Phenytoin: the drug of choice in tricyclic antidepressant overdose?

Tricyclic antidepressants seem to have at least three types of effect on the heart: anticholinergic, adrenergic, and quinidine-like. Although the therapeutic emphasis in tricyclic antidepressant overdose has been on reversing the anticholinergic effects with physostigmine, there is considerable evidence suggesting that the life-threatening manifestations of tricyclic antidepressant overdose--the conduction defects, bradyarrhythmias, heart block, etc--are much more like quinidine and are more appropriately treated with phenytoin, or other drugs which enhance intracardiac conduction and myocardial contractility.