Use of Left Atrial Intracardiac Echocardiography and Electroanatomic Mapping for a Zero-Fluoroscopy Pulsed Field Ablation Workflow in Pulmonary Vein and Posterior Wall Isolation

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EP LAB DIGEST. 2024;24(10):20-23.

Ronuk M Modi, MD¹, and Eduardo B Saad, MD^1,2
1Beth Israel Deaconess Medical Center, Boston, Massachusetts; ²Hospital Samaritano Botafogo, Rio de Janeiro, RJ, Brazil

Pulsed field ablation (PFA) for pulmonary vein isolation (PVI) has emerged as a novel technique in catheter ablation of atrial fibrillation (AF). Initial

experience of clinical use in Europe and recent trials in the United States have shown noninferior outcomes compared to thermal ablation with regard to freedom from AF as well as comparable safety outcomes.^1,2 The initial protocols suggest routine fluoroscopy to visualize catheter shape and positioning of the now commercially available multielectrode pentaspline (Farapulse, Boston Scientific) PFA catheter. Intracardiac echocardiography (ICE) has been a well-established adjunctive tool in thermal ablation to limit radiation exposure in accordance with the As Low As Reasonably Achievable (ALARA) principle, inform procedural anatomy, and facilitate transseptal puncture and real-time catheter and lesion visualization.³ As PFA uptake increases with commercial availability in the United States, the intraprocedural use of ICE will also need to be adapted to best match the new procedural techniques. 

This case description highlights our workflow for a safe and efficient zero-fluoroscopy PFA PVI and posterior wall isolation (PWI) using near-field ICE (in the left atrium [LA]) and electroanatomic mapping (EAM). 

Case Presentation

A 60-year-old man with a history of moderate multivessel coronary artery disease, heart failure with mid-range ejection fraction, hypertension, and paroxysmal AF was referred for ablation. He had previously been managed with rate control medications since initial diagnosis of AF in 2022, but given suspected contribution of AF to his cardiomyopathy, he was referred for catheter ablation aimed at rhythm control. Given his history of persistent AF, wide area PVI and PWI were planned.

After presenting to the electrophysiology (EP) lab in fasting state and on uninterrupted anticoagulation with apixaban, the patient was intubated and placed under general anesthesia with standard mechanical ventilation, then prepped and draped in sterile fashion. The right femoral vein was accessed twice with 8 French (F) and 7F sheaths under ultrasound guidance. The left femoral vein (LFV) was accessed with an 11F sheath under ultrasound guidance. A ViewFlex ICE catheter (Abbott) was inserted via the LFV sheath and advanced to the right atrium (RA). Prior to subsequent catheter insertion, the ICE catheter was advanced to the right ventricle (RV) and rotated in clockwise fashion to visualize the left ventricle and rule out baseline pericardial effusion. Further clockwise rotation allowed visualization of the leftward aspect of the LA, including the coumadin ridge, LA appendage, and left superior PV. A decapolar catheter was advanced to the RV for backup pacing through the 7F sheath using EAM guidance. 

A VersaCross wire system (Boston Scientific) was used to perform transseptal puncture, with the dilator subsequently exchanged for the 17F Faradrive sheath (Boston Scientific). At this point, after dilation of the transseptal site, the sheath was retracted to the RA with the wire in a fixed position in the left superior PV (using ICE to confirm position). The ICE catheter was then anteriorly flexed with the wire crossing the interatrial septum in view and slowly advanced to pass alongside the wire into the LA (Video 1). Using posterior tilt and clockwise/counterclockwise rotation, the LA appendage and each of the PVs was directly visualized. The Faradrive sheath was then advanced back into the LA over the wire, such that both were in the LA using the same transseptal access site. 

Through the transseptal sheath, detailed mapping of the LA using a multipolar catheter (Advisor HD Grid Mapping Catheter, Sensor Enabled, Abbott) was performed to define anatomy and baseline endocardial voltage, which was normal in this case. The Farapulse catheter was then advanced into the LA over a J wire, which was clearly visible with ICE in the LA. The wire was also pinned directly into the EAM to allow visualization of its tip without fluoroscopy.⁴ The wire was sequentially advanced into each PV and used to advance the ablation catheter in both “basket” and “flower” configurations up to the ostia and antrum of each vein, respectively, for PFA applications (Figures 1 and 2, Videos 2-4). The ICE catheter enabled undoubtful confirmation of adequate tissue contact of the splines of the ablation catheter, appropriately centered position in each vein, and dynamic surveillance of appropriate wire positioning. 

