Pulsed Field Ablation of the Porcine Ventricle Using a Focal Lattice-Tip Catheter

Abstract

Background: Our understanding of catheter-based pulsed field ablation (PFA) of the ventricular myocardium is limited. We conducted a series of exploratory evaluations of ventricular PFA in swine ventricles. Methods: A focal lattice-tip catheter was used to deliver proprietary biphasic monopolar PFA applications to swine ventricles under general anesthesia, with guidance from electroanatomical mapping, fluoroscopy, and intracardiac echocardiography. We conducted experiments to assess the impact of (1) delivery repetition (2×, 3×, or 4×) at each location, (2) epicardial PFA delivery, and (3) confluent areas of shallow healed endocardial scar created by prior PFA (4 weeks earlier) on subsequent endocardial PFA. Additional assessments included PFA optimized for the ventricle, lesion visualization by intracardiac echocardiography imaging, and immunohistochemical insights. Results: Experiment no. 1: lesions (n=49) were larger with delivery repetition of either 4× or 3× versus 2×: length 17.6±3.9 or 14.2±2.0 versus 12.7±2.0 mm ( P <0.01, P =0.22), width 13.4±1.8 or 10.6±1.3 versus 10.5±1.1 mm ( P <0.01, P =1.00), and depth 6.1±2.1 or 5.1±1.3 versus 4.2±1.0 mm ( P <0.01, P =0.21). Experiment no. 2: epicardial lesions (n=18) were reliably created and comparable to endocardial lesions: length 24.6±9.7 mm (n=5), width 15.6±4.6 mm, and depth 4.5±3.7 mm. Experiment no. 3: PFA (n=16) was able to penetrate to a depth of 4.8 (interquartile range, 4.5–5.4) mm in healthy myocardium versus 5.6 (interquartile range, 3.6–6.6) mm in adjacent healed endocardial scar ( P =0.79), suggesting that superficial scar does not significantly impair PFA. Finally, we demonstrate, PFA optimized for the ventricle yielded adequate lesion dimensions, can result in myocardial activation, can be visualized by intracardiac echocardiography, and have unique immunohistochemical characteristics. Conclusions: This in vivo evaluation offers insights into the behavior of endocardial or epicardial PFA delivered using the lattice-tip catheter to normal or scarred porcine ventricular myocardium, thereby setting the stage for future clinical studies.

Opportunities and Challenges in Catheter-Based Irreversible Electroporation for Ventricular Tachycardia

“…Langendorff and whole-animal studies have been completed in swine [ 52 , 53 , 54 , 55 , 56 , 57 ], canine [ 58 ], ovine [ 59 ], and even rabbit [ 60 ] models using various PFA catheter types and methodologies. Consensus findings include the creation of transmural lesions via concentrated apoptosis with no evidence of thermal-based tissue damage.…”

A High‐Precision, Low‐Voltage Pulsed Field Ablation Device with Capability of Minimally Invasive Surgery

“…[6] Major medical companies are already ahead of the curve, acquiring or developing their own PFA catheters (such as FaraPulse from Boston Scientific Corporation, PulseSelect from Medtronic, and Varipulse from Johnson and Johnson) and putting them into clinical trials to collect first-line data and seek food and drug administration approval. [11][12][13][14] While still in the preclinical stage, several studies have demonstrated the excellent efficiency, safety, and durability of PFA. [8,12,[15][16][17] However, to date, these electrodes featuring large dimensions (25-35 mm) and insufficient ablation precision (at least a dozen millimeters) have often led to "overkill" during myocardial conduction block.…”

“…[ 6 ] Major medical companies are already ahead of the curve, acquiring or developing their own PFA catheters (such as FaraPulse from Boston Scientific Corporation, PulseSelect from Medtronic, and Varipulse from Johnson and Johnson) and putting them into clinical trials to collect first‐line data and seek food and drug administration approval. [ 11–14 ]…”

How intramyocardial fat can alter the electric field distribution during Pulsed Field Ablation (PFA): Qualitative findings from computer modeling

“…The experimental data comparing PFA lesions on healthy myocardium and scar (healed infarction) tend to be rather scarce and are limited to pre-clinical models [3−5]. The preliminary results suggest that a superficial scar does not significantly impair PFA and creates lesion depths in healthy myocardium similar to adjacent healed endocardial scars (4.8 and 5.6 mm, respectively) [ 3 ]. Although the preliminary experimental data suggests that PFA may be superior to RFA in terms of being able to ablate viable myocardium separated from the catheter by collagen and fat [ 5 ], there is as yet no formal analysis based on physical laws that describes the process by which intramyocardial fat can affect the electric field distribution and alter the size of the PFA-induced lesion.…”