[Lowering of pulmonary-arterial pressure with nitroprusside in mitral stenosis and cor pulmonale (author's transl)].

Nitroprusside was infused intravenously (20, 40, 80 and 200 mug/min) in nine patients with pulmonary hypertension due to mitral stenosis (group I), nine with precapillary pulmonary hypertension associated with primary lung disease (group II) and nine with normal pulmonary-arterial pressures (group III). The mean pulmonary-arterial pressure was markedly reduced at a rate of 20 mug/min in group I and II, while higher doses were necessary in group III to produce a similar effect. Mean arterial pressure was decreased in all three groups and was dose-related. Heart rate rose, stroke volume fell during nitroprusside administration, while cardiac output remained unchanged. Pulmonary vascular resistance was reduced on 20 mug/min in group I, but only on 200 mug/min or more in group II, and unchanged at all dosages in group III. Peripheral vascular resistance declined in all three groups on nitroprusside infusion, which is apparently of value in the short-term lowering of pulmonary hypertension.