[A case of primary pulmonary hypertension with high venous thromboxane B2 concentration]

A 30-year-old male was admitted because of dyspnea, which had started three years before the admission. Chest roentgenogram showed prominence of the proximal pulmonary arteries and diminished vascularity of the peripheral pulmonary arteries. Electrocardiogram showed right axis deviation and right ventricular hypertrophy. Right heart catheterization revealed a markedly elevated pulmonary arterial pressure and pulmonary vascular resistance with normal capillary wedge pressure. Oximetry showed no evidence of intracardiac shunt. Perfusion lung scan revealed nonsegmental, patchy defects in both lungs. Pulmonary arteriography showed no evidence of pulmonary thromboembolism. From the above findings, primary pulmonary hypertension was diagnosed. Nifedipine, ISDN, prazosin, and captopril were administered to evaluate the short term-effect of he vasodilators. Nifedipine was found to be the most effective. The venous thromboxane B2 level was high. After oxygen therapy, venous thromboxane B2 level fell within the normal range following improvement of arterial oxygenation and decrease in venous FDP level. Hemodynamic changes induced by ice-water hand immersion showed marked increase in the mean pulmonary arterial pressure and total pulmonary arterial resistance. These results suggested that chemical mediators such as thromboxane, and pulmonary arterial vasospasm were involved in the pathogenesis.