Effects of Electrode-Tissue Proximity on Cardiac Lesion Formation Using Pulsed Field Ablation

Area of Science:

• Cardiovascular Medicine
• Biomedical Engineering
• Electrophysiology

Background:

• Pulsed field ablation (PFA) is an emerging energy modality for treating cardiac arrhythmias.
• The influence of electrode-tissue proximity on PFA lesion formation requires further investigation.
• This study evaluates how electrode-tissue distance impacts cardiac lesion creation using a bipolar PFA system.

Purpose of the Study:

• To assess the effect of varying electrode-tissue proximity on cardiac lesion dimensions.
• To determine the optimal electrode-tissue distance for effective lesion formation in PFA.
• To validate experimental findings with numerical modeling.

Main Methods:

• A 4-electrode prototype catheter delivered PFA on the epicardial surface of an isolated porcine heart model.
• An offset tool controlled electrode-tissue distances at 0 mm, 2 mm, and 4 mm.
• Lesion dimensions were quantified using tetrazolium chloride staining; numerical models were employed for validation.

Main Results:

• Cardiac lesion depth and width decreased proportionally with increasing electrode-tissue distance.
• Average lesion depths were 4.3 mm (0 mm offset), 2.7 mm (2 mm offset), and 1.3 mm (4 mm offset).
• Numerical models accurately predicted ex vivo lesion formation across different offset distances.

Conclusions:

• Close electrode-tissue proximity (0 mm offset) resulted in the deepest cardiac lesions.
• A linear relationship exists between lesion depth and offset distance.
• Maximizing electric field penetration through close proximity enhances the likelihood of achieving transmural lesions with PFA.