Bipolar Electroporation Across the Interventricular Septum: Electrophysiological, Imaging, and Histopathological Characteristics.

BACKGROUND: Pulsed electric field (PEF) ablation is an emerging modality for the treatment of cardiac arrhythmias. Data regarding effects on the interventricular septum are limited, and the optimal delivery protocol and electrode configuration remain undefined. OBJECTIVES: This study sought to evaluate the electrophysiological, imaging, and histological characteristics of bipolar direct-current PEF delivered across the interventricular septum. METHODS: PEF was applied between identical solid-tip ablation catheters positioned on either side of the septum in a chronic canine model. Intracardiac and surface electrophysiological data were recorded following delivery. In 4 animals, cardiac magnetic resonance (CMR) was performed early (6 ± 2 days) and late (30 ± 2 days) postablation. After 4 weeks of survival, cardiac specimens were sectioned for histopathological analysis. RESULTS: In 8 canines, PEF was delivered in 27 separate septal sites (45 ± 17 J/site) with either microsecond or nanosecond PEF. Acute complications included transient complete atrioventricular block in 5 animals (63%) after delivery at the anterobasal septum, with right bundle branch block persisting in 3 (38%). Ventricular fibrillation occurred in 1 animal during microsecond but not nanosecond PEF. Postprocedural CMR showed prominent edema and significant left ventricular systolic dysfunction, which recovered with late imaging. At 4 weeks, 36 individual well-demarcated lesions were demonstrated by CMR and histopathology. Lesion depth measured by histology was 2.6 ± 2.1 mm (maximum 10.9 mm and near transmural). CONCLUSIONS: Bipolar PEF ablation of the interventricular septum is feasible and can produce near transmural lesions. Myocardial stunning, edema, and conduction system injury may occur transiently. Further studies are required to optimize safe delivery and efficacious lesions.

Injectable Flexible Subcutaneous Electrode Array Technology for Electrocardiogram Monitoring Device.

Implantable cardiac monitors have undergone considerable miniaturization. However, they continue to be associated with complications such as infection, bleeding/bruising, and device extrusion or migration. In this paper, we demonstrate the feasibility of using a small, flexible, injectable, subcutaneous microelectrode-based device to record electrocardiograms (ECGs). We describe the fabrication process and demonstrate the ease of insertion of the injectable ECG device in vivo swine model. We also demonstrate our device's high-density channel microelectrode array's ability to detect the P, R, and T waves. The amplitude of these waves showed excellent correlation with distance of the bipolar electrodes used to detect them. Given the success of our initial studies, this device has the potential to improve the safety profile of implantable cardiac monitors and simplify the implantation procedure to allow for placement in a primary care setting.