Atrial tachycardia with slow pathway conduction mimicking typical atrioventricular nodal reentrant tachycardia.

A 68-year-old woman with palpitations underwent electrophysiologic testing. During burst atrial pacing the PR interval exceeded the RR interval and induced a supraventricular tachycardia consistent with a typical AV nodal reentrant tachycardia (AVNRT). Radiofrequency ablation of the slow pathway during the tachycardia immediately produced 2 : 1 AV conduction. After slow AV nodal pathway ablation an atrial tachycardia (AT) remained inducible with the earliest atrial activation around the HB region. Radiofrequency ablation at the site of earliest atrial activation interrupted the AT without AV block. AT originating from the HB region with slow pathway conduction may mimic typical AVNRT.     

Irregular atypical atrioventricular nodal reentrant tachycardia: Incidence, electrophysiological characteristics, and effects of slow pathway ablation

BACKGROUND: Atrioventricular (AV) nodal reentrant tachycardias (AVNRT) with variable AV relationships are infrequently observed and might be misdiagnosed as atrial tachycardia. OBJECTIVE: This single-center, retrospective study was performed to elucidate the mechanism of AVNRT showing variable AV relationship. METHODS: This study included a total of 340 patients with all forms of AVNRT. The induced AVNRTs were classified into those with variations in the AV relationship (>or=30 ms) (irregular AVNRT) and those without (regular AVNRT). RESULTS: A total of 364 AVNRTs (typical and atypical form = 297 and 67) were induced in the 340 patients. Of the 364 AVNRTs, the variations in the AV relationship were observed in 8 atypical AVNRTs (2%) induced in 8 patients (2%). The patients with irregular atypical AVNRT were significantly younger than those with regular typical AVNRT and those with regular atypical AVNRT (35+/-15 vs 51+/-18 and 47+/-16 years, respectively). Irregular atypical AVNRTs showed atypical Wenckebach periodicity with simultaneous prolongation in the A-A intervals and Wenckebach block proximal to the His bundle. Irregular atypical AVNRTs showed a shorter tachycardia cycle length (TCL) (305+/-78 ms vs 381+/-95 ms; P<.05) and higher prevalence of eccentric coronary sinus (CS) activation than regular atypical AVNRTs (5 (63%) of 8 tachycardias vs 15 (25%) of 59 tachycardias; P<.05). An ablation applied to the earliest retrograde activation sites (CS and right inferoseptum = 5 and 3 cases, respectively) eliminated all irregular atypical AVNRTs. CONCLUSION: The variations in the AV relationship were observed exclusively during atypical AVNRT in 2% of all AVNRT cases. Irregular atypical AVNRT was characterized by younger age of the patients and shorter TCL, and it more frequently required an ablation inside the CS for success. We postulate that the noted irregularity was attributable to the short TCL that gave rise to the unstable conduction in the tachycardia circuit and Wenckebach block in the lower common pathway.     

快径间断逆传是房室结折返性心动过速的少见电生理表现

报道 4例房室结折返性心动过速 (AVNRT)的少见电生理表现———快径间断逆传。 4例经心电图和食管电生理检查证实为AVNRT的病人 ,心内电生理检查中心室刺激无快径逆传 ,遂静脉注射异丙肾上腺素和消融阻断慢径后观察室房 (VA)传导特点。结果 :4例病人基础电生理检查均无快径逆传。静脉注射异丙肾上腺素后心室刺激 ,3例显示快径逆传并诱发AVNRT ,1例仍不显示快径逆传。消融阻断慢径后 ,4例病人均显示良好的快径逆传。结论 :快径间断逆传是AVNRT的少见电生理特点 ,慢径和快径相互干扰是其产生的重要机制之一。     

射频消融治疗房室结折返性心动过速的方法学研究——判断慢径阻断的新指标

改良房室结折返性心动过速 (AVNRT)慢径消融的方法学 ,以探讨判断慢径阻断的新指标。 6 0例AVNRT病人接受慢径射频消融术 ,根据X线影像部位和局部电图特点确定消融靶点 ,心房快速刺激 (S1S1)显示慢径前传放电消融 ,以 10s内慢径前传阻滞作为有效消融指标并以此连续放电达 30s。消融后房室结双径传导消失 ,不再诱发AVNRT为手术终点。 6 0例病人均达到消融终点。共消融 36 1个靶点 ,其中放电不足 10s者 2 80个、放电 30s者 81个 ,后者中 6 0个为有效消融靶点。有效阻断慢径者表现为放电 6 .9± 1.8(2 .8～ 10 )s慢径前传阻滞 ,S1刺激经快径前传。所有病人术后 3～ 7天食管电生理复查不再诱发AVNRT。随访 3～ 19个月无AVNRT复发。结论 :显示慢径前传消融可客观判断放电消融的有效性 ,避免盲目延长放电时间所造成的无效心肌损伤     

