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.