Alpha-adrenergic blockade in pheochromocytoma is used before beta-blockade because:

• A. To prevent unopposed alpha-adrenergic vasoconstriction
• B. To decrease heart rate
• C. To prevent hyperkalemia
• D. To reduce volume status

Answer: (A)

The key idea is that in pheochromocytoma the excess catecholamines drive alpha-adrenergic–mediated vasoconstriction as well as beta-adrenergic effects on the heart. If you block beta receptors first, you remove the heart’s compensatory mechanisms (like reducing tachycardia) but you leave alpha-mediated vasoconstriction unopposed, which can cause a dangerous rise in blood pressure. Starting with alpha-adrenergic blockade blunts the vasoconstrictive drive, lowers systemic vascular resistance, and stabilizes blood pressure. Only after adequate alpha-blockade is achieved should beta-blockade be added to control tachycardia and reduce arrhythmia risk. This sequence minimizes intraoperative hypertensive crises during tumor manipulation.