从慢慢型和慢快型房室结折返性心动过速电生理特性的差异分析折返环的不同

目的从慢慢型房室结折返性心动过速（AVNRT）和慢快型AVNRT的电生理特性的差异分析两型AVNRT间折返环的不同.方法在500例AVNRT患者中的59例慢慢型和60例慢快型之间,比较部分电生理特性的异同;同时在部分慢慢型和慢快型患者中应用2种方法（1）比较起搏时和心动过速时的HA间期的长度;（2）比较心动过速时心室刺激重整心动过速的不同.比较下传共径（LCP）的异同.结果慢慢型的前传慢径和逆传慢径有明显不同的传导时间;慢慢型的逆传慢径与慢快型的逆传快径有明显不同的传导时间和递减特性;和慢快型相比,2种方法均显示慢慢型有较长的LCP.结论 （1）慢慢型AVNRT中前传慢径和逆传慢径的传导时间明显不同;慢慢型较慢快型有较长的下传共径;（2）研究结果支持慢慢型AVNRT可能应用房室结的右侧后延伸和左侧后延伸分别形成心动过速的前传和逆传支而形成折返.     

快速心房起搏时SV间期与SS间期的比值在房室结折返性心动过速慢径消融中的应用

评价快速心房起搏时最快 1∶1房室传导的SV间期 (SV间期 )与 1∶1房室传导的最短S1S1间期 (SS间期 )的比值 (SV/SS)在房室结折返性心动过速 (AVNRT)慢径消融中的应用 ,将AVNRT分为房室结功能曲线连续组 (Ⅰ组 ,10例 )及房室结功能曲线不连续组 (Ⅱ组 ,17例 )测量心房分级递增刺激时的SS间期与SV间期及SV/SS ,并进行消融前、后和组间比较。结果显示 ,两组消融后SV间期较消融前明显缩短 (Ⅰ组 :2 2 1.0± 2 2 .3vs 35 7.0± 43.7ms;Ⅱ组 :2 0 2 .1± 30 .6vs 379.4± 44 .2ms,P均 <0 .0 5 ) ;消融前后SS间期无明显变化 (Ⅰ组 :310 .0± 40 .6vs 30 8.0± 36 .8ms;Ⅱ组 :332 .9± 48.1vs 336 .5± 6 2 .3ms) ;两组中所有患者消融前SV/SS比值均 >1,而消融后SV/SS比值均 <1。结论 :SV/SS可作为慢径消融成功终点的辅助观察指标之一 ,尤其对于房室结传导曲线呈连续性者 ,使用此方法可简便地观察消融终点 ,增加消融的目的性。     

隐匿性拖带时起搏后间期与慢径消融成功靶点的关系

评价应用隐匿性拖带方法对准确靶点消融的有效性及探讨常规慢径靶点部位与房室结折返性心动过速(AVNRT)折返环的关系。可反复诱发的持续性典型AVNRT的患者 34例 ,消融导管在后或中间隔标测到A/V≤ 0 .5处 ,然后诱发心动过速 ,在高位右房 (HRA)和冠状窦口 (CSO)超速起搏产生隐匿性拖带 ,并按常规方法进行慢径消融。比较隐匿性拖带时靶点部位起搏后间期与心动过速周长的差值 (PPI-TCL值 )在成功靶点与不成功靶点区别。结果 :HRA超速起搏发生隐匿性拖带时 ,His束记录部位A波均为逆向夺获。而CSO超速起搏拖带时 ,32例His束记录部位A波为顺向夺获 ,另 2例为逆向夺获。在这 32例中共记录 5 4个靶点 ,成功靶点的PPI-TCL值明显小于不成功靶点 (12 .4± 5 .8msvs 32 .1± 18.6ms,P <0 .0 1)。PPI-TCL值≤ 2 0ms对靶点成功消融的敏感性和特异性分别为 84%、81%。结论 :本研究提示常规慢径消融成功部位作为房室结外的后部延伸组织参与组成AVNRT折返环或距其非常近。在可持续发作和诱发的AVNRT患者中 ,CSO部位起搏拖带顺向心房夺获时 ,靶点部位测出的PPI-TCL值≤ 2 0ms,可作为一种新的慢径路电生理定位消融方法     

