Slow pathway modification for atrioventricular node re-entrant tachycardia: fast junctional tachycardia predicts adverse prognosis

Novel tissue-pressure sensing technology using a wide-band dielectric imaging system: An in vivo study

BACKGROUND

A novel dielectric wide-band imaging system with tissue pressure (TP) technology provides real-time contact force (CF) monitoring using non-CF catheters. This study sought to investigate the feasibility, safety, and efficacy of ablation with TP technology.

METHODS

Eighty-five patients with supraventricular tachycardia (SVT) were ablated with real-time monitoring of CF by TP technology and compared with 85 patients who underwent ablation with a conventional non-TP approach. Baseline characteristics, procedural data, and TP data were analyzed in the study. Ablation applications in the TP group were then subdivided into good contact and poor contact groups according to the TP level for analysis.

RESULTS

The TP group had a significantly shorter procedural time (16.2 ± 6.9 min vs. 19.9 ± 10.0 min, p = 0.033), shorter ablation time (334.6 ± 166.9 s vs. 391.3 ± 195.7 s, p = 0.049), and fewer mean numbers of radiofrequency catheter ablation (RFCA) deliveries (6.2 ± 3.2 vs. 7.6 ± 5.2, p = 0.047) than the non-TP group. The achieved average percentage of TP >3 g was significantly higher in the good-contact group (97.94% vs. 15.48%, p < 0.001). The median impedance decreases during RFCA in the good contact group and poor contact group were 4.10 (0.30-6.88) Ω and 2.60 (-0.05-4.98) Ω at 10 s, 4.45 (0.58-8.25) Ω and 2.88 (0.23-5.70) Ω at 20 s, and 4.67 (1.95-9.08) Ω and 2.97 (-0.26-6.33) Ω at 30 s, respectively (p < 0.05 for comparisons between categories). All patients achieved acute success, and no complications were observed. Two patients in the TP group and one patient in the non-TP group experienced recurrence during follow-up.

CONCLUSION

TP-technology guided ablation of SVT is feasible, efficient, and safe.

Slow-Pathway Visualization by Using Panoramic View: A Novel Ablation Technique for Ablation of Atrioventricular Nodal Reentrant Tachycardia

(1) Background: The panoramic view of a novel wide-band dielectric mapping system could show the individual anatomy. We aimed to compare the feasibility, efficacy and safety of the panoramic view guided approach for ablation of AVNRT with the conventional approach. (2) Methods: Ablation distributions in eight patients were retrospectively analyzed using the panoramic view. The para-slow-pathway (para-SP) region was divided into three regions, and the region that most frequently appeared with the appropriate junctional rhythm or eliminated the slow-pathway was defined as the adaptive slow-pathway (aSP) region. Twenty patients with AVNRT were then ablated in the aSP region under the panoramic view and compared with 40 patients using the conventional approach. (3) Results: Thirty ablation points were analyzed. The majority of effective points (95.0%) were located in the inferior and anterior portions of the para-SP region and defined as the aSP region. Baseline characteristics, fluoroscopic duration, and mean number of ablations were similar among the two groups. The panoramic view group had a significantly higher percentage of appropriate junctional rhythm (81.9% ± 26.0% vs. 55.7% ± 30.5%, p = 0.002) than the conventional group. (4) Conclusions: The use of the panoramic view for AVNRT ablation achieved similar clinical endpoints with higher ablation efficiency than the conventional approach.

Effectiveness of a 3D mapping benchmark for ablation in patients with atrioventricular nodal reentrant tachycardia

BACKGROUND

Avoiding excessively fast junctional rhythm (JR) during slow pathway (SP) modification for atrioventricular nodal reentrant tachycardia (AVNRT) helps prevent serious atrioventricular block. This study investigated the usefulness of a predictive ablation point that lies near the boundary line between appropriate and excessively fast JRs with three-dimensional (3D) electroanatomical mapping in AVNRT patients.

METHODS

Participants were 141 consecutive patients with common AVNRT who received anatomical ablation to an antegrade SP at our institution between August 2013 and December 2019. Patients were divided into two groups: Group A, treated using a location marker that predicts successful ablation sites in a 3D mapping system, and Group B, treated prior to the development of this marker and therefore without it.

