Coronary sinus blood flow and sampling for detection of unrecognized myocardial ischemia and injury.

Fifteen patients were studied to detect unrecognized intraoperative ischemia or necrosis in perioperative myocardial infarction (MI) associated with coronary bypass. Simultaneous arterial and coronary sinus blood samples were analyzed for lactate and both total and MB-CPK. Coronary sinus flow measurements were done coincident with sampling in seven patients. Five had perioperative MI diagnosed by positive pyrophosphate scan and electrocardiogram. Although normal initially (mean 19 +/- 5.0%), lactate extraction after thoracotomy, before aortic cross-clamping, became abnormal in 12 patients with more pronounced abnormality in those with perioperative MI (-19 +/- 9.0%). Net efflux of lactate was higher in perioperative MI (mean 0.6 +/- 0.2 vs 0.016 +/- 0.04 mM/L) than in non-MI patients. All patients had detectable total and MB-CPK (mean 295 and 31 IU/L, respectively) and all those with coronary disease had a positive arterial-coronary sinus gradient for MB-CPK (mean 9 IU/L). Perioperative MI patients had a higher gradient than non-MI patients (mean 25 vs 2 IU/L) and with one exception that gradient exceeded 5-7 IU/L. It is concluded that severe ischemia before aortic cross-clamping precedes perioperative MI and may contribute to release of CPK into coronary sinus blood. Improvement in the techniques of anesthesia and intraoperative myocardial preservation are suggested.