Atrioventricular nodal reentrant tachycardia with ventriculoatrial block and unsuccessful ablation of the slow pathway

We report the case of failed slow pathway ablation in a woman with typical AV nodal reentrant tachycardia (AVNRT) and periods of Wenckebach-like second-degree VA block and 2:1 VA block. The occurrence of VA block during AVNRT suggests the upper turnaround point of the circuit is confined to the AV node. This supports the notion that, at least in some cases, the location of the reentrant circuit for AVNRT is completely in the compact AV node.     

PR/RR Interval Ratio During Rapid Atrial Pacing:

Method for Confirming Slow Pathway Conduction. Introduction: Although the AV conduction curve in patients with AV nodal reentrant tachycardia (AVNRT) is usually discontinuous, many patients with this arrhythmia do not demonstrate criteria for dual AV nodal pathways. During rapid atrial pacing, the PR interval often exceeds the pacing cycle length when there is anterograde conduction over the slow pathway and AVNRT is induced. The purpose of this prospective study was to determine the diagnostic value of the ratio of the PR interval to the RR interval during rapid atrial pacing as an indicator of anterograde slow pathway conduction in patients undergoing electrophysioiogic testing. Methods and Results: The PR and RR intervals were measured during rapid atrial pacing at the maximum rate with consistent 1:1 AV conduction in four study groups: (1) patients with inducible AV nodal reentry and the classical criterion for dual AV nodal pathways during atrial extrastimulus testing (AVNRT Group 1); (2) patients with inducible AV nodal reentry without dual AV nodal pathways (AVNRT Group 2); (3) control subjects ≤ 60 years of age without inducible AV nodal reentry; and (4) control subjects > 60 years of age without inducible AV nodal reentry. For both groups of patients with inducible AV nodal reentry, AV conduction was assessed before and after radiofrequency ablation of the slow AV nodal pathway. Before slow pathway ablation, the PR/RR ratio exceeded 1.0 in 12 of 13 AVNRT Group 1 patients (mean 1.27 ± 0.21) and 16 of 17 AVNRT Group 2 patients (mean 1.18 ± 0.15, P = NS Group 1 vs Group 2). After slow pathway ablation, the maximum PR/RR ratio was < 1.0 in all AVNRT patients (Group 1 = 0.59 ± 0.08, P < 0. 00001 vs before ablation: Group 2 = 0.67 ± 0.11; P < 0.00001 vs before ablation). Among both groups of control subjects, the PR/RR ratio was > 1.0 in only 3 of 27 patients with no relation to patient age. Conclusion: The ratio of the PR interval to the RR interval during rapid atrial pacing at the maximum rate with consistent 1:1 AV conduction provides a simple and clinically useful method for determining the presence of slow AV nodal pathway conduction. This finding may be particularly useful in patients with inducible AV nodal reentry without dual AV nodal physiology on atrial extrastimulus testing.     

心室起搏拖带对房室结折返性和间隔旁路参与的房室折返性心动过速的鉴别作用

目的　研究心动过速时心室起搏拖带对房室结折返性心动过速 (AVNRT )和间隔旁路参与的顺向型房室折返性心动过速 (间隔旁路ORT)的鉴别意义。方法　 30例AVNRT和 2 5例间隔旁路ORT病人在心动过速发生后 ,采用较心动过速的周长 (TCL)短 10～ 4 0ms的周长行右心室起搏拖带心动过速。测量右心室起搏之前的心室 心房 (VA)间期和TCL。停止起搏后 ,测量最后一次刺激信号至最后起搏拖带的心房激动 (SA)间期 ,以及起搏后间期 (PPI)。结果　所有 30例AVNRT病人的SA -VA间期 >85ms、PPI-TCL >115ms,而 2 5例ORT病人的SA -VA间期 <85ms、PPI-TCL <115ms。结论　PPI TCL和SA VA间期是鉴别AVNRT和间隔旁路ORT的非常可靠的指标 ,具有较高的特异性。     

