Slow Pathway Ablation Research Articles

Improved clinical outcome by means of three-dimensional electroanatomically- guided slow pathway elimination with irrigated, contact- force sensing catheter

Abstract Background Slow pathway (SP) ablation, in the context of atrioventricular node reentrant tachycardia (AVNRT) treatment could result in either complete elimination or only modification of the SP with ambiguity regarding associated benefits. Purpose Three-dimensional electroanatomical mapping (3D-EAM) with irrigated, contact-force sensing may be used adjunctively aiming to complete SP elimination. Our purpose was to compare a 3D-EAM based strategy targeting SP elimination to the conventional fluoroscopic approach with respect to clinical outcome. Methods Eighty-four consecutive AVNRT patients (33 males, mean age 50.1±11.7 years) underwent a conventional fluoroscopic ablation approach (N=42) or a 3D-EAM-guided ablation irrigated, contact-force sensing catheter (ThermoCool SmartTouch ST, Biosense Webster, Inc.) focusing on complete SP elimination (N=42). Results Several procedural parameters improved with 3D-EAM use, including fluoroscopy time (2.0±4.3min vs 11±4.0min) and slow pathway elimination frequency (100% vs 50%, all p<0.001). Altogether, over a mean follow-up of approximately 2.0 years, recurrence occurred in 6 of 42 (14.3%) in the conventional group as compared to 1 of 42 (2.4%) in the EAM-based group (P =0.04). Conclusions The present study showed that an EAM-based SP elimination strategy is not only feasible and safe but it is also accompanied by improved clinical outcome in the setting of AVNRT ablation.

Novel approach of slow pathway ablation in common atrioventricular nodal reentrant tachycardia by peak frequency map

Abstract Background It is difficult to visualize slow pathway in atrioventricular nodal reentrant tachycardia (AVNRT) even with recent high-density mapping. This could be because the slow pathway potential is buried by the potential of atrial working cells during sinus rhythm and tachycardia. In other words, it is extremely difficult for conventional 3D mapping systems to annotate slow pathway potential even though the histological run of slow pathway is known .[1], [2] Purpose The purpose of this study is to visualize the atrial myocardial junction of rightward inferior extension by the peak frequency map of Ensite X in common AVNRT and to evaluate whether relative high frequency (HF) sites in low voltage area extending from Koch's triangle to tricuspid annulus (TA) is effective targets of slow pathway ablation and the characteristics of junctional rhythm (JR) after radiofrequency application. Methods This study is single-center prospective cohort study. In 37 consecutive common AVNRT patients, novel approach and conventional approach of slow pathway ablation were performed in 17 and 20 patients, respectively. The conventional approach is anatomical and electrophysiological approach. Peak frequency map was performed during sinus rhythm with HD-grid catheter in novel approach patients. A frequency scanning is performed to locate relative HF sites on the tricuspid annulus. Radiofrequencey application is 30 W, 30-60 sec, and the end point was no inducibility or until one echo under load of isoproterenol. Results The success rate was 100 % with two approaches. The relative HF sites in low voltage area were distributed at the TA side from 4 to 5 o'clock in all novel approach patients, mean peak frequency in success site was 419 ± 87 Hz. The distance to His bundle from success site was farther (24.8 ± 4.9 vs. 12.8 ± 4.4 mm, p<0.001), JR was slower (93 ± 14 vs. 118 ± 10 bpm, p=0.013), time to JR occurrence was shorter (3.0 ± 1.3 vs. 7.6 ± 4.6 sec, p=0.003), and elimination rate of jump up (78 % vs. 40 %, p=0.06) was higher in novel approach. Conclusions The relative HF sites in low voltage area at TA side from 4 to 5 o'clock by peak frequency map could be novel target of slow pathway ablation with high success rate and sufficient safety and efficiency.peak frequency map

Analysis of junctional beats during slow pathway ablation: illuminating the mechanism of typical and atypical AV nodal re-entrant tachycardia

Analysis of junctional beats during slow pathway ablation: illuminating the mechanism of typical and atypical AV nodal re-entrant tachycardia

Pivoting turn-around activation guided successful slow pathway ablation in the cavotricuspid isthmus

Pivoting turn-around activation guided successful slow pathway ablation in the cavotricuspid isthmus

Slow pathway ablation in pediatric patients: long-term outcomes in a high-volume center according to baseline electrophysiologic characteristics

