Figure 1. Correlation between regional acidosis and myoglobin release.

Tissue pH was monitored during the distal anastomoses performed during OPCAB. We noted varying degrees of intramyocardial acidosis despite coronary occlusion times that were nearly identical between anastomoses and always <15 minutes. Myoglobin release was measured at the completion of OPCAB, 30 minutes after protamine administration. A transcardiac gradient was calculated by analyzing myoglobin levels from blood samples obtained simultaneously from the aorta and coronary sinus. A strong linear correlation between the mean regional pH change intraoperatively and transcardiac myoglobin release postoperatively.