Atypical Fast-Slow Atrioventricular Nodal Reentrant Tachycardia Incorporating a "Superior" Slow Pathway: A Distinct Supraventricular Tachyarrhythmia

SVT quest: The adventure diagnosing narrow QRS tachycardia

In the field of cardiac electrophysiology, there is a universal desire: the discovery of a flawless diagnostic maneuver for supraventricular tachycardias (SVTs). This is not merely a wish but a shared odyssey. To improve diagnostic accuracy and achieve sufficient sensitivity and specificity, numerous diagnostic maneuvers have been proposed. However, each has its limitations and prompts a search for new diagnostic techniques. This continuous cycle of discovery and refinement, which we titled "SVT Quest" is reviewed in chronological sequence. This adventure in diagnosing narrow QRS tachycardia unfolds in 3 steps: Step 1 involves differentiating atrial tachycardia from other SVTs based on the observations such as V-A-V or V-A-A-V response, ΔAA interval, VA linking, the last entrainment sequence, and response to the atrial extrastimulus. Step 2 focuses on differentiating orthodromic reciprocating tachycardia from atrioventricular nodal reentrant tachycardia based on the observations such as tachycardia reset upon the premature ventricular contraction during His refractoriness, uncorrected/corrected postpacing interval, differential ventricular entrainment, orthodromic His capture, transition zone analysis, and total pacing prematurity. Step 3 characterizes the concealed nodoventricular/nodofascicular pathway and His-ventricular pathway-related tachycardia based on observations such as V-V-A response, ΔatrioHis interval, and paradoxical reset phenomenon. There is no single diagnostic maneuver that fits all scenarios. Therefore, the ability to apply multiple maneuvers in a case allows the operator to accumulate evidence to make a likely diagnosis. Let's embark on this adventure!

Recurrent episodes of atrioventricular nodal reentrant tachycardia: Sites of ablation success, ablation endpoint, and primary culprits for recurrence

Background

Atrioventricular nodal reentrant tachycardia (AVNRT) sometimes recurs even after anatomical slow pathway (SP) ablation targeting the rightward inferior extension (RIE). This multicenter study aimed to determine the reasons for AVNRT recurrence.

Methods and Results

Forty-six patients were treated successfully for recurrent AVNRT. Initial treatment was for 38 slow-fast AVNRTs, 3 fast-slow AVNRTs, 2 slow-slow AVNRTs, 2 slow-fast and fast-slow AVNRTs, and 1 noninducible AVNRT. All initial treatments were of RF application to the RIE; SP elimination was achieved in 11, dual AVN physiology was seen in 29, and AVNRT remained inducible in 5. The recurrent AVNRTs included 34 slow-fast AVNRTs, 6 fast-slow AVNRTs, 3 slow-slow AVNRTs, 2 slow-fast and fast-slow AVNRTs, and 1 slow-fast and slow-slow AVNRTs. Successful ablation site was within the RIE in 39 and left inferior extension in 7. In 30 of 39, the successful RIE site was in the same area or higher than that of the initial procedure.

Conclusion

For a high majority (around 85%) of patients in whom AVNRT recurs after initial ablation success, the site of a second successful procedure will be within the RIE even though the RIE was originally targeted. Furthermore, a high majority (around 86%) of sites of successful ablation will be higher than those originally targeted.

Atrial tachycardia ablation through the sub-pulmonary ventricle in a patient with multiple malformations associated with congenitally corrected transposition of the great arteries and double-sided slow-pathway

A 46-year-old woman with congenitally corrected transposition of the great arteries (ccTGA) associated with dextrocardia, situs viscerus inversus, and left superior vena cava persistence presented with an incessant supraventricular tachycardia. Electrophysiological study was not conclusive in differential diagnosis of atrial tachycardia versus atypical atrioventricular (AV) nodal reentrant tachycardia, also due to the unconventional anatomy of the coronary sinus. By a comprehensive mapping of cardiac chambers, a double side slow-pathway was localized in both atrial chambers and subsequently ablated by radiofrequency delivery without tachycardia changes. Aortic root and cusps were devoid of electrical activity. The muscular part of the sub-pulmonary ventricle at the level of interatrial septum showed an earliest activation signal of -90 ms and ablation of this site was effective in abolish the tachycardia. This is the first case to report technical concerns of septal atrial tachycardia ablation in ccTGA associated with multiple anatomical malformations. Moreover, some peculiarities have been reported for the first time including the presence of double-side AV nodal slow-pathway and atypical localization of the tachycardia origin into the muscular part of the sub-pulmonary ventricle instead of posterior pulmonary cusp.