Abstract Background Slow pathway ablation (SPA) in pediatric patients with documented paroxysmal supraventricular tachycardia (PSVT) has been proven safe and effective. Arrhythmia induction is often difficult in the pediatric population. Accordingly, empirical SPA is frequently adopted in this population. Real-world data about long-term outcomes of slow pathway ablation (SPA) in relation to tachycardia inducibility and electrophysiologic characteristics in pediatric patients with PSVT in a high-volume center are lacking. Purpose To compare long-term clinical outcomes of SPA in pediatric patients with and without intraprocedural documentation of DAVP and AV nodal reentrant tachycardia induction. Methods In this retrospective sigle-center study, all SPA procedures performed on pediatric patients (under 18 years) at our Institution since 2016 were considered. All patients had documented PSVT with short RP interval, no evidet ventricular pre-excitatio on surface ECG and normal echocardiography. Baseline EPS was performed to exclude the presence of concealed accessory pathway and isoproterenol infusion was used to exclude focal atrial tachycardias. According to intraprocedural EP characteristics, three group of patients were identified: Group 1 with AVNRT induction; Group 2 with dual atrioventricular nodal physiology (DAVP) and no tachycardia induction; Group 3 without DAVP. According to previous documentation of a short RP PSVT and after discussion with patients’ families, SPA was performed in all patients. The endpoint of the ablation was to eliminate slow pathway conduction and AV node re-entrant beat. Follow up visits were scheduled three and twelve months after ablation for all patients. Results 1734 patients underwent SPA since 2016 at our Institution. 1092 patients (73.4%) showed AVNRT induction during EPS (Group 1). 433 patients (14.2%) showed DAVP without tachycardia induction (Group 2). 209 patients (12.4%) didn’t show DAVP at EPS (Group 3). Age and gender were similar among the three groups. SPA was performed with acute procedural success in all patients. After 36-month median follow-up, freedom from palpitations was 98.5% in Group 1, 97.1% in Group 2 and 92.3% in Group 3. A survival analysis showed the best outcomes in group 1 and no significant difference in recurrence rate among the groups 2 and 3 (Figure 1). No permanent heart blocks, neither other major complication was observed. Conclusions When performed by experienced operators and in high-volume centers, SPA is a safe and effective procedure in pediatric patients with documented short RP PSVT. Success rate is highest with AVNRT induction and good without AVNRT induction, regardless of AV node dual conduction at baseline EPS. Such high success rate depends on careful exclusion of others arrhythmia mechanisms (i.e., focal atrial tachycardias, AV re-entrant tachycardias) that, although infrequent in children, are the main determinants of arrhythmia recurrences.

Activation map of koch triangle: a novel approach to AVNRT ablation using CARTO 3 v7

Abstract Background Ablation of slow pathway (SP) is the standard approach for atrioventricular nodal reentry tachycardia (AVNRT) treatment (1). Low-voltage bridge is an optimal target during mapping using low x-ray exposure (2,3). Purpose We want to assess a new tool to identify SP by activation mapping of Koch’s triangle using CARTO PRIME V7 Methods Triangle of Koch 3D-activation map were obtained from intracardiac contact mapping during low x-ray CARTO 3 procedures (Figure 1). In 60 patients (39 % males, mean age 60.3 ± 14.7 years) undergoing ablation for AVNRT, an automatic activation map using a DECANAV mapping catheter and CARTO Confidense, Coherent, and FAM DX software modules were obtained. Results We indentified SP in all patients as the latest atrioventricular node activation area; RF catheter ablation (RFCA) elicited junctional beats. The mean dose-area product (DAP) was 16.5 ± 2.7 cGy/cm2, the mean fluoroscopy time exposure was 2.9 ± 2 min, the mean ablation index was 428.6 ± 96.6, and the mean contact force was 8 ± 2.8 g. There were no adverse event during the procedure and no AVNRT recurrences during a mean follow-up of 14.3 ± 8.3 months. Conclusions Ablation of the SP by automatic mapping using Confidense, Coherent, and FAM DX software modules is a new approach to AVNRT ablation. The CARTO3 V7 system defines a 3D map of the latest AV node activation area during sinus rhythm allowing a highly effective RFCA under low fluoroscopy time exposure without recurrences or AV blocks.Figure 1

