A patient with SVT on verapamil is inadvertently given IV beta-blocker. Which hemodynamic catastrophe results and what reversal agent is used?

• A Refractory ventricular fibrillation; reverse with amiodarone
• B Sinus tachycardia; no specific reversal needed
• C Severe AV block and cardiogenic shock; reverse with IV calcium gluconate, glucagon, and high-dose insulin euglycemic therapy ✓
• D Acute hypertensive crisis; reverse with phentolamine

Explanation

Verapamil blocks L-type calcium channels in cardiac nodal tissue; beta-blockers block beta1 receptors reducing cAMP. Combining both agents causes additive suppression of SA/AV node function and myocardial contractility, producing severe AV block and cardiogenic shock — a pharmacodynamic interaction unique to verapamil (less risk with dihydropyridine CCBs). Treatment involves IV calcium (to overcome calcium channel blockade), glucagon (bypasses beta receptor to activate adenylyl cyclase), and high-dose insulin euglycemic therapy (HIET) for calcium channel blocker toxicity.

Reference: KD Tripathi, Essentials of Medical Pharmacology, 8th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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