Fast-slow atrioventricular nodal re-entrant tachycardia incorporating superior and inferolateral left atrial slow pathways

BACKGROUND

A 70-year-old man revealed a rare type of atrioventricular nodal re-entrant tachycardia (AVNRT) involving distinct retrograde pathways, superior slow pathway, and inferolateral left atrial slow pathway.

RESULT

Radiofrequency ablation was successfully performed on the noncoronary cusp and in the left atrium, respectively, to eliminate the tachycardias.

DISCUSSION AND CONCLUSION

Due to the anomalous electrical conduction patterns, careful diagnosis and ablation strategies were necessary to avoid the risk of atrioventricular block. These findings underscore the diversity and complexity of AVNRT and highlight the importance of tailored therapeutic approaches.

Optimal method for ablation of atypical AVNRT

BACKGROUND

Considering that ablation of atypical AVNRT may be unsuccessful after ablation at the right posterior septum, in this study, we aimed to present an optimal method for ablation of atypical AVNRT. Also, we evaluated the efficacy of this technique for preventing recurrences.

METHODS

This is a prospective, double-center study. It was conducted on 62 patients with atypical AVNRT referred for radiofrequency ablation. The patients were randomly divided into two groups before ablation: 1-Group A (n = 30): treated with conventional ablation at the anatomic area of the slow pathway; 2-Group B (n = 32): ablation was done 2 mm higher in the septum during fluoroscopy.

RESULTS

The mean age of patients in groups A and B were 54 ± 11.7 and 55 ± 12.2, respectively (P = 0.43). In group A, ablation was successful in 24 (80%) patients following right-sided slow pathway ablation, and the remaining patients required further treatment with either a left-side approach (N = 4, 13.3%) or ablation of additional regions (N = 2, 6.7%). In group B, ablation was successful in all patients. After a 48-month follow-up, recurrence of symptomatic atypical AVNRT was detected in 4 (13.3%) patients of group A and none of group B patients (p < 0.001).

CONCLUSION

In patients with atypical AVNRT, ablation 2 mm above the conventional area is more promising regarding success rate and recurrence of the arrhythmia.

Retrograde fast pathway cryoablation inside the coronary sinus for slow-fast atrioventricular nodal reentrant tachycardia in a patient with persistent left superior vena cava

INTRODUCTION

Persistent left superior vena cava (PLSVC) is accompanied by enlarged coronary sinus (CS) and deformation of the triangle of Koch. This makes anatomical evaluation of the atrioventricular (AV) nodal pathways difficult.

METHODS

We attempted cryoablation of retrograde fast pathway located in the enlarged CS roof of PLSVC for slow-fast AV nodal reentrant tachycardia (AVNRT) induced by inadvertent antegrade fast pathway elimination during ablation of left atrial tachycardia.

RESULTS

Slow-fast AVNRT was successfully eliminated without AV block progression.

CONCLUSIONS

This is the first case of successful retrograde fast pathway ablation of the CS ostial roof for slow-fast AVNRT with PLSVC.

A narrow QRS tachycardia with an atrial sequence not identical to that during ventricular pacing: what is the mechanism?

A 53-year-old man was referred to our hospital because of symptomatic palpitations This article is protected by copyright. All rights reserved.

