Sections View Full Chapter Figures Tables Videos 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|Favorite Figure|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|Favorite Figure|Download Slide (.ppt) GET ACCESS TO THIS RESOURCE 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 Get Free Access Through Your Institution Contact your institution's library to ask if they subscribe to McGraw-Hill Medical Products. Access My Subscription GET ACCESS TO THIS RESOURCE Subscription Options Pay Per View Timed Access to all of AccessEmergency Medicine 24 Hour $34.95 (USD) Buy Now 48 Hour $54.95 (USD) Buy Now Best Value AccessEmergency Medicine Full Site: One-Year Individual Subscription $595 USD Buy Now View All Subscription Options