CORONARY-BYPASS FLOW DURING USE OF INTRAAORTIC BALLOON PUMPING AND LEFT-VENTRICULAR ASSIST DEVICE

Background. Intraaortic balloon pumping (IABP) and left ventricular as sist device (LVAD) are used for left ventricular support when low card iac output occurs after a coronary bypass operation for serious corona ry artery disease. There are hemodynamic differences in blood flow in various kinds of coronary artery bypass grafts, caused by their inhere nt physiologic characteristics. The hemodynamic effects of left ventri cular assistance with IABP and LVAD on blood now through various coron ary artery bypass grafts were investigated. Methods. An ascending aort a-coronary bypass graft (ACB), an internal thoracic artery, and a desc ending aorta-coronary bypass graft were anastomosed to the left anteri or descending coronary artery in a canine model. In this experimental model, the blood now to the same coronary bed in the three types of gr afts could be evaluated. Blood flow in the left anterior descending co ronary artery through the three types of coronary bypass grafts was st udied in this model during or in the absence of ventricular assistance . Results. In the control study, the systolic blood now did not diner among the three types of grafts, but the diastolic now decreased in th e following order: with the ACB, the internal thoracic artery, and the descending aorta-coronary bypass graft. The systolic now during IABP and LVAD was similar to the control flows. Use of IABP increased the d iastolic flow by 75.3% +/- 12.4% of the control value in the ACB, 37.9 % +/- 25.0% in the internal thoracic artery, and 21.2% +/- 11.4% in th e descending aorta-coronary bypass graft. The LVAD increased the diast olic flow by 97.7% +/- 18.7% of the control value in the ACB, 64.5% +/ - 25.7% in the internal thoracic artery, and 63.0% +/- 27.9% in the de scending aorta-coronary bypass graft. The diastolic blood flows in the left anterior descending coronary artery and the three types of graft s were significantly greater with IABP than the control values, and si gnificantly greater with LVAD than with IABP and the control values. T he degrees of increase of diastolic flows in the left anterior descend ing coronary artery and the ACB with IABP and LVAD were significantly greater than in the arterial grafts (p < 0.01). Conclusions. The diast olic flows in the internal thoracic artery and descending aorta-corona ry bypass graft increased less than in the native left anterior descen ding coronary artery and ACB during left ventricular assistance, parti cularly with IABP. It is important for the selection of tactics for th e management of catastrophic status after coronary bypass grafting to consider the hemodynamic characteristics of the graft. (C) 1998 by The society of Thoracic Surgeons.