Low-energy, single-pulse surface stimulation defibrillates large mammalian ventricles.

Abstract Background Strong electric shocks are the gold-standard for ventricular defibrillation, but are associated with pain and tissue damage. We hypothesize that targeting the excitable gap (EG) of reentry with low-energy surface stimulation is a less damaging and painless alternative for ventricular defibrillation. Objective Determine the conditions under which low-energy surface stimulation defibrillates large mammalian ventricles. Methods Low-energy surface stimulation was delivered with five 7 cm long electrodes placed 1-2 cm apart on the endocardial and epicardial surfaces of perfused pig left ventricle (LV). Rapid pacing (>4Hz) was used to induce reentry from a single electrode. A 2 ms defibrillation pulse ≤0.5A was delivered from all electrodes with a varied time delay from the end of the induction protocol (0.1-5 sec). Optical mapping was performed and arrhythmia dynamics analyzed. For mechanistic insight, simulations of the VF induction and defibrillation protocols were performed in-silico with an LV model emulating the experimental conditions, and electrodes placed 0.25-2 cm apart. Results In living LV, reentry was induced with varying complexity and dominant frequencies ranging between 3.5 to 6.2 Hz over 8 sec post-initiation. Low-energy defibrillation was achieved with energy 75% of the EG, which blocked reentry Conclusions Defibrillation with low-energy single-pulse surface stimulation is feasible with energies below the human pain threshold (100 mJ). Optimal defibrillation occurs when arrhythmia complexity is minimal and electrodes capture >75% of the EG.