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Background: This study aimed to investigate the impact of aging on electrophysiological characteristics in patients with atrioventricular nodal re-entrant tachycardia (AVNRT)., Methods and Results: The 2,111 patients who underwent an electrophysiological study and radiofrequency (RF) catheter ablation of AVNRT were enrolled. The patients were divided into 4 groups according to age (group 1: < 20 years; group 2: 20-39 years; group 3: 40-59 years; and group 4: ≥ 60 years). The gender distribution differed with age. The atrio-Hisian interval, and effective refractory periods (ERP) of the right atrium, ventricle, antegrade slow pathway, retrograde slow pathway and fast pathway, and tachycardia cycle length all increased with age. However, a paradoxical change in the fast pathway ERP was noted. The fast pathway ERP was significantly longer in group 2 than in other groups, and was associated with the largest tachycardia window. The response to catecholamines was similar between different age groups. Procedure time, radiation time, and complications did not differ. However, the number of RF impulses was higher in group 2 compared with other groups (7.6 ± 9.3, P=0.04), which might imply a differing complexity during the ablation., Conclusions: Paradoxical aging changes of AVN electrophysiological characteristics were associated with a different atrioventricular nodal conduction property and the number of RF impulses.

Purpose of Review: Atrioventricular nodal reentrant tachycardia (AVNRT) is the most common arrhythmia in patients with regular supraventricular tachycardia. Selective radio frequency catheter ablation of the slow pathway has afforded an ideal method to treat most patients with AVNRT. However, there are still some controversies and recent developments concerning the ablation for patients with AVNRT. The purpose of this review is to elucidate the anatomy and physiology of the atrioventricular node and implications for the ablation of AVNRT., Recent Findings: The sequential ablation sites for slow pathway ablation are suggested as the isthmus between tricuspid annulus and coronary sinus ostium, the tricuspid edge of coronary sinus ostium by moving the ablation catheter tip slightly in and out of the coronary sinus, the septum lower than coronary sinus ostium, moving higher up on the half of Koch's triangle along the septum, one or two burns inside the first centimeter of the coronary sinus, left side of the septum., Summary: It is imperative to recognize the detailed anatomy and physiology of the atrioventricular node in every individual patient before the ablation of AVNRT.

Background: The significant role of bundle branch block during atrioventricular nodal reentrant tachycardia (AVNRT) is not clear. The purposes of this study were to study the effects of complete right bundle branch block (RBBB) on electrophysiological parameters during AVNRT and to define the significance of complete RBBB during AVNRT., Methods and Results: According to characteristics of electrocardiogram during sinus rhythm and AVNRT, 50 patients who underwent catheter ablation for slow-fast AVNRT were divided into three groups. Group I included 20 patients who had narrow QRS (< or = 110 ms) during sinus rhythm and AVNRT. Group II included 18 patients who had persistent RBBB (< or = 120 ms) during sinus rhythm and AVNRT. Group III included 12 patients who had narrow QRS during sinus rhythm, but they had narrow QRS and transient RBBB during AVNRT. The atrio-His (AH) interval (296+/-60 vs. 288+/-75 ms), His-ventricular (HV) interval (36+/-11 vs. 35+/-11 ms), His-atrial (HA) interval (72+/-24 vs. 71+/-28 ms), VA(HRA) interval (defined as the interval between the onset of ventricular depolarization and the onset of atrial activity of right high atrium; 34+/-24 vs. 37+/-25 ms), VA(CSO) interval (defined as the interval between the onset of ventricular depolarization and the onset of atrial activity of coronary sinus ostium; 13+/-28 vs. 26+/-23 ms) and tachycardia cycle length (TCL; 368+/-67 vs. 359+/-73 ms) during AVNRT were similar between group I and group II (all P > 0.05). In group III, the AH interval (255+/-81 vs. 246+/-83 ms), HV interval (44+/-5 vs. 42+/-11 ms), HA interval (66+/-19 vs. 70+/-15 ms), VA(HRA) interval (27+/-15 vs. 29+/-16 ms), VA(CSO) interval (23+/-25 vs. 21+/-25 ms) and TCL (322+/-76 vs. 316+/-77 ms) were not significantly different between AVNRT with narrow QRS and those with transient RBBB (all P > 0.05)., Conclusions: Persistent RBBB and transient RBBB have no significant effects on the electrophysiological parameters during AVNRT. These findings suggest that RBBB might not influence the conduction of lower common pathway or the circuit of AVNRT.

