Use of cyclic antidepressants in patients with cardiac conduction disturbances.

Cyclic antidepressants can produce cardiac complications in patients with certain types of cardiac conduction abnormalities. Most cyclic antidepressants have a quinidinelike effect on the heart, which, in combination with Type I antiarrhythmic agents such as quinidine, disopyramide and procainamide, may induce heart block and potentially lethal arrhythmias in susceptible individuals. Patients with known cardiovascular disease warrant careful evaluation before tricyclic therapy is initiated. Guidelines are presented for identifying high-risk patients and for using cyclic antidepressants in patients with cardiac conduction abnormalities.