Cryoablation of Septal Accessory Pathways in Children: Midterm Results

2024 HRS expert consensus statement on arrhythmias in the athlete: Evaluation, treatment, and return to play

Youth and adult participation in sports continues to increase, and athletes may be diagnosed with potentially arrhythmogenic cardiac conditions. This international multidisciplinary document is intended to guide electrophysiologists, sports cardiologists, and associated health care team members in the diagnosis, treatment, and management of arrhythmic conditions in the athlete with the goal of facilitating return to sport and avoiding the harm caused by restriction. Expert, disease-specific risk assessment in the context of athlete symptoms and diagnoses is emphasized throughout the document. After appropriate risk assessment, management of arrhythmias geared toward return to play when possible is addressed. Other topics include shared decision-making and emergency action planning. The goal of this document is to provide evidence-based recommendations impacting all areas in the care of athletes with arrhythmic conditions. Areas in need of further study are also discussed.

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.

Ablation of manifest septal accessory pathways: a single-center experience

BACKGROUND

Ablation of septal accessory pathways (SAPs) is associated with an increased risk of heart block. Data on outcomes of SAP ablation in adults are limited.

OBJECTIVES

To describe outcomes of SAP ablation in our center.

METHODS

Patients with Wolff-Parkinson-White syndrome (WPW) undergoing an EP study at our center between January 2008 and August 2019 were identified from our institutional database. Location of the pathway was noted as anteroseptal (AS), midseptal (MS), or posteroseptal (PS). Outcomes of the ablation including success, complication rates, and recurrences were also recorded.

RESULTS

Thirty-three patients with SAP underwent 35 EP studies: AS (n = 13), MS (n = 5), and PS (n = 15). Thirty pathways were targeted for ablation, two of which required a 2nd procedure resulting in 32 attempts at ablation in 30 patients. In the remaining 3 patients, SAP did not have malignant features and were not targeted for ablation. Single-procedure success rate was 28/30 (93.33%): 9/10 AS, 5/5 MS, and 14/15 PS ablations. One AS pathway was successfully ablated during a 2nd procedure. Two complications were observed: 1 pericardial effusion in a patient who underwent epicardial mapping and ablation of both PS and right free wall APs. Additionally, transient 2:1 AV block occurred during an MS pathway ablation that recovered during follow-up and did not require permanent pacing procedure.

CONCLUSION

In this single-center experience, ablation of manifest SAP was associated with high success rates and low complication rates. No instances of permanent heart block requiring pacing occurred.

Validation of a novel automated signal analysis tool for ablation of Wolff-Parkinson-White Syndrome

Background

In previous pilot work we demonstrated that a novel automated signal analysis tool could accurately identify successful ablation sites during Wolff-Parkinson-White (WPW) ablation at a single center.

Objective

We sought to validate and refine this signal analysis tool in a larger multi-center cohort of children with WPW.

Methods

A retrospective review was performed of signal data from children with WPW who underwent ablation at two pediatric arrhythmia centers from 2008–2015. All patients with WPW ≤ 21 years who underwent invasive electrophysiology study and ablation with ablation signals available for review were included. Signals were excluded if temperature or power delivery was inadequate or lesion time was < 5 seconds. Ablation lesions were reviewed for each patient. Signals were classified as successful if there was loss of antegrade and retrograde accessory pathway (AP) conduction or unsuccessful if ablation did not eliminate AP conduction. Custom signal analysis software analyzed intracardiac electrograms for amplitudes, high and low frequency components, integrated area, and signal timing components to create a signal score. We validated the previously published signal score threshold 3.1 in this larger, more diverse cohort and explored additional scoring options. Logistic regression with lasso regularization using Youden’s index criterion and a cost-benefit criterion to identify thresholds was considered as a refinement to this score.

Results

347 signals (141 successful, 206 unsuccessful) in 144 pts were analyzed [mean age 13.2 ± 3.9 years, 96 (67%) male, 66 (45%) left sided APs]. The software correctly identified the signals as successful or unsuccessful in 276/347 (80%) at a threshold of 3.1. The performance of other thresholds did not significantly improve the predictive ability. A signal score threshold of 3.1 provided the following diagnostic accuracy for distinguishing a successful from unsuccessful signal: sensitivity 83%, specificity 77%, PPV 71%, NPV 87%.

Conclusions

An automated signal analysis software tool reliably distinguished successful versus unsuccessful ablation electrograms in children with WPW when validated in a large, diverse cohort. Refining the tools using an alternative threshold and statistical method did not improve the original signal score at a threshold of 3.1. This software was effective across two centers and multiple operators and may be an effective tool for ablation of WPW.

