Distortion of Right Superior Pulmonary Vein Anatomy by Balloon Catheters as a Contributor to Phrenic Nerve Injury

2024 European Heart Rhythm Association/Heart Rhythm Society/Asia Pacific Heart Rhythm Society/Latin American Heart Rhythm Society expert consensus statement on catheter and surgical ablation of atrial fibrillation

In the last three decades, ablation of atrial fibrillation (AF) has become an evidence-based safe and efficacious treatment for managing the most common cardiac arrhythmia. In 2007, the first joint expert consensus document was issued, guiding healthcare professionals involved in catheter or surgical AF ablation. Mounting research evidence and technological advances have resulted in a rapidly changing landscape in the field of catheter and surgical AF ablation, thus stressing the need for regularly updated versions of this partnership which were issued in 2012 and 2017. Seven years after the last consensus, an updated document was considered necessary to define a contemporary framework for selection and management of patients considered for or undergoing catheter or surgical AF ablation. This consensus is a joint effort from collaborating cardiac electrophysiology societies, namely the European Heart Rhythm Association, the Heart Rhythm Society, the Asia Pacific Heart Rhythm Society, and the Latin American Heart Rhythm Society.

2024 European Heart Rhythm Association/Heart Rhythm Society/Asia Pacific Heart Rhythm Society/Latin American Heart Rhythm Society expert consensus statement on catheter and surgical ablation of atrial fibrillation

In the last three decades, ablation of atrial fibrillation (AF) has become an evidence-based safe and efficacious treatment for managing the most common cardiac arrhythmia. In 2007, the first joint expert consensus document was issued, guiding healthcare professionals involved in catheter or surgical AF ablation. Mounting research evidence and technological advances have resulted in a rapidly changing landscape in the field of catheter and surgical AF ablation, thus stressing the need for regularly updated versions of this partnership which were issued in 2012 and 2017. Seven years after the last consensus, an updated document was considered necessary to define a contemporary framework for selection and management of patients considered for or undergoing catheter or surgical AF ablation. This consensus is a joint effort from collaborating cardiac electrophysiology societies, namely the European Heart Rhythm Association, the Heart Rhythm Society (HRS), the Asia Pacific HRS, and the Latin American HRS.

2024 European Heart Rhythm Association/Heart Rhythm Society/Asia Pacific Heart Rhythm Society/Latin American Heart Rhythm Society expert consensus statement on catheter and surgical ablation of atrial fibrillation

In the last three decades, ablation of atrial fibrillation (AF) has become an evidence-based safe and efficacious treatment for managing the most common cardiac arrhythmia. In 2007, the first joint expert consensus document was issued, guiding healthcare professionals involved in catheter or surgical AF ablation. Mounting research evidence and technological advances have resulted in a rapidly changing landscape in the field of catheter and surgical AF ablation, thus stressing the need for regularly updated versions of this partnership which were issued in 2012 and 2017. Seven years after the last consensus, an updated document was considered necessary to define a contemporary framework for selection and management of patients considered for or undergoing catheter or surgical AF ablation. This consensus is a joint effort from collaborating cardiac electrophysiology societies, namely the European Heart Rhythm Association, the Heart Rhythm Society, the Asia Pacific Heart Rhythm Society, and the Latin American Heart Rhythm Society .

Efficacy and safety of visually guided laser balloon versus cryoballoon ablation for paroxysmal atrial fibrillation: a systematic review and meta-analysis

Background

Newly developed catheter ablation (CA) techniques, such as laser balloon ablation (LBA) and cryoballoon ablation (CBA), have been introduced in recent years and emerged as valuable alternatives to conventional radiofrequency CA strategies for paroxysmal atrial fibrillation (PAF) patients. However, evidence comparing LBA and CBA remain controversial. Thus, we conducted this meta-analysis to assess the efficacy and safety between these two techniques.

Methods

Scientific databases (PubMed, Embase) and relevant websites (the Cochrane Library, ClinicalTrials.gov) were systematically searched from inception to March 2023. The primary outcomes of interest were the AF recurrence and the procedure-related complications. Secondary outcomes included procedural time, fluoroscopy time, and left atrial (LA) dwell time.

