Electrophysiological markers predicting impeding AV‐block during ablation of atrioventricular nodal reentry tachycardia

1 Background

Radiofrequency (RF) ablation of the slow pathway (SP) in atrioventricular nodal reentry tachycardia (AVNRT) is occasionally complicated with atrioventricular block (AVB) often predicted by junctional beats (JB) with loss of ventriculo‐atrial (VA) conduction.

2 Methods

We analyzed retrospectively 153 patients undergoing ablation of SP for typical AVNRT. Patients were divided into two age groups: 127 ≤ 70 years and 26 > 70 years. We analyzed the interval between the atrial electrogram in the His‐bundle position and the distal ablation catheter [A(H)‐A(RFd)] and between the distal ablation catheter and the proximal coronary sinus catheter [A(RFd)‐A(CS)] before RF applications with and without JB. We evaluated if these intervals can be used as predictors of JB incidence and also of JB with loss of VA conduction. We also assessed if age influences the risk of loss of VA conduction.

3 Results

The A(H)‐A(RFd) and A(RFd)‐A(CS) intervals were significantly shorter in RF applications causing JB than those without JB (33 ± 11 ms vs 39 ± 9 ms, P < 0.001, 14 ± 9 ms vs 20 ± 7 ms, P < 0.001, respectively). The A(H)‐A(RFd) and A(RFd)‐A(CS) intervals were also significantly shorter in RFs causing JB with VA block than those with VA conduction (29 ± 11 ms vs 35 ± 11 ms, P < 0.001, 8 ± 8 ms vs 17 ± 8 ms, P < 0.001, respectively). Patients > 70 years had shorter intervals (36 ± 11 ms vs 29 ± 8 ms, P  =  0.012, 17 ± 8 ms vs 13 ± 7 ms, P  =  0.027, respectively), while VA block was more common in this age group.

4 Conclusions

The A(H)‐A(RFd) and A(RFd)‐A(CS) intervals can be used as markers for predicting JB occurrence as well as impending AVB. JB with loss of VA conduction occur more often in older patients possibly due to a higher position of SP.     

冠状窦呈偏心性激动的不典型房室结折返性心动过速的电生理特征及导管消融

目的 总结冠状窦（coronary sinus, CS）呈偏心性激动的不典型房室结折返性心动过速（atrioventricular nodal reentry tachycardia, AVNRT）的电生理特点、鉴别诊断及消融方法。方法 回顾性收集2014年1月至2018年12月在复旦大学附属中山医院心内科进行射频消融治疗的524例AVNRT患者的临床资料。其中,CS呈偏心性激动的不典型AVNRT患者共16例,男性6例、女性10例,平均年龄（56.6±11.4）岁。分析16例不典型AVNRT患者的体表心电图和腔内心电图特点、诱发方式、鉴别诊断及射频消融策略。结果 16例CS呈偏心性激动的AVNRT患者的心电图均表现为RP间期>PR间期,P波在Ⅱ、Ⅲ、aVF导联中倒置;发作时12例患者房室传导比例为1∶1,4例患者为2∶1或3∶1;13例患者可以轻易通过心室拖带的方式进行鉴别,2例患者需要多次拖带才能成功,1例患者多次拖带下心房-心室（atrioventricular,VA）仍然分离;14例患者在右心房后间隔靠近三尖瓣环处成功消融,3例患者在CS内成功消融。结论 CS呈偏心性激动的...     

Fast pathway ablation in a patient with PR prolongation

The classical form of typical atrioventricular node reentrant tachycardia (AVNRT) is a “slow-fast” pathways tachycardia, and the usual therapy is an ablation of the slow pathway since it carries a low risk of atrioventricular (AV) block. In patients with long PR interval and/or living on the anterograde slow pathway, an alternative technique is required. We report a case of a 42-year-old lady with idiopathic restrictive cardiomyopathy, persistent atrial fibrillation status post pulmonary vein isolation, and premature ventricular complex ablation with a systolic dysfunction, who presented with incessant slow narrow complex tachycardia of 110 bpm that appeared to be an AVNRT. Her baseline EKG revealed a first-degree AV block with a PR of 320 ms. EP study showed no evidence of anterograde fast pathway conduction. Given this fact, the decision was to attempt an ablation of the retrograde fast pathway. The fast pathway was mapped during tachycardia to its usual location into the anteroseptal region, then radiofrequency ablation in this location terminated tachycardia. After ablation, she continued to have her usual anterograde conduction through slow pathway and the tachycardia became uninducible. In special populations with prolonged PR interval or poor anterograde fast pathway conduction, fast pathway ablation is the required ablation for typical AVNRT.     