Discrimination of atypical atrioventricular nodal reentrant tachycardia from atrial tachycardia by the V-A-A-V response

INTRODUCTION

The electrophysiological discrimination between fast-slow (F/S-) atrioventricular (AV) nodal reentrant tachycardia (NRT) and atrial tachycardia (AT) originating from the interatrial septum remains challenging. While a V-A-A-V response may occur immediately after ventricular induction or entrainment of either tachycardia, the electrophysiological dissimilarities in that response between the two tachycardias remain unclear. The purpose of this study was to identify a diagnostic indicator discriminating F/S-AVNRT from AT by examining the difference in the V-A-A-V response between the two tachycardias.

METHODS

This retrospective study included 17 patients with F/S-AVNRT [7 with common-form F/S-AVNRT using a typical slow pathway (SP) and 10 with superior type F/S-AVNRT using a superior SP] and 10 patients with reentrant AT. All 27 patients presented with long RP supraventricular tachycardia and an initial V-A-A-V response upon ventricular induction or entrainment. The V-A-A-V response in patients with F/S-AVNRT was due to dual atrial responses. We measured the interval between the first (A1) and second atrial electrogram (A2) of V-A-A-V and calculated ΔAA by subtracting A1-A2 from the tachycardia cycle length.

RESULTS

V-A-A-V responses were observed most often upon ventricular induction of F/S-AVNRT (6±5 times) as well as AT (6±6 times; P = 0.87). The V-A-A-V response upon ventricular entrainment was observed in a single patient with F/S-AVNRT versus 10 all patients with AT (P<0.001). ΔAA ranged between -80 and 228 ms in F/S-AVNRT and between -184 and 26 ms in AT. A ΔAA >26 ms predicted a diagnosis of F/S-AVNRT with a 76% sensitivity and 100% specificity, while a ΔAA ←80 ms predicted a diagnosis of AT with a 50% sensitivity and 100% specificity.

CONCLUSIONS

ΔAA is a useful, confirmatory, diagnostic indicator of F/S-AVNRT versus AT associated with the V-A-A-V response. This article is protected by copyright. All rights reserved.

Pacing site- and rate-dependent shortening of retrograde conduction time over the slow pathway after atrial entrainment of fast-slow atrioventricular nodal reentrant tachycardia

Introduction

We tested our hypothesis that atrial entrainment pacing (EP) of a) the common‐type (com‐) fast‐slow (F/S‐) atypical atrioventricular nodal reentrant tachycardia (AVNRT) using a typical slow pathway (SP), or b) the superior‐type (sup‐) F/S‐AVNRT using a superior SP, both modify the retrograde conduction time across the SP immediately after termination of EP (retro‐SP‐time).

Methods

We measured the difference in the His‐atrial interval (HA difference) immediately after cessation of EP, performed at 2 ± 2 rates from the high right atrium (HA[1]‐HRA) versus from the proximal coronary sinus (HA[1]‐CS) in 17 patients with com‐F/S‐AVNRT and 11 patients with sup‐F/S‐AVNRT. We also measured the atrial‐His and HA intervals of the first and second cycles immediately after cessation of EP and during stable tachycardia.

Results

Unequal responses, defined as a ≥ 20‐ms HA difference at ≥1 EP rates, were observed in 16 patients (57%), including 7 with com‐ and 9 with sup‐F/S‐AVNRT. Irrespective of the EP rate, all unequal responses of com‐F/S‐AVNRT were due to a shorter HA[1]‐CS than HA[1]‐HRA, with a mean 34 ± 11 ms HA difference, whereas all unequal responses of sup‐F/S‐AVNRT were due to a longer HA[1]‐CS than HA[1]‐HRA, with a mean 49 ± 25 ms HA difference. The unequal responses resolved within two cycles after the cessation of EP.

Conclusions

We have identified a little‐known pacing site‐ and pacing rate‐dependent shortening of the retro‐SP‐time.

Antegrade slow pathway mapping of typical atrioventricular nodal reentrant tachycardia based on direct slow pathway capture

BACKGROUND

Radiofrequency (RF) ablation of typical atrioventricular nodal reentrant tachycardia (tAVNRT) is performed without revealing out the location of antegrade slow pathway (ASp). In this study, we studied a new electrophysiological method of identifying the site of ASp.

