Danger of vasodilator therapy for pulmonary hypertension in patent foramen ovale

A 23-year-old woman with systemic lupus erythematosus was found to have severe pulmonary hypertension with secondary patency of the foramen ovale. Infusion of hydralazine increased the basal right-to-left shunt and resulted in a dramatic fall in arterial oxygen pressure, with subsequent irreversible cardiovascular collapse. Vasodilator therapy appears to be hazardous in patients with severe pulmonary hypertension and patent foramen ovale.