METYROSINE AND PHEOCHROMOCYTOMA

Background: Severe hemodynamic instability may occur during surgery fo r removal of pheochromocytoma, unless there is preoperative pharmacolo gical treatment.Objective: To evaluate the effects of metyrosine (alph a-methyl-p-tyrosine), a catecholamine synthesis inhibitor, and alpha-b lockade with prazosin or phenoxybenzamine on cardiovascular morbidity during surgery for pheochromocytoma. Methods: A retrospective analysis was made of patients followed up at the Medical College of Georgia, A ugusta, during 28 years who received metyrosine and prazosin (n=6), me tyrosine and phenoxybenzamine alone (n=14), phenoxybenzamine alone (n= 6), or no medication (n=7) during 3 weeks before tumor removal. The pe rcentage of patients not requiring pressors or phentolamine during the intraoperative period as well as the perioperative peak systolic pres sures and peak heart rates were estimated in each group. Results: Ther e was a significant (P<.05) increase in intraoperative peak systolic p ressures without preoperative treatment (mean+/-SD, 243+/-40 mm Hg) vs metyrosine (mean+/-SD, 168+/-27 mm Hg). Ninety-five percent of patien ts who received metyrosine did not require pressors intraoperatively v s 50% with phenoxybenzamine alone. Eighty-one percent of patients pret reated with metyrosine did not require intraoperative phentolamine vs 33% with phenoxybenzamine alone and 29% without medications. Two patie nts in the no medication group died as a result of hypertensive crisis . Conclusions: The combination of alpha-metyrosine and alpha-blockade results in better blood pressure control and less need for use of anti hypertensive medication or pressors during surgery, compared with the classical method of single-agent adrenergic blockade. Preoperative tre atment with metyrosine along with an alpha-blocker is a useful strateg y for decreasing the surgical morbidity in patients with pheochromocyt oma and assumes greater importance as long as the availability of phen tolamine for intraoperative use is a problem.