Electroanatomic mapping-guided pediatric catheter ablation with limited/zero fluoroscopy

Objective:

The use of fluoroscopy in pediatric catheter ablation has decreased because of mapping systems. In this study, we present the efficiency and reliability of the electroanatomic mapping system in nonfluoroscopic pediatric catheter ablation.

Methods:

The medical records of patients aged <18 years who underwent ablation between November 2016 and April 2018 were evaluated. Fluoroscopy was not used in cases involving ablation of right sided-arrhythmia foci. Fluoroscopy was used only for trans-septal puncture or retroaortic approach/coronary angiography.

Results:

A total of 76 patients underwent catheter ablation for 78 supraventricular and ventricular tachyarrhythmia substrates under the guidance of EnSite Velocity system. Fluoroscopy was used in only 14 (18.4%) of these substrates. The mean fluoroscopy duration in these 14 procedures was 5.4±3.15 min. No complications were noted, except a temporary right bundle branch block in one patient and pericardial effusion in another following cryoablation. The acute success rate in achieving complete elimination of arrhythmia substrates was 97.4% (76/78). The recurrence rate was 5.1% (4/78) at follow-up.

Conclusion:

Fluoroscopy can be completely eliminated in most pediatric catheter ablation procedures with the use of mapping systems by achieving high acute success rates and acceptable low complication rates.

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.

Limited fluoroscopy catheter ablation of accessory pathways in children

BACKGROUND

Limited fluoroscopy ablation using 3D electro-anatomical system (3DS) has been used for arrhythmias in children, however it is not a common practice. We aimed to facilitate a fluoroscopy limited approach for ablation of accessory pathways (AP) in children.

METHODS

Following electrophysiologic (EP) catheter placement a single dual-plane fluoroscopic image (right anterior oblique-30° and left anterior oblique-60° views) was acquired and the 3DS views were rotated to be a perfect match to the fluoroscopy. Ninety-four consecutive pediatric patients [mean age 11.8±4.1 (4.2-18) years, 61.7% males] with Wolf-Parkinson-White syndrome underwent ablation of an AP. Fifty-seven had manifest AP, 54 had left-sided AP (LSAP) and 40 had right-sided AP (RSAP).

RESULTS

The acute success rate was 95.7% (90/94), with a recurrence rate of 1.1% (1/90) at a mean follow-up of 13±5.5 (4.4-22.9) months. Mean procedure and fluoroscopy times were 144±45 (55-262)min and 1.8±1.4 (0.1-5.6)min, respectively. Comparison of the first 20 procedures to the next 74 procedures demonstrated an extended procedure time (171±53min vs 135±38min, p<0.005), however the fluoroscopy time, the number of long applications, the time to effect, and the acute success rate were similar. There were no permanent ablation-related complications.

CONCLUSIONS

A limited fluoroscopy approach for ablation of AP in children using 3DS is easily acquired, adapted, reduces the fluoroscopy time, and has an excellent efficacy and safety profile.

[Cryoablation: Clinical applications in cardiac electrophysiology from their biophysical bases]

Cryoablation is an energy alternative to radiofrequency for ablation of various arrhythmias, where its unique biophysical properties offer a greater safety profile. Since its first use for the surgical treatment of different arrhythmias until its conceptualization in the current technical transcatheter, cryoablation has proven not to be only a safe source of energy, but also an effective source in the long-term. While the radiofrequency has been the energy most used for isolation of pulmonary veins in atrial fibrillation ablation, technological advances in cryoballon have managed to simplify the procedure without sacrificing its effectiveness. Cryoablation has been widely used for arrhythmias located in high-risk locations, such as the ablation of the atrioventricular nodal reentrant tachycardia and septal accessory pathways, due to its theoretical null risk of complete AV block. This review intends to give the clinical applications of the cryothermy through a thorough understanding of their biophysical basis.

Optimizing outcomes of catheter ablation in infants and toddlers

Since the introduction of transcatheter ablation in the late 1980s, there has been significant technical development. With a very high success rate and low complication rate, ablation has now become the standard of care in children and adults. However, long-term data remain insufficient and the application of ablation therapy in small children is debatable. In this review, current treatment strategies and results in toddlers and infants will be discussed. There has been improvement in success rate and complication rate for ablation in small children. Technological advancements in non-fluoroscopic electroanatomical mapping systems (3D systems) have led to the reduction of radiation and have facilitated ablations in complex cases. However, long-term effects of ablation lesions in small children remain a potential concern.