Dual AVN physiology can be demonstrated by a variety of maneuvers. To determine whether AVN recovery times following a blocked extrastimulus facilitate or obscure detection of dual AVN physiology, 11 patients (9-17 years) were studied with dual AVN pathways by using single and double atrial extrastimuli. With a single atrial extrastimuli, the premature atrial stimulus (A2) was coupled to basic atrial beats (A1). The fast and slow AVN recovery curves were constructed with plots of the nodal conduction time against the recovery time (A1A2,A2H2). With double atrial extrastimuli, a fixed blocked A2 beat (A2B) was followed by a scanning atrial beat (A3). The nodal recovery property post-A2B was studied by plots of A2BA3,A3H3. In all patients the recovery curve of the fast pathway post-A2B had a leftward shift when compared to that of the pre-A2B curve (i.e., the AH was shortened at the same recovery time). The window of slow pathway conduction post-A2B disappeared totally in five patients and decreased significantly in six patients (post-A2B: 26 +/- 42 ms; pre-A2B: 80 +/- 65 ms, P < 0.05). In the six patients that still had slow pathway conduction post-A2B, the slow pathway effective refractory period post-A2B was significantly less than that of pre-A2B (215 +/- 38 vs 268 +/- 16 ms, P < 0.05). The fast pathway effective refractory period post-A2B was also diminished significantly (235 +/- 62 vs 357 +/- 76 ms, P < 0.0001). The authors conclude that blocked atrial beats decrease the visibility of the slow pathway conduction.

Right Atrial Substrate of Supraventricular Tachyarrhythmias. Background:Voltage mapping has been used to detect diseased myocardium. However, accurate determination of the local atrial voltage at the same site, and simultaneous recordings from multiple mapping sites were limited. The purpose of this study was to investigate the right atrial (RA) substrate properties in patients with supraventricular tachyarrhythmias (SVT).Methods and Results:Forty patients (aged 55± 20 years) undergoing noncontact mapping and ablation of SVT constituted the study population. There were eight patients with atrioventricular node reentrant tachycardia (AVNRT), eight patients with focal atrial tachycardia (AT), 14 patients with atrial flutter (AFL), and 10 patients with atrial fibrillation (AF). The mean peak negative voltage (PNV) was analyzed in virtual unipolar electrograms, which were obtained from 256 equally distributed RA endocardial sites during sinus rhythm (SR), atrial pacing, and tachycardia. The mean PNV of global RA during SR (−1.34± 0.22 vs.−0.90± 0.40 vs.−1.00± 0.36 vs.−0.85± 0.35 mV, P= 0.04), atrial pacing at cycle lengths of 500 ms (−1.30± 0.29 vs.−0.70± 0.35 vs.−0.76± 0.25 vs.−0.64± 0.26 mV, P= 0.02), and 300 ms (−1.54± 0.47 vs.−0.94± 0.21 vs.−0.75± 0.27 vs.−0.57± 0.22 mV, P<0.01) were significantly greater in patients with AVNRT compared to AT, AFL, and AF. Furthermore, the mean PNV decreased during atrial pacing with shorter pacing cycle length was demonstrated only in patients with AFL and AF.Conclusion:Negative unipolar voltage analysis of global RA showed different RA substrate characteristics during various SVT. The substrate property of activation and cycle length-dependent voltage reduction may be related to the development of AFL and AF.(J Cardiovasc Electrophysiol, Vol. 16, pp. 1-8, March 2005) [ABSTRACT FROM AUTHOR]

