Atrioventricular conduction before and after the radiofrequency catheter ablation of a nodal reentry tachycardia circuit
Pappone, C.; De Simone, A.; Stabile, G.; Senatore, G.; Lamberti, F.; Solimene, F.; Turco, P.; Santomauro, M.; Chiariello, M.
Cardiologia 39(8): 565-575
1994
ISSN/ISBN: 0393-1978 PMID: 7805072 Document Number: 5019
Aim of our study was to retrospectively evaluate atrioventricular conduction 24 hours after selective radiofrequency catheter ablation of the fast pathway or after selective ablation of the slow pathway of the atrioventricular nodal reentrant tachycardia circuit. Electrophysiologic modifications were retrospectively analyzed in 47/48 patients successfully submitted to fast pathway ablation and in 90/93 patients successfully submitted to slow pathway ablation. The atrioventricular conduction intervals (P-Q and a-H), both anterograde and retrograde Wenckebach point, the effective refractory period of atrioventricular node and the atrioventricular node function curve were evaluated before and after selective radiofrequency catheter ablation of slow and fast pathway. We identified the fast pathway ablation potential as: A:V ratio>2:1, His electrogram s 150 n V. The slow pathway potential was identified as the widest, sharpest and latest atrial electrogram recorded during sinus rhythm in the posteroseptal region of the atrioventricular junction or as the widest, sharpest and earliest observed during retrograde conduction. We observed a significant increase in the P-Q and a-11 intervals in patients submitted to fast pathway ablation, while no significant modification of these parameters was appreciated in patients submitted to slow pathway ablation. No significant modification of anterograde Wenckebach point (NS) was observed in patients submitted to successfully ablation of fast pathway while a statistically significant increase in anterograde Wenckebach point (p=0.03) was observed in patients submitted to slow pathWay ablation. After selective fast pathway ablation, retrograde conduction was absent in 82.9% of patients submitted to ablation; in the remaining 17.1% a significant increase of retrograde Wenckebach point was observed. We did not observe any significant modification of retrograde conduction in patients submitted to selective ablation of slow pathway. After fast pathway ablation, in all patients, we observed a discontinuous Atrioventricular node function curve while three different atrioventricular conduction patterns were present after slow pathway ablation: non slow pathway anterograde conduction and no discontinuous atrioventricular node function curve with a higher effective refractory period of the atrioventricular node in 48 patients (53.3%); evidence of slow pathway anterograde conduction and discontinuous atrioventricular node function curve with no inducible echo beats in 33 patients (36.7%); presence of slow pathway anterograde conduction, of discontinuous atrioventricular node function curve and of inducible echo beats (less than 5) in 9 patients (10%). Our study demonstrates that atrioventricular conduction pattern after selective ablation of fast or slow pathway is compatible with the present idea of anatomic structure of atrioventricular junction. While fast pathway ablation significantly modifies the retrograde conduction of atrioventricular node, the partial or total ablation of the slow pathway or of the junctional anisotropic myocardium can be associated to an increase of the effective refractory period of atrioventricular node or of the Wenckebach point. In our experience we observed no complete atrioventricular block and this suggests that selective ablation of slow or fast pathway is associated to a sufficient reserve of atrioventricular conduction.
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