Unpredictable response to vasodilator therapy in primary pulmonary hypertension.

A 49-year-old man with severe primary pulmonary hypertension unresponsive to multiple vasodilators showed beneficial response to intravenous (i.v.) isoproterenol with significant decrease in the pulmonary vascular resistance and increase in the cardiac output. However, the patient became dependent on i.v. isoproterenol and eventually died suddenly following an episode of bradyarrhythmia. Autopsy confirmed severe primary pulmonary hypertension. As the response to vasodilator therapy can be unpredictable in PPH, sequential hemodynamic evaluation of drugs is necessary for finding an optimal therapeutic agent.