One of the most dramatic scenes in medicine is reviving a patient in ventricular fibrillation using a defibrillator. An international team of scientists however has developed a new low-energy method that may take a lot of the drama out of the procedure. Their technique, called LEAP (Low-Energy Anti-fibrillation Pacing), reduces the energy required for defibrillation by 84%. LEAP, tested in dogs, works by applying a series of five small shocks, instead of one large one. It takes advantage of the shape of the heart’s vasculature, which affects spatial patterns of electric currents, creating ‘virtual electrodes’ that essentially amplify the voltage applied to the tissue.
The technique was first developed and tested in isolated pieces of dog atria and ventricles, and then later in the atria of living dogs, to which the low-power charge was delivered using coiled wire intra-atrial electrodes. The required voltage is at or below what researchers believe is the pain threshold for electric shocks, but there is still room for optimization to reduce the voltage even more. In vivo testing in the ventricles is currently underway with preliminary results being positive. While there is still a long way to go before we will see this technique in clinical use, one of the main benefits could be in patients wearing ICD’s who frequently receive shocks when their devices falsely detect fibrillation. The initial results from testing the technique are published in this week’s issue of Nature.