Unusual induction of slow-fast atrioventricular nodal reentrant tachycardia. Report of two cases

INTRODUCTION: Generally, the induction of typical atrioventricular nodal reentrant tachycardia (AVNRT) occurs with a premature atrial stimulus that blocks in the fast pathway and proceeds down the slow pathway slowly enough to allow the refractory fast pathway time to recover. We describe two cases in which a typical AVNRT was induced in an unusual fashion. RESULTS: The first case is a 41-year-old man with paroxysmal supraventricular tachycardia. During the electrophysiology study, the atrial extrastimulus inducing the typical AVNRT was conducted simultaneously over the fast (AH) and the slow pathway (AH'). A successful ablation of the slow pathway was performed. During the follow-up no recurrence was noted. The second case is a 52-year-old woman with a Wolff-Parkinson-White syndrome due to a left posterior accessory pathway. After 5 minutes of atrioventricular reentrant tachycardia (AVRT) induced by a ventricular extrastimulus, a variability of the antegrade conduction was noted in presence of the same VA conduction. In fact, a short AH interval (fast pathway) alternated with a more prolonged AH intervals (slow pathway) that progressively lengthened until a typical AVNRT was induced. The ablation of the accessory pathway eliminated both tachycardias. DISCUSSION: A rare manifestation of dual atrioventricular nodal pathways is a double ventricular response to an atrial impulse that may cause a tachycardia with an atrioventricular conduction of 1:2. In our first case, an atrial extrastimulus was simultaneously conducted over the fast and the slow pathway inducing an AVNRT. This nodal reentry implies two different mechanisms: 1) a retrograde block on the slow pathway impeding the activation of the slow pathway from the impulse coming down the fast pathway, and 2) a critical slowing of conduction in the slow pathway to allow the recovery of excitability of the fast pathway. Interestingly, in the second case, during an AVRT the atrial impulse suddenly proceeded alternately over the fast and the slow pathway. The progressive slowing of conduction over the slow pathway until a certain point which allows the recovery of excitability of the fast pathway determines the AVNRT. This is a case of "tachycardia-induced tachycardia" as confirmed by the fact that the ablation of the accessory pathway eliminated both tachycardias.     

Location of the lower turnaround point in typical AV nodal reentrant tachycardia: a quantitative model

INTRODUCTION: Recent observations suggest that the circuit of AV nodal reentrant tachycardia (AVNRT) may extend down to the His bundle. The purpose of this study was to develop a quantitative model indicating the location of the lower turnaround point in AVNRT. METHODS AND RESULTS: Slow pathway modification was performed in 70 patients with typical AVNRT. During sinus rhythm, ventricular pacing was performed with the AVNRT cycle length. During AVNRT, the HinitAinit interval was measured from initial His to the initial atrial deflection recorded in the His-bundle lead. During ventricular pacing, the HendAinit interval was measured from end of the His to the beginning of the atrial deflection. It was hypothesized that x reflects conduction time from the lower turnaround point to Ainit, whereas y reflects conduction time from the lower turnaround point to Hinit. Anterograde conduction during AVNRT and retrograde conduction during ventricular pacing were assumed to be identical if there was 1:1 retrograde conduction at the AVNRT cycle length. The following formulas describe the relation of the measured parameters: x - y = HinitAinit; and x + y = HendAinit. Resolving both formulas yields the unknown x and y: y = (HendAinit - HinitAinit)/2, x = (HendAinit + HinitAinit)/2. These criteria were present in 52 of 70 patients. The mean cycle length of AVNRT was 355 +/- 42 msec, mean HinitAinit was 54 +/- 27 msec, and mean HendAinit was 60 +/- 29 msec. Accordingly, in 20 of 52 patients, the lower turnaround point was located within the His bundle (y = -15.4 +/- 16.1 msec), in 3 of 52 it was in the nodal-His junctional area (y = 0), and in 29 of 52 it was above the His bundle (y = +12.7 +/- 10.3 msec). The HinitAinit interval was significantly longer (66 +/- 32 msec vs 47 +/- 20 msec; P = 0.02) and the HendAinit interval was significantly shorter (45 +/- 30 msec vs 69 +/- 24 msec; P = 0.004) when the first group was compared with the others. CONCLUSION: In about 1 of 3 of patients with typical AVNRT, the lower turnaround point of the circuit is within the His bundle; in more than half of the patients it is above the His bundle. These data do not support the concept that all AVNRTs have an intranodal circuit, but are in accordance with the finding of longitudinal dissociation of the His bundle.     

