Pulsed-Field Ablation in Ventricular Myocardium Using a Focal Catheter

Abstract

Background - Pulsed-field ablation (PFA) is a rapid and nonthermal energy with higher selectivity to myocardial tissue in comparison to radiofrequency ablation (RFA). However, its effects on ventricular myocardium, and titration of lesion dimensions have not been well studied. This study examined the effect of PFA on ventricular myocardium, and the influence of application repetition on lesion dimensions. Methods - An 8Fr lattice catheter with a compressible 9 mm nitinol tip was used with a PFA generator (Affera Inc) applying a bipolar and biphasic waveform (±1.3-2.0 kV, 4 sec per application). We examined the impact of single applications (1x) vs four repetitive applications (4x) interspaced by 10 seconds. The latter was performed to determine whether repetitions of a similar electrical field can increase lesion dimensions. Experiments were performed in an in-vivo porcine model and a survival period of 24 hours (n=6) or 23±5.4 days (n=6) for evaluation of early and late histopathological effects. Results - PFA in ventricular myocardium showed repetition dependency. Acute lesion depth and volume increased from 5.6±1.43mm and 860±362mm 3 to 8.8±0.74mm and 2383±548mm 3 for 1x and 4x applications, respectively (P<0.001 for both comparisons). This effect was maintained in the chronic lesion phase with lesion depth and volume of 3.9±0.92mm and 655±286mm 3 compared with 7.3±0.83mm and 2170±488mm 3 , respectively (P<0.001 for both comparisons). Acute lesions showed well demarcated necrotic core without coagulation necrosis while chronic lesions showed tissue thinning with fibro-fatty replacement. Conclusions - PFA in ventricular myocardium exhibits repetition dependency as lesion dimension increases with consecutive applications of a similar electrical field.

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

“…Lesion dimensions progressively increased with increased repetitions (2, 3, and 4 repeats), with the depth increasing from 4.2±1.0 mm (2× repetitions) to 6.1±2.1 mm (4× repetitions; P =0.003). This confirms and elaborates previous findings by both our group and recently by Yavin et al, 7 who demonstrated improved depth by comparing 1 application against 4 repeat applications.…”

“…As previously described, this 7.5F bidirectionally-deflectable catheter has a tip containing 9 mini-electrodes/temperature sensors and location sensors allowing for 3-dimensional localization. 4 , 5 , 7 PFA is applied as a monopolar field from the entire lattice tip (to a grounding electrode) using a proprietary biphasic waveform. The catheter is irrigated at 4 and 15 mL/min at baseline and during ablation, respectively.…”

“…Indeed, recent studies have expanded the ability of this lattice-tip catheter to generate ventricular lesions. 7 Accordingly, in this preclinical series of porcine experiments, we explored focal ventricular PFA using the lattice-tip catheter to assess: the impact of PF delivery repetition, the effect of PFA on healed endocardial scar, epicardial ventricular PFA, the effect of PFA delivery optimized for ventricular tissue, ultrasonic lesion visualization, and immunohistochemical staining characteristics.…”

Stereotactic Radiotherapy in the Management of Ventricular Tachycardias

“…62,63 Preliminary results in patients with atrial fibrillation are exciting 64,65 and animal experiments for VT ablation have also shown encouraging results. 66 In summary, the promising early experience with irreversible electroporation suggests that soon, catheter ablation of VT could be more efficacious and probably safer. Such improvement may heavily influence the refinement or the need for SBRT in VT management.…”

Taking the “pulse” of pulsed‐field ablation: Real‐world experience

“…Even a subtherapeutic, single delivery of PFA can cause electrograms to disappear. Furthermore, data has shown that repetitive applications 10 are required to “push” the depth of the lesion to its maximum – explaining the eight pre‐determined applications that were delivered per site in this manuscript. But how does an operator assess when enough deliveries have been placed?…”