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

Heart Rhythm

IHU-LIRYC, Electrophysiology and Heart Modeling Institute, Fondation Bordeaux Université, Pessac, Bordeaux, France; Centre National De La Recherche Scientifique, Institut de Mathématiques de Bordeaux, UMR5251, Bordeaux, France. Electronic address:

Published: February 2022

AI Article Synopsis

  • Strong electric shocks are typically used for ventricular defibrillation, but they cause pain and tissue damage, leading to the hypothesis that low-energy surface stimulation could provide a less harmful alternative.
  • The study aimed to find the conditions necessary for low-energy surface stimulation to effectively defibrillate large mammal ventricles, specifically through experiments conducted on pig left ventricles.
  • Results showed that low-energy defibrillation is possible with energies below the human pain threshold when applied effectively to the excitable gap of reentry, especially in simpler arrhythmias.

Article Abstract

Background: Strong electric shocks are the gold standard for ventricular defibrillation but are associated with pain and tissue damage. We hypothesized that targeting the excitable gap (EG) of reentry with low-energy surface stimulation is a less damaging and painless alternative for ventricular defibrillation.

Objective: The purpose of this study was to determine the conditions under which low-energy surface stimulation defibrillates large mammalian ventricles.

Methods: Low-energy surface stimulation was delivered with five electrodes that were 7 cm long and placed 1-2 cm apart on the endocardial and epicardial surfaces of perfused pig left ventricle (LV). Rapid pacing (>4 Hz) was used to induce reentry from a single electrode. A 2 ms defibrillation pulse ≤0.5 A was delivered from all electrodes with a varied time delay from the end of the induction protocol (0.1-5 seconds). 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 seconds postinitiation. Low-energy defibrillation was achieved with energy <60 mJ and electrode separations up to 2 cm for less complex arrhythmia. In simulations, defibrillation consistently occurred when stimulation captured >75% of the EG, which blocked reentry <2.9 mm in front of the leading reentrant wavefront.

Conclusion: 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.

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Source
http://dx.doi.org/10.1016/j.hrthm.2021.10.006DOI Listing

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