Extra-ostial pulmonary venous isolation: use of epicardial ablation to eliminate a point of conduction breakthrough

Sustained Apnea for Epicardial Access With Right Ventriculography: The SAFER Epicardial Approach

BACKGROUND

Epicardial access (EA) has emerged as an increasingly important approach for the treatment of ventricular arrhythmias and to perform other interventional cardiology procedures. EA is frequently underutilized because the current approach is challenging and carries a high risk of life-threatening complications.

OBJECTIVE

The purpose of this study was to determine the efficacy and safety of the SAFER (Sustained Apnea for Epicardial Access With Right Ventriculography) epicardial approach.

METHODS

Consecutive patients who underwent EA with the SAFER technique were included in this multicenter study. The primary efficacy outcome was the successful achievement of EA. The primary safety outcomes included right ventricular (RV) perforation, major hemorrhagic pericardial effusion (HPE), and bleeding requiring surgical intervention. Secondary outcomes included procedural characteristics and any complications. Our results were compared with those from previous studies describing other EA techniques to assess differences in outcomes.

RESULTS

A total of 105 patients undergoing EA with the SAFER approach from June 2021 to February 2023 were included. EA was used for ventricular tachycardia ablation in 98 patients (93.4%), left atrial appendage closure in 6 patients (5.7%), and phrenic nerve displacement in 1 patient (0.9%). EA was successful in all subjects (100%). The median time to EA was 7 minutes (IQR: 5-14 minutes). No cases of RV perforation, HPE, or need of surgical intervention were observed in this cohort. Comparing our results with previous studies about EA, the SAFER epicardial approach resulted in a significant reduction in major pericardial bleeding.

CONCLUSIONS

The SAFER epicardial approach is a simple, efficient, effective, and low-cost technique easily reproducible across multiple centers. It is associated with lower complication rates than previously reported techniques for EA.

Percutaneous Epicardial Approach to Catheter Ablation of Cardiac Arrhythmias

Since their introduction >2 decades ago, percutaneous catheter-based epicardial mapping and ablation have become widely adopted by cardiac electrophysiologists around the world. Although epicardial mapping has been used for catheter ablation of a wide variety of cardiac arrhythmias, its most common use is for ablation of intramural and subepicardial substrates that give rise to ventricular tachycardia, particularly in patients with nonischemic cardiomyopathy. As such, the subxiphoid percutaneous epicardial approach has emerged as an important adjunct, and, in some cases, is the preferred strategy in this regard. This review discusses the rationale and indications for epicardial catheter mapping and/or ablation. This paper also reviews the prevalence of epicardial arrhythmias and their electrocardiographic criteria. In addition, it examines the anatomy of the pericardium and commonly used epicardial access techniques, as well as the optimal methodologies for epicardial mapping and ablation and the impact of epicardial fat. Finally, this review discusses the potential of the various complications associated with the percutaneous epicardial approach, in addition to patient-specific risk factors, and potential strategies to mitigate the risk of complications.

Epicardial Catheter Ablation of Atrial Fibrillation

Atrial fibrillation (AF) can cause significant symptoms despite control of ventricular rate, and for some patients a rhythm-control strategy is more appropriate. Because antiarrhythmic drugs have limited efficacy for treating AF and can cause significant side effects, nonpharmacologic therapy has found a growing role in the treatment of this arrhythmia. While endocardial catheter ablation has shown superior results over drug therapy, long-term clinical outcomes are still disappointing, especially for persistent AF. This article discusses percutaneous epicardial catheter ablation, the rationale for using this approach to treat AF, anatomy relevant to the approach, challenges in performing such procedures, and finally, the potential future directions in this promising new field.

Evaluation of catheter ablation of periatrial ganglionic plexi in patients with atrial fibrillation

Recent data suggests that the cardiac autonomic nervous system has an important role in the initiation and maintenance of atrial fibrillation (AF). This study investigated (1) the feasibility of identifying and targeting these autonomic ganglia using endocardial radiofrequency stimulation and ablation, respectively; (2) the efficacy of endocardial ablation to completely eliminate the vagal response elicited from epicardial stimulation; and (3) the effect of autonomic ablation on the acute inducibility of AF. The study included 18 patients referred for catheter ablation of suspected vagal-mediated AF. The endocardial left atrial surface was stimulated at high frequency (20 to 50 Hz) to elicit a vagal response. In selected patients (n = 5), pericardial access was obtained using a subxyphoid puncture to permit epicardial stimulation. Catheter ablation of the putative autonomic ganglionic sites was performed from the left atrial endocardium using irrigated radiofrequency energy. After ablation of all identifiable autonomic ganglia, high-frequency pacing was repeated to induce AF. In all patients, stimulation at certain endocardial sites elicited a vagal response. Endocardial ablation abrogated this vagal responsiveness. Furthermore, for sites accessible from the pericardium, the vagal response elicited using epicardial stimulation was also eliminated. Despite successful ablation of these ganglia, AF was still inducible in 17 of 18 patients. In conclusion, successful ablation of autonomic ganglia from an endocardial approach can be reliably achieved using an irrigated catheter. In addition, ablation of these structures in patients with vagal-mediated AF is insufficient to prevent its acute reinduction with high-frequency atrial stimulation.

Isolating the Posterior Left Atrium and Pulmonary Veins with a "Box" Lesion Set: Use of Epicardial Ablation to Complete Electrical Isolation

Similar to the surgical mini-maze procedure, the posterior "box" lesion set employs linear ablation lesions along the anterior aspects of both sets of PVs connected by a roof line and an inferior line to electrically isolate the PVs and complete posterior LA wall en masse. However, creating fully transmural linear atrial lesions can be difficult to achieve, even with an irrigated ablation catheter. This report details a case wherein a combined endocardial and epicardial approach was required to create an electrically continuous posterior box lesion in a patient with persistent AF.

Errors in pulmonary vein identification and ostia location in the absence of pulmonary vein imaging

BACKGROUND

A key point in atrial fibrillation (AF) ablation is the ability to identify the pulmonary vein (PVs) and locate their ostia.

OBJECTIVES

The purpose of this study was to assess the error margin of PV identification and ostia location in the absence of previous PV imaging.

METHODS

This study was performed in patients referred for catheter ablation of AF. PVs were reconstructed before ablation using the CARTO system. The operator tagged the superior and inferior edges of the PV ostia before and after examining the corresponding PV angiograms. The distances between the tagged PV ostia were measured using CARTO software.

RESULTS

A total of 105 location estimations of 54 PVs were analyzed. The location of PV ostia without angiography deviated from the angiographic PV ostia by a median of 13 mm (95% confidence interval = 11-14 mm; P < .0001). In 84 of the 105 estimations (80%), wrong tagging was performed inside the PV. A multiple logistic regression revealed that, at sites displaying PV potentials, the left atrial potential amplitude was an independent predictor of location at the angiographic PV ostium (odds ratio 24 [95% confidence interval = 3.7-227] per 1-mV increase). Receiver operator characteristic analysis set the optimal cutoff level at 0.7 mV. Use of this criterion improved the accuracy of PV ostium location by 4 mm (95% confidence interval = 1-6 mm; P = .005).

CONCLUSION

Attempts at PV identification and ostia location in the absence of previous PV imaging are subject to a broad error margin.