Aortocoronary bypass grafting: a comparison of HTK cardioplegia vs. intermittent aortic cross-clamping✩

OBJECTIVE: Intermittend, hypothermic aortic cross-clamping (IAC) with myocardial fibrillation and cardioplegic arrest (CA) have been established both as effective methods for coronary artery bypass surgery (CABG). Nevertheless, there exists controversy about the more beneficial cardioprotective effect of one of these procedures in CABG-patients. METHODS: In this prospective study we compared the clinical outcome, ischemic serum-markers (CK, CK-MB, Troponin I), electrocardiogram (ECG)-changes, and hemodynamic data of 103 patients. Randomization in group I (IAC; n=52) or group II (CA; n=51) was done consecutively, all data were compared by Student's t-test or chi(2)-test and P<0.05 was regarded as significant. The Bretschneider-HTK solution was used for cardioplegic arrest. Data were collected before operation, before ischemic arrest, after 5 and 60 min of reperfusion, 1 and 6 h after operation, 1, 2 and 10 days postoperatively. RESULTS: There were no significant differences between both groups regarding general patient data: age (IAC: 64. 8+/-9.2 vs. CA: 63.8+/-9.0 years), left ventricular function (ejection fraction: IAC: 62+/-14 vs. CA: 64+/-13%), the amount of bypassed vessels (IAC: 3.4+/-0.5 vs. CA: 3.6+/-0.5), total bypass time (IAC: 113+/-31 vs. CA 108+/-20 min). The total time of ischemia was significantly less in the IAC group with 37+/-10 vs. 48+/-10 min in the CA group. In the IAC-group, a higher mortality was noticed (7. 7 vs. 3.9%; N.S.). This was combined with a significantly higher amount of patients with peak serum-values of CK-MB (>40 U/l) and troponin I (>50 ng/ml), 17 in the IAC-group (33%) vs. eight in CA-group (16%). Cerebral strokes were seen in two IAC-patients and none in CA-patients (NS). ECG-changes occurred in 22 IAC patients (42%) vs. 16 CA patients (31%); persistent ischemia related ECG-changes in six IAC (11.5%) vs. five CA-patients (9.8%). CONCLUSIONS: Both cardioprotective methods, IAC and HTK-cardioplegia, seem to offer sufficient myocardial protection in normal CABG-procedures. Although neurologic disorders and mortality rates were higher in patients with intermittent aortic cross-clamping, the differences to the cardioplegia group were not significant. According to the analysis of increased ECG-changes, higher CK-MB and troponin I values, which occurred especially in patients with myocardial ischemia time longer than 40 min, we conclude that cardioplegic arrest with HTK seems to offer more beneficial effects in procedures with prolonged ischemia.