearts (p less than 0.01). Hypothermia prevented this decline in the beating, but not the fibrillating, hearts. With respect to contractile function in the distal myocardial segment, local occlusion techniques cause an injury similar to that reported for aortic cross-clamping.