Atypical AV nodal reentry with bystander accessory pathway: an unusual mechanism of preexcited tachycardia

We present an unusual mechanism of preexcited tachycardia--atypical AV nodal reentry with bystander AP. It can be differentiated from other preexcited tachycardias by its variable degree of preexcitation (either spontaneous or in response to atrial pacing), higher degree of preexcitation with pacing near the origin of the AP than during tachycardia, inability to preexcite the tachycardia by either late atrial or ventricular premature beats, the presence of nonpreexcited atypical AV nodal reentry tachycardia following successful AP ablation, and by exclusion of atrial tachycardia.     

A Nodoventricular Fiber Associated with Dual AV Nodal Conduction, AV Nodal Reentrant Tachycardia, and Anterior Location of the Slow AV Nodal Pathway

We present a case of a patient with a nodoventricular tract, associated with dual AV nodal conduction and AV nodal reentrant tachycardia, and an anteroseptal location of the slow AV nodal pathway. The remarkable feature of this case is the site of successful ablation, in the anteroseptum just anterior and superior to the His bundle, where both preexcitation and dual AV nodal physiology were abolished.     

Frequency of spontaneous and inducible atrioventricular nodal reentry tachycardia in patients with idiopathic outflow tract ventricular arrhythmias

OBJECTIVES: We sought to assess the frequency of spontaneous or inducible atrioventricular nodal reentry tachycardia (AVNRT) in patients referred for radiofrequency ablation (RFA) of idiopathic outflow tract ventricular arrhythmias. BACKGROUND: In patients with no obvious heart disease, AVNRT and outflow tract ventricular tachycardia (VT) are the most frequently encountered supraventricular and ventricular tachycardias, respectively. An increased coexistence of the two arrhythmias has been recently suggested. METHODS: In 68 consecutive patients referred for RFA of an idiopathic ventricular outflow tract arrhythmia, a stimulation protocol including repeated bursts of rapid atrial pacing, up to triple atrial extrastimuli during sinus rhythm and rapid ventricular pacing was performed before and after isoproterenol infusion following RFA of the ventricular arrhythmia. In patients with inducible AVNRT, RFA of the slow pathway was performed. RESULTS: Of the 68 study patients, 17 (25%) had either spontaneous AVNRT documented prior to RFA of the ventricular arrhythmia (n = 4) or inducible AVNRT at the time of RFA of the ventricular arrhythmia (n = 13). AVNRT was induced by atrial pacing in 15 (88%) of 17 patients: in 3 patients without isoproterenol and in 12 patients during isoproterenol infusion. Uncomplicated RFA of the slow pathway was successfully achieved in all patients with inducible AVNRT. CONCLUSION: Spontaneous or inducible AVNRT is relatively common in patients with idiopathic outflow tract ventricular arrhythmias. Atrial stimulation, especially when performed after isoproterenol infusion plays a major role in AVNRT inducibility. Although we performed RFA of the slow pathway in patients with inducible AVNRT and no prior tachycardia documentation, the question whether this is mandatory remains unsettled.     

Unexpected Complete AV Block Following Transcatheter Ablation of a Left Posteroseptal Accessory Pathway

Radiofrequency catheter ablation is the procedure of choice for the nonpharmacological treatment of AV connections that are responsible for debilitating tachycardia. This article describes a patient with a manifest left posteroseptal accessory pathway and recurrent syncopes in whom a transient complete AV block occurred after transcatheter radiofrequency ablation of the left posteroseptal pathway. Three electrical abnormalities were present in this patient: AV infra-Hisian block, a left posteroseptal accessory pathway, and an AV nodal reentry tachycardia. This case report reminds you that one should be prepared for all fall backs during catheter ablation.     

The different ablation effects on atrioventricular nodal reentrant tachycardia in children with and without dual nodal pathways