METHODS

This study included 19 patients. Repeated series of very high-output single extrastimulations (VhoSESts) were delivered at the anatomical slow pathway region during tAVNRT. Tachycardia cycle length (TCL), coupling interval (CI), and return cycle (RC) were measured and the prematurity of VhoSESts [ΔPM (= TCL - CI)] and the prolongation of RCs [ΔPL (= RC - TCL)] were calculated. Pacing sites were classified into two categories: (i) ASp capture sites [DSPC(+) sites], where two different RCs were shown, and ASp non-capture sites [DSPC(-) sites], where only one RC was shown. RF ablation was performed at DSPC(+) sites and/or sites with catheter-induced mechanical trauma (CIMT) to ASp.

RESULTS

DSPC(+) sites were shown in 13 patients (68%). RF ablation was successful in all patients without any degree of atrioventricular block nor recurrence. Total number of RF applications was 1.8 ± 1.1. Minimal distance between successful ablation sites and DSPC(+)/CIMT sites and His bundle (HB) electrogram recording sites was 1.9 ± 0.8 mm and 19.8 ± 6.1 mm, respectively. ΔPL of more than 92.5 ms, ΔPL/TCL of more than 0.286, and ΔPL/ΔPM of more than 1.565 could identify ASp with sensitivity of 100%, 91.1%, and 88.9% and specificity of 92.9%, 97.0%, and 97.6%, respectively.

CONCLUSIONS

Sites with ASp capture and CIMT were close to successful ablation sites and could be useful indicators of tAVNRT ablation.

Superior-Type Fast-Slow Atrioventricular Nodal Reentrant Tachycardia Phenotype Mimicking the Slow-Fast Type

BACKGROUND

Superior-type fast-slow (sup-F/S-) atrioventricular nodal reentrant tachycardia (AVNRT) is a rare AVNRT variant using a superior slow pathway (SP) as the retrograde limb. Its intracardiac appearance, characterized by a short atrio-His (AH) interval and the earliest site of atrial activation in the His-bundle, is an initial indicator for making a diagnosis.

METHODS

Among 22 consecutive patients with sup-F/S-AVNRT, 3 (age, 68-81 years) patients had an apparent slow-fast (S/F-) AVNRT characterized by a long AH interval and the earliest site of atrial activation in or superior to the His-bundle region (tachy-long-AH).

RESULTS

The diagnosis of sup-F/S-AVNRT was based on the standard criteria in 2 patients and on the occurrence of Wenckebach-type atrioventricular block during tachycardia, which was attributable to a block at the lower common pathway (LCP) below the circuit of the AVNRT, detected owing to the lower common pathway potentials, in one patient. As with the typical S/F-AVNRT, tachy-long-AH was induced after a jump in the AH interval. In contrast to typical S/F-AVNRT, fluctuation in the ventriculoatrial interval was observed during the tachy-long-AH. Ventricular overdrive pacing was unable to entrain or terminate the tachy-long-AH. Moreover, the tachy-long-AH reciprocally transited to/from sup-F/S-AVNRT spontaneously or was triggered by ventricular contractions while the atrial cycle length and earliest site of atrial activation remained unchanged. Both tachycardias were cured by ablation at a single site in the right-side para-Hisian region of 2 patients and the noncoronary aortic cusp of one patient. Collectively, the essential circuit of both tachycardias was identical, and the tachy-long-AH was diagnosed as another phenotype of sup-F/S-AVNRT accompanied by sustained antegrade conduction via another bystander slow pathway breaking through the His-bundle owing to the repetitive antegrade block at the lower common pathway, thus representing a long AH interval during the ongoing sup-F/S-AVNRT.

CONCLUSIONS

An unknown sup-F/S-AVNRT phenotype exists that apparently mimics the typical S/F-AVNRT and is also an unknown subtype of apparent S/F-AVNRT.

