Left ventricular function in the early postoperative stage--cardioplegic baneful effect is lost in the first 24 hours

Early postoperative left ventricular function was investigated in 42 patients with left ventricular volume overload caused by valvular regurgitation. Preoperatively, left ventricular contractile function, stroke work and stress relations were all evaluated. Anoxic index (AnI) was considered as an index of myocardial preservation. Postoperatively, the cardiac function was estimated as the left ventricular stroke work index (SWI) after 3, 6, 24 and 48 hours of post-cardiopulmonary bypass. The release of CK-MB isoenzyme was also measured at the same time as an indication of myocardial injury. AnI and the postoperative SWI3 and SWI6 showed negative correlations in 6 hours, while preoperative SWI0 and postoperative SWI24 and SWI48 showed positive correlations after 24 hours, and SWI0 showed positive or negative correlations to the preoperative 8 parameters. It was observed that ejection fraction, end-systolic wall stress to end-systolic volume index ratio and tension volume ejection showed positive, while left ventricular end-diastolic pressure showed negative correlations to SWI48. However, none of these indexes showed any significant correlations during the first 24 hours following surgery. On the other hand, AnI and the total release of CK-MB isoenzyme showed a positive correlation. These data suggest that the cardioplegic baneful effect on cardiac function might be lost in the first 24 hours after surgery.