Characteristics of Atrial Tachycardia due to Small versus Large Reentrant Circuits after Ablation of Persistent Atrial Fibrillation.
ABSTRACT BACKGROUND: While macro-reentrant atrial tachycardias (AT) have been reasonably well described, little is known about small reentrant circuits. OBJECTIVE: The goal of the study was to compare characteristics of large and small reentrant circuits after ablation of persistent atrial fibrillation (AF). METHODS: Seventy-seven patients (age=61±10 years; LA=46±6 mm; EF=0.52±0.13) underwent a procedure for post-ablation AT. The p-wave duration, circuit size, electrogram characteristics, and conduction velocity were determined. RESULTS: AT was due to macro-reentry in 62 patients (80%), a small reentrant circuit in 13 (17%), and a focal mechanism in 2 (3%). The p-wave duration during small reentrant ATs was shorter than that during macro-reentry (174±12 vs. 226±22 ms; p<0.0001). The duration of fractionated electrograms at the critical site was longer in small vs. large circuits (167±43 vs. 98±38 ms, respectively, p<0.0001), and accounted for a greater percentage of the tachycardia cycle length (59±18 vs. 38±14%, respectively, p<0.0001). The mean diameters of macro-reentrant vs. small reentrant circuits were 44±7 and 26±11 mm, respectively (p<0.0001). The mean conduction velocity along the small circuits was lower (0.5±0.2 vs. 1.2±0.3 m/s, p<0.0001). Catheter ablation eliminated the AT in all 77 patients. CONCLUSIONS: AT due to a small reentrant circuit after ablation of AF may be distinguished from macro-reentry by a shorter p-wave duration, and the presence of long-duration electrograms at the critical site owing to extremely slow conduction. These features may aid the clinician in mapping of post-ablation ATs.
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ABSTRACT: One of the most important proarrhythmic complications after left atrial (LA) ablation is regular atrial tachycardia (AT) or flutter. Those tachycardias that occur after atrial fibrillation (AF) ablation can cause even more severe symptoms than those from the original arrhythmia prior to the index ablation procedure since they are often incessant and associated with rapid ventricular response. Depending on the method and extent of LA ablation and on the electrophysiological properties of underlying LA substrate, the reported incidence of late ATs is variable. To establish the exact mechanism of these tachycardias can be difficult and controversial but correlates with the ablation technique and in the vast majority of cases the mechanism is reentry related to gaps in prior ablation lines. When tachycardias occur, conservative therapy usually is not effective, radiofrequency ablation procedure is mostly successful, but can be challenging, and requires a complex approach.Current Cardiology Reviews 10/2014; DOI:10.2174/1573403X10666141013122400
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