Sections View Full Chapter Figures Tables Videos Annotate Full Chapter Figures Tables Videos Supplementary Content +++ ECG Findings ++ Tachycardia QRS complex widening QT prolongation Prominent terminal R wave in aVR or V1 Prominent S in lead I +++ Pearls ++ Tricyclic antidepressants (TCAs) produce their effects by several mechanisms. Anticholinergic effects may induce tachycardia, and sodium channel blockage may lead to QRS widening. The QRS widening seen in a TCA overdose has a nonspecific pattern and is typically unlike any bundle branch block morphology. ECG effects are rate dependent and become more pronounced with tachycardia and acidosis. ++ FIGURE 23.53A Tricyclic Antidepressant Toxicity. (ECG contributor: Saralyn R. Williams, MD.) Graphic Jump LocationView Full Size||Download Slide (.ppt) ++ FIGURE 23.53B 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. Graphic Jump LocationView Full Size||Download Slide (.ppt) Your MyAccess profile is currently affiliated with '[InstitutionA]' and is in the process of switching affiliations to '[InstitutionB]'. Please click ‘Continue’ to continue the affiliation switch, otherwise click ‘Cancel’ to cancel signing in. Get Free Access Through Your Institution Learn how to see if your library subscribes to McGraw Hill Medical products. Subscribe: Institutional or Individual Sign In Username Error: Please enter User Name Password Error: Please enter Password Forgot Username? Forgot Password? Sign in via OpenAthens Sign in via Shibboleth