房室结折返性心动过速中西医结合诊治进展与临床案例

房室结折返性心动过速占阵发性室上性心动过速的20%~30%。成人常发于40岁以前,中青年多见,男女发病率相似。中医对这类病症成因的认识,此证为少阳病,系肝脾之气横逆,胃气上冲而至。单纯看起效快慢,中医中药的作用不如西医明显,但中药对此病的根治有其独特的优势,而且相对经济、安全、副作用小。因此,在治疗中怎样发挥中医中药的这些长处,结合西医起效快捷,作用环节明确的特点,充分体现中西医结合的优势,造福患者,是今后发展的方向。     

Fast-Slow Type of Atrioventricular Nodal Reentrant Tachycardia: Horizontal Dissociation of the AV Node During Tachycardia

Two patients with recurrent supraventricular tachycardia are presented. The tachycardia was initiated and terminated by atrial extrastimulation beyond the atrial relative refractory period and the atrial activation sequence during the tachycardia was low to high. The induction of tachycardia was dependent on a critical AH interval. In patient 1 who had ventriculoatrial conduction, the tachycardia was initiated by the premature ventricular stimulation followed by double atrial response. In patient 2 the ventriculoatrial conduction was not observed. In both patients, the unchanged atrial cycle length during the tachycardia with antegrade Wenckebach AH block was observed. When AH block occurred during tachycardia the first AH interval was shorter than the subsequent HA interval. In patient 2 verapamil (5 mg) prolonged the atrial cycle length during tachycardia and rapid intravenous injection of adenosine triphosphate (10 mg) terminated the tachycardia. Oral diltiazem (280 mg/day) suppressed the tachycardia in patient 1. These findings suggest that the mechanism of tachycardia may be fast-slow type of AV nodal reentry in the upper portion of the AV node and this type of arrhythmia has tendency to show incessant form.     

房室结有效不应期与房室结折返性心动过速射频消融术后复发的关系(附7例报告)

目的　探讨房室结有效不应期 (AVNERP)与房室结折返性心动过速 (AVNRT)射频消融术(RFCA)后复发的关系。方法　回顾分析 196例AVNRT行RFCA后 7例复发者两次心电生理检查结果。其中男 2例 ,女 5例。年龄 2 4～ 5 5岁。术后复发时间 3月～ 1年不等。结果　①心电生理检查证实 7例均为AVNRT术后复发者 ;②第一次RFCA后 ,AVNERP与慢径ERP的绝对平均差值为 35 .71ms,第二次RFCA后 ,差值为 111.4 3ms,两者相比 ,有明显的差异 ;③ 7例复发者 ,经第二次RFCA后 ,至今无 1例复发( >1年 )。结论　AVNRTRFCA术后 ,AVNERP明显延长 ,应作为RFCA成功的标准之一 ,且对术后是否复发有着重要的临床意义     

Simultaneous antegrade dual AV node conduction initiates AV nodal re-entrant tachycardia (a rare initiation mechanism)

Typical atrioventricular nodal reentrant tachycardia (AVNRT) is the most common paroxysmal supraventricular tachycardia among adults. The concept of dual pathway physiology remains widely accepted, although this physiology likely results from the functional properties of anisotropic tissue within the triangle of Koch, rather than anatomically distinct tracts of conduction. AVNRT is typically induced with anterograde block over the fast pathway and conduction over the slow pathway, with subsequent retrograde conduction over the fast pathway. On rare occasions, anterograde AV node conduction occurs simultaneously through fast and slow pathways resulting in two ventricular beats in response to one atrial beat. We report a case of AVNRT where the tachycardia is always induced by the same mechanism described above. Successful ablation was achieved by slow pathway modification.