Cold and warm blood cardioplegia

Comparison of three strategies for myocardial protection during coronary artery bypass graft surgery based on markers of cardiac damage

OBJECTIVES

To evaluate myocardial damage during coronary artery bypass grafting using three different intermittent cardioplegia and then measuring cTnI and CKMBm release.

DESIGN AND METHODS

Forty-two patients belonging to the hypothermic crystalloid (n = 16), hypothermic (n = 13), and normothermic blood (n = 13) groups were collected when removing the aortic cross-clamp (t = 0) and after 4, 12, 24 and 48 h. For each patient, cumulative cTnI and CKMBm release was calculated as the five measurement mean. There were no significant preoperative and operative differences in the three groups.

RESULTS

In the normothermic group, cTnI mean values at 4, 12, and 24 h were significantly lower than those in both hypothermic groups; moreover, CKMBm mean values were higher at 4, 12, and 24 h in the hypothermic crystalloid group and at 4 and 12 h in the hypothermic blood group than in the normothermic group. In the normothermic group, the area under the curve of the release of both markers was significantly lower than in the hypothermic groups. No significant difference was reported in the release of both markers in hypothermic groups.

CONCLUSIONS

A strategy of normothermic cardioplegia seems to preserve myocardium better than hypothermic cardioplegia.

Cardiopulmonary bypass support for treatment of left ventricular failure following coronary artery bypass grafting: the effects on epicardial microflow and graft flow

The relationship between graft blood flow, epicardial microflow and mean arterial pressure were studied to evaluate the use of repeated cardiopulmonary bypass (CPB) support for intraoperative heart failure following aorto-coronary bypass surgery. Ten patients with unstable angina and suffering from intraoperative heart failure (group A) were compared to 22 patients with stable angina (group B). In group A, during heart failure, the mean arterial pressure fell by 41% (29.9 +/- 6.8 mmHg, p < 0.01), graft flow (GF) by 67% (9.2 +/- 2.6 ml/min, p < 0.01) and epicardial microflow by 64% (19 +/- 4 AU, p < 0.01). After 15-56 min of assisted CPB support, the epicardial microflow and GF were partially restored. There were significant correlations between GF, epicardial microflow and CPB time. In group B, after protamine infusion, the epicardial microflow and GF were significantly greater than group A values (66 +/- 14 AU, p < 0.001 and 29 +/- 9 ml/min, p < 0.001, respectively). It is concluded that the use of temporary assisted CPB support to treat intraoperative heart failure allows the recovery of the myocardium and thereby restores the mean arterial pressure. The recovery of GF and epicardial flow occurred to a lesser extent. CPB support appeared to be suitable for about 60 min, probably because of increasing disturbance to the GF and the epicardial microcirculation.

Warm heart surgery: a prospective comparison between normothermic and tepid temperature

Due to concerns about complications from normothermic core temperature during cardiopulmonary bypass, we initiated a prospective randomized study of 200 consecutive patients. In one group (group A), both the heart and the body temperature were kept at 37 degree C. In the second group (group B), both the body and myocardial temperature were allowed to drift down to 34 degree C. There were no differences between these two groups in age, sex, preoperative numbers of elective, urgent, emergent, redo patients, or coronary artery bypass (CAB), valve, CAB/valve procedures. Their preoperative neurological, pulmonary, renal, and vascular disease status were similar. Preoperative EF was 53% in group A (100 patients) and 52.5% in group B (100 patients). Group A required more volume (p = 0.001) and had less urine output (p = 0.03) during and post bypass. Group A required more phenylephrine hydrochloride (p = 0.05) and had more difficulty managing blood pressure. Strokes and renal failure necessitating dialysis occurred more often in group A but without statistical significance. More difficulties occurred in the normothermic (37 degrees C) group and cardioprotective effects of warm heart surgery may remain intact at 34 degrees C. Mild "drifted/tepid" hypothermic heart surgery could be a better and safer procedure.