Pathophysiology
Clinical meaning
Pheochromocytoma crisis is a life-threatening catecholamine surge from an adrenal medullary tumor (or extra-adrenal paraganglioma) releasing massive quantities of epinephrine, norepinephrine, and/or dopamine. The catecholamine flood activates alpha-1 receptors (severe peripheral vasoconstriction causing hypertensive emergency with SBP >250 mmHg), beta-1 receptors (tachycardia, arrhythmias, increased contractility), and beta-2 receptors (hyperglycemia, hypokalemia). Crisis can be triggered by tumor manipulation during surgery, anesthesia induction, tyramine-containing foods, medications (metoclopramide, tricyclic antidepressants, opioids, corticosteroids), or may occur spontaneously. Uncontrolled hypertension can cause hypertensive encephalopathy, hemorrhagic stroke, myocardial infarction, aortic dissection, or flash pulmonary edema. The defining management principle is that ALPHA-blockade must be established BEFORE beta-blockade โ giving a beta-blocker first removes beta-2-mediated vasodilation, causing unopposed alpha-mediated vasoconstriction and potentially fatal hypertensive crisis.