Which of the following is the appropriate management strategy of pheochromocytoma-associated hypertension?A. α-adrenergic blockade only
Correct Answer: C
Blood pressure management is critical in the preoperative management of pheochromocytoma prior to definitive treatment via surgical resection. α-adrenergic receptor blockade (particularly α1-mediated vasoconstriction) should be established prior to β-adrenoreceptor blockade, as unopposed αadrenergic receptor stimulation can cause a hypertensive crisis and place a patient at high risk for heart attack, stroke, and death.
Phenoxybenzamine is a long-acting, nonselective, noncompetitive αantagonist (α1 > α2) often used to control blood pressure prior to surgery. Phentolamine is an intravenous, rapid-acting, nonselective α-antagonist (α1 = α2) often used to control blood pressure perioperatively. While selective α1-blockers such as prazosin, terazosin, and doxazosin may offer a more favorable adverse effect profile, they are not used to prepare patients for surgery due to their incomplete α-blockade.
Once α-blockade is established, β-blockade should be initiated to treat or prevent tachycardia. Both noncardioselective β-blockers, such as propranolol, and cardioselective β-blockers, such as metoprolol, have been used for heart rate control prior to surgery. Esmolol is an intravenous, rapid, short-acting, β1-selective blocker often to control heart rate perioperatively.
Metyrosine is an oral medication which inhibits tyrosine hydroxylase, the rate-limiting step in catecholamine synthesis. It is often used for patients with malignant pheochromocytoma or in whom surgery is contraindicated. Of note, it can also be prescribed for patients with a pheochromocytoma who do not respond to phenoxybenzamine or phentolamine therapy, or as an adjunct to therapy.