Simple differential entrainment screens ablation strategy for slow-fast atrioventricular nodal reentrant tachycardia

BACKGROUND

Ablation of slow-fast atrioventricular nodal reentrant tachycardia (S/F-AVNRT) is occasionally refractory. We hypothesized that the site of ablation for curing S/F-AVNRT can be screened by simple differential atrial entrainment pacing (EP) from the high right atrium (HRA) and proximal coronary sinus (prox-CS).

METHODS

We enrolled 43 patients with S/F-AVNRT who underwent successful differential atrial EP followed by successful ablation of slow pathway (SP) using step-wise approach, and compared the atrio-His (A-H) interval at the recording of His bundle immediately after EP from the HRA [A-H(HRA)], with the interval between atrial deflection at the prox-CS and His bundle electrogram after EP at an identical cycle length from the prox-CS [A-H (prox-CS)].

RESULTS

A typical A-H(CS) shorter than A-H(HRA), consistent with typical SP conduction, was observed in 39 patients (91%), and an atypical A-H(HRA) shorter than A-H(CS) was observed in 4 patients (9%). Successful ablation was obtained at the posteroseptum/midseptum in 32/7 patients with typical responses but only at the midseptum in all 4 patients with atypical responses (P = .0027). The atypical responses predicted a necessity for ablation at the midseptum, with positive and negative predictive values of 100% and 82%, respectively. The mechanism of an atypical response remains unclear but may involve an anatomical variation of Koch's triangle and/or the participation of a variant of the SP, including the superior SP, over which retrograde conduction was observed more frequently in patients with atypical responses (P = .0013).

CONCLUSIONS

Differential atrial EP predicts the ablation site for successfully curing S/F-AVNRT.

Pathophysiology, Diagnosis, and Ablation of Atrioventricular Node-dependent Long-R-P Tachycardias

Atrioventricular (AV) node–dependent long-R–P tachycardias are a unique group of supraventricular tachycardias that include atypical AV nodal reentrant tachycardia (AVNRT), atypical AVNRT with a concealed bystander nodofascicular (NF)/nodoventricular (NV) accessory pathway inserting into the slow pathway of the AV node, the permanent form of junctional reciprocating tachycardia, and orthodromic NF/NV reciprocating tachycardia. Here, we discuss the complex pathophysiology, diagnosis, and ablation of these intriguing arrhythmias.

Atypical Slow-Slow Atrioventricular Nodal Reentrant Tachycardia with Use of a Superior Slow Pathway

We report a case of atypical slow-slow atrioventricular nodal reentrant tachycardia (AVNRT) utilizing a superior slow pathway as a retrograde limb. The standard electrophysiological criteria confirm the diagnosis of this AVNRT by successfully excluding a diagnosis of atrial tachycardia and atrioventricular reentrant tachycardia. The earliest atrial activation during tachycardia was found at the interatrial septum 17.5 mm superior to the site identified during retrograde conduction with the fast pathway. The tachycardia was not inducible after ablation at the right posterior septum, consistent with successful ablation of the typical slow pathway.

Supraventricular tachycardia with atrial activation earliest at the His bundle region-What is the mechanism?

A 70-year-old man with recurrent symptomatic supraventricular tachycardia was referred for catheter ablation. Atrial activation was earliest at the His bundle region with HA longer than AH.

Atypical Fast-Slow Atrioventricular Nodal Reentrant Tachycardia Using a Slow Pathway Extending to the Superoanterior Right Atrium

We report a case of atypical fast-slow atrioventricular nodal reentrant tachycardia (AVNRT) using a slow pathway variant extending to the superoanterior right atrium. The AVNRT diagnosis was confirmed by using standard electrophysiological criteria that exclude a diagnosis of atrial tachycardia and atrioventricular reentrant tachycardia. The earliest atrial activation during tachycardia was found in the superoanterior right atrium adjacent to the tricuspid annulus, where the first delivery of radiofrequency energy terminated and eliminated the inducibility of the tachycardia.