BACKGROUND: Previous studies in adults have shown a significant shortening of the fast pathway effective refractory period (ERP) after successful slow pathway ablation. However, information on atrioventricular nodal reentrant tachycardia (AVNRT) in children is limited. The purpose of this retrospective study was to investigate the different effects of radiofrequency (RF) catheter ablation in pediatric AVNRT patients between those with and without dual atrioventricular (AV) nodal pathways. METHODS: From January 1992 to August 2004, a total 67 pediatric patients with AVNRT underwent an electrophysiologic study and RF catheter ablation at our institution. We compared the electrophysiologic characteristics between those obtained before and after ablation in the children with AVNRT with and without dual AV nodal pathways. RESULTS: Dual AV nodal pathways were found in 37 (55%) of 67 children, including 36 (54%) with antegrade and 10 (15%) with retrograde dual AV nodal pathways. The antegrade and retrograde fast pathway ERPs in children with dual AV nodal pathways were both longer than the antegrade and retrograde ERPs in children without dual AV nodal pathways (300 +/- 68 vs 264 +/- 58 ms, P = 0.004; 415 +/- 70 vs 250 +/- 45 ms, P < 0.001) before ablation. In children with antegrade dual AV nodal pathways, the antegrade fast pathway ERP decreased from 300 +/- 68 ms to 258 +/- 62 ms (P = 0.008). The retrograde fast pathway ERP also decreased after successful ablation in the children with retrograde dual AV nodal pathways (415 +/- 70 vs. 358 +/- 72 ms, P = 0.026). CONCLUSION: The dual AV nodal physiology could not be commonly demonstrated in pediatric patients with inducible AVNRT. After a successful slow pathway ablation, the fast pathway ERP shortened significantly in the children with dual AV nodal pathways.     

The most common site of success and its predictors in radiofrequency catheter ablation of the slow atrioventricular nodal pathway in children

Background: Locating ablation targets on the slow pathway in children as one would in adults may not accommodate the dimensional changes of Koch's triangle that occur with heart growth. We investigated the most common site of success and the effect of a variety of variables on the outcome of slow pathway ablation in children. Methods: A total of 116 patients (ages 4–16 years) with structurally normal hearts underwent radiofrequency ablation of either the antegrade or the retrograde slow pathway. Ablation sites were divided into eight regions (A1, A2, M1, M2, P1, P2, CS1, and CS2) at the septal tricuspid annulus. Results: Ablation was successful in 112 (97%) children. The most common successful ablation sites were at the P1 region. The less the patient weighed, the more posteriorly the successful site was located (P = 0.023, OR 0.970, 95% CI 0.946–0.996), and the more likely the slow pathway was eliminated rather than modified: median weight was 46.7 kg (range, 14.5–94.3 kg) in the eliminated group and 56.5 kg (range, 20–82.6 kg) in the modified group (P = 0.021, OR 1.039, 95% CI 1.006–1.073). Conclusions: The most common site of success for slow pathway ablation in children is at the P1 region of the tricuspid annulus. The successful sites in lighter children are more posteriorly located. Weight is also a predictor of whether the slow pathway is eliminated or only modified.     

Modification of Atrioventricular Conduction by Selective AV Nodal Artery Catheterization

The effects of selective AV nodal artery embolization on AV nodal function was investigated in six closed-chest adult dogs. Programmed atrial stimulation was performed to determine control values for AV nodal effective refractory period (AVN-ERP) and the paced cycle length at which AV nodal Wenckebach conduction occurred (WCL). Using standard percutaneous femoral techniques of coronary artery catheterization, a flexible infusion catheter was positioned selectively in the AV nodal artery. Proper positioning of the catheter was confirmed angiographically and by selective acetylcholine (ACH) infusion into the AV nodal artery, which caused transient complete AV nodal block in three dogs, and for the group, caused lengthening of both AVN-ERP and WCL. Following cessation of ACH infusion and autonomic blockade with atropine 0.04 mg/kg and propranolol 0.2 mg/kg, denervated recontrol values for AVN-ERP and WCL were 192 msec and 243 msec, respectively. The AV nodal artery was then embolized with a suspension of cross-linked collagen fibrils in either normal saline or absolute ethanol. Successful embolization of the AV nodal artery, confirmed angiographically, caused an acute increase in AVN-ERP (243 msec, P less than 0.05 compared to denervated control) and WCL (287 msec, P = 0.058 compared to denervated control). However, at a mean follow-up of 37 days, only one animal exhibited a chronic increase in AVN-ERP and WCL. Selective AV nodal artery catheterization can be performed using standard percutaneous catheterization techniques. Selective administration of agents with direct cidal effects on the AV node using this technique may provide an alternative to conventional methods of catheter ablation of AV conduction in patients with drug-resistant supraventricular arrhythmias.     

Multiple Anterograde and Retrograde AV Nodal Pathways: Demonstration by Multiple Discontinuities in the AV Nodal Conduction Curves and Echo Time Intervals

Programmed electrical cardiac stimulation was performed in a 40-year-old man with documented recurrent, sustained ventricular tachycardia which was refractory to standard medical therapy. Both the presence of several discontinuities in the AV nodal conduction curves during atrial and ventricular stimulation and the time intervals of the AV nodal echo phenomena suggested the presence of multiple AV nodal pathways. The results of this study are of interest in further increasing our understanding of the electrophysiologic behavior of the human AV node.     