DECENNIAL ANALYSIS OF AVNRT ABLATION IN A SINGLE CENTRE

Abstract Background Transcatheter ablation represents the first line therapy for atrio–ventricular nodal re–entrant tachycardia (AVNRT). Both radiofrequency (RF) and cryoablation (CRYO) have been shown to be effective, with a better safety profile for CRYO. Data on very long–term efficacy are scarces. Purpose To review our experience in AVNRT ablation performed in the last ten years and evaluate safety, efficacy and very long–term outcome of RF and CRYO. Methods We retrospectively analyzed all patients who underwent AVNRT ablation (RF or CRYO) between January 2013 and May 2023 at our centre. The majority of procedures were performed under electro–anatomical mapping (EAM) guidance to reduce radiation exposure. Acute efficacy endpoint was defined as slow pathway ablation, while long–term outcome was defined as the absence of AVNRT recurrence. Results A total of 387 consecutive patients (60,5% F; mean age 48 ± 19 years) were included; CRYO was performed in 241 patients (62%), RF in 131 patients (34%), hybrid approach (CRYO+RF) in 15 patients (4%). AVNRT induction was obtained during EPS in 295 cases (76%), in 25,4% after isoprotenerol administration. No significant differences for baseline characteristics were observed between the two groups except for age (CRYO: 42,2 ± 18 years vs RF 57,19 ± 16,5 years p <0.001). In pediatric population CRYO was performed in 93% of procedures. Figure 1 shows the distribution of RF/CRYO over 10 years at our centre, with a trend of significant increase in CRYO utilizations in the last years. Acute success was achieved in all 387 cases (100%; delta WP 28,5 ± 23,1 ms, delta AVN ERP 72,4 ± 44,7 ms). No permanent AV block or major periprocedural complications occurred, however transient AH prolongation was observed in 0.8% in CRYO pts vs 2,8% RF pts. The mean follow–up was 73±45 months, range 6–129 months. Overall long–term success rate was 93,3%, ranging from 91,3 % in CRYO and 96,6% in RF. Recurrence occurred in 26 cases (6,7%) after a median time of 20 months (4–40months). Recurrent AVNRT were treated with RF in the majority of cases, CRYO in 6 procedures, hybrid in only 1 case. Conclusions Transcatheter ablation is a safe and effective therapy for AVNRT. Our very long–term outcome data confirmed very high success rate even after 10 years follow–up. The increasing choice for CRYO may be due to the increasing number of pediatric and young patient referred to our centre.

Peak frequency annotation algorithm–guided slow pathway ablation in typical atrioventricular nodal reentrant tachycardia

BackgroundThe slow pathway potential is difficult to annotate because it is buried within the atrial potential. Omnipolar technology near field can automatically annotate the peak frequency potential associated with acquired intracardiac electrograms. ObjectivesThis study aimed to visualize the junction between the transitional cells and the slow pathway using a peak frequency map with omnipolar technology near field and evaluate whether the high-frequency site around the tricuspid annulus (TA) is an effective target for slow pathway ablation. MethodsThis prospective observational study enrolled 37 patients with typical atrioventricular nodal reentrant tachycardia. Patients underwent slow pathway ablation using a peak frequency map (n = 17) and the conventional approach based on anatomical and electrophysiological findings (n = 20). ResultsHigh-frequency sites were distributed at the TA side of the 4–5 o’clock position in all patients mapped using the peak frequency map of OTNF. The distance to the His bundle from the successful ablation site was farther (24.0 ± 4.8 mm vs 12.7 ± 4.0 mm; P < .0001), junctional rhythm was slower (88 ± 17 beats/min vs 115 ± 12 beats/min; P < .0001), the time to junctional rhythm after radiofrequency application was shorter (3.4 ± 1.4 seconds vs 8.2 ± 4.6 seconds; P < .0001), and the elimination rate of jump ups (71% vs 30%; P = .02) was higher in the peak frequency map–guided group. ConclusionThe high-frequency site of the TA at 4–5 o’clock in the peak frequency map could be a novel target of slow pathway ablation with high safety, efficiency, and efficacy.

The optimal slow pathway ablation site in atrioventricular nodal reentrant tachycardia cases with an inferiorly located His bundle.

