Myocardial preservation: effect of venous drainage

We compared the effect of three methods of venous drainage on myocardial temperature, coronary blood flow as determined with radioactive microspheres, myocardial metabolites (lactate, adenosine triphosphate [ATP], and glycogen), and left ventricular function before, during, and after cardiopulmonary bypass with hypothermic, hyperkalemic cardioplegic arrest. Venous drainage was established in the 6 dogs in Group 1 using a Sarns 51F cavoatrial catheter, in the 7 dogs in Group 2 using two USCI 32F vena caval catheters with tourniquets, and in the 7 dogs in Group 3 using two USCI 32F vena caval catheters without tourniquets. The lowest myocardial temperature was achieved in Group 1 (7.26 degrees +/- 0.45 degrees C compared with 10.45 degrees +/- 0.56 degrees C in Group 2 and 9.78 degrees +/- 0.43 degrees C in Group 3) (p less than 0.001). Myocardial rewarming to 20 degrees C was not significantly different among the groups. Myocardial ATP and lactate levels were similar in all three groups. Myocardial glycogen levels were maintained during ischemia in Group 1 (1,010 +/- 76 mg/dl compared with 686 +/- 39 mg/dl in Group 2) (p less than 0.005). Myocardial blood flow was similar in all groups during the preischemic periods, but during reperfusion a markedly decreased flow was seen in all areas of the myocardium in Group 1 compared with Group 2 (p less than 0.004). Left ventricular function, as measured by the maximum rate of rise of left ventricular pressure, stroke work, and pressure/volume curves, was similar in all groups. We interpret the postischemic blood flow data, glycogen levels, and ventricular compliance differences to suggest that the dogs in Group 1 had less ischemia.