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 Access profile is currently affiliated with [InstitutionA] and is in the process of switching affiliations to [InstitutionB]. Please select how you would like to proceed. Keep the current affiliation with [InstitutionA] and continue with the Access profile sign in process Switch affiliation to [InstitutionB] and continue with the Access profile sign in process 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 Error: Incorrect UserName or Password Username Error: Please enter User Name Password Error: Please enter Password Sign in Forgot Password? Forgot Username? Sign in via OpenAthens Sign in via Shibboleth You already have access! Please proceed to your institution's subscription. Create a free profile for additional features.