Slow pathway ablation for atrioventricular nodal reentry using a right internal jugular vein approach: a case series

BACKGROUND: Inferior venous access to the right heart is not possible in some patients due to congenital or acquired obstruction of the inferior vena cava (IVC). Although right-sided electrophysiology procedures have been performed successfully in patients with a previously placed IVC filter by direct placement of catheters through the filter, an alternative approach is necessary in some patients. METHODS: This case series describes three patients with an IVC filter who underwent successful ablation of the slow pathway for typical atrioventricular (AV) nodal reentrant tachycardia using a superior vena cava (SVC) approach via the right internal jugular (IJ) vein. Two separate introducer sheaths were placed into the IJ vein using separate punctures. This permitted placement of a standard deflectable ablation catheter and an additional catheter in the right atrium to monitor for ventriculoatrial conduction during the junctional rhythm associated with ablation of the slow AV nodal pathway. RESULTS: Catheter ablation was successful in each patient. The number of radiofrequency current applications was 7, 17, and 27. There were no procedural complications and no patient had recurrent tachycardia during follow-up. CONCLUSIONS: Catheter ablation of the slow AV nodal pathway can be performed successfully and safely in patients with inferior venous barriers to the right heart using an SVC approach via the right IJ vein.     

Inducible atrioventricular nodal reentry tachycardia in infants with a history of neonatal orthodromic reciprocating tachycardia

Atrioventricular nodal reentry tachycardia (AVNRT) is an uncommon mechanism of supraventricular tachycardia in neonates in whom orthodromic reciprocating tachycardia (ORT) predominates. We report three patients with structurally normal hearts who presented with neonatal ORT, documented by transesophageal electrophysiology studies at 2 to 3 weeks of age. At follow-up study at 8-12 months of age, no infant had inducible ORT, suggesting spontaneous regression of congenital accessory pathways; however, each had inducible tachycardia consistent with the typical form of AVNRT. The clinical significance of this finding is unknown and warrants further study.     

Isoproterenol facilitation of slow pathway ablation in incessant dual atrioventricular nodal nonreentrant tachycardia

Catheter ablation of the slow atrioventricular (AV) nodal pathway is the treatment of choice for dual AV nodal nonreentrant tachycardia. Rapid ventricular rates during incessant tachycardia may compromise catheter stability and increase the risk of AV block. Conduction via the slow AV nodal pathway may mimic junctional beats with retrograde block, which is an indicator to cease ablation. We report a case of incessant dual AV nodal nonreentrant tachycardia where intravenous isoproterenol was instrumental in facilitating catheter ablation by eliminating these two factors.     

Changes of the RR Interval and the QRS Morphology in AV Nodal Tachycardia: Further Evidence for Extranodal Involvement

A young patient wilh AV nodal tachycardia was referred for ablation. During electrophysiological testing, a stable succession of up to four different RR intervals with comcomitantly changing QRS morphologies were recorded. This observation might reflect the conduction of the reentry circuit through different extranodal "pathways" in the low right atrium. Radiofrequency current was applied near the ostium of the coronary sinus; this abolished conduction through the slow pathway, as dual AV conduction was no longer present. She remains free of recurrences for a follow-up period of 8 months.     

Comparative Atrioventricular Node Properties After Radiofrequency Ablation and Operative Therapy of Atrioventricular Node Reentry

The anatomical substrate for atrioventricular (AV) node reentry is unclear. To gain insights into the mechanism of cure of AV node reentry by nonpharmacological techniques, we compared AV node properties in 53 patients undergoing operative therapy (perinodal dissection) and 43 undergoing radiofrequency ablation (28 posterior approach, 15 anterior approach). Anterior radiofrequency ablation was associated with significant AH prolongation (62 ±18 msec vs 136 ± 64 msec, P < 0.0001), loss of "fast" pathway physiology, and no change in the anterograde refractory period of the AV node (273 ± 24 msec vs 268 ± 28 msec, P = NS). Posterior radiofrequency ablation did not change the AH interval (67 ± 17 msec vs 68 ± 17 msec, P = NS), prolonged AV node effective refractory period (275 ± 48 msec vs 320 ± 55 msec, P < 0.0001), and was associated with loss of "slow pathway" physiology. Operative treatment prolonged the AH interval (66 ±18 msec vs 83 ± 37 msec, P < 0.0001) and the AV node effective refractory period (264 ± 52 msec vs 364 ±112 msec, P < 0.0001), and affected dual pathway physiology inconsistently. These data support the view that the "fast" and "slow" pathways are distinct perinodal entities that can be selectively ablated. The operative approach causes more diffuse and variable injury to the AV node region.     

