EFFECTIVE CONTROL OF REFRACTORY PULMONARY-HYPERTENSION AFTER CARDIAC OPERATIONS

Objectives: Inhaled nitric oxide is a promising therapy to control pul monary hypertension. However, pulmonary hypertension caused by valvula r heart disease is often refractory to inhaled nitric oxide. The objec tive of this study was to determine whether the combination of inhaled nitric oxide plus dipyridamole will cause a response in patients with pulmonary hypertension undergoing cardiac operations who had not resp onded to inhaled nitric oxide alone, Methods: Responses in 10 patients (62 +/- 7 years) with pulmonary hypertension caused by aortic or mitr al valvular disease (mean pulmonary artery pressure, greater than or e qual to 30 mm Hg) were studied in the operating room after valve repla cement. The effect of inhaled nitric oxide alone (40 ppm) on pulmonary vascular resistance, mean pulmonary artery pressure, cardiac output, and mean arterial pressure was determined. Inhaled nitric oxide admini stration was then stopped and patients were given dipyridamole (0.2 mg /kg intravenously); the effect of inhaled nitric oxide plus dipyridamo le was then examined, Results: Dipyridamole effected a response in pat ients who had not responded to nitric oxide, Pulmonary vascular resist ance and mean pulmonary artery pressure were significantly reduced and cardiac output was increased without change in mean arterial pressure , Conclusions: Patients with refractory pulmonary hypertension in whom inhaled nitric oxide alone fails to cause a response may respond to c ombined therapy of inhaled nitric oxide plus dipyridamole. This therap y may be particularly valuable in patients with dysfunction of the rig ht side of the heart as a result of pulmonary hypertension because of its effective lowering of right ventricular afterload.