INTRAAORTIC BALLOON COUNTERPULSATION IMPROVES RIGHT-VENTRICULAR FAILURE RESULTING FROM PRESSURE-OVERLOAD

Background. Right ventricular (RV) dysfunction is common after heart t ransplantation, and myocardial ischemia is considered to be a signific ant contributor. We studied whether intraaortic balloon counterpulsati on would improve cardiac function using a model of acute RV pressure o verload. Methods. In 10 anesthetized sheep, RV failure was induced usi ng a pulmonary artery constrictor. Baseline measurements included mean systemic blood pressure, RV peak systolic pressure, cardiac index, an d RV ejection fraction. Myocardial and organ perfusion were measured u sing radioactive microspheres. Results. After pulmonary artery constri ction, there was an increase in RV peak systolic pressure (32 +/- 2 to 60 +/- 3 mm Hg: p < 0.01) and a decrease in mean systemic blood press ure (68 +/- 4 to 49 +/- 2 mm Hg; p < 0.01), RV ejection fraction (0.51 +/- 0.04 to 0.16 +/- 0.02; y < 0.01), and cardiac index (2.48 +/- 0.0 4 to 1.02 +/- 0.11; y < 0.01). Blood flow to the RV did not change sig nificantly, but there was a significant reduction in blood now to the left ventricle. The initiation of intraaortic balloon counterpulsation (1:1) using a 40-L intraaortic balloon inserted through the left femo ral artery resulted in an increase in mean systemic blood pressure (49 +/- 2 to 61 +/- 3 mm Hg; p < 0.01), cardiac index (1.02 +/- 0.11 to 1 .45 +/- 0.14; p < 0.05), RV ejection fraction (0.16 +/- 0.02 to 0.23 /- 0.02; p < 0.01), and blood flow to the left ventricle. Conclusions. In a model of right heart failure, the institution of intraaortic bal loon counterpulsation caused a significant improvement in cardiac func tion. Although RV ischemia was not demonstrated, the augmentation of l eft coronary artery blood flow by intraaortic balloon counterpulsation and subsequent improvement in left ventricular function suggest that left ventricular ischemia contributes to RV dysfunction, presumably th rough a ventricular interdependence mechanism. Therefore, study of the safety and efficacy of intraaortic balloon counterpulsation in the ma nagement of patients with acute right heart dysfunction is warranted. (C) 1997 by The Society of Thoracic Surgeons.