In a 22-year-old woman with primary pulmonary hypertension resistant to all previous attempts to reduce the pulmonary vascular resistance, there was dramatic improvement after the first dose of nifedipine, 20 mg po, which was not sustained with subsequent doses. While there was a persistent reduction in systemic vascular resistance, the initial drug-related reduction in pulmonary vascular resis...

After repair of a Bochdalek diaphragmatic hernia, shunting of blood away from the lungs produced progressive hypoxaemia in a neonate. Changes in plasma concentrations of the vasoconstrictor prostanoid thromboxane were associated with changes in pulmonary vascular resistance in this infant. Plasma concentrations of the vasodilator prostanoid prostacyclin were also monitored during acute changes ...

OBJECTIVE Endothelin-1 concentrations are increased in patients with increased mean pulmonary arterial pressure, pulmonary blood flow, and pulmonary vascular resistance. However, endothelin-1 concentrations have not been well characterized in patients with congenital heart disease and normal pulmonary vascular resistance. In particular, it is unclear whether pressure or flow is the key regulato...

go a variable clinical course largely determined by the size of the septal defect and the level of pulmonary vascular resistance.'-7 In perhaps half of the cases, the septal defect closes or becomes smaller.' Of those infants who retain large septal defects, some may maintain a high pulmonary vascular resistance from birth; in most, the resistance probably undergoes at least a transient decreas...

OBJECTIVES This investigation sought to determine whether endothelium-derived nitric oxide contributes to hypoxia-induced systemic vasodilation and pulmonary vasoconstriction in humans. BACKGROUND Endothelium-derived nitric oxide contributes to basal systemic and pulmonary vascular resistance. During hypoxia, systemic vasodilation and pulmonary vasoconstriction occur. There are some data indi...

We have studied six patients who had undergone mitral valve replacement. Estimations of cardiac output and of pulmonary vascular resistance were made, beginning two hours after the finish of the operation. Glucagon, 10 mg, was given intravenously, and cardiac output and pulmonary vascular resistance were measured 5 minutes and 30 minutes later. In all six cases there was a significant decrease ...

Intrinsic oscillatory activity, or vasomotion, within the microcirculation has many potential functions, including modulation of vascular resistance. Alterations in oscillatory activity during pregnancy may contribute to the marked reduction in vascular resistance. The purpose of this study was 1) to mathematically model the oscillatory changes in vessel diameter and determine the effect on vas...

go a variable clinical course largely determined by the size of the septal defect and the level of pulmonary vascular resistance.'-7 In perhaps half of the cases, the septal defect closes or becomes smaller.' Of those infants who retain large septal defects, some may maintain a high pulmonary vascular resistance from birth; in most, the resistance probably undergoes at least a transient decreas...

go a variable clinical course largely determined by the size of the septal defect and the level of pulmonary vascular resistance.'-7 In perhaps half of the cases, the septal defect closes or becomes smaller.' Of those infants who retain large septal defects, some may maintain a high pulmonary vascular resistance from birth; in most, the resistance probably undergoes at least a transient decreas...

1 The hepatic portal vein of the anesthetized dog was cannulated and perfused with blood derived from the cannulated superior mesenteric vein. 2 The portal vein was perfused at constant flow, the hepatic portal venous pressure being monitored continuously together with the inferior vena caval pressure. From these measurements, the hepatic portal venous vascular resistance was calculated. 3 Nora...