What is a common sign of TCA toxicity?

A common sign of tricyclic antidepressant (TCA) toxicity is a prolonged QRS interval. TCAs can cause cardiotoxic effects, primarily by blocking sodium channels in the cardiac tissue, which leads to slowing of conduction through the His-Purkinje system. This effect manifests as a lengthening of the QRS complex on an electrocardiogram (ECG). A prolonged QRS interval is significant as it indicates an increased risk of life-threatening ventricular arrhythmias, which are a concern in TCA overdose situations.

Other common symptoms of TCA toxicity may include dilated pupils, anticholinergic effects (such as dry mouth and urinary retention), seizures, and altered mental status, but the prolonged QRS interval is specifically notable for its association with cardiac complications in these patients. Understanding the cardiac effects of tricyclics is crucial for the management and treatment of overdose cases, making the recognition of a prolonged QRS interval an important clinical finding.