RESULTS

The average age was 61.9 ± 16.9 years, and 41.1% of patients were male. Excessively fast JRs appeared less frequently in Group A than in Group B, though this difference did not reach significance. The distance from the His bundle to the successful ablation point was significantly longer in Group A than in Group B (13.4 ± 4.5 vs 10.8 ± 4.4 mm, P < .01). The number of ablations near the successful ablation point was significantly lower in Group A (6.5 ± 5.2 vs 11.4 ± 9.9, P < .01), and a greater number of accelerated JRs at the successful ablation point were observed in Group A (46.9 ± 29.2 vs 32.8 ± 19.2, P < .01).

CONCLUSION

Using our benchmark for a predictive successful ablation point in 3D mapping simplifies and improves common AVNRT ablation procedures.

How to Approach Difficult Cases of AVNRT

OPINION STATEMENT

Our approach to the ablation of atrioventricular nodal reciprocating tachycardia (AVNRT), the most common supraventricular tachycardia, is as follows: We first attempt ablation in the right atrial posteroseptum anterior to the coronary sinus ostium with a 4-mm non-irrigated tip catheter. If ablation within the triangle of Koch is unsuccessful with radiofrequency (RF), we switch to cryoablation and target a more superior (mid septal) region. We also utilize cryoablation if RF ablation produces transient VA block (absence of retrograde conduction during junctional rhythm) or a fast junctional rhythm (<350 msec). If cryoablation were to fail, or is not available, we would then suggest ablation within the coronary sinus targeting the roof (2-4 cm from the os) using a 3.5-mm irrigated tip catheter. If tachycardia were still inducible despite these measures, we would then proceed with transseptal puncture (given our greater experience with this over a retrograde aortic approach) and perform RF ablation along the posteroseptal left atrium and inferoseptal mitral annulus utilizing an irrigated tip catheter. In our experience, cryoablation reliably results in elimination of the slow pathway. The only left atrial ablation for AVNRT at our institution in the past year was performed because a patent foramen ovale allowed for rapid left atrial access, facilitating left atrial ablation of the slow pathway.

Cryoablation Versus Radiofrequency Ablation in AVNRT: Same Goal, Different Strategy

Catheter ablation is nowadays the first therapeutic option for AVNRT, the most common benign supraventricular tachycardia. Both cryotherapy and radiofrequency energy may be used to ablate the slow pathway. This paper compares both techniques, evaluates results published in literature and gives feedback on some typical aspects of cryo- and RF ablation. Although both techniques have satisfying success rates in AVNRT ablation, with a higher safety profile of cryoablation towards creation of inadvertent atrioventricular block, it remains paramount that the operator respects the distinctive traits of each technique in order to obtain an optimal result in every patient.

Atrial pacing during radiofrequency deliveries for catheter ablation of para-Hisian arrhythmias

BACKGROUND

Atrial pacing during radiofrequency (RF) deliveries is a technique to facilitate rapid recognition of impaired atrioventricular (AV) conduction during slow pathway ablation of AV nodal reentrant tachycardia. The objective of our study was to report this technique in the catheter ablation of para-Hisian arrhythmias.

METHODS

The study included a total of 48 patients who underwent ablation of para-Hisian arrhythmias including accessory pathways (APs), atrial tachycardias (ATs), and ventricular arrhythmias (VAs) in 6, 9, and 33 patients, respectively.

RESULTS

AT was successfully eliminated in all cases without any accelerated junctional rhythm (JR) occurring. JR appeared during RF deliveries in 20 patients (3 with APs, 17 with VAs). In 11 of 20 patients, RF deliveries were terminated when JR appeared and restarted during atrial pacing at a faster rate than the JR. No transient complete AV block was observed in the 11 patients, however it occurred in 1 of the remaining 9 without atrial pacing (p=0.25). Small His bundle potentials were recorded at the effective ablation site before the RF delivery in 11 (55%) patients. No patients had any AV conduction disturbances at the end of and after the procedure. APs were successfully eliminated in 2 of 3 patients. VAs were completely and partially eliminated in 10 and 4 of 17 patients, respectively.

CONCLUSIONS

Atrial pacing during RF applications might be helpful to avoid AV conduction disturbances during catheter ablation of APs close to the His bundle and idiopathic VAs originating in the vicinity of the His bundle.

