Oesophageal Injury During AF Ablation: Techniques for Prevention

Reduced Continuity Index with Proactive Esophageal Cooling Compared to Luminal Temperature Monitoring During Radiofrequency Ablation: Improved Lesion Continuity with Esophageal Cooling

Background

Proactive esophageal cooling is FDA cleared to reduce the likelihood of esophageal injury during radiofrequency ablation for treatment of atrial fibrillation (AF). Long-term follow-up data have also shown improved freedom from arrhythmia with proactive esophageal cooling compared to luminal esophageal temperature (LET) monitoring during pulmonary vein isolation (PVI). One hypothesized mechanism is improved lesion contiguity (as measured by the Continuity Index) with the use of cooling. We aimed to compare the Continuity Index of PVI cases using proactive esophageal cooling to those using LET monitoring.

Methods

Continuity Index was calculated for PVI cases at two different hospitals within the same health system using a slightly modified Continuity Index to facilitate both real-time calculation during observation of PVI cases and retrospective determination from recorded cases. The results were then compared between proactively cooled cases and those using LET monitoring.

Results

Continuity Indices for a total of 101 cases were obtained; 77 cases using proactive esophageal cooling and 24 cases using traditional LET monitoring. With proactive esophageal cooling, the average Continuity Index was 2.7 (1.3 on the left pulmonary vein, and 1.5 on the right pulmonary vein). With LET monitoring, the average Continuity Index was 27.3 (14.3 on the left, and 12.9 on the right), for a difference of 24.6 (p < 0.001).

Conclusion

Proactive esophageal cooling during PVI is associated with significantly improved lesion contiguity when compared to LET monitoring. This finding may offer a mechanism for the greater freedom from arrhythmia seen with proactive cooling in long-term follow-up.

Fluoroless catheter ablation of atrial fibrillation: a step-by-step workflow

Catheter ablation is an important therapeutic strategy for patients with atrial fibrillation (AF). While some critical steps of the procedure have traditionally relied on fluoroscopy, advances in electroanatomic mapping and the growing use of intracardiac echocardiography have made non-fluoroscopic AF ablation a reality. This hands-on review provides an overview on how to perform radiofrequency ablation of AF without the use of fluoroscopy, focusing on technical aspects, new technologies, and troubleshooting.

Evaluating temperature gradients across the posterior left atrium with radiofrequency ablation

INTRODUCTION

Esophageal injury is a well-known complication associated with catheter ablation. Though novel methods to mitigate esophageal injury have been developed, few studies have evaluated temperature gradients with catheter ablation across the posterior wall of the left atrium, interstitium, and esophagus.

METHODS

To investigate temperature gradients across the tissue, we developed a porcine heart-esophageal model to perform ex vivo catheter ablation on the posterior wall of the left atrium (LA), with juxtaposed interstitial tissue and esophagus. Circulating saline (5 L/min) was used to mimic blood flow along the LA and alteration of ionic content to modulate impedance. Thermistors along the region of interest were used to analyze temperature gradients. Varying time and power, radiofrequency (RF) ablation lesions were applied with an externally irrigated ablation catheter. Ablation strategies were divided into standard approaches (SAs, 10-15 g, 25-35 W, 30 s) or high-power short duration (HPSD, 10-15 g, 40-50 W, 10 s). Temperature gradients, time to the maximum measured temperature, and the relationship between measured temperature as a function of distance from the site of ablation was analyzed.

RESULTS

In total, five experiments were conducted each utilizing new porcine posterior LA wall-esophageal specimens for RF ablation (n = 60 lesions each for SA and HPSD). For both SA and HPSD, maximum temperature rise from baseline was markedly higher at the anterior wall (AW) of the esophagus compared to the esophageal lumen (SA: 4.29°C vs. 0.41°C, p < .0001 and HPSD: 3.13°C vs. 0.28°C, p < .0001). Across ablation strategies, the average temperature rise at the AW of the esophagus was significantly higher with SA relative to HPSD ablation (4.29°C vs. 3.13°C, p = .01). From the start of ablation, the average time to reach a maximum temperature as measured at the AW of the esophagus with SA was 36.49 ±  12.12 s, compared to 16.57 ±  4.54 s with HPSD ablation, p < .0001. Fit to a linear scale, a 0.37°C drop in temperature was seen for every 1 cm increase in distance from the site of ablation and thermistor location at the AW of the esophagus.