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...     

Radiofrequency Catheter Ablation of an Intraatrial Reentrant Tachycardia: Evidence of an Area of Slow Conduction

Radiofrequency catheter ablation for infraatrial reentrant tachycardia has not been previously reported. This article describes a patient with a demonstrable area of slowed conduction in ihe lateral right atrium that responded to radiofrequency catheter ablation in the area of the fractionated eiectrogram ivith elimination of the tachycardia. This patient also had the common form of atrioventricular nodal reentrant tachycardia, which was also successfully ablated.     

Modification of antegrade slow pathway is not crucial for successful catheter ablation of common atrioventricular nodal reentrant tachycardia

We tested the hypothesis that in some patients affected by typical AVNRT, successful catheter ablation treatment may be achieved independently of specific measurable electrophysiological modifications of antegrade AV node conducting properties. Standard electrophysiological parameters and comparable antegrade AV node function curves were obtained, before and after successful ablation, in 104 patients (mean age 52 +/- 16 years; 69 women and 35 men) affected by the common form of AVNRT. The end point of the ablation procedure was noninducibility of AVNRT and of no more than one echo beat. For the purpose of this study, AV node duality was defined as an increase of > or = 50 ms in the A2H2 interval in response to a 10 ms decrease of the A1A2 coupling interval. Before ablation, AV node duality was present in 65 patients (62%) and absent in 39 patients (37%). Ablation caused measurable modifications of electrophysiological properties of the AV node in most patients with elicited AV node duality, but not in most patients without demonstrable AV node duality. After ablation, AV node duality persisted in 20 patients who had it before, whereas a new duality that could not be elicited before appeared in 5 patients. During 19 +/- 6 months of follow-up, clinical AVNRT recurred in 1 of 45 patients who had disappearance of AV node duality after ablation, in 1 of 34 patients who did not show AV node duality before and after ablation, and in 1 of 20 patients who had persistence of AV node duality after ablation. In conclusion, modifications of antegrade conduction properties of the AV node are not crucial for the cure of AVNRT in many patients.     

The 1998 NASPE prospective catheter ablation registry

The results of the NASPE Prospective Voluntary Registry are reported. A total of 3,357 patients were entered. For those undergoing atrioventricular (AV) junctional ablation (646 patients), the success rate was 97.4% and significant complications occurred in 5 patients. A total of 1,197 patients underwent AV nodal modification for AV nodal reentrant tachycardia, which was successful in 96.1% and the only significant complication was development of AV block (1%). Accessory pathway ablation was performed in 654 patients and was successful in 94%. Major complications included cardiac tamponade (7 patients), acute myocardial infarction (1 patient), femoral artery pseudoaneurysm (1 patient), AV block (1 patient), pneumothorax (1 patient), and pericarditis (2 patients). A total of 447 patients underwent atrial flutter ablation and acute success was achieved in 86% of patients. Significant complications included inadvertent AV block (3 patients), significant tricuspid regurgitation (1 patient), cardiac tamponade (1 patient), and pneumothorax (1 patient). Atrial tachycardia was attempted for 216 patients and the success rate was higher for those with right atrial (80%) or left atrial (72%) compared to those with septal foci (52%). A total of 201 patients underwent ablation for ventricular tachycardia. The success rate was higher for those with idiopathic ventricular tachycardia compared to those with ventricular tachycardia due to ischemic heart disease or cardiomyopathy. While the number of AV junction ablation were higher for those > 60 years of age, there was no significant difference in the success rate or incidence of complication comparing patients > or = 60 to those < 60 years of age. In addition, we found no differences in incidence of success or complications comparing large volume centers (> 100 ablation/year) with lower volume centers or between teaching and non-teaching hospitals.     

Persistent VA dissociation during atrioventricular nodal reentry tachycardia: The existence of upper common pathway

The existence of the upper common pathways is not well‐established yet. This case describes atrioventricular nodal reentry tachycardia with persistent ventriculoatrial dissociation that proof of upper common pathway existence.