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B-PO03-028 BIPOLAR PULSED ELECTRIC FIELD ABLATION OF THE INTERVENTRICULAR SEPTUM

      Background

      Ablation of deep septal substrate with thermal energy sources conveys many challenges including inadequate lesion depth, inadvertent steam pops, and conduction system injury.

      Objective

      Pulsed electric fields (PEF) were delivered across the interventricular septum as a preclinical proof-of-concept for transmural ablation through irreversible electroporation.

      Methods

      In 8 healthy canine 4-week survival experiments, microsecond (n=2; 75-189J/animal) or nanosecond (n=6; 107-275J/animal) duration PEF were applied in a bipolar fashion between solid-tip ablation catheters positioned on either side of the septum in 2-5 separate locations. Radiofrequency (RF) control lesions were delivered for comparison at non-septal sites.

      Results

      Nanosecond PEF did not result in sustained ventricular tachyarrhythmias or skeletal muscle stimulation as opposed to microsecond PEF. Transient complete heart block was seen in 4 after delivery at the basal septum. Of these, bundle branch block persisted in 3 animals. Two animals died due to intractable VF during the initial experiment: 1 during microsecond delivery and another during an RF lesion. At 4 weeks of survival, 36 individual well-demarcated ablation lesions were demonstrated on both sides of the septum by cardiac MRI, necropsy, and histology. Lesion depth measured by histology was 2.62±2.06 mm with a maximum of 10.9 mm and transmurality in 1 animal.

      Conclusion

      Bipolar irreversible electroporation of the interventricular septum is feasible and can result in transmural septal ablation lesions. Conduction system injury may occur at least transiently and further refinement is required to improve safety.
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