Pearls and Pitfalls of Pulsed Field Ablation

Abstract

Pulsed field ablation (PFA) was recently rediscovered as an emerging treatment modality for the ablation of cardiac arrhythmias. Ultra-short high voltage pulses are leading to irreversible electroporation of cardiac cells subsequently resulting in cell death. Current literature of PFA for pulmonary vein isolation (PVI) consistently reported excellent acute and long-term efficacy along with a very low adverse event rate. The undeniable benefit of the novel ablation technique is that cardiac cells are more susceptible to electrical fields whereas surrounding structures such as the pulmonary veins, the phrenic nerve or the esophagus are not, or if at all, minimally affected, which results in a favorable safety profile that is expected to be superior to the current standard of care without compromising efficacy. Nevertheless, the exact mechanisms of electroporation are not yet entirely understood on a cellular basis and pulsed electrical field protocols of different manufactures are not comparable among one another and require their own validation for each indication. Importantly, randomized controlled trials and comparative data to current standard of care modalities, such as radiofrequency- or cryoballoon ablation, are still missing. This review focuses on the "pearls" and "pitfalls" of PFA, a technology that has the potential to become the future leading energy source for PVI and beyond.

Keywords: Ablation; Atrial fibrillation; Electroporation; Pulmonary vein isolation; Pulsed field ablation.

Figure 1. Pearls and Pitfalls of PFA. Summary of the main “pearls” (light green) and “pitfalls” (red) of PFA as well as the future perspectives of the technology.

IRE = irreversible electroporation; PFA = pulsed field ablation; PV = pulmonary vein; PVI = pulmonary vein isolation; RF = radiofrequency.

Figure 2. Pulsed electric field waveform parameters. An exemplary overview of the most relevant pulsed electric field waveform characteristics and adjustable parameters for designing electroporation protocols. Each parameter setting and various pulse shapes available, its combinations and alterations result in different electric field strengths and influence the effect of electroporation, successful ablation, and safety.

Figure 3. Pulsed Field Ablation with the pentaspline catheter for PVI. Fluoroscopy-guided PVI using the FARAPULSE^TM system. Fluoroscopic images in LAO 40°. (A) PV angiography of the left inferior PV illustrates the PV ostium to ease optimal catheter placement. (B) Pentaspline catheter is positioned at the PV ostium in basket configuration. The indentation of the splines (arrow) suggests catheter-tissue contact. (C) Pentaspline catheter in its flower position. The backward flexing suggests catheter-tissue contact. A J-tip guidewire was advanced deep inside the PV to improve catheter stability. (D) Electrograms during pulsed electric field application (white: surface electrocardiogram, yellow: pentaspline ablation catheter, green: coronary sinus catheter). Note the attenuation of the atrial electrograms of the pentaspline catheter (yellow) after the first of in total 8 applications per PV.

LAO = left anterior oblique; PV = pulmonary vein; PVI = pulmonary vein isolation.

Figure 4. Visualization of the pentaspline pulsed field ablation catheter in 3-dimensional electroanatomical mapping system to guide LA posterior wall isolation and roof isolation. The FARAPULSE^TM ablation catheter in flower configuration for LA posterior wall isolation and LA roof isolation in a patient after multiple prior LA procedures and significant atrial fibrillation burden. Empirical re-ablation of all durably isolated PV was additionally performed under fluoroscopic guidance. Shown are voltage maps generated with the PENTARAY^TM mapping catheter (Biosense Webster, Diamond Bar, CA, USA) in a posterior-anterior projection. Voltage settings were 0.10–0.50 mV. Pre-ablation maps (left panes) show a diseased left atrium, and catheter visualization of in total 6 ablation locations in the CARTO^®3 electroanatomical mapping system (Biosense Webster). Post ablation voltage maps (right panes) demonstrate isolation of the posterior wall, the LA roof (posterior-anterior view oblique to roof) and the PV.

LA = left atrium, PV = pulmonary vein.

Figure 5. CENTAURI^TM generator with compatible monitor and pulsed electric field application. (A) Monitor for ECG-triggering (top), CENTAURI^TM generator (middle) with round connector boxes (bottom) for single-tip ablation catheters and integration in 3-dimensional electroanatomical mapping systems. (B) Electrograms during single-tip pulsed electric field application (top white: surface ECG, yellow: pentaspline mapping catheter positioned in contralateral pulmonary vein during ablation, lower white: single-tip ablation catheter, green: coronary sinus catheter).

ECG = electrocardiogram.

Figure 6. Voltage maps in the setting of PVI using single-tip PFA. Pre- and post-ablation voltage maps in the context of a single-tip PVI using the CENTAURI^TM generator for PFA. The connector box was used for the connection with the CARTO^®3 electroanatomical mapping system. Shown are voltage maps generated with the PENTARAY^TM mapping catheter (Biosense Webster, Diamond Bar, USA) in a posterior-anterior projection. Voltage settings were 0.10–0.50 mV. Ablation was performed with a THERMOCOOL SMARTTOUCH^TM catheter (Biosense Webster, Diamond Bar, CA, USA). Left: pre-ablation voltage map. Middle: post-ablation voltage map with PFA points bilateral around PVs. Right: post-ablation voltage map demonstrating bilateral PVI.

PFA = pulsed field ablation; PV = pulmonary vein; PVI = pulmonary vein isolation.