RIGHT-VENTRICULAR FAILURE - INSIGHTS PROVIDED BY A NEW MODEL OF CHRONIC PULMONARY-HYPERTENSION

This study was designed to examine the effects of both nitric oxide an d milrinone on pulmonary hemodynamics and right ventricular function u sing a newly established model of monocrotaline pyrrole-induced chroni c pulmonary hypertension, Sixteen mongrel dogs (23-25 kg) were used, A ll animals underwent percutanous pulmonary artery catheterization to m easure right heart hemodynamics prior to and 8 weeks after a right atr ial injection of either monocrotaline pyrrole (MCTP, n=8) or placebo ( CTL, n=8), Eight weeks postinjection, all hearts were instrumented wit h a pulmonary artery flow probe and intracavitary micromanometers. Dat a were collected at baseline as well as following both nitric oxide an d milrinone administration, There was no significant difference in the baseline hemodynamic measurements between the two groups, Eight weeks postinjection, significant increases in the pulmonary artery pressure and pulmonary vascular resistance were observed in MCTP compared with CTL, Both nitric oxide and milrinone resulted in significant improvem ents in pulmonary vascular resistance, pulmonary blood flow, and right ventricular contractility. In addition, nitric oxide caused a signifi cant improvement in pulmonary artery pressure and transpulmonary effic iency, while milrinone led to a significant increase in right ventricu lar hydraulic power, This study demonstrates the web-known clinical ef fects of nitric oxide and milrinone in improving pulmonary hypertensio n, which were also associated with an increase in pulmonary blood flow , transpulmonary efficiency, and right ventricular hydraulic power in the setting of monocrotaline pyrrole-induced chronic pulmonary hyperte nsion.