Results

Seven clinical trials with a total of 637 patients were finally enrolled. No significant differences were found between LBA and CBA in terms of AF recurrence [16.3% vs. 22.7%, odds ratio (OR) = 0.66, 95% confidence interval (CI): 0.42-1.05, p = 0.078] or total procedural-related complications (8.4% vs. 6.4%, OR = 1.33, 95% CI: 0.71-2.51, p = 0.371). LBA had a significantly longer procedural time [weighted mean difference (WMD) = 38.03 min, 95% CI: 13.48-62.58 min, p = 0.002] and LA dwell time (WMD = 46.67 min, 95% CI: 14.63-78.72 min, p = 0.004) than CBA, but tended to have shorter fluoroscopy time.

Conclusions

LBA and CBA treatment have comparable efficacy and safety for PAF patients. LBA was associated with longer procedural and LA dwell times compared with CBA. Further large-scale studies are warranted to compare these two techniques with the newest generations.Systematic Review Registration: https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=426513, identifier (CRD42023426513).

Comparison of phrenic nerve injury and its effect on the extrapulmonary vein structures with cryoballoon and hot-balloon ablation systems: considering the lesion created on the superior vena cava as a surrogate marker

Preventing phrenic nerve injury (PNI) during balloon-based ablation is essential. The superior vena cava-right atrial (SVC-RA) junction is located just opposite the balloon position during right superior pulmonary vein (RSPV) ablation, and the phrenic nerve runs nearby on the lateral side. We compared the occurrence of PNI between the two balloon-based ablation systems and also the lesions created at the SVC-RA junction, which were expected to represent the effect on extra-PV structures. Cryoballoon ablation (CBA, n = 110) and hot-balloon ablation (HBA, n = 90) were performed in atrial fibrillation patients. High-density maps of the SVC-RA junction were created in 93 patients (CBA = 53, HBA = 40), and the damaged area (< 1.0 mV) was determined as an "SVC lesion". CBA had a higher occurrence of transient PNI (7.3% vs 1.1%, p = 0.035), but all recovered during the 6-month follow-up. An apparent SVC lesion was documented in 43% of the patients (40/93), and all patients with PNI had this lesion. CBA created a frequent (CBA vs HBA = 55% vs 28%, p = 0.008) and wider (0.8[0.4-1.7] cm² vs 0.5[0.3-0.7] cm², p = 0.005) SVC lesion than HBA. A multivariate analysis revealed that the use of a CBA system was a predictive factor of the occurrence of SVC lesions. CBA had a higher occurrence of transient PNI but not a permanent form. Every patient with PNI had lesions on the SVC-RA junction, and CBA revealed more substantial ablation effects at the SVC-RA junction than HBA. This may be caused by the different characteristics of the two balloon-based ablation systems and their balloon positions.

Laser balloon in pulmonary vein isolation for atrial fibrillation: current status and future prospects

INTRODUCTION

Visually guided laser balloon (LB) catheter has been an established modality dedicated for pulmonary vein (PV) isolation in patients with atrial fibrillation. The newly updated version of this novel device has technically evolved recent years.

AREAS COVERED

This review will summarize the contemporary technical evolution of LB catheter. Available efficacy outcomes and the historical change of ablation style will be evaluated. Furthermore, the future perspectives for clinical practice are discussed.

EXPERT COMMENTARY

The initial LB ablation system provided comparable clinical results in PV isolation with other technologies, but with a unique strategical concept enabling the direct visualization of the tissue to cauterize. With multigenerational development, the LB catheter has been equipped with more compliant balloon for favorable PV occlusion and a robotically motor driven continuous ablation mode (RAPID mode). These technical innovations changed the concept of the ablation strategy using LB catheter as 'point-by-point' into 'single-shot' fashion. The remaining tasks are further improvements such as equipping with real-time recording system of intracardiac electrogram, durable structured balloon and the instrument for visualizing the cauterization area in a 360-degree panoramic view, which includes potential possibilities to develop this novel device to the more optimal device for PV isolation.

