Preoperative Medical Preparation

Surgery is the mainstay of treatment for most patients; however, preoperative medical preparation is critical. Alpha-adrenergic blockade should be initiated at the time of diagnosis and maximized preoperatively to prevent potentially life-threatening cardiovascular complications, which can occur as a result of excess catecholamine secretion during surgery. Complications may include:

Phenoxybenzamine (a nonselective alpha-antagonist) is the usual drug of choice; prazosin, terazosin, and doxazosin (selective alpha-1-antagonists) are alternative choices.[1,2] Prazosin, terazosin, and doxazosin are shorter acting than phenoxybenzamine, and therefore, the duration of postoperative hypotension is theoretically less than with phenoxybenzamine; however, there is less overall experience with selective alpha-1-antagonists than with phenoxybenzamine.

A preoperative treatment period of 1 to 3 weeks is usually sufficient; resolution of spells and a target low normal blood pressure for age indicate that alpha-adrenergic blockade is adequate. During alpha-adrenergic blockade, liberal salt and fluid intake should be encouraged because volume loading reduces excessive orthostatic hypotension both preoperatively and postoperatively. If tachycardia develops or if blood pressure control is not optimal with alpha-adrenergic blockade, a beta-adrenergic blocker (e.g., metoprolol or propranolol) can be added, but only after alpha-blockade. Beta-adrenergic blockade must never be initiated before alpha-adrenergic blockade; doing so blocks beta-adrenergic receptor-mediated vasodilation and results in unopposed alpha-adrenergic receptor-mediated vasoconstriction, which can lead to a life-threatening crisis.