Effect of pulsatile and nonpulsatile flow during cardiopulmonary bypass on left ventricular ejection fraction early after aortocoronary bypass surgery

Although aortocoronary bypass graft has successfully relieved angina in most patients, concern has been expressed about possible deterioration or failure of improvement of left ventricular performance. With use of intraaortic balloon pumping to produce pulsatile flow during cardiopulmonary bypass, left ventricular ejection fraction and end-diastolic volume index were compared in a consecutive series of 40 men undergoing elective aortocoronary bypass, 20 of whom had pulsatile flow and 20 who had mean flow during cardiopulmonary bypass. Left ventricular ejection fraction and end-diastolic volume index were measured before and 1 to 12 days after operation using a collimated scintillation probe and indium^113m. In the group receiving nonpulsatile flow the ejection fraction decreased from 52.2 ± 2.9 percent (mean ± standard error of the mean) to 38.7 ± 3.2 percent on the first postoperative day and 43.0 ± 3.4 percent on the 10th day (P < 0.001). In the group receiving pulsatile flow, the ejection fraction increased from 51.4 ± 3.0 percent to 61.6 ± 3.4 percent on day 1 and 65.8 ± 2.9 percent on day 10 (P < 0.001). Three of 20 (15 percent) in the group with nonpulsatile flow had an increase of ejection fraction compared with 17 of 20 (85 percent) in the group given pulsatile flow. Left ventricular end-diastolic volume index was not significantly altered in either group. Two men (10 percent) in each group had post-operative myocardial infarction. The ejection fraction increased despite infarction in both patients given pulsatile flow but decreased in both patients with infarction given mean flow. In a series of 235 patients intraoperative infarction occurred in 8 of 109 patients given pulsatile flow (incidence 7.3 percent) but in 14 of 126 patients given mean flow (incidence 11.1 percent) (P < 0.05). These results suggest that pulsatile flow during cardiopulmonary bypass (1) improves left ventricular ejection fraction in the early postoperative period in patients undergoing aortocoronary bypass and (2) may enhance myocardial preservation in these patients.