After wide antrum PVI, the ablation catheter was also used in “flower” formation to deliver additional lesions in the posterior LA wall for isolation (Video 5). A total of 58 lesions (10 lesions per PV, 18 lesions on PW) were applied and tagged by projection of the ablation catheter position on the EnSite NavX (Abbott) LA map (Figure 3). LA voltage mapping was then repeated using the multielectrode mapping catheter, which confirmed successful PVI and PWI (Figure 4, Video 6). Prior to completion of the procedure, repeat ICE evaluation showed no pericardial effusion. The catheters were then removed from the body, and a combination figure-of-8 suture and vascular closure device were used to achieve hemostasis. 

Discussion

The emergence of PFA has introduced the potential for PVI procedures to become safer and more reproducible, but at the same time, requires adaptation to new procedural workflows. As zero-fluoroscopy PVI has become more popular with radiofrequency (RF) ablation in recent years, many operators may wish to develop a similar workflow with PFA, as patients and providers stand to benefit from no radiation exposure and decreased lead use. To do so safely, ICE is an instrumental tool in offering real-time anatomic assessment to guide each step of the procedure. 

The evaluation of transseptal puncture position and pre- and post-procedure assessment for pericardial effusion are similar to techniques used previously in RF ablation. However, the monitoring of positioning and shape of the PFA catheter are new challenges. These are further heightened by the potential use of EAM systems that are not inherently designed to visualize the PFA catheter with the degree of reproducibility and accuracy that electrophysiologists are accustomed to in RF ablation. When the PFA catheter, sheath, and wire are not sensor-enabled, it becomes more critical to have a second tool for visual feedback. In our experience, advancing the ICE catheter to the LA allows for high-definition detailed imaging with the best possible visual confirmation of these components as well as detailed anatomical assessment. While conventional ICE imaging from the RA can be used, image definition is much less precise and there are often artifact/interference issues from the interatrial septum, especially to appropriately visualize the right PVs. Positioning in the LA overcomes these issues and allows for more consistent near-field views of the sheaths and catheters. 

While much of the additional value of ICE relates to enhancing safety, there are also considerations regarding the efficacy of ablation when using ICE to visualize the PFA catheter prior to lesion delivery. It has been shown that direct tissue-catheter contact contributes to the depth of PFA lesion formation.^5,6 Without direct visualization, the ability to achieve consistent tissue contact in the absence of fluoroscopy relies on the tactile sensation of the operator or the accuracy of the EAM in projecting catheter position. Conversely, with ICE positioned in the LA, the opposition of the PFA catheter splines to the tissue can be easily and undoubtfully confirmed prior to lesion application in the PVs as well as along the roof, ridge, and posterior wall, allowing precise and consistent high-quality lesion formation. 

Conclusion

Use of ICE in combination with EAM during PFA procedures for AF allows for a highly precise and safe zero-fluoroscopy workflow through detailed visualization of relevant anatomical structures, dynamic confirmation of catheter positioning, shape and alignment, and undoubtful verification of tissue contact with the splines of the catheter. ICE positioning in the LA allows for superior near-field image quality and high-definition guidance of the entire procedure. 

Disclosure: The authors have completed and returned the ICMJE Form for Disclosure of Potential Conflicts of Interest and report no conflicts of interest regarding the content herein. 

References

1. Reddy VY, Gerstenfeld EP, Natale A, et al. Pulsed field or conventional thermal ablation for paroxysmal atrial fibrillation. N Engl J Med. 2023;389(18):1660-1671. doi:10.1056/NEJMoa2307291

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3. Gianni C, Sanchez JE, Della Rocca DG, et al. Intracardiac echocardiography to guide catheter ablation of atrial fibrillation. Card Electrophysiol Clin. 2021;13(2):303-311. doi:10.1016/j.ccep.2021.03.009

4. Alzahrani A, Farjo P, Powers EM, et al. Novel methodology for nonfluoroscopic wire visualization during pulsed field ablation for the treatment of atrial fibrillation. Heart Rhythm. 2024:S1547-5271(24)02527-X. doi:10.1016/j.hrthm.2024.04.093

5. Mattison L, Verma A, Tarakji KG, et al. Effect of contact force on pulsed field ablation lesions in porcine cardiac tissue. J Cardiovasc Electrophysiol. 2023;34(3):693-699. doi:10.1111/jce.15813

6. Howard B, Verma A, Tzou WS, et al. Effects of electrode-tissue proximity on cardiac lesion formation using pulsed field ablation. Circ Arrhythm Electrophysiol. 2022;15(10):e011110. doi:10.1161/CIRCEP.122.011110