Tricyclic Antidepressants in the Intensive Care Unit

Tricyclic antidepressants (TCAs) are one of the most commonly prescribed classes of antidepressant medica tions, and they may account for more than 25% of all serious drug overdoses for persons admitted to adult intensive care units (ICUs). TCA overdose is the most common life-threatening drug ingestion in the United States, with an in-hospital mortality ranging from 0.6 to 15%. Manifestations of a significant overdose include anticholinergic effects (fever, mydriasis, tachycardia, and urinary retention), central nervous system toxicity (confusion, agitation, coma, hallucinations, and grand mal seizures), respiratory depression, and cardiovascu lar toxicity (ventricular tachycardia or fibrillation, hypotension, and conduction defects). The principal cardiovascular findings associated with therapeutic doses of TCAs are discussed and grouped into three categories: (1) electrocardiographic changes—sinus tachycardia, repolarization abnormalities, conduction disturbances, and ventricular arrhythmias; (2) mild depression of myocardial contractility; and (3) sudden cardiac death. The therapeutic feasibility and selection of a TCA for patients with preexisting cardiovascular disease is discussed, and current recommendations on the diagnosis and management of TCA overdoses are reviewed.