Atrioventricular nodal reentrant tachycardia ablation with radiofrequency energy during ongoing tachycardia: is it feasible?

Introduction

Radiofrequency (RF) ablation of the slow pathway for treatment of atrioventricular nodal reentrant tachycardia (AVNRT) is conventionally performed during sinus rhythm.

Aim

To evaluate the clinical and electrophysiological features and the short- and long-term results of slow pathway RF ablation during ongoing AVNRT.

Material and methods

A total of 282 consecutive patients with AVNRT undergoing RF catheter ablation were analysed. Patients whose tachycardia episodes could not be controlled during RF energy application and who underwent slow pathway ablation or modification during ongoing tachycardia formed the study group (group 1, n = 16) and those ablated during sinus rhythm formed the control group (group 2, n = 266).

Results

Of the clinical characteristics, only the frequency of tachycardia attacks was higher in group 1 (3.3 ±1.2 vs. 2.1 ±0.9 attacks/month, p < 0.001). Among the baseline electrophysiological measurements, the echo zone lasted significantly longer in group 1 than in group 2 (78 ±25 ms vs. 47 ±18 ms; p < 0.001). The immediate procedural success rate was 100% in both groups. There were no significant differences between groups regarding the mean number of radiofrequency energy applications (5.2 ±4.2 vs. 5.8 ±3.9), total procedure times (42.4 ±30.5 min vs. 40.2 ±29.4 min) and fluoroscopy times (11.4 ±8.5 min vs. 12.2 ±9.3 min) (p > 0.050 for all). All patients were followed-up for 29 ±7 months; only 2 patients (< 1%) in group 2 recurred (p > 0.050). No permanent atrioventricular block was observed.

Conclusions

The RF catheter ablation or modification of the slow pathway during ongoing AVNRT is feasible with acceptable short- and long-term efficacy and safety. However, this approach needs to be clarified with large-scale studies.

Radiofrequency ablation for pre-excitation syndromes and AV nodal re-entrant tachycardia

Radiofrequency catheter ablation for supraventricular tachycardia was introduced in 1990. Since then it has become the standard for definitive treatment of pre-excitation syndromes and atrioventricular re-entrant tachycardia. In general, catheter ablation of supraventricular tachycardia results in improved outcomes compared to pharmacologic treatment. Over 95% of patients will be successfully treated with catheter ablation with less than a 5% chance of recurrence and <1% risk of major complications.

How to avoid development of AV block during RF ablation: anatomical and electrophysiological analyses at the time of AV node ablation

BACKGROUND

With an aim to identify risk factors that can serve for prevention of atrioventricular (AV) block (AVB) during radiofrequency (RF) ablation, we conducted anatomical and electrophysiological investigations at the time of AV node ablation (AVNA).

METHODS AND RESULTS

Ten patients who underwent AVNA were enrolled. RF energy was delivered from posterior region of septal annulus of the tricuspid valve to the His bundle potential (HBP) recording site using a stepwise approach. In each delivery, atrial/ventricle potential amplitude ratio (A/V ratio), HBP, and juctional ectopy (JE) that appeared during RF delivery were evaluated. Furthermore, fluoroscopic distance between ablation site and HBP recording site (anatomical H-ABL distance) and electrophysiological H-ABL interval were measured. HBP was recorded in 25 of total 70 RF deliveries. When HBP was recorded, the A/V ratio was significantly greater in the group with AVB than without AVB (1.6 ± 2.3 mV vs 0.1 ± 0.2 mV, P = 0.02). The minimum cycle length (CL) of JE was significantly shorter in the group with AVB than without AVB (438 ± 112 ms vs 557 ± 178, ms, P = 0.04). AVB developed frequently when H-ABL distance was less than 15 mm from right anterior oblique view 30° and 12 mm from left anterior oblique view 45° and when H-ABL interval was less than 10 ms. AVB did not develop over the above values.

CONCLUSIONS

HBP with high A/V ratio, JE with short CL, short H-ABL distance, and short H-ABL interval of less than 10 ms should be avoided to prevent AVB during RF ablation at the near site of AV node.

