Why the study?
Does ablation in the slow-pathway region alter electrophysiological properties similarly in AVNRT patients with smooth versus discontinuous AV node function curves?
Does ablation in the slow-pathway region alter electrophysiological properties similarly in AVNRT patients with smooth versus discontinuous AV node function curves?
Ablation of the slow-pathway region in AVNRT patients with smooth AV node function curves successfully eliminates the slow pathway component, demonstrating that smooth curves still consist of distinct fast and slow pathways.
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Supports slow-pathway elimination in smooth-curve AVNRT; hypothesis-generating for uniform ablation mechanisms across curve types.
BACKGROUND: Some patients with otherwise typical AV node reentry do not manifest discontinuous AV node function curves. We examined the effects of an ablation in the slow-pathway region in patients with smooth AV node function curves. METHODS AND RESULTS: Fifteen patients with AV node reentrant tachycardia (AVNRT) and discontinuous AV node function curves were compared with 15 patients with AVNRT and smooth AV node function curves. In the group with discontinuous curve, the "net" anterograde effective refractory period (AERP) of the AV node increased (270 +/- 28 versus 304 +/- 37 ms, P = .03) and AERP of the remaining fast pathway decreased (367 +/- 100 versus 304 +/- 37 ms, P = .026) after the ablation. In the group with a smooth curve, the AERP of the AV node increased (266 +/- 42 versus 299 +/- 76 ms, P = .07) and the anterograde Wenckebach cycle length increased (336 +/- 66 versus 379 +/- 86 ms, P = .008) after the ablation. Retrograde conduction over the AV node was similar in both groups and was unchanged after ablation. The longest attainable AH interval (AHmax) measured during atrial extrastimulus testing was more prolonged in patients with a discontinuous curve than in patients with a smooth curve (326 +/- 48 versus 250 +/- 70 ms, P = .002). The AHmax shortened in both groups after ablation (326 +/- 48 versus 173 +/- 34 ms, P < .0001, and 250 +/- 70 versus 179 +/ 34 ms, P < .0003, respectively) and were similar. Successful ablation in the slow-pathway zone in patients with a smooth AV node function curve resulted in the loss of the "tail" of the curve representing the slow pathway. CONCLUSIONS: These data suggest that the smooth AV node function curve consists of two distinct components representing both fast and slow AV node pathways even when the typical discontinuity is absent.
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Sheahan et al. (1996) studied this question.
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