Objectives: This study sought to describe the clinical features and sites of successful ablation for incessant nodofascicular (NF) and nodoventricular (NV) tachycardias.
Background: Incessant supraventricular tachycardias have been associated with tachycardia-induced cardiomyopathies and have been previously attributed to permanent junctional reciprocating tachycardias, atrial tachycardias, and atrioventricular nodal re-entrant tachycardias. Incessant concealed NF and NV tachycardias have not been described previously.
Methods: Three cases of incessant concealed NF and NV re-entrant tachycardias were identified from 2 centers.
Results: The authors describe 3 cases with incessant supraventricular tachycardia resulting from NV (2 cases) and NF (1 case) pathways. Atrioventricular nodal re-entrant tachycardia was excluded by His synchronous premature ventricular complexes that either delayed or terminated the tachycardia. Ventricular pacing showed constant and progressive fusion in cases 1 and 3. In 2 cases, there was spontaneous initiation with a 1:2 response (cases 1 and 3); the presence of retrograde longitudinal dissociation or marked decremental pathway conduction in cases 1 and 3 sustains these tachycardias. The NV pathway was successfully ablated in the slow pathway region in case 3 and at the right bundle branch in case 1. The NF pathway was successfully ablated within the proximal coronary sinus in case 2.
Conclusions: This is the first report of incessant supraventricular tachycardia using concealed NF or NV pathways. These tachycardias demonstrated spontaneous initiation from sinus rhythm with a 1:2 response and retrograde longitudinal dissociation or marked decremental pathway conduction. Successful ablation was achieved at either right-sided sites or within the coronary sinus.
Keywords: incessant tachycardias; nodofascicular pathway; nodoventricular pathway.
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