CONCLUSION

Both SA and HPSD ablation strategies resulted in markedly higher temperatures measured at the AW of the esophagus compared to the esophageal lumen, raising concern about the value of clinical intraluminal temperature monitoring. The temperature rise at the AW was lower with HPSD. A significant time delay was seen to reach the maximum measured temperature and a modest increase in distance between the site of ablation and thermistor location impacted the accuracy of monitored temperatures.

Anesthetic Considerations in the Electrophysiology Laboratory: A Comprehensive Review

Catheter ablation procedures for arrhythmias or implantation and/or extraction of cardiac pacemakers can present many clinical challenges. It is imperative that there is clear communication and understanding between the anesthesiologist and electrophysiologist during the perioperative period regarding the mode of ventilation, hemodynamic considerations, and various procedural complications. This article provides a comprehensive narrative review of the anesthetic techniques and considerations for catheter ablation procedures, ventilatory modes using techniques such as high-frequency jet ventilation, and strategies such as esophageal deviation and luminal temperature monitoring to decrease the risk of esophageal injury during catheter ablation. Various hemodynamic considerations, such as the intraprocedural triaging of cardiac tamponade and fluid administration during catheter ablation, also are discussed. Finally, this review briefly highlights the early research findings on pulse-field ablation, a new and evolving ablation modality.

Acquired atrioesophageal fistula: Need it be lethal? Sizing up the problem, diagnostic modalities, and best management

BACKGROUND AND AIM OF THE STUDY

An atrioesophageal fistula is a devastating complication of ablation for atrial fibrillation. For the surgeon facing this dreaded complication, it may be a 'once in a lifetime' case. This review aims to describe the clinical problem and evaluate the outcome of different surgical techniques to start guiding cardiothoracic surgeons toward those which offer the best chance of survival.

METHODS

An electronic search retrieved 125 articles containing 195 cases of atrioesophageal fistula secondary to atrial fibrillation ablation. Reports of pericardio-esophageal or mediastino-esophageal fistula were excluded.

RESULTS

The median age was 61 and 143 (73%) cases occurred in males. Fever (n = 147; 75%) and neurological dysfunction (n = 151; 77%) were the most common symptoms. The median time from ablation to symptom onset was 21 days (interquartile range: 12-28). The most sensitive thoracic imaging modality was computed tomography (n = 135/153; 90%). Immediate deterioration occurred during 11/58 (19%) oesophago-gastro-duodenoscopies. Mortality was lower in patients who had surgery (39%) compared with endoscopic intervention (94%) or conservative management (97%). Patients who had atrial repair combined with esophageal repair or oesophagectomy were more likely to survive than those who had atrial repair alone (OR 6.97; p < .001). Isolation of the esophageal aspect of the fistula conferred an additional survival benefit (OR 5.85; p = .02).

CONCLUSIONS

Fever, neurological symptoms, and chest pain in the context of recent ablation should prompt immediate evaluation. Urgent CT thorax should be arranged and repeated if initially unremarkable. Esophageal instrumentation should be avoided due to the risk of catastrophic air embolism or massive hemorrhage. The best way forward is emergency surgical repair; the combination which offers the best survival benefit is atrial repair combined with esophageal surgery and isolation of the esophageal aspect of the fistula.

Recovery of Conduction Following High-Power Short-Duration Ablation in Patients With Atrial Fibrillation: A Single-Center Experience

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Esophageal Squamous Cell Carcinoma After Radiofrequency Catheter Ablation Thermal Injury

Radiofrequency ablation is a common treatment for atrial fibrillation, and esophageal complications are exceedingly rare. This report describes the case of a patient with no other known cancer risk factors who had esophageal squamous cell carcinoma that developed at the site of esophageal thermal injury, which occurred during a radiofrequency catheter ablation procedure.

The Convergent Atrial Fibrillation Ablation Procedure: Evolution of a Multidisciplinary Approach to Atrial Fibrillation Management

The treatment of AF has evolved over the past decade with increasing use of catheter ablation in patients refractory to medical therapy. While pulmonary vein isolation using endocardial catheter ablation has been successful in paroxysmal AF, the results have been more controversial in patients with long-standing persistent AF where extrapulmonary venous foci are increasingly recognised in the initiation and maintenance of AF. Hybrid ablation is the integration of minimally invasive epicardial ablation with endocardial catheter ablation, and has been increasingly used in this population with better results. The aim of this article was to analyse and discuss the evidence for the integration of catheter and minimally invasive surgical approaches to treat AF with specific focus on convergent ablation and exclusion of the left atrial appendage using a surgically applied clip.

