The Endpiont Evaluation Of Radionfrequent Ablation In Patients With Continuous Atrioventricular Node Function Curves Of Atrioventricular Node Reentrant Tachycardia

Objective The dual AV node pathway is the basic physiology of atrioventricular nodal reentrant tachycardia(AVNRT). Most of typical AVNRT (about 85%) usually has dual AV nodal pathyway physiology, a jump(≥ 50ms) of the AH interval, demonstrated by a discontinuous AV node function curve. However, others haven' t the character of the jump of the AH interval, and have shown the occurrence of typical AVNRT without this discontinuity when subjects have been tested at multiple the AH interval is determined as an important indicator for the endpoint of radionfrequent ablation in AVNRT patients, however,the patients with continuous AV node function curve cannot use this indicator , which bring the some difficulty to determine the endpiont of radionfrequent ablation. Whether the successful ablation sites in these tachycardias with continuous AV node function curves are different from those with discontions curves remains unknown. Through to study electrophysiological characteristics of continuous AV node function curve offer some indicator for the endpoint of radionfrequent ablation in patients who had AVNRT along with continuous AV node function curves.Methods and Result 32 patients with typical atrioventricular nodal reentrant tachycardia were devided into two groups. Group 1 included 11 patients with continuous atrioventricular nodal function curves, group 2 included 21 patients with discontinuous AV nodal function curves. AVmaxwas shorter in group 1 than group 2(276.57 + 23.34, 353.71 ±31.44 )at baseline.lt shortened in group 2(353.71+31.44 vs 207.29 ± 36.10 , p<0. 05)but remained in group 1 (276. 57 + 23. 34 vs 224. 00±55. 07, p>0. 05)after ablation. The PR/RR ratio exceeded 1.0 in AVNRT Group 1 patients(means 1. 06 +0.05)and Group 2 patients(meansl. 10+0. 09). After slow pathway ablation, the maximum PR/RR ratio was <1.0 in both two AVNRT groups(group 1=0.77 ±0. ll;Group 2=0.67 + 0. 11).Conclusions There are three conclusions in this study. First, the refractory periods of the fast and slow pathways may be similar. As a demonstration of discontinuity is dependent on a difference between the maximal conduction time of the fast pathway and the minimal conduction time of the slow pathway, an AH jump may not be present during atrial pacing if this difference in the conduction times of the two pathways is too small. It is the mechanisms to explain the continuous AV node function curves in AVNRT. Second, significant shortenting of the maximal AH interval and loss of the "tail" of the conduction curve representing the slow pathway which can be determined the endpiont of radionfrequent ablation .Third, the PR/RR interval ratio <1.0 during atrial pacing at the maximal rate with stable 1:1 AV conduction after radiofrequency ablation suggests successful elimination of AVNRT.