Acute Procedural Complications of Cryoballoon Ablation: A Comprehensive Review

Catheter ablation is increasingly performed for treatment of atrial fibrillation (AF). Balloon based procedures have been developed aiming at safer, easier and more effective treatment as compared to point to point ablation. In the present review article, we aimed to discuss acute procedural complications of cryoballoon ablation.

How to Prevent, Detect and Manage Complications Caused by Cryoballoon Ablation of Atrial Fibrillation

Atrial fibrillation is the most common cardiac arrhythmia and the prevalence is increasing every year. Patients who fail to maintain sinus rhythm with use of anti-arrhythmic drug therapy are referred for catheter ablation. Cryoballoon (CB) ablation has emerged as an effective and alternative treatment option to traditional point-by-point radiofrequency ablation, but there can be complications. This article reviews the incidence, presentation, risk factors, management and preventative strategies of three major complications associated with CB ablation: phrenic nerve injury, atrial oesophageal fistula and bronchial injury. Although these complications are rare, electrophysiologists should institute measures to identify high-risk patients, implement best-practice techniques to minimise risks and maintain a high index of suspicion to recognise the complications quickly and implement correct treatment strategies.

Left phrenic nerve injury during electrical isolation of left-sided pulmonary veins with the second-generation cryoballoon

BACKGROUND

Phrenic nerve (PN) palsy (PNP) is the most frequent complication of cryoballoon ablation (CBA) of atrial fibrillation (AF). The major complication of this technique seems to be right-sided PN injury (PNI) following ablation of the right pulmonary veins (PVs). We sought to assess the incidence and prognosis of left-sided PNI during CBA.

METHODS

CBA was performed in 448 patients with AF. During the ablation of the left-sided PVs, the PN was paced from the left subclavian vein with a pacing output just exceeding the threshold by 10 ∼ 20%. The right and left arm 12-lead electrocardiogram electrodes were positioned 5 cm above the xiphoid process and 16 cm along the left costal margin. The amplitude of the compound motor action potentials was recorded during the CBA.

RESULTS

Two thousand one hundred seventy-eight CBA applications were delivered in 1,094 left-sided PVs. PNI occurred in 29 patients (6.5%); the PN could be captured by an increasing pacing output in 21 patients (4.7%), and premature termination of the freezing was required to avoid PNP in eight patients (1.8%). The PN function recovered before discharge; however, it took 7 months for one patient to completely recovery from the PNP.

CONCLUSIONS

Left-sided PNP could be provoked during a left-sided CBA procedure. Assessment of the left PN during the CBA was necessary to prevent left-sided PNP.

Comparison of Phrenic Nerve Injury during Atrial Fibrillation Ablation between Different Modalities, Pathophysiology and Management

Atrial fibrillation ablation has emerged as an effective tool in the management of symptomatic atrial fibrillation. Currently, the electrophysiologists are striving to maximize the success while minimizing complications. Phrenic nerve injury (PNI) is one of the concerning complications, especially in cases of cryoballoon ablation. Due to anatomical proximity to atrial tissue, phrenic nerve is particularly susceptible to injury. With evolving monitoring techniques it is now possible to minimize the likelihood of a permanent PNI. However, the challenge remains to detect PNI at the earliest and to avoid further damage to the nerve. In this review, we discuss pertinent anatomical principles, techniques to avoid PNI and management in cases where PNI is encountered.

Prevalence and Pre-Procedural Predictors Associated With Right Phrenic Nerve Injury in Electromyography-Guided, Second-Generation Cryoballoon Ablation: Single Large Balloon and Single 3-Minute Freeze Techniques

OBJECTIVES

This study aimed to evaluate the incidence and pre-procedural predictors of right phrenic nerve injury (PNI) in electromyography-guided, second-generation cryoballoon (CB) ablation.

BACKGROUND

Second-generation CBs perform better pulmonary vein isolation (PVI) than first-generation CBs; however, right PNI remains a concern.

METHODS

One hundred consecutive patients with paroxysmal atrial fibrillation who underwent cryoablation were prospectively enrolled. Contrast-enhanced cardiac multidetector computed tomography (MDCT) was obtained pre-procedurally. PVI was performed with one 28-mm second-generation balloon using a 3-min freeze technique under electromyography guidance.

RESULTS

In all, 377 of 392 (96.2%) PVs were isolated using a CB. In 9 (9.0%) patients, right PNI was observed during the ablation of the right superior PV (RSPV). All events occurred during freezing, except for 1 that occurred during thawing. Right peri-cardiophrenic bundles (RPCBs) were identified at the level of the RSPV on MDCT in 97 patients. In the logistic regression analysis, the distance from the RSPV ostium to the RPCBs (hazard ratio: 0.263; 95% confidence interval [CI]: 0.110 to 0.630; p = 0.003) was the sole predictor of PNI. The optimal cutoff point for the distance for predicting right PNI was 12.4 mm (sensitivity 96.6%, specificity 88.9%) with an area under the curve of 0.968 (95% CI: 0.922 to 1.000). The PNI resolved spontaneously within 1 day and 2 months in 6 and 2 patients, respectively, and at 8 months in the remaining patient, with delayed recognition of an electromyography decrease.

CONCLUSIONS

Persistent right PNI is a rare complication during electromyography-guided, second-generation CB ablation. Electromyography should be monitored even during the thawing time. Pre-procedural MDCT might be useful for risk stratification of right PNI.

Effect of cryoballoon inflation at the right superior pulmonary vein orifice on phrenic nerve location

BACKGROUND

Cryoballoon catheter ablation was developed to simplify ablation for atrial fibrillation (AF). Initial enthusiasm for its widespread use has been dampened by phrenic nerve (PN) injury (PNI).

OBJECTIVE

The purpose of this study was to assess the effect of cryoballoon inflation at the right superior pulmonary vein (RSPV) orifice on PN location and to elucidate the potential mechanism of PNI.

METHODS

Twenty patients with paroxysmal atrial fibrillation underwent ablation performed with a second-generation 28-mm cryoballoon catheter. Before ablation, the pacing-determined PN course was delineated along the right atrium. PN location and its relation to the RSPV as well as RSPV surface distortions after balloon inflation were established with a NavX mapping system.

RESULTS

During RSPV ablation, the inflated balloon surface extended anteriorly 6.3 ± 1.8 mm outside the RSPV. This narrowed the distance between the PN capture points in the RSPV vs PN location from 11.4 ± 5.0 mm to 7.5 ± 5.0 mm (P = .0002) and increased the PN capture area from 1.9 ± 1.3 cm(2) to 3.2 ± 1.8 cm(2) (P = .0004). Furthermore, the PN capture points shifted toward the orifice within the RSPV and after balloon inflation were located significantly closer to the orifice in the 3 patients with transient PNI than in those without PNI.

CONCLUSION

Cryoballoon inflation at the RSPV orifice alters PV/left atrial surface geometry, reducing the distance between the energy delivery source and the PN and increasing PN area, possibly explaining the mechanism of PNI. PN pacing within the RSPV after balloon inflation may be useful for preventing PNI.

MRI Reconstructions of Human Phrenic Nerve Anatomy and Computational Modeling of Cryoballoon Ablative Therapy

The primary goal of this computational modeling study was to better quantify the relative distance of the phrenic nerves to areas where cryoballoon ablations may be applied within the left atria. Phrenic nerve injury can be a significant complication of applied ablative therapies for treatment of drug refractory atrial fibrillation. To date, published reports suggest that such injuries may occur more frequently in cryoballoon ablations than in radiofrequency therapies. Ten human heart-lung blocs were prepared in an end-diastolic state, scanned with MRI, and analyzed using Mimics software as a means to make anatomical measurements. Next, generated computer models of ArticFront cryoballoons (23, 28 mm) were mated with reconstructed pulmonary vein ostias to determine relative distances between the phrenic nerves and projected balloon placements, simulating pulmonary vein isolation. The effects of deep seating balloons were also investigated. Interestingly, the relative anatomical differences in placement of 23 and 28 mm cryoballoons were quite small, e.g., the determined difference between mid spline distance to the phrenic nerves between the two cryoballoon sizes was only 1.7 ± 1.2 mm. Furthermore, the right phrenic nerves were commonly closer to the pulmonary veins than the left, and surprisingly tips of balloons were further from the nerves, yet balloon size choice did not significantly alter calculated distance to the nerves. Such computational modeling is considered as a useful tool for both clinicians and device designers to better understand these associated anatomies that, in turn, may lead to optimization of therapeutic treatments.

