Novel approach for low-voltage termination of anatomically defined reentry

Abstract

Implantable cardioverter defibrillator (ICD) therapy for termination of cardiac arrhythmias is not optimal. High energy electrical shocks can cause side effects including electroporation, tissue damage, pain and traumatic patient experience. Reducing the shock energy would result in a profound improvement of the therapy. Eighty percent of patients receiving ICD therapy have a history of coronary artery disease and thus have the substrate for anatomically defined reentrant tachyarrhythmia. An applied electric field induces virtual electrode polarization at anatomical heterogeneities, which may also serve as the core of anatomical reentry. We have shown theoretically that interaction of the electric field with the core of reentry could potentially result in a 100-fold reduction of defibrillation energy. Methods and Results: We used a superfused isolated rabbit right ventricular preparation as a model of the endocardial border zone (n 14). Survival of only 50-200 m of the endocardial layer was verified by anti-Connexin43 immunostaining. Stable reentry was induced by burst pacing. Monophasic shocks (10 ms, 0.2-3.6 V/cm) were applied parallel to the endocardium from mesh electrodes located in the bath. Optical imaging revealed that the stable reentrant circuits were pinned to the endocardial trabeculae and were maintained with a cycle length of 155.78 38.58 ms. A total of 192 reentries were initiated and terminated by appropriately timed virtual electrode-induced excitation of either the anatomical obstacle serving as the core of reentry or a heterogeneity near the core. E50 (field at which 50% of reentries were terminated) was 1.4 V/cm, which corresponds to 3.4 times the average field excitation threshold. Conclusions: These results indicate that low-voltage termination of reentry is achievable and may be a promising new alternative to conventional ICD therapy.