Simultaneous measurement of coronary sinus oxygen saturation and blood flow during terminal warm blood cardioplegia in coronary artery bypass grafting.

Simultaneous measurement of coronary venous oxygen saturation and coronary venous blood flow is an essential method that reveals myocardial oxygen metabolism. But there have been no reports of the simultaneous measurements during warm blood cardioplegic infusion in cardiac surgery. Thirteen patients underwent elective coronary artery bypass grafting in our unit. Simultaneous measurement of coronary venous oxygen saturation (ScsO2) and coronary venous blood flow (Fcs) was carried out during terminal warm blood cardioplegia. Fcs increased rapidly and reached plateau level (178 +/- 18 ml/min) between 0 and 1 min after blood cardioplegic infusion. But ScsO2 increased slowly and reached a peak level (84 +/- 3%) between 1 and 2 min after blood cardioplegic infusion, and then dropped gradually. Using the Fick formula, myocardial oxygen consumption at 5 min after blood cardioplegic infusion was 3.7 ml/min/heart. Simultaneous continuous measurements of ScsO2 and Fcs were useful monitors of the myocardial distribution of the blood cardioplegic solution, and cleared the myocardial oxygen metabolism during terminal warm blood cardioplegia.