LEE, S-H.,et al.: Electrophysiological Characteristics of Junctional Rhythm During Ablation of the Slow Pathway in Different Types of Atrioventricular Nodal Reentrant Tachycardia. Background:Junctional rhythm (JR) is commonly observed during radiofrequency (RF) ablation of the slow pathway for atrioventricular (AV) nodal reentrant tachycardia. However, the atrial activation pattern and conduction time from the His-bundle region to the atria recorded during JR in different types of AV nodal reentrant tachycardia have not been fully defined.Methods:Forty-five patients who underwent RF ablation of the slow pathway for AV nodal reentrant tachycardia were included; 27 patients with slow-fast, 11 patients with slow-intermediate, and 7 patients with fast-slow AV nodal reentrant tachycardia. The atrial activation pattern and HA interval (from the His-bundle potential to the atrial recording of the high right atrial catheter) during AV nodal reentrant tachycardia (HASVT) and JR (HAJR) were analyzed.Results:In all patients with slow-fast AV nodal reentrant tachycardia, the atrial activation sequence recorded during JR was similar to that of the retrograde fast pathway, and transient retrograde conduction block during JR was found in 1 (4%) patient. The HAJR was significantly shorter than the HASVT (57± 24 vs 68± 21 ms, P<0.01). In patients with slow-intermediate AV nodal reentrant tachycardia, the atrial activation sequence of the JR was similar to that of the retrograde fast pathway in 5 (45%), and to that of the retrograde intermediate pathway in 6 (55%) patients. Transient retrograde conduction block during JR was noted in 1 (9%) patient. The HAJR was also significantly shorter than the HASVT (145± 27 vs 168± 29 ms, P= 0.014). In patients with fast-slow AV nodal reentrant tachycardia, retrograde conduction with block during JR was noted in 7 (100%) patients. The incidence of retrograde conduction block during JR was higher in fast-slow AV nodal reentrant tachycardia than slow-fast (7/7 vs 1/11, P<0.01) and slow-intermediate AV nodal reentrant tachycardia (7/7 vs 1/27, P<0.01).Conclusions:In patients with slow-fast and slow-intermediate AV nodal reentrant tachycardia, the JR during ablation of the slow pathway conducted to the atria through the fast or intermediate pathway. In patients with fast-slow AV nodal reentrant tachycardia, there was no retrograde conduction during JR. These findings suggested there were different characteristics of the JR during slow-pathway ablation of different types of AV nodal reentrant tachycardia.(PACE 2005; 28:111–118) [ABSTRACT FROM AUTHOR]

The present study investigated the incidence and predictors of permanent pacemaker (PPM) implantation for late atrioventricular block (AVB) in patients with atrioventricular nodal reentrant tachycardia (AVNRT) who received ablation. The data from 3,442 patients with AVNRT who received ablation were analyzed. Those who developed late AVB (>1 month after ablation) and received a PPM were identified. The incidence of PPM implantation in 1,148 matched patients with Wolff-Parkinson-White syndrome and in the whole population of Taiwan were compared. Of the patients with AVNRT receiving ablation (mean follow-up duration 128.3 ± 62.5 months), 15 (0.4%) received PPM implantation for late AVB (mean interval after catheter ablation 95.4 ± 55.0 months). Only age (odds ratio 1.05, p = 0.02) and transient AVB (odds ratio 8.55, p [ 0.01) during the procedure were independently associated with PPM implantation for late AVB. The patients with AVNRT had a greater incidence of PPM implantation due to late AVB compared to the matched patients with Wolff-Parkinson-White syndrome. The annual incidence of PPM implantation for AVB was also greater in the patients with AVNRT than in the general population. In conclusion, the incidence of PPM implantation for late AVB in patients with AVNRT who received catheter ablation was low but still greater than that in patients with Wolff-Parkinson-White syndrome and the general population in Taiwan. [ABSTRACT FROM AUTHOR]