Atrioventricular Nodal Re-entrant Tachycardia Ablation: Unusual Function of Slow Pathway

Slow pathway (SP) ablation is an acceptable, standard method for atrioventricular nodal re-entrant tachycardia (AVNRT) ablation. The exact role of SP in the human heart and the possible negative implications of SP ablation are unknown. The current case report describes an unusual, brief, functional heart block, following radiofrequency ablation of the SP. Our findings highlight the peculiar property of the SP in maintaining conduction over an atrioventricular (AV) node, in circumstances of extreme autonomic imbalance. SP can be ablated without major conduction problems for AVNRT. Careful pre-ablation evaluation of the AV conduction pattern may assist in predicting occurrences of this type of heart block.

Prediction of Primary Slow-Pathway Ablation Success Rate according to the Characteristics of Junctional Rhythm Developed during the Radiofrequency Catheter Ablation of Atrioventricular Nodal Reentrant Tachycardia

BACKGROUND

Nowadays, developed junctional rhythm (JR) that occurs during slow-pathway radiofrequency (RF) catheter ablation of atrioventricular nodal reentrant tachycardia (AVNRT) has been focused upon as a highly sensitive surrogate end point for successful radiofrequency ablation. This study was conducted to assess the relationship between the presence and pattern of developed JR during the RF ablation of AVNRT and a successful outcome.

METHODS

Seventy-five patients aged between 14 and 88 who underwent slow-pathway RF ablation due to symptomatic AVNRT were enrolled into the study and received a total of 162 RF energy applications. Combined anatomic and electrogram mapping approach was used for slow-pathway RF ablation. The ablation procedure consisted of 60-second, 60 °C temperature-controlled energy delivery. After each ablation pulse, successful ablation was assessed according to the loss of AVNRT inducibility via isoproterenol infusion. Four different patterns were considered for the developed JR, namely sparse, intermittent, continuous, and transient block. Success ablation rate was assessed with respect to the position, pattern, and number of junctional beats.

RESULTS

Successful RF ablation with a loss of AVNRT inducibility was achieved in 43 (57.3%) patients using 119 RF energy applications (73.5%). JR developed in 133 of the 162 (82.1%) applications with a given sensitivity of 90.8% and low specificity of 41.9% as an end point of successful RF ablation, with a negative predictive value of 62.1%. The mean number of the developed junctional beats was significantly higher in the successful ablations (p value < 0.001), and the ROC analysis revealed that the best cut-off point of the cumulative junctional beats for identifying accurate AVNRT ablation therapy is 14 beats with 90.76 % sensitivity and 90.70% specificity. There were no significant differences in terms of successful ablation rates according to the four different patterns of JR and its positions (p value=0.338, p value=0.105, respectively) in the univariate analyses.

CONCLUSION

JR is a sensitive but non-specific predictor of the successful RF ablation of AVNRT. Nevertheless, according to the results, its specificity could increase with the presence of more than 14 cumulative junctional beats. Although the development of JR during slow-pathway RF ablation seems not to be reliable as a success end point, its absences could be a marker of requiring more energy application to ablate the slow pathway.

The significance of repetitive ventricular responses induced by radiofrequency energy application for idiopathic left ventricular tachycardia

In radiofrequency (RF) ablation for idiopathic left ventricular tachycardia (ILVT), the termination of tachycardia during RF ablation is considered a hallmark of success. However, in cases of patients with difficulty of induction of ventricular tachycardia (VT), the evaluation of procedural success can be problematic. We have observed thermal responses reflected as ventricular rhythm change to RF energy delivered on sinus rhythm for ILVT. We therefore describe the significance of repetitive ventricular responses. The study subjects were 11 ILVT patients for whom RF energy was delivered during sinus rhythm because of difficulty in re-induction of tachycardia. During each energy delivery, we focused on the occurrence of repetitive ventricular responses especially exhibiting a similar morphology to clinical VT. The repetitive ventricular responses were noted in 10 of 11 patients. Two patients received a second procedure due to the recurrence of ILVT. The mean follow-up period was 36.2+/-12.8 months. The clinical course of the remaining patients was favorable and without recurrence of ILVT. Based on the favorable clinical outcomes, ablation-induced repetitive ventricular responses with similar QRS morphology to clinical ILVT are useful markers for selecting an ablation site and could be used as an additional mapping method, termed as "thermal mapping".

