title: Ventricular fibrillation mechanisms and cardiac restitutions: An investigation by simulation study on whole-heart model.
abstract: BACKGROUND
  The action potential duration (APD) and the conduction velocity (CV) restitution have been reported to be important in the maintenance and conversion of ventricular fibrillation (VF), whose mechanisms remain poorly understood. Multiple-wavelet and/or mother-rotor have been regarded as the main VF mechanisms, and APD restitution (APDR) and CV restitution (CVR) properties are involved in the mutual conversion or transition between VF and ventricular tachycardia (VT).
  
  
  RESULTS
  The effects of APDR (both its slope and heterogeneity) and CVR on VF organization and conversion were examined using a "rule-based" whole-heart model. The results showed that different organizations of simulated VF were manifestations of different restitution configurations. Multiple-wavelet and mother-rotor VF mechanisms could recur in models with steep and heterogeneous APDR, respectively. Suppressing the excitability either decreased or increased the VF complexity under the steep or shallow APDR, respectively. The multiple-wavelet VF changed into a VT in response to a flattening of the APDR, and the VT degenerated into a mother-rotor VF due to the APDR heterogeneity.
  
  
  CONCLUSIONS
  Our results suggest that the mechanisms of VF are tightly related to cardiac restitution properties. From a viewpoint of the "rule-based" whole-heart model, our work supports the hypothesis that the synergy between APDR and CVR contributes to transitions between multiple-wavelet and mother-rotor mechanisms in the VF.
authors: Biomedical Information Technology Lab, the University of Aizu, Tsuruga, Ikki-machi, Aizu-Wakamatsu, Fukushima 965-8580, Japan.
authors: Yi
authors: Y
authors: Zheng
authors: Department of Cardiovascular Medicine, Tohoku University Graduate School of Medicine, Seiryo-Machi 1-1, Aoba-ku, Sendai, Miyagi 980-8574, Japan. Electronic address: daming.wei@ekgtechnol.com.
authors: Daming
authors: D
authors: Wei
authors: Biomedical Information Technology Lab, the University of Aizu, Tsuruga, Ikki-machi, Aizu-Wakamatsu, Fukushima 965-8580, Japan.
authors: Xin
authors: X
authors: Zhu
authors: Biomedical Information Technology Lab, the University of Aizu, Tsuruga, Ikki-machi, Aizu-Wakamatsu, Fukushima 965-8580, Japan.
authors: Wenxi
authors: W
authors: Chen
authors: Department of Cardiovascular Medicine, Tohoku University Graduate School of Medicine, Seiryo-Machi 1-1, Aoba-ku, Sendai, Miyagi 980-8574, Japan.
authors: Koji
authors: K
authors: Fukuda
authors: Department of Cardiovascular Medicine, Tohoku University Graduate School of Medicine, Seiryo-Machi 1-1, Aoba-ku, Sendai, Miyagi 980-8574, Japan.
authors: Hiroaki
authors: H
authors: Shimokawa
mesh_terms: D000200:Action Potentials; D003198:Computer Simulation; D005260:Female; D006801:Humans; D008297:Male; D008955:Models, Cardiovascular; D014693:Ventricular Fibrillation / Q000503:physiopathology*
keywords: Action potential duration restitution; Computer simulation; Conduction velocity restitution; Ventricular fibrillation; Whole-heