A-V dissociation revisited

Abstract

We have touched upon the semantic impasse that plagues discussions of A-V dissociation and given our reasons for preferring to avoid the terms interference, complete and incomplete A-V dissociation, and nonparoxysmal A-V nodal tachycardia. We have stressed Pick's admirable dictum that A-V dissociation is never a primary disturbance, described the various ways in which the term is used, and defended as virtually inescapable the use of A-V dissociation in a quasi-specific way for a group of cognate arrhythmias that would otherwise be nameless. We have described and illustrated many of the mechanisms that lead to dissociation with special attention to related phenomena and variants including: isorhythmic dissociation, fusion beats, the “zone” of potential dissociation, dissociated nodal pacemakers, paired capture beats, altered contours of capture beats and the many variants resulting from block-dissociation, including the effects of concealed and supernormal conduction. We have placed emphasis on the bedside diagnosis of A-V dissociation and have stressed 2 important pitfalls, namely, the folly of diagnosing complete A-V block in the presence of A-V dissociation with accelerated idionodal or idioventricular rhythms; and the doubtful value of signs of dissociation as evidence of ventricular tachycardia. Finally, we have briefly alluded to certain modes of therapy applicable to various patterns of A-V dissociation.