The optimal slow pathway (SP) ablation site in cases with an inferiorly located His bundle (HIS) remains unclear. In 45 patients with atrioventricular nodal reentrant tachycardia, the relationship between the HIS location and successful SP ablation site was assessed in electroanatomical maps. We assessed the location of the SP ablation site relative to the bottom of the coronary sinus ostium in the superior-to-inferior (SPSI), anterior-to-posterior (SPAP), and right-to-left (SPRL) directions. The HIS location was assessed in the same manner. The HIS location in the superior-to-inferior direction (HISSI), SPSI, SPAP, and SPRL were 17.7±6.4, 1.7±6.4, 13.6±12.3, and -1.0±13.0mm, respectively. The HISSI was positively correlated with SPSI (R2=0.62; P<.01) and SPAP (R2=0.22; P<.01), whereas it was not correlated with SPRL (R2=0.01; P=.65). The distance between the HIS and SP ablation site was 17.7±6.4mm and was not affected by the location of HIS. The ratio of the amplitudes of atrial and ventricular potential recorded at the SP ablation site did not differ between the high HIS group (HISSI≥13mm) and low HIS group (HISSI<13mm) (0.10±0.06vs. 0.10±0.06; P=.38). In cases with an inferiorly located HIS, SP ablation should be performed at a lower and more posterior site than in typical cases.

Novel near-field detection algorithm–guided slow pathway ablation in atrioventricular nodal reentrant tachycardia

Novel near-field detection algorithm–guided slow pathway ablation in atrioventricular nodal reentrant tachycardia

Efficacy and safety between radiofrequency ablation and types of cryoablation catheters for atrioventricular nodal reentrant tachycardia: A Network Meta-analysis and Systematic Review.

Atrioventricular nodal reentrant tachycardia (AVNRT) is the most common supraventricular tachycardia referred for ablation. Periprocedural conduction system damage was a primary concern during AVNRT ablation. This study aimed to assess the incidence of permanent atrioventricular (AV) block and the success rate associated with different types of catheters in slow pathway ablation. A literature search was performed to identify studies that compared various techniques, including types of radiofrequency ablation (irrigated and nonirrigated) and different sizes of catheter tip cryoablation (4, 6, and 8-mm), in terms of their outcomes related to permanent atrioventricular block and success rate. To assess and rank the treatments for the different outcomes, a random-effects model of network meta-analysis, along with p-scores, was employed. A total of 27 studies with 5110 patients were included in the analysis. Overall success rates ranged from 89.78% to 100%. Point estimation showed 4-mm cryoablation exhibited an odds ratio of 0.649 (95%CI: 0.202-2.087) when compared to nonirrigated RFA. Similarly, 6-mm cryoablation had an odds ratio of 0.944 (95%CI: 0.307-2.905), 8-mm cryoablation had an odds ratio of 0.848 (95%CI: 0.089-8.107), and irrigated RFA had an odds ratio of 0.424 (95%CI: 0.058-3.121) compared to nonirrigated RFA. Our study found no significant difference in the incidence of permanent AV block between the types of catheters. The success rates were consistently high across all groups. These findings emphasize the potential of both RF ablation (irrigated and nonirrigated catheter) and cryoablation as viable options for the treatment of AVNRT, with similar safety and efficacy profile.

Empirical slow pathway ablation in patients with paroxysmal palpitations and pounding in the neck: A 15-year follow-up

Empirical slow pathway ablation in patients with paroxysmal palpitations and pounding in the neck: A 15-year follow-up

Low voltage mapping in atrio-ventricular nodal reentry tachycardia ablation: safety and efficacy in a single center experience

