Reversibility of primary pulmonary hypertension during six years of treatment with oral diazoxide.

A 32 year old woman presented with a syncopal attack and dyspnoea on exertion. A diagnosis of primary pulmonary hypertension was confirmed by clinical examination, cardiac catheterisation, and pulmonary angiography. Her symptoms resolved completely with oral diazoxide and the pulmonary arterial pressure was reduced to normal levels over a period of six years. When diazoxide was discontinued on two separate occasions pulmonary hypertension recurred. This demonstrated the continued presence of the underlying stimulus for vasoconstriction.