Importance of the relationship between sinus cycle length and junctional rhythm cycle length (occured during radiofrequency ablation) in predicting the successful modification of the slow pathway in Atrioventricular Nodal Re-entrant Tachycardias

BACKGROUND

In atrioventricular nodal re-entrant tachycardias (AVNRT), the achievement of Junctional Rhythms (JR) during Radiofrequency Ablation (RF) is a sensitive but non-specific marker of success. Our aim is to analyze prospectively the predictors of non-inducibility of AVNRT, focusing on the characteristics of the JR.

METHODS

We included 75 patients with reproducibly inducible AVNRT. Ablation was performed following an electro-anatomical approach. After each application, the induction protocol was repeated.

RESULTS

A total of 341 applications were performed. Although the achievement of >/=1 JR was necessary to obtain the non-inducibility, and the cumulative number of junctional beats (CJB) was higher in effective applications, no CJB cut-off was associated with a success rate higher than 75%. After the observation of a significant correlation between the sinus cycle length (CL) pre-RF and the CL of the JR (JR-CL) (c=0.52; p<0.001), the sinus CL pre-RF/JR-CL ratio (CL-ratio) adequately differentiated the successful vs. unsuccessful applications: 1.41+/-0.23 vs. 1.17+/-0.2 (p<0.001). In a multivariate analysis, a CBJ 11 (p<0.001) and a CL-ratio 1.25 (p<0.001) were found to be the only independent predictors of success. The combination of >/= 11 of CJB with a CL ratio >/= 1.25 achieved non-inducibility in 97% of our patients.

CONCLUSION

1) The specificity of the occurrence of JR as a marker of the successful ablation of AVNRT is increased by the CL-ratio. 2) The achievement of >/= 11 of CJB with a CL ratio >/= 1.25 predicts non-inducibility in almost all patients.

Junctional rhythm quantity and duration during slow pathway radiofrequency ablation in patients with atrioventricular nodal re-entry supraventricular tachycardia

AIM

The occurrence of accelerated junctional rhythm during radiofrequency energy delivery at the region of the slow pathway is a well-recognized marker of successful treatment of atrioventricular nodal re-entry tachycardia (AVNRT). Our aim was to evaluate if the quantity and duration of accelerated junctional rhythm during radiofrequency ablation of the slow pathway is correlated with residual slow pathway conduction.

METHODS AND RESULTS

Forty consecutive patients with AVNRT undergoing radiofrequency ablation of slow pathway who developed accelerated junctional rhythm during ablation were included. We compared accelerated junctional rhythm quantity and duration between two groups: group A, without echo beats and group B, with echo beats on post-ablation electrophysiology study. The total amount of accelerated junctional rhythm was significantly greater in group A than in group B [75.0 (63.5-165.0) vs. 36.0 (24.0-65.0), P=0.006], as well as total duration of accelerated junctional rhythm [47.0(33.5-81.0) s vs. 23.0 (16.0-42.0) s, P=0.006]. The cycle length of accelerated junctional rhythm did not differ between the two groups [510.0 (445.0-545.0) ms vs. 500.0 (450.0-585.0) ms, P=0.5).

CONCLUSIONS

The amount and duration of accelerated junctional rhythm is correlated with the total abolishment abolition of slow pathway conduction. A higher amount and duration of accelerated junctional rhythm during radiofrequency applications may be an additional marker of successful ablation.

Transvenous radiofrequency catheter ablation of atrioventricular nodal reentrant tachycardia and its pitfalls: A rationale for cryoablation?

Today, radiofrequency (RF) catheter ablation of atrioventricular nodal reentrant tachycardia (AVNRT) is accompanied by a high success, a low recurrence, and a low complication rate. Despite the fact that over the years this technique has been refined, several shortcomings still remain. In this overview, the most important pitfalls in the treatment of AVNRT with RF energy are discussed. Cryotherapy has the ability to overcome some of them. Both ice mapping and cryo-adherence are important characteristics of this energy source to study prospective ablation sites before a definitive and irreversible lesion is created. Theoretically, this could lead to less applications with less tissue damage and abolish the risk for permanent conduction disturbances. The early experience with this technique will be described. Until now, it still has to be proven that in a large cohort of patients, cryotherapy is at least as effective, and safer than RF.