Abstract Background Atrio-ventricular nodal reentry tachycardia (AVNRT) is one of the most common supraventricular arrhythmias. Transcatheter ablation is the first-choice strategy for its treatment. Despite various ablation techniques, using different signal analyses and different energy sources, the reported incidence rate of AVNRT recurrences and high-grade or complete atrioventricular block are about 5% and 1% respectively. Voltage mapping for slow pathway localization is a novel technique for the treatment of AVNRT, that may increase procedural safety and effectiveness, particularly in pediatric patients. Purpose To evaluate the safety and efficacy of ablation of slow conduction pathway identified via three-dimensional voltage mapping of Koch’s triangle. Methods 108 consecutive patients (45% male, mean age 58.6±15.4 years) scheduled for AVNRT ablation in our center underwent three-dimensional voltage mapping of the right atrial septum and Koch’s triangle. Voltage map was aimed at detecting an area of low voltage (voltage bridge) below the His bundle (adjusting the high-voltage slider to 1,5 mV), corresponding to the slow conduction pathway. Focusing on this target, we evaluated the number of radiofrequency (RF) pulses and RF time application for effective ablation of the slow conduction pathway defined by accelerated junctional rhythm (AJR) induction during RF delivery and absence of post-ablative AVNRT inducibility. After RF ablation, all patients underwent clinical evaluation every 3 months to identify AVNRT recurrences. Results Voltage mapping was performed in all patients. The mean duration of mapping was 5.7±3.8 minutes. In all patients, a low voltage bridge could be identified. Using this target, RF was delivered until AJR was elicited (mean number of RF pulses at 30W, 50°C = 1.5±1.1; mean time to AJR: 25±12 s). After successful ablation of the slow conduction pathway, AVNRT was no more inducible. No atrioventricular conduction defect (atrioventricular block of any grade) occurred after RF ablation in any patient (AH pre vs. AH post: 148.5±22.8 ms vs. 153.6±17.8 ms, p=n.s.; HV pre vs. HV post: 20.5±18.7 ms vs. 21.8±17.3 ms, p=n.s.; Wenkebach point pre vs. Wenkebach point post: 320.4±45.3 ms vs. 326.2±38.7 ms, p=n.s.). All patients were discharged without antiarrhythmic drug therapy. Overall, during a 2-year follow up, 4 patients had a recurrence of AVNRT (incidence rate of recurrences: 0.025/year). Conclusions Voltage mapping can easily identify the low voltage bridge area of Koch’s triangle as a target for slow pathway ablation. RF ablation of the slow pathway identified in this way is safe and effective. Success in slow pathway ablation can be achieved with a low number of very precise RF pulses. This approach can prevent the risk of ablation-related atrioventricular conduction defects and reduce the risk of AVNRT recurrences.

The zero fluoroscopic approach to avnrt ablation significantly reduces radiation without compromising safety, efficacy or procedure time compared to a conventional or minimal fluoroscopic approach

Abstract Introduction In 2020, we showed that ablation of AVNRT (induced under conventional fluroscopy) with a 3D electro-anatomical mapping system (EAMS) (minimal X-RAY group) significantly reduces radiation exposure without compromising safety, efficacy and procedure time compared to a procedure performed entirely under conventional fluoroscopy (X-RAY group). Purpose The objective of this study was to determine whether the direct use of EAMS in selected patients with a high probability of induction of AVNRT could reduce radiation exposure to near zero without compromising the safety, efficacy and duration of the procedure (EAMS group) Methods We compare the 136 patients in the X-RAY group, the 141 patients in the minimal X-RAY group with 39 patients included in the EAMS group (included between July 2020 and December 2022). All procedures were performed at a single centre in Belgium using the same 3D electroanatomical mapping system. In the EAMS group, fluoroscopy had to be used to guide catheter progression for only 5 patients. We compared radiation dose, acute success, complication rates and procedure duration. Results AVNRT induction was achieved in 38 of 39 patients in the EAMS group. Only one patient was not inducible, but the slow pathway ablation was performed on the basis of the arrythmic ECG recording which was highly suggestive of AVNRT; the success of the ablation could therefore not be validated acutely. Radiation dose in the EAMS group was significantly lower compared to the minimal X-RAY group and X-RAY group (8,5 vs 1179 and 2686 mgray.cm2, p &amp;lt;0,0001) and fluroscopic time was obviously shorter (0,02 vs 2,5 and 8,6 minutes, p&amp;lt;0,0001). Procedural time (74,3 vs 70 and 69 mon, p = NS) and success rate (97,5% vs 99 and 98%, p = NS) were not significantly different in the three groups. No serious complications were observed in any group. No minimal complication were reported in the zero-fluoroscopy group. Conclusion AVRNT catheter ablation using a zero-fluoroscopic approach with EAMS significantly reduces radiation exposure without compromising safety, efficacy or procedure time.

