An elderly woman on digoxin for atrial fibrillation develops nausea, xanthopsia, and bigeminy with a serum potassium of 2.9 mEq/L after recent furosemide escalation. She then develops sustained ventricular tachycardia. The definitive treatment is:

• A Intravenous potassium chloride infusion alone
• B Intravenous lidocaine bolus and infusion
• C Digoxin-specific antibody fragments (Fab) ✓
• D Synchronized direct current cardioversion

Explanation

Life-threatening digoxin toxicity with ventricular arrhythmias is treated with digoxin-specific Fab fragments, which bind free digoxin and rapidly reverse toxicity. Hypokalemia from loop diuretics potentiates toxicity because low extracellular potassium reduces competition for the Na/K-ATPase binding site. While correcting potassium is necessary, it is adjunctive. Electrical cardioversion is hazardous in digitalis toxicity as it may provoke refractory ventricular fibrillation. Lidocaine may be used if Fab is unavailable but is not definitive.

Reference: Katzung's Basic and Clinical Pharmacology, 15th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.