Multiple Shifts of the Earliest Retrograde Atrial Activation Site Along the Tricuspid Annulus During the Fast-Slow Form of Atrioventricular Nodal Reentrant Tachycardia by Radiofrequency Modification

A 70-year-old woman was admitted for treatment of supraventricular tachycardia. Ventriculoatrial conduction was revealed through programmed ventricular stimulation; the coronary sinus ostium (CSos) was the earliest atrial activation site. The fast-slow forms of atrioventricular nodal reentrant tachycardia (AVNRT) were induced by ventricular extra-stimuli. During tachycardia, the earliest atrial activation site was located at the bottom of CSos. Radiofrequency (RF) energy application to this site resulted in the delay of local electrical potential, prolongation of tachycardia cycle length, and a shift of the earliest retrograde activation site to the roof of CSos. Subsequent ablation induced a similar shift to the inferior tricuspid annulus and to the right posterior septum. Finally, RF energy application to the right posterior septum resulted in the termination of tachycardia, which was not induced afterward. Multiple shifts in the earliest retrograde atrial activation site along the tricuspid annulus after each slow pathway ablation suggested that annular tissue plays a substantial role as a substrate for AVNRT.

Atypical Fast-Slow Atrioventricular Nodal Reentrant Tachycardia Utilizing a Slow Pathway Extending to the Inferolateral Right Atrium

Background: The existence of atypical fast-slow (F/S) atrioventricular (AV) nodal reentrant tachycardias (NRT) using slow pathway (SP) variants connected to the right atrial (RA) inferolateral (inf) free wall (FW) along the tricuspid annulus (TA), has been neither confirmed nor precisely characterized.

Methods and Results: We studied 7 patients (mean age, 48±16 years; 5 men) with F/S-AVNRT with long RP intervals and an earliest atrial activation at the RA inf-FW along the TA (inf-F/S-AVNRT). AV reentrant tachycardia was excluded on observation of the transition zone criteria in all 7 patients. Atrial tachycardia was excluded on the observation of a V-A-V activation sequence after the induction or entrainment of the tachycardia from the right ventricle in all. During the tachycardia, low-frequency, fractionated potentials (LP) preceding the local atrial electrogram were recorded near the site of the earliest atrial activation in 6 patients. Observations of conduction delay and block of the LP during ventricular entrainment or ablation of the tachycardia indicated that LP reflect retrograde activation via the inf-SP. Retrograde SP conduction was interrupted at the site of earliest atrial activation in 3 patients, and in the right posterior septum in 4 patients.

Conclusions: inf-F/S-AVNRT are distinct supraventricular tachycardia incorporating an SP variant connected to the RA inf-FW along the TA in the retrograde direction, which were eliminated by ablation.

Catheter Ablation of Atypical Atrioventricular Nodal Reentrant Tachycardia

Background:

Because of its low prevalence, data on atypical atrioventricular nodal reentrant tachycardia (AVNRT) are scarce, and the optimal ablation method has not been established. Our study aimed at assessing the efficacy and safety of conventional slow pathway ablation, as applied for typical cases, in atypical AVNRT.

Methods:

We studied 2079 patients with AVNRT subjected to slow pathway ablation. In 113 patients, mean age 48.5±18.1 years, 68 female, atypical AVNRT or coexistent atypical and typical AVNRT without other concomitant arrhythmia was diagnosed. Ablation data and outcomes were compared with a group of age- and sex-matched control patients with typical AVNRT.

Results:

Fluoroscopy and radiofrequency current delivery times were not different in the atypical and typical groups, 20.3±12.2 versus 20.8±12.9 minutes ( P =0.730) and 5.9±5.0 versus 5.5±4.5 minutes ( P =0.650), respectively. Slow pathway ablation was accomplished from the right septum in 110 patients, and from the left septum in 3 patients, in the atypical group. There was no need for additional ablation lesions at other anatomic sites, and no cases of atrioventricular block were encountered. Recurrence rates of the arrhythmia were 5.6% in the atypical (6/108 patients) and 1.8% in the typical (2/111 patients) groups in the next 3 months following ablation ( P =0.167).

Conclusions:

Conventional ablation at the anatomic area of the slow pathway is the therapy of choice for symptomatic AVNRT, regardless of whether the typical or atypical form is present.