A 65-year-old woman on quinidine develops a seizure and the monitor shows polymorphic ventricular tachycardia with a twisting QRS axis. Which drug is the acute treatment of choice to terminate this arrhythmia?

• A Lidocaine
• B Amiodarone
• C Propranolol
• D Magnesium sulfate ✓

Explanation

Torsades de Pointes is a polymorphic ventricular tachycardia associated with QT prolongation. The acute treatment of choice is intravenous magnesium sulfate, which stabilizes the cardiac membrane and suppresses early afterdepolarizations. Lidocaine and amiodarone are less effective, and amiodarone can further prolong the QT interval, worsening the condition.

Reference: Harrison's Principles of Internal Medicine, 21st ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.