Spatial and Time-Course Thermodynamics During Pulmonary Vein Isolation Using the Second-Generation Cryoballoon in a Canine In Vivo Model

Background—

Thermodynamics in the left atrium–pulmonary vein (PV) junction, phrenic nerve, and esophagus during PV isolation (PVI) using the second-generation cryoballoon are not known.

Methods and Results—

Twenty dogs underwent PVI using second-generation cryoballoon. Ablations were performed for ≤2 deliveries based on PVI without a bonus freeze. Inner balloon, balloon surface, and tissue temperatures were monitored during cryoablation. The tissue thermocouples were placed on the epicardial surface of the left atrium–PV junction, as well as on the phrenic nerve and within the esophagus. A total of 259 cryoballoon and 229 tissue tissue thermocouples profiles during 53 cryoablations of 40 PVs were analyzed. Acutely, PVI was achieved in 36 of 40 PVs (90%). Conductive tissue cooling spread radially from the balloon–left atrium–PV contact point. The lowest tissue temperatures were dependent on the distance of the tissue thermocouples to the balloon surface ( r =0.85; P <0.001). In addition, blood flow leaks around the balloon had a warming effect on the balloon and tissue temperature profiles. Chronic isolation (mean, 48±16 days) was achieved in 27 of 36 PVs (75%). In 8 of 9 acutely isolated but with chronic reconnection PVs, the blood flow leak location was concordant with chronic reconnection gap. Although only 1 esophageal ulcerated lesion was observed, neither phrenic nerve palsy nor severe PV stenosis was seen in any dogs.

Conclusions—

Variance in tissue thermodynamics during cryothermal ablation depends on the distance from balloon and peri-balloon blood flow leaks. This information may be useful for successful PVI without severe complications.

Cryoballoon ablation of pulmonary veins for paroxysmal atrial fibrillation: first results of the North American Arctic Front (STOP AF) pivotal trial

OBJECTIVES

This study sought to assess the safety and effectiveness of a novel cryoballoon ablation technology designed to achieve single-delivery pulmonary vein (PV) isolation.

BACKGROUND

Standard radiofrequency ablation is effective in eliminating atrial fibrillation (AF) but requires multiple lesion delivery at the risk of significant complications.

METHODS

Patients with documented symptomatic paroxysmal AF and previously failed therapy with ≥ 1 membrane active antiarrhythmic drug underwent 2:1 randomization to either cryoballoon ablation (n = 163) or drug therapy (n = 82). A 90-day blanking period allowed for optimization of antiarrhythmic drug therapy and reablation if necessary. Effectiveness of the cryoablation procedure versus drug therapy was determined at 12 months.

RESULTS

Patients had highly symptomatic AF (78% paroxysmal, 22% early persistent) and experienced failure of at least one antiarrhythmic drug. Cryoablation produced acute isolation of three or more PVs in 98.2% and all four PVs in 97.6% of patients. PVs isolation was achieved with the balloon catheter alone in 83%. At 12 months, treatment success was 69.9% (114 of 163) of cryoblation patients compared with 7.3% of antiarrhythmic drug patients (absolute difference, 62.6% [p < 0.001]). Sixty-five (79%) drug-treated patients crossed over to cryoablation during 12 months of study follow-up due to recurrent, symptomatic AF, constituting drug treatment failure. There were 7 of the resulting 228 cryoablated patients (3.1%) with a >75% reduction in PV area during 12 months of follow-up. Twenty-nine of 259 procedures (11.2%) were associated with phrenic nerve palsy as determined by radiographic screening; 25 of these had resolved by 12 months. Cryoablation patients had significantly improved symptoms at 12 months.

