Comparison between cryotherapy and radiofrequency energy sources for parahisian accessory pathway percutaneous ablation

BACKGROUND

Catheter ablation of parahisian accessory pathways (PHAP) are challenging due to their proximity to the normal conduction system. Retrospective studies suggest that cryoablation has a better safety profile but a higher recurrence rate when compared to radiofrequency ablation (RFCA). The objective of this study was to compare the results of parahisian AP ablation performed by electrophysiologists with experience in both technologies.

METHODS

Prospective single-center, non-blinded and 1:1 model was used. Patients included had parahisian AP confirmed by an electrophysiological study and referred for radiofrequency or cryotherapy ablation according to current guidelines, under fluoroscopic guidance. No electroanatomic mapping was used.

RESULTS

A total of 30 patients (mean age of 25±9.4 years; 90% male) were enrolled between Oct/2018 to Feb/2020. Acute success rate between RFCA and CRYO were similar (93% vs. 87%, p = 0.54). A nonsignificant reduction in short-term recurrence rate for RFCA (14% vs. 30%, p = 0.3) and mechanical trauma (6% vs. 20%; p = 0.28) was observed. Long-term recurrence rate and event-free survival time were similar in both groups after 1-year follow-up (p = 0.286). No persistent complete AV block or conduction disturbance was also observed.

CONCLUSION

Considering the limitation of a small sample size and the lack of use of electroanatomic mapping for RFCA, the efficacy and safety profile of parahisian AP ablation with RFCA was not different from CRYO, when performed by experienced electrophysiologists. No cases of permanent complete AV block were reported with either energy modalities.

Cryoablation to improve catheter stability and ablation success in the right atrioventricular groove

Catheter instability can limit ablation success of arrhythmia substrates at the right atrioventricular groove. We describe cases where cryoablation improved catheter stability, enabling ablation success.

Methods and results

Four patients with supraventricular tachycardia (SVT) substrates at the right atrioventricular groove had radiofrequency ablation procedures limited by poor catheter contact. Cryoablation offered improved catheter stability, and all four patients achieved acute ablation success using cryoablation. Three patients had long-term success and one patient later required repeat radiofrequency ablation.

Conclusions

For patients with arrhythmia substrates at the right atrioventricular groove, cryoablation may be a useful adjunctive technique in cases with catheter instability.

Transcatheter cryo-ablation of septal accessory pathways, multicenter observational study in Japan

BACKGROUND

Ablation using radiofrequency energy has to be carefully performed when the arrhythmia substrate is located in close proximity to the atrioventricular (AV) node due to the risk of inadvertent permanent AV block. The aim of this study was to evaluate the efficacy and safety of catheter-based cryo-therapy for septal accessory pathways (APs).

METHODS

A total of eleven patients (median = 56.3 years, range 13-74 years) with septal APs underwent cryoablation. Ice-mapping was performed during sinus rhythm and an AV reciprocating tachycardia utilizing the APs as a requisite limb with cooling of the catheter tip temperature to a maximum of -30℃ for less than 45 s. Cryo-ablation was performed for 4 min at a temperature of -80℃ only if ice-mapping abolished the pre-excitation or retrograde conduction over the AP without injury to the AV nodal conduction.

RESULTS

Cryo-ablation was acutely successful in all eleven patients. No permanent cryo-related complications or adverse outcomes were reported. During the follow-up (range 14-26 months), no patients experienced any arrhythmia recurrences.

CONCLUSION

Ice-mapping was a feasible and reliable method to determine the exact location of the APs owing to the possibility of validating the ablation site. Cryo-ablation of APs located near the AV junction is a safe and efficacious technique with a high success rate over the long term.

IRB INFORMATION

Ethical Committee of Japan Red Cross Yokohama City Bay Hospital #2018-19.

Cryoablation of the right anteroseptal or midseptal accessory pathways in children: A 2-year single-center experience

BACKGROUND

Radiofrequency catheter ablation (RFCA) in the septum close to the atrioventricular node or His bundle has an increased risk of irreversible complications. Cryothermal energy has the advantages of reversible cryomapping and increased catheter stability. The study aims to evaluate the efficacy and safety of cryoablation of the right anteroseptal or midseptal accessory pathways (APs) in pediatric patients.

METHOD

A retrospective review was performed with 26 pediatric patients (16 males and 10 females; median age 6.0 years and average body weight 24.9 kg) with paroxysmal supraventricular tachycardia (PSVT) in our Pediatric Heart Center from 2014 to 2016. Half of them had manifest APs. All the children underwent cryoablation for the treatment of PSVT because of the right anteroseptal or midseptal APs (16 cases had right anteroseptal APs and 10 cases had right midseptal APs).

RESULTS

Acute cryoablation success was achieved in 23 cases (88%, 23/26). Atrioventricular block (AVB) occurred in eight cases (31%, 8/26) during the procedures and normal atrioventricular conduction recovered in seven cases except a case with I°AVB. During follow-up, three cases recurred (13%, 3/23) and no permanent high degree AVB was found.

CONCLUSION

Cryoablation of the right anteroseptal or midseptal APs in pediatric patients is both safe and effective.

Novel use of a 3-dimensional mapping system in cryoablation of right-sided and septal accessory pathways: playback ablation

PURPOSE

Despite recent advances in the treatment of eliminating accessory pathways (APs), catheter-induced mechanical block (bump) of APs has been reported to result in a less favorable outcome with high primary failure and recurrence rates. The real bump site cannot always be precisely reapproached under fluoroscopy so physicians can perform ablation to a location different from where the mechanical block was encountered. In this paper, we describe this novel use of a 3-dimensional (3D) mapping system (playback ablation) with a case series.

METHODS

The EnSite Velocity system (St. Jude Medical, St. Paul, MN, USA), a 3D mapping system, has a unique function that records the positional information of catheters in a 3D geometric map and the local potential of catheters continuously. This function enables physicians to specify the bump site in a 3D geometric map and apply ablation to the bump site even if the catheter moves away from the bump site.

RESULTS

This technique helped us eliminate APs in two patients with bump of APs, and they have been free of preexcitation and arrhythmias without the use of anti-arrhythmic drugs for more than 3 months.

CONCLUSIONS

This technique may contribute to improving long-term success in patients with mechanical block of APs.

Cryoablation with an 8-mm-Tip Catheter for Right-Sided Accessory Pathways in Children

BACKGROUND

Cryoablation is increasingly utilized in children because of its safety profile. Recently, larger catheter tips have been more widely used to improve long-term success rates. The aim of this study was to assess the safety and efficacy of 8-mm-tip catheters for cryoablation of right-sided accessory pathways (APs) in children.

METHODS

Electrophysiological procedures were performed using the EnSite™ system (St. Jude Medical Inc., St. Paul, MN, USA).

RESULTS

Between July 2010 and July 2014, 54 patients (mean age: 13.1 ± 3.7 years) underwent cryoablation using an 8-mm-tip catheter. In 18 of 54 (33%) patients where an 8-mm-tip catheter was the first-choice catheter, the success rate was 18 of 18 (100%). There was a history of previous failed attempts or recurrence with radiofrequency ablation and/or 6-mm-tip cryoablation in 36 of 54 (67%) patients. The success rate in these patients was 24 of 36 (67%). No fluoroscopy was used in 34 of 54 procedures. The recurrence rate was six of 42 (14%) during a mean follow-up period of 32 ± 15 months. In one patient, transient atrioventricular block occurred.

CONCLUSIONS

Cryoablation with an 8-mm-tip catheter for right-sided APs in children who weigh over 40 kg appears to be safe and acutely effective in cases where conventional ablation methods fail and also as a first choice for ablation procedure. However, the recurrence rate still seems to be high.

Efficacy and safety of cryoablation of parahissian accessory pathways in children: a single institution study

BACKGROUND

Catheter cryoablation of supraventricular tachycardias involving the perinodal regions is considered to be a safer alternative compared to radiofrequency ablation. Limited information is available for efficacy, midterm outcomes, and complications regarding the ablation of parahissian accessory pathways (APs) in pediatric patients.

METHODS

A retrospective review of all pediatric patients who underwent cryoablation for treatment of a parahissian AP was performed.

RESULTS

Twenty-five patients (median age 13 years and weight 45.6 kg) underwent cryoablation of a parahissian AP. Median number of cryolesions applied was four (range: 3-6). Initial procedural success was achieved in 23 patients (23/25, 92%). Transient third-degree atrioventricular (AV) block was noted in two patients. There was no permanent AV block. Transient right bundle branch block (RBBB) was observed in one patient and permanent RBBB occurred in two patients. Of the patients successfully ablated with cryo, there was only one recurrence (1/23, 4.3%) over a follow-up of 17.5 months (range 6-34 months).

CONCLUSION

Cryoablation of parahissian APs is both safe and effective with a low risk of recurrence in pediatric patients.

Simultaneous Accessory Pathway and AV Node Mechanical Block

We report a clinical case of a 22-year-old female referred to our institution due to palpitations and preexcitation. Her ECG suggested a right superior paraseptal accessory pathway (AP), which was localised during the electrophysiological study at the superior paraseptal region in close proximity to the His recordings. Reproducible orthodromic reciprocating tachycardia was induced by atrial pacing with extrastimuli. Cryo-mapping performed in the area of earliest atrial activation was not able to terminate the tachycardia. A second attempt, slightly more posterior, caused mechanical block of the AP, which rendered the tachycardia non-inducible. More pressure with the ablation catheter determined a Wenckebach type supra-hisian AV block, which was transient but reproducible. Given this finding no ablation was done. Simultaneous block to the AP and the atrioventricular node has rarely been reported using radiofrequency energy. However, to our knowledge this phenomenon has not been previously reported in large series using cryo-thermal energy.

Cryoablation of anteroseptal accessory pathways in children with limited fluoroscopy exposure

Due to its safety profile, cryoablation is used increasingly in pediatric patients, especially for septal arrhythmia substrates. Recent advances in electroanatomical-mapping technologies have resulted in a decrease or complete elimination of fluoroscopy exposure during catheter ablation procedures. The aim of this study was to assess the efficacy and safety of cryoablation of anteroseptal accessory pathways (APs) using electroanatomical-mapping system guidance with limited fluoroscopy exposure. A total of 24 patients underwent cryoablation of anteroseptal APs between July 2010 and April 2012. Cryomapping was performed with a 6 mm-tip catheter at -30 °C before the lesions were delivered. An 8 mm-tip catheter was used in one patient. The EnSite system (St. Jude Medical, St Paul, MN) was used in all procedures. The mean age was 11.9 ± 4.3 years. Acute success rate was 95.8 % (23 of 24). The mean procedure and cryoablation durations were 168 ± 58 min and 1,463 ± 525 s, respectively. Limited fluoroscopy was used only in 7 patients, and the mean fluoroscopy time was 1.7 ± 1.8 min (range 0.1-4 min) in these patients. Recurrence was noted in 2 patients (8.7 %) who underwent a second successful cryoablation procedure. The patient who underwent a failed attempt during the first procedure was successfully treated with a repeat procedure. The resultant long-term success rate was 100 % at a mean follow-up period of 14.2 ± 7.7 months. There were no complications except for transient atrioventricular block in one patient. Cryoablation of anteroseptal APs can be performed effectively and safely in children using a limited fluoroscopic approach with the help of electroanatomical-mapping systems.