A 19-year-old woman is brought 3 hours after ingesting a large quantity of her mother's amitriptyline. She is comatose with a heart rate of 140, blood pressure 80/50 mm Hg, and a QRS duration of 160 ms on ECG. The single most appropriate immediate therapy for the cardiac abnormality is:

• A IV amiodarone infusion
• B IV calcium gluconate
• C IV sodium bicarbonate bolus ✓
• D IV adenosine

Explanation

Tricyclic antidepressant cardiotoxicity comes from fast sodium channel blockade, which widens the QRS and depresses contractility and conduction. Sodium bicarbonate raises serum pH and extracellular sodium, relieving the channel blockade; it is the specific antidote for QRS widening and hypotension in TCA overdose. Amiodarone adds further sodium channel blockade and is avoided, calcium treats calcium channel blocker toxicity, and adenosine has no role here.

Reference: Goldfrank's Toxicologic Emergencies, 11th ed.

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Written and medically reviewed by the StethoPrep medical team.