The Role of the Electrophysiologist in Convergent Ablation

Catheter ablation is a well-established treatment for patients with AF in whom sinus rhythm is desired. Both radiofrequency catheter ablation and cryoablation are widely performed, rapidly developing techniques. Convergent ablation is a novel hybrid technique combining an endocardial radiofrequency ablation with a minimally invasive epicardial surgical ablation. Some suggest that hybrid ablation may be more effective than lone endocardial ablation in achieving the elusive goal of maintaining sinus rhythm in patients with non-paroxysmal AF. In this article, the authors examine the safety and efficacy of catheter ablation and convergent ablation for long-standing, persistent AF. We also outline the crucial role that electrophysiologists play, not only as a procedure operator, but also as the coordinator and developer of this multidisciplinary service.

Esophageal cooling for protection during left atrial ablation: a systematic review and meta-analysis

Purpose

Thermal damage to the esophagus is a risk from radiofrequency (RF) ablation of the left atrium for the treatment of atrial fibrillation (AF). The most extreme type of thermal injury results in atrio-esophageal fistula (AEF) and a correspondingly high mortality rate. Various strategies for reducing esophageal injury have been developed, including power reduction, esophageal deviation, and esophageal cooling. One method of esophageal cooling involves the direct instillation of cold water or saline into the esophagus during RF ablation. Although this method provides limited heat-extraction capacity, studies of it have suggested potential benefit. We sought to perform a meta-analysis of published studies evaluating the use of esophageal cooling via direct liquid instillation for the reduction of thermal injury during RF ablation.

Methods

We searched PubMed for studies that used esophageal cooling to protect the esophagus from thermal injury during RF ablation. We then performed a meta-analysis using a random effects model to calculate estimated effect size with 95% confidence intervals, with an outcome of esophageal lesions stratified by severity, as determined by post-procedure endoscopy.

Results

A total of 9 studies were identified and reviewed. After excluding preclinical and mathematical model studies, 3 were included in the meta-analysis, totaling 494 patients. Esophageal cooling showed a tendency to shift lesion severity downward, such that total lesions did not show a statistically significant change (OR 0.6, 95% CI 0.15 to 2.38). For high-grade lesions, a significant OR of 0.39 (95% CI 0.17 to 0.89) in favor of esophageal cooling was found, suggesting that esophageal cooling, even with a low-capacity thermal extraction technique, reduces the severity of lesions resulting from RF ablation.

Conclusions

Esophageal cooling reduces the severity of the lesions that may result from RF ablation, even when relatively low heat extraction methods are used, such as the direct instillation of small volumes of cold liquid. Further investigation of this approach is warranted, particularly with higher heat extraction capacity techniques.

Complications of Cryoballoon Pulmonary Vein Isolation

Since the cryoballoon (CB) was introduced into clinical practice, more than 400,000 patients have undergone a pulmonary vein (PV) isolation with a CB throughout the world. Although the efficacy of the first-generation CB was limited, the recently introduced second-generation CB has achieved a greater uniformity in cooling, which has facilitated a shorter time to PV isolation, shorter procedural times, higher rates of freedom from atrial fibrillation and low rates of PV reconnections. Currently, a single short freeze strategy with a single 28 mm balloon has become the standard technique based on the balance of procedural efficacy and safety. However, enhanced cooling characteristics may also result in a greater potential for collateral damage to non-cardiac structures. Knowledge about the potential complications is essential when performing the procedure. In this article, we describe the important complications that should be noted during a CB procedure, and how to minimise the risk of complications based on our experience.

The Year in Electrophysiology: Selected Highlights From 2018

This article is the first in an annual series for the Journal of Cardiothoracic and Vascular Anesthesia. The authors thank the editor-in-chief, Dr. Kaplan, the associate editor-in-chief, Dr. Augoustides, and the editorial board for the opportunity to start this series, namely the research highlights of the year that pertain to electrophysiology in relation to cardiothoracic and vascular anesthesia. This first article focuses on esophageal thermal injury during radiofrequency ablation, perioperative management of patients presenting for ablation procedures, left atrial appendage occlusion devices, and, finally, heart failure diagnostic devices.