[Precapillary pulmonary hypertension of uncertain etiology]

A 39-year-old man was hospitalized for investigation of increasing dyspnoea for 3 month. On admission he was found to have bilateral ankle oedema, an enlarged liver and loud systolic murmur over the lower sternum.

There were signs of right heart strain/hypertrophy on the chest radiogram and echocardiogram. After treatment of right heart failure cardiac catheterization indicated moderate precapillary pulmonary hypertension (PH) with a mean pulmonary artery pressure (PAPm) of 24 mm Hg and pulmonary vascular resistance (PVR) of 470 dyn.s.cm-5 at rest. All known causes having been excluded, the PH was classified as idiopathic.

Evidence of acute pulmonary vascular reactivity was obtained with nitric oxide (NO) inhalation and oral diltiazem, a calcium-channel blocker. The latter, at a dosage of 3 x 120 mg daily, had after 13 days achieved a persisting reduction of PVR at rest and a reduction in PAP rise during exercise.

After exclusion of other causes, the acute right heart failure was found to be due to primary pulmonary hypertension. The therapeutic efficacity of diltiazem as a vasodilator can be predicted from the response to inhaled NO.