HEMODYNAMIC AND INOTROPIC EFFECTS OF NITRIC-OXIDE IN PULMONARY-HYPERTENSION

Right ventricular failure following cardiac transplantation is most co mmonly related to pre-existent recipient pulmonary hypertension second ary to chronic congestive heart failure. Although nitric oxide has had some role clinically in improving pulmonary hemodynamics and right ve ntricular function in this setting, an appropriate large-animal model of stable pulmonary hypertension has not been available for basic inve stigation of this problem. This study was designed to examine the hemo dynamic and inotropic effects of inhaled nitric oxide using a canine m odel of monocrotaline pyrrole-induced chronic pulmonary hypertension. Eight mongrel dogs (22-25 kg) were used. All animals underwent percuta neous pulmonary artery catheterization to measure right heart hemodyna mics prior to and 8 weeks after a right atrial injection of monocrotal ine pyrrole. Eight weeks post-injection, all hearts were instrumented with a pulmonary artery how probe, sonomicrometric dimension transduce rs, and micromanometers. Data were collected at baseline and following nitric oxide administration. Eight weeks post-monocrotaline pyrrole i njection, significant increases were observed in the pulmonary hemodyn amics compared to pre-injection. Nitric oxide led to significant decre ases in pulmonary vascular impedance. Significant improvements in pulm onary blood how transpulmonary efficiency, and right ventricular contr actility were also observed. This investigation demonstrates the well- known clinical effects of nitric oxide in improving pulmonary hemodyna mics which were also associated with an increase in pulmonary blood fl ow, transpulmonary efficiency, and right ventricular contractility in the setting of monocrotaline pyrrole-induced pulmonary hypertension. ( C) 1997 Academic Press.