Recognition and therapy of digitalis toxicity

Abstract

Complicating the recognition of digitalis toxicity are certain electrophysiological phenomena which may result in arrhythmias which mimic toxic effects of the glycosides. In particular, the “rule of bigeminy”, aberrancy of intraventricular conduction, ”concealed” toxicity, concealed conduction into the AV junction, and exit block complicate the diagnosis of excessive digitalization. Of the various arrhythmias indued by digitalis, atrial tachycardia with block, nonparoxysmal junctional tachycardia, bidirectional “ventricular” tachycardia, ventricular premature systoles, ventricular tachycardias, multiple ectopic arrhythmias, AV dissociation, and the coexistance of conduction defects with ectopic beats or rhythms are of particular interest either (1) because of a high degree of correlation with digitalis toxicity or (2) because the recognition of the arrhythmia may present complexities which need consideration. The discussion in this review focuses on these complexities of arrhythmia interpretation as a manifestation of digitalis toxicity.