Abstract 13443: Dead Antegrade Fast Pathway: A Dilemma for Atrioventricular Nodal Re-Entry Tachycardia Ablation

Background: Catheter ablation is the first-line treatment option for symptomatic atrioventricular nodal re-entry tachycardia (AVNRT). Ablation of the slow pathway is preferred over the fast pathway in Typical AVNRT, given that it has a lower risk of heart block. Still, baseline conduction abnormalities and findings on the Electrophysiology (EP) study can alter the ablation strategy. Case: We report a case of a 61-year-old male who was referred to EP clinic for symptomatic suspected AVNRT. His baseline electrocardiogram (EKG) showed normal sinus rhythm with PR prolongation, right bundle branch block, and left anterior fascicular block. EP study was performed, which showed prolonged AH interval with normal HV interval (Figure 1). Typical AVNRT was induced with a premature atrial complex; there was no AV nodal jump before the tachycardia, but it had a long AH interval (Figure 2). There was no evidence of pre-excitation. Discussion: Since there was no antegrade conduction through the fast pathway, conventional slow pathway ablation was not viable as it would make the patient pacemaker (PM)-dependent. Even ablating the fast pathway, though not PM-dependent, would still put him at risk for complete heart block, especially when his antegrade conduction via the slow pathway was unreliable. Hence PM was discussed with the patient before ablation. The fast pathway was mapped and ablated (Figures 3, 4, and 5) without complication, and PM was implanted. Conclusion: This case emphasizes the role of fast pathway ablation in symptomatic AVNRT in patients with conduction abnormalities and the importance of EP study to see the need for PM post-ablation.

Long-Term Follow-Up of Empirical Slow Pathway Ablation in Pediatric and Adult Patients with Suspected AV Nodal Reentrant Tachycardia.

The aim of this study was to assess long-term efficacy and safety of empirical slow pathway (ESP) ablation in pediatric and adult patients with a special interest in patients without dual AV nodal physiology (DAVNP). A retrospective single-center review of patients who underwent ESP ablation between December 2014 and September 2022 was performed. Follow-up included telephone communication, letter questionnaire and outpatient presentation. Recurrence was based on typical symptoms. 115 patients aged 6-81 years (median age 36.3 years, 59.1% female; 26 pts < 18 years) were included. A typical history was present in all patients (100%), an ECG documentation of narrow complex tachycardia in 97 patients (84%). Patients were divided into three groups: Group 1 without DAVNP (n = 23), Group 2 with AH jump (n = 30) and Group 3 with AH jump and at least one AV nodal echo beat (n = 62). No permanent AV block was observed. During a median follow-up of 23.6 ± 22.7 months, symptom recurrence occurred in 7/115 patients (6.1%) with no significant difference between the groups (p = 0.73, log-rank test). Symptom recurrence occurred significantly more often in patients without (5/18 patients; 27%) as compared to patients with ECG documentation (2/97 patients; 2.1%; p = 0.025). No correlation between age and success rate was found (p > 0.1). ESP ablation is effective and safe in patients with non-inducible AVNRT. Overall, recurrence of symptoms during long-term follow-up is low, even if no DAVNP is present. Tachycardia documentation before the EP study leads to a significantly lower recurrence rate following ESP ablation.

Atrioventricular nodal reentry tachycardia treatment using CARTO 3 V7 activation mapping: a new era of slow pathway radiofrequency ablation is under coming.

Slow pathway (SP) ablation is the cornerstone for atrioventricular nodal reentry tachycardia (AVNRT) treatment, and a low-voltage bridge offers a good target during mapping using low x-ray exposure. We aimed to assess a new tool to identify SP by activation mapping using the last CARTO3® version, i.e., CARTO PRIME® V7 (Biosense Webster, Diamond Bar, CA, USA). Right atrial septum and triangle of Koch 3D-activation map were obtained from intracardiac contact mapping during low x-ray CARTO 3® procedure. In 60 patients (mean age 60.3 ± 14.7, 61% females) undergoing ablation for AVNRT, an automatic activation map using a DECANAV® mapping catheter and CARTO® Confidense™, Coherent, and FAM DX software modules were obtained. The SP was identified in all patients as the latest atrioventricular node activation area; RF catheter ablation (RFCA) in that region elicited junctional beats. The mean procedural time was 150.3 ± 48.3 min, the mean fluoroscopy time exposure was 2.9 ± 2 min, the mean dose-area product (DAP) was 16.5 ± 2.7 cGy/cm2. The mean number of RF applications was 3.9 ± 2, the mean ablation index was 428.6 ± 96.6, and the mean contact force was 8 ± 2.8 g. There were no adverse event during the procedure, and no AVNRT recurrences occurred during a mean follow-up of 14.3 ± 8.3 months. Ablation of the SP by automatic mapping using Confidense™, Coherent, and FAM DX software modules is an innovative, safe, and effective approach to AVNRT ablation. The CARTO3® V7 system shows on a 3D map the latest AV node activation area during sinus rhythm allowing low fluoroscopy time and highly effective RFCA.

