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Narrow complex tachycardia with VA block: diagnostic and therapeutic implications
M H Hamdan1, J M Kalman, M D Lesh
1University of Texas, Southwestern/Dallas Veteran's Affairs Medical Center, USA. Mohammed@ep4.ucsf.edu
Pacing and Clinical Electrophysiology : PACE
|June 20, 1998
Summary
Narrow complex tachycardia with ventriculoatrial (VA) block is challenging to diagnose. Nodofascicular pathways are common but poorly responsive to ablation, unlike other causes.
Area of Science:
- Cardiology
- Electrophysiology
- Cardiac Arrhythmias
Background:
- Narrow complex tachycardia with ventriculoatrial (VA) block is uncommon.
- Differential diagnosis includes various reentrant and automatic tachycardias.
- Previous reports are limited to isolated case studies.
Purpose of the Study:
- To review experience with narrow complex tachycardia and VA block.
- To highlight diagnostic challenges and therapeutic implications.
- To identify features suggestive of specific tachycardia mechanisms.
Main Methods:
- Retrospective review of six patients with narrow complex tachycardia and VA block.
- Attempted radiofrequency ablation of the arrhythmogenic site.
- Analysis of electrophysiological findings to differentiate tachycardia mechanisms.
Main Results:
- Three patients had evidence of nodofascicular pathways.
- Two patients showed intermittent antegrade conduction over a left-sided nodofascicular tract.
- Two patients had automatic junctional tachycardia, and one had AV nodal reentry.
- Radiofrequency ablation was unsuccessful for nodofascicular tachycardia but effective for others.
Conclusions:
- Nodofascicular pathways are a common cause of narrow complex tachycardia with VA block.
- Specific electrophysiological criteria can suggest nodofascicular tachycardia.
- Nodofascicular tachycardia has a poor response to radiofrequency ablation compared to AV nodal reentry and automatic junctional tachycardia.