Abstract 18140: Effective Point Electric Stimulation for Cardiac Spiral Wave Termination
Introduction: Low energy defibrillation by point electric shocks has been explored. Several experimental and computer simulation studies revealed that timing and location of stimulation are crucial factors for post-shock cardiac spiral wave (SW) dynamics. However, it is still challenging to terminate single SW by point electric shocks reliably.
Hypothesis: Relative position of a point electric shock with a moving spiral wave tail and an anatomical block line determines defibrillation success and failure.
Method: Spiral waves were induced on a perfused 2D whole rabbit heart model by S1-S2 shock protocol, followed by a point biphasic shock (+10V 4ms, -10V 2ms) from an electrode. The stimulation electrode was located on LV surface near AV groove, an anatomical block line. Electric shocks were applied at different timings, from 240ms to 310ms after S1-S2 shocks. Transmembrane potential was measured by optical mapping in 512x512 pixels, 1000 fps. Trajectories of the spiral core which moved rapidly just after the stimulation were identified by spiral core tracking algorithm based on analysis of spatial phase variance.
Result: In cases SW was terminated by the point stimulation (4 of 13 episodes), the stimulation was applied to the tail of the depolarized area. The spiral core shifted along that tail line to reach AV groove and finally disappeared. In some cases of termination failure, stimulation did not capture because the electrode was in the depolarized area at the stimulus timing. In other cases of failure, although the stimulus moved the spiral core, the direction was not toward AV groove and SW sustained consequently.
Conclusion: Point electric shocks applied between the SW core and anatomical boundaries at the timing of vulnerable period are effective for SW termination.
Author Disclosures: N. Tomii: None. M. Yamazaki: None. T. Arafune: None. H. Honjo: None. N. Shibata: None. I. Sakuma: None.
- © 2016 by American Heart Association, Inc.