MILRINONE IMPROVES PULMONARY HEMODYNAMICS AND RIGHT-VENTRICULAR FUNCTION IN CHRONIC PULMONARY-HYPERTENSION

Background. Right ventricular failure after cardiac transplantation is commonly related to preexisting recipient pulmonary hypertension. Thi s study was designed to investigate the effects of intravenous milrino ne on pulmonary hemodynamic indices and right ventricular function in a canine model of monocrotaline pyrrole-induced chronic pulmonary hype rtension. Methods. Eight mongrel dogs underwent pulmonary artery cathe terization to measure right-sided hemodynamic indices before and 6 wee ks after a right atrial injection of monocrotaline pyrrole. Six weeks after injection, all hearts were instrumented with a pulmonary artery flow probe, ultrasonic dimension transducers, and micromanometers. Dat a were collected at baseline and after milrinone infusion. Results. Si x weeks after monocrotaline pyrrole injection, significant increases i n the pulmonary artery pressure and pulmonary vascular resistance were observed. Milrinone led to significant increases in right ventricular function as well as significant improvements in pulmonary vascular re sistance, pulmonary blood flow, and left ventricular filling. Conclusi ons. This investigation demonstrates the well-known hemodynamic and in otropic effects of milrinone which, in the setting of monocrotaline py rrole-induced pulmonary hypertension, were also associated with signif icant increases in pulmonary blood flow and left ventricular filling. (C) 1997 by The Society of thoracic Surgeons.