CONCLUSIONS

The STOP AF trial demonstrated that cryoballoon ablation is a safe and effective alternative to antiarrhythmic medication for the treatment of patients with symptomatic paroxysmal AF, for whom at least one antiarrhythmic drug has failed, with risks within accepted standards for ablation therapy. (A Clinical Study of the Arctic Front Cryoablation Balloon for the Treatment of Paroxysmal Atrial Fibrillation [Stop AF]; NCT00523978).

Diaphragmatic electromyography during cryoballoon ablation: a novel concept in the prevention of phrenic nerve palsy

BACKGROUND

Hemidiaphragmatic paralysis is the most frequent complication associated with cryoballoon ablation for atrial fibrillation. To date, no preventive strategy has proved effective.

OBJECTIVE

We sought to assess the feasibility of diaphragmatic electromyography during cryoballoon ablation, explore the relationship between altered signals and phrenic nerve palsy, and define characteristic changes that herald hemidiaphragmatic paralysis.

METHODS

Cryoballoon ablation was performed in the right superior pulmonary vein or superior vena cava in 16 mongrel dogs weighing 37.7 ± 2.4 kg, at sites determined by phrenic nerve capture. During ablation, the phrenic nerve was paced at 60 bpm from the superior vena cava while recording diaphragmatic compound motor action potentials (CMAPs) by esophageal decapolar catheters. Diaphragmatic excursion was monitored by fluoroscopy and abdominal palpation.

RESULTS

Before ablation, the CMAP amplitude was 592 (interquartile range 504, 566) μV, initial latency 21.5 ± 4.2 ms, peak latency 64.7 ± 21.1 ms, and duration 101.7 ± 13.3 ms. Hemidiaphragmatic paralysis was obtained in all dogs 62 ± 34 seconds into the cryoapplication. The CMAP amplitude decreased exponentially, with no patterned changes in latencies and duration. Discriminatory analyses by receiver-operating curve characteristics identified a 30% reduction in CMAP amplitude as the most predictive cutoff value for hemidiaphragmatic paralysis (c-statistic 0.965; P<.0001). This criterion presaged diaphragmatic paralysis, as detected by abdominal palpation, by 31 ± 23 seconds.

CONCLUSION

Diaphragmatic electromyographic signals could be reliably recorded during cryoballoon ablation. An exponential decrease in CMAP amplitude precedes diaphragmatic paralysis, with a 30% reduction yielding the best discriminatory potential. A promising safety margin was detected, which merits prospective validation.

Esophageal endoscopy results after pulmonary vein isolation using the single big cryoballoon technique

INTRODUCTION

Reversible esophageal thermal lesions after cryoballoon pulmonary vein isolation (CB-PVI) have been reported when using variable balloon sizes. The aim of this study was to investigate (1) the incidence of esophageal thermal lesions, and (2) esophageal temperature changes associated with CB-PVI using the single big cryoballoon technique.

METHODS AND RESULTS

Thirty-eight patients with atrial fibrillation underwent successful CB-PVI using only the 28 mm cryoballoon. Luminal esophageal temperature (LET) was continuously monitored by 3 thermocouples. Fluoroscopic distance from cryoballoon to esophagus probe was retrospectively evaluated in RAO 30 degrees and LAO 40 degrees projections. All patients underwent postprocedural esophageal endoscopy. Average minimal LET was lower during freezing at inferior PVs, when compared to superior PVs: 35.4 +/- 0.9 (range: 32.6 to 37.4; RSPV); 31.5 +/- 7.5 (2.5 to 37.6; RIPV); 32.9 +/- 5.2 (8.5 to 36.5; LSPV); and 30.3 +/- 8.4 degrees C (-6 to 36.7 degrees C; LIPV); P = 0.001. We found steep temperature gradients over distance (1) from the cryoballoon center (LETs < 10 degrees C confined to a distance of < 15 mm in both RAO 30 degrees and LAO 40 degrees projections), and (2) along the esophagus long axis, underscoring the need for multiple measurement sites. None of the patients showed esophageal thermal lesions at endoscopy after 3 +/- 1 (range 1-7) days. No AEF occurred during a follow-up of 125 +/- 78 days.

CONCLUSION

In a cohort of AF patients treated by the single big cryoballoon technique, CB-PVI was not associated with thermal esophageal lesions.