Termination of slow-fast atrioventricular reentrant tachycardia by a single cryoablation of the slow pathway guided by a fractionation map.

This is a slow-fast atrioventricular nodal reentrant tachycardia (AVNRT) case wherein the fractionation map-guided cryoablation of the slow pathway (SP) successfully terminated the tachycardia. In this case, the Advisor™ HD Grid catheter and fractionation map in the EnSite™ X EP system with relatively high-sensitive settings were useful for detecting the target SP area. Direct AVNRT termination by cryomapping at the fractionated potential area might be a quick and safe ablation strategy, which may provide a new workflow for SP ablation.

Novel method to avoid serious injurious effects on the atrioventricular nodal (AVN) conduction during catheter ablation of the AVN slow pathway utilizing cryofreezing energy

BackgroundSlow pathway elimination of the atrioventricular node (AVN) is essential to treat AVN reentrant tachycardia (AVNRT). However, injury to the AVN conduction (IAVN) is one of the serious complications. Cryofreezing energy is expected to reduce the incidence of IAVN. This study aimed to investigate the usefulness of a novel method to avoid IAVN during cryoablation of AVNRT. MethodsA total of 157 patients (average age, 65.8 years; male, 71) suffering from AVNRT were included. Once the AVNRT terminated during cryo-ablation, then rapid atrial constant pacing (RACP) was performed during freezing at a rate lower 10 bpm than that inducing Wenchebach AV block in 74 (47.1 %) patients (Group A). The RACP rate was decreasingly reduced by 10 bpm in case of the occurrence of IAVN. When the RACP reached 100 bpm, the cryoablation was prematurely terminated. Group B patients (83 = 52.9 %) underwent cryoablation during sinus rhythm. All patients were allocated in a randomized fashion. We compared the severity of the IAVN between Groups A and B. ResultsThere were no significant differences at 12 months regarding the freedom from the AVNRT between Groups A and B. However, the duration of the IAVN was significantly longer in Group B than A (p = 0.02). There were no significant differences regarding the distance between the His recording sites and successful ablation sites between Groups A and B. No permanent IAVN requiring pacemaker implantation was provoked in either group. ConclusionRACP was useful to avoid sustained and serious IAVN during cryoablation of AVNRT.

Electroanatomical Mapping System-Guided vs. Intracardiac Echocardiography-Guided Slow Pathway Ablation: A Randomized, Single-Center Trial.

Radiofrequency (RF) catheter ablation is an effective treatment option for targeting the slow pathway (SP) in atrioventricular nodal reentry tachycardia (AVNRT). Previous data suggested that using intracardiac echocardiography (ICE) guidance could improve procedural outcomes when compared to using fluoroscopy alone. In this prospective study, we aimed to compare the effectiveness of an electroanatomical mapping system (EAMS)-guided approach with an ICE-guided approach for SP ablation. Eighty patients undergoing SP ablation for AVNRT were randomly assigned to either the ICE-guided or EAMS-guided group. If the procedural endpoint was not achieved after 8 RF applications; patients were allowed to crossover to the ICE-guided group. The ICE-guided approach reduced the total procedure time (61.0 (56.0; 66.8) min vs. 71.5 (61.0; 80.8) min, p < 0.01). However, the total fluoroscopy time was shorter (0 (0-0) s vs. 83.5 (58.5-133.25) s, p < 0.001) and the radiation dose was lower (0 (0-0) mGy vs. 3.3 (2.0-4.7) mGy, p < 0.001) with EAMS-guidance. The ICE-guided group had a lower number of RF applications (4 (3-5) vs. 5 (3.0-7.8), p = 0.03) and total ablation time (98.5 (66.8-186) s vs. 136.5 (100.5-215.8) s, p = 0.02). Nine out of 40 patients (22.5%) in the EAMS-guided group crossed over to the ICE-guided group, and they were successfully treated with similar RF applications in terms of number, time, and energy compared to the ICE-guided group. There were no recurrences during the follow-up period. In conclusion, the utilization of ICE guidance during SP ablation has demonstrated notable reductions in procedural time and RF delivery when compared to procedures guided by EAMS. In challenging cases, an early switch to ICE-guided ablation may be the optimal choice for achieving successful treatment.