"Left-variant" atypical atrioventricular nodal reentrant tachycardia: electrophysiological characteristics and effect of slow pathway ablation within coronary sinus

Introduction: Recent anatomical and electrophysiological studies have demonstrated the presence of leftward posterior nodal extension (LPNE); however, its role in the genesis of atrioventricular nodal reentrant tachycardia (AVNRT) is poorly understood. This study was performed to characterize successful slow pathway (SP) ablation site and to elucidate the role of LPNE in genesis of atypical AVNRT with eccentric activation patterns within the coronary sinus (CS).
Methods and Results: Among 45 patients with atypical AVNRT (slow-slow/fast-slow/both = 20/22/3 patients) with concentric (n = 37, 82%) or eccentric CS activation (n = 8, 18%), successful ablation site was evaluated. Among 35/37 patients (95%) with concentric CS activation, ablation at the conventional SP region outside CS eliminated both retrograde SP conduction and AVNRT inducibility. Among eight patients with eccentric CS activation, the earliest retrograde atrial activation was found at proximal CS 16 ± 4 mm distal to the ostium during AVNRT. The earliest retrograde activation site was located at inferior to inferoseptal mitral annulus, consistent with the presumed location of LPNE. Ablation at the conventional SP region with electroanatomical approach only rendered AVNRT nonsustained without elimination of retrograde SP conduction in seven of eight patients (88%). Ablation targeted to the earliest retrograde atrial activation site within proximal CS (15 ± 4 mm distal to the ostium); however, eliminated retrograde SP conduction and rendered AVNRT noninducible in six of eight patients (75%).
Conclusion: In 75% of "left-variant" atypical AVNRT, ablation within proximal CS was required to eliminate eccentric retrograde SP conduction and render AVNRT noninducible, suggesting LPNE formed retrograde limb of reentrant circuit.     

心室融合波伴心房激动提前对间隔旁路逆传的房室折返性心动过速的诊断作用

目的 观察心室融合波伴心房激动提前对间隔旁路逆传的顺向型房室折返性心动过速(OAVRT)的诊断作用。方法 按心内电生理检查标准和射频消融结果，将47例符合人选条件的患者分为两组：房室结折返性心动过速(AVNRT)组和间隔旁路逆传的0AVRT组，分别为24例和23例。心动过速时行心室期前程序刺激(RS2刺激)和心室快速刺激，测量体表心电图上心室融合波之后的心房激动时间是否提前。结果 RS2刺激和心室快速刺激均能形成多个心室融合波。AVNRT组无l例伴有心房激动提前(特异性100％)，而OAVRT组在心室刺激成分明显的心室融合波时，心房激动均被提前(敏感性100％)。两组间的差异十分显著(P＜0．001)。结论 心室融合波伴心房激动时间提前是诊断间隔旁路逆传OAVRT的可靠指标，具有敏感性和特异性高的特点，而且也可用于未能记录到希氏束电图的患者。     

快慢型房室结折返性心动过速的电生理特点

目的分析快慢型房室结折返性心动过速（AVNRT）患者的临床特征、心电网和电生理检查特点、射频消融治疗特点,旨在为临床长RP。心动过速鉴别提供帮助。方法11例经心内电生理检查证实为慢快型房室结折返性心动过速的患者,回顾性分析其临床特征、心电图特点及电生理检查特点及射频消融治疗。结果心动过速表现为窄QRs波心动过速,RP’〉P’R,P。在Ⅱ、Ⅲ、aVF导联倒置,RP’间期为350±25ms,心率为1664-30bpm。11例患者中有3例出现室房逆传跳跃现象。心房程序刺激无明显跳跃现象,11例均可由心房StS：刺激诱发心动过速发作,且容易诱发,容易终止。心动过速发作时,5例CS9．10A波最早,6例HiS的A波最早,其中1例静推ATP心动过速终止。11例患者中9例经房室结改良消融传统慢径获得成功,2例在冠状静脉窦内消融成功,术后随访3个月以上均未再发作心动过速。结论长RP’心动过速的诊断和鉴别诊断有一定困难,如能排除慢旁道和房速,应考虑快慢型房室结折返性心动过速。     

