HEMODYNAMIC AND INOTROPIC EFFECTS OF MILRINONE AFTER HEART-TRANSPLANTATION IN THE SETTING OF RECIPIENT PULMONARY-HYPERTENSION

Background: Right ventricular failure remains an important cause of ea rly morbidity and death after heart transplantation and is commonly re lated to preexistent recipient chronic pulmonary hypertension, which o ccurs as a result of long-standing congestive heart failure. In this s tudy, the hemodynamic and inotropic effects of milrinone were assessed after bicaval heart transplantation in the setting of monocrotaline p yrrole-induced recipient chronic pulmonary hypertension. Methods: Twen ty dogs were used for 10 successfully completed transplantation experi ments. Recipient animals underwent right atrial injection of 3 mg/kg m onocrotaline pyrrole 4 months before transplantation. Hemodynamic and functional data were taken 1 hour after termination of cardiopulmonary bypass and after milrinone infusion. Myocardial function was assessed with load-insensitive means (preload-recruitable stroke work) and pul monary vascular impedance was calculated with Fourier analysis. Result s: At the time of transplantation, before cardiopulmonary bypass, pulm onary hemodynamic indexes in recipient animals were significantly incr eased when compared with donors and were further significantly increas ed after cardiopulmonary bypass. Two animals died after transplantatio n as a result of acute right ventricular failure. In surviving animals milrinone infusion led to significant increases in right ventricular function, which occurred in association with significant improvements in pulmonary vascular impedance and transpulmonary efficiency. Conclus ions: In the setting of monocrotaline pyrrole-induced recipient pulmon ary hypertension, milrinone was associated with significant improvemen ts in pulmonary vascular impedance, right ventricular function, and tr anspulmonary efficiency. These data suggest that milrinone is an effec tive means to improve right ventricular dysfunction and pulmonary vasc ular efficiency after bicaval heart transplantation in the setting of recipient chronic pulmonary hypertension.