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ECG Findings

  • Tachycardia

  • QRS complex widening

  • QT prolongation

  • Prominent terminal R wave in aVR or V1

  • Prominent S in lead I


  1. Tricyclic antidepressants (TCAs) produce their effects by several mechanisms. Anticholinergic effects may induce tachycardia, and sodium channel blockage may lead to QRS widening.

  2. The QRS widening seen in a TCA overdose has a nonspecific pattern and is typically unlike any bundle branch block morphology.

  3. ECG effects are rate dependent and become more pronounced with tachycardia and acidosis.


Tricyclic Antidepressant Toxicity. (ECG contributor: Saralyn R. Williams, MD.)


Prominent S wave in lead I (arrowhead) with prominent terminal R wave in aVR (arrow). The QRS complex is wide (double arrow), the QT interval is prolonged, and the patient is tachycardic.

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