Cryoablation in pediatric atrioventricular nodal reentry: Electrophysiologic effects on atrioventricular nodal conduction

BACKGROUND: Cryoablation for treatment of atrioventricular nodal reentrant tachycardia (AVNRT) is safe and efficacious. Information on the effects of cryoablation on atrioventricular (AV) nodal conduction is limited. OBJECTIVES: The purpose of this study was to evaluate the effects of cryoablation on AV nodal conduction in pediatric patients with AVNRT. METHODS: We retrospectively analyzed electrophysiologic studies before and after successful cryoablation. Patients were divided into two groups: group 1 (n = 22, age 14 +/- 3 years) had baseline discontinuous atrial-to-His interval (AH) conduction curves; and group 2 (n = 13, age 12 +/- 4 years, P = .054) had continuous curves. RESULTS: At baseline, group 1 had longer measurements of maximal AH with A1A2, AV nodal effective refractory period, and AV block cycle length. Postcryoablation, both group 1 and group 2 showed decreases in maximal AH with A1A2 pacing or atrial overdrive pacing and in the finding of PR > or = RR with atrial overdrive pacing (group 1: 55% vs 5%, P < .001; group 2: 69% vs 0%, P < .001). A significant increase in overall AV effective refractory period and a decrease in AV block cycle length were found in group 1 but not group 2. Fifty percent of group 1 patients had complete abolition of slow pathway conduction. CONCLUSION: Successful cryoablation for treatment of AVNRT is associated with a reduction in PR > or = RR and with decreases in maximal AH with A1A2 pacing or atrial overdrive pacing. Further study is needed to determine the usefulness of these parameters for assessment of ablation efficacy or as proxies for AVNRT inducibility.     

Anterograde slow pathway is not the same as retrograde slow pathway conducted in the reverse direction in patients with uncommon atrioventricular nodal reentrant tachycardia

INTRODUCTION: The aim of this study was to examine the location of anterograde and retrograde slow pathways in 16 patients with uncommon atrioventricular nodal reentrant tachycardia (AVNRT), including the fast-slow form in 10, slow-slow form in 5, and both fast-slow and slow-slow forms in 1. METHODS AND RESULTS: Patients were divided into two groups according to the approach used for slow pathway ablation in the initial radiofrequency catheter ablation (RFCA): one approach used earliest atrial activation during tachycardia (ES group, n = 9), and the other used a slow potential during sinus rhythm (SP group, n = 7). When the initial RFCA failed to eliminate slow pathway conduction in the ES group, an additional RFCA guided by a slow potential was performed. The ratio of lengths from the His-bundle region to the RFCA site and coronary sinus ostium (Abl/His-CS ratio) and the ratio of amplitudes of atrial and ventricular potentials at the RFCA site (A/V ratio) were compared between the two groups. In the initial RFCA, retrograde slow pathway conduction was eliminated without impairment of anterograde slow pathway conduction in 8 (89%) patients from the ES group, and bidirectional slow pathway conduction was eliminated in 6 (86%) patients from the SP group. Residual anterograde slow pathway conduction that was preserved after the initial RFCA in 8 of 9 patients was eliminated by an additional slow potential-guided RFCA. Both the Abl/His-CS ratio (0.86 +/- 0.07 vs 0.73 +/- 0.11, P = 0.01) and A/V ratio (0.80 +/- 0.31 vs. 0.14 +/- 0.01, P < 0.001) were higher in the ES group than the SP group. The ratios for the residual anterograde slow pathway ablation in the ES group were similar to those in the SP group. CONCLUSION: The results of this study suggest that the retrograde slow pathway runs more on the atrial side of the tricuspid valve annulus at the level of the coronary sinus ostium compared with the anterograde slow pathway, although both pathways run parallel or are fused in portions more proximal to the His bundle.     

射频导管消融慢径路治疗程控刺激不能诱发且无明显跳跃的房室结折返性心动过速疗效分析

目的观察无A—H间期跳跃和不能诱发的房室结折返性心动过速（AVNRT）慢径路消融特点和远期疗效。方法经电生理检查证实无旁道参与的阵发性室上性心动过速患者100例,分成三组：能诱发AVNRT,有明显跳跃（A组,n=40）;不能诱发AVNRT,但有A—H间期〉50ms的明显跳跃（B组,1=40）;不能诱发AVNRT且没有A—H间期〉50ms的明显跳跃（C组．n=20）。比较术后各组电生理数值及消融远期疗效。结果与消融术前相比．术后各组患者的房室结顺传文氏周期均延长（P〈0．05）;消融术后房室结顺传有效不应期较术前缩短,差异有统计学意义（P〈0．05）;三组均出现缓慢交接区心律。术后随访12个月．各组复发率差异无统计学意义（P〉0．05）。结论无A—H间期跳跃且程控刺激不能诱发的AVNRT的慢径路消融是安全有效的。缓慢交接区心律是消融有效的标志。     

Para-Hisian entrainment: a novel pacing maneuver to differentiate orthodromic atrioventricular reentrant tachycardia from atrioventricular nodal reentrant tachycardia

INTRODUCTION: Para-Hisian pacing during sinus rhythm can help to identify the presence of an accessory pathway (AP). In this maneuver, the retrograde activation time and pattern are compared during capture and loss-of-capture of the His bundle while pacing from a para-Hisian position. However, identification of a retrograde AP does not necessitate that it is operative during the tachycardia of interest; conversely, slowly conducting or "distant" bypass tracts may not be identified. We evaluated the utility of entrainment or resetting of tachycardias from the para-Hisian position to help distinguish atrioventricular nodal reentrant tachycardia (AVNRT) from orthodromic atrioventricular tachycardia (AVRT). METHODS AND RESULTS: Para-Hisian entrainment/resetting was evaluated in 50 patients: 33 with AVNRT and 17 with AVRT. The maneuvers were performed using a standard quadripolar catheter placed at the His position: low output for right ventricular (RV) capture and high output for both RV and His capture. The retrograde atrial activation sequence, SA interval (interval from stimulus to earliest retrograde atrial activation), and "local" VA interval (interval between the ventricular and atrial electrograms at the site of earliest retrograde atrial activation) were compared between His and His/RV capture. The DeltaSA was > 40 ms in patients with AVNRT and was < 40 ms in all but one patient with AVRT. In concert with the DeltaSA interval, the DeltaVA interval was able to fully define the mechanism of the tachycardia in all patients studied. CONCLUSION: Para-Hisian entrainment/resetting can determine the course of retrograde conduction operative during narrow complex tachycardias. It is a useful diagnostic maneuver in differentiating AVNRT and orthodromic AVRT.     

Participation of a concealed atriohisian tract in the reentrant circuit of the slow-fast type of atrioventricular nodal reentrant tachycardia.

BACKGROUND: The retrograde fast pathway in typical atrioventricular nodal reentrant tachycardia (AVNRT) exhibits marked variation in its electrophysiologic properties. OBJECTIVE: The purpose of this study was to characterize the retrograde fast pathway and localize the lower turnaround site of the reentrant circuit in typical AVNRT. METHODS: Seventy-four patients with typical AVNRT were divided into two groups according to the response of the retrograde fast pathway to intravenous administration of adenosine triphosphate (ATP) during ventricular pacing: ATP-S [n = 47 (63.5%)] with and ATP-R without [n = 27 (36.5%)] His-atrial (H-A) block. H-A intervals were measured from the most proximal His-bundle electrogram to the earliest atrial activation during the tachycardia (HAt) and entrainment pacing from the parahisian right ventricular region (HAe). It was postulated that the HAt was the difference in conduction time between the lower common pathway (x) and retrograde fast pathway (y) (HAt = y - x), whereas HAe was the sum of the two (HAe = y + x). Hence, x = (HAe-HAt)/2. x >0 suggested the presence of a lower common pathway, whereas x <0 suggested the absence of a lower common pathway and lower turnaround site within the His bundle. RESULTS: x was significantly smaller in ATP-R than ATP-S (-6 +/- 5 vs 4 +/- 4 ms, P <.05) and was <0 in 23 (85%) of 27 ATP-R patients. The maximal increment in H-A interval during ventricular pacing was significantly longer in ATP-S than ATP-R (35 +/- 33 vs 2 +/- 2 ms, P <.05). CONCLUSION: A concealed atriohisian tract totally bypassing the atrioventricular node constituted the retrograde fast pathway in one third of all typical AVNRT cases.