Pulmonary Hypertension of Unknown Cause

¹ Resident in Medicine.
² Assistant Professor of Medicine.

A 42 year-old woman, observed since 1948 for a blood disorder, developed physical signs of pulmonary hypertension. The electrocardiogram changed from normal to right ventricular strain and hypertrophy while heart fluoroscopy showed increasing prominence of the pulmonary artery and right ventricle. Lung function studies were normal. Heart catheterization revealed a pulmonary artery pressure of 78/32 mm. Hg. and a pulmonary capillary pressure of 2 mm. Hg. The total pulmonary vascular resistance was 1800 dynes cm.^-5 secs. There was no evidence of intracardiac shunt. Lung biopsy showed marked medial hypertrophy of the arterioles plus modest intimal proliferation.

The cause of pulmonary hypertension in this case is not known, but it is clearly acquired. There is no evidence that the marked medial arteriolar hypertrophy is a consequence of previous vasospasm although a vasospastic element has been demonstrated in similar cases. Medial arteriolar hypertrophy occurs in both the congenital and acquired forms of primary pulmonary hypertension and hence is not a helpful differential diagnostic point.