An atrial pheochromocytoma-induced hypertensive crisis resistant to nitroprusside.

A malignant pheochromocytoma with several unique features was studied. Initially, its histological and catecholamine secretory properties and physiological effects were terminated by an infarct prior to its excision in 1973. However, in 1985 a metastasis was resected from the right atrium. Hypertensive crisis during surgery was controlled by the administration of phentolamine but not by nitroprusside. Within 2 months, it was again detected at this same site. Biochemical studies confirmed its recurrence. The tumor did not respond to chemotherapy with vincristine, cyclophosphamide and dacarbazine, but there has been physiological and biochemical improvement from inhibiting catecholamine biosynthesis with metyrosine. We recommend that both phentolamine and sodium nitroprusside be readily available during resection of a pheochromocytoma.