A new technique that uses low-power electrical impulses to treat cardiac arrhythmias such as atrial fibrillation (AF) could lead to the development of painless defibrillation methods.

Researchers at the ENS Lyon physics laboratory (France) and the Max Planck Institute for Dynamics and Self-Organization (Göttingen, Germany) used a conventional cardiac catheter to study the effects of Low-Energy Anti-fibrillation Pacing (LEAP) on AF. They applied a series of five low-intensity impulses to the heart of an animal suffering from arrhythmia; after a few seconds, the heart started to beat regularly again. The technique is based on the same principle as existing defibrillators, but it elicits a different response in the heart. Shortly after the shock, the cardiac tissue can no longer transmit electrical signals; the chaotic activity stops, and the heart can then resume its normal functioning. The use of a lower electric field necessitates that the shock be repeated several times.

Additionally, since it uses low electric fields, the new LEAP technique should be less painful and less damaging to cardiac tissue than existing defibrillators, reducing the energy needed for defibrillation by 80%. It also offers the advantage of restoring heart rhythm more gradually than current techniques. Each impulse activates more tissue, gradually eliminating any turbulent cardiac activity. The blood vessels and other cardiac heterogeneities, such as the misalignment of heart fibers, act as control centers: once activated, they make it possible to "reprogram" the heart. The next step is to test the technique on human patients. The study was published in the July 13, 2011, issue of Nature.

“Demonstrated on animals for atrial fibrillation, these results could also apply to the treatment of ventricular fibrillation, a fatal form of arrhythmia,” concluded study coauthor physicist Alain Pumir, PhD, of ENS Lyon. “LEAP could make it possible to eliminate pain while improving the treatment's success rate, in addition to prolonging the life of the batteries used to power implanted or external defibrillators.”

AF is characterized by the uncoordinated action of certain cells in the cardiac muscle tissue. As a result, chaotic electrical impulses propagate in the heart, preventing regular contractions and hampering the organ's capacity to circulate blood throughout the organism. Since it is not possible to reduce AF and restore normal heart rhythm by medication alone, the most effective treatment is still the application of an external electrical shock using a defibrillator. Although brief, the high-intensity impulse can damage the tissues and it is often perceived as being very painful. Until now, it was considered impossible to reduce the intensity without running the risk of an unsuccessful defibrillation.

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