Safety and efficacy aspects of pulsed field ablation catheters as a function of electrode proximity to blood and energy delivery method

BACKGROUND: Pulsed field ablation (PFA) is a promising technology based on electroporation. It is unclear if different catheter designs imply efficacy and safety differences. OBJECTIVE: To vary geometry, blood exposure, and energy delivery methods among 3 representative catheter designs, and then compare lesion transmurality, extra-atrial safety, and embolic risk. METHODS: A computed tomography–derived computer model was used. Balloon, flexible-circuit splined, and circular catheters were placed near the left pulmonary veins. Four energy delivery methods were tested: multi-unipolar, sequential unipolar, interlaced, and wide interlaced. A posterior wall target was defined. Efficacy was defined as percent target with >600 V/cm. Safety aspects included aortic/esophageal electroporation damage and a bubble-generation surrogate (electrode current density), with 90% transmurality requirement. RESULTS: Balloon catheters had highest efficacy, followed by flexible polymer splined and circular catheters. On energy delivery methods, the multi-unipolar one was most efficacious, followed by interlaced bipolar and sequential-unipolar ones. Electroporation risks to aorta and esophagus were highest with multi-unipolar energy delivery. Bubble risk was lowest with balloon catheters. CONCLUSION: Computer models show that catheters with electrodes on a balloon surface or on flexible circuit splines are about 4 times more efficacious than circular catheters with electrodes exposed to atrial blood. Multi-unipolar energy delivery methods have a higher risk of electroporating aortic and esophageal tissue, when compared to bipolar interlaced methods. Considering embolic risks, circular catheters had the highest bubble-generating potential. A balloon or flexible circuit splined system with a wide interlaced delivery method showed the best balance in efficacy and safety.