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Key Features

  • Class Ia antiarrhythmic agents

    • Quinidine

    • Disopyramide

    • Procainamide

  • Class Ic antiarrhythmic agents

    • Flecainide

    • Propafenone

Clinical Findings

  • Arrhythmias

  • Syncope

  • Hypotension

Diagnosis

  • Blood levels of quinidine and procainamide (and active metabolite NAPA) are generally available from hospital laboratory

  • ECG monitoring for QRS and QT interval prolongation

    • Widening of the QRS complex (> 100–120 ms)

    • With type Ia drugs, a lengthened QT interval and atypical or polymorphous ventricular tachycardia (torsades de pointes) may occur

Treatment

  • Activated charcoal

    • Administer 60–100 g orally or via gastric tube, mixed in aqueous slurry for ingestions within 1 h

    • Do not use for comatose or convulsing patients unless they are endotracheally intubated

  • Consider gastric lavage for recent (1 h) large ingestions

  • Consider whole bowel irrigation for ingestion of sustained-release formulations

  • Perform continuous cardiac monitoring

  • Treat cardiotoxicity (hypotension, QRS interval widening) with intravenous boluses of sodium bicarbonate, 50–100 mEq

  • Torsades de pointes ventricular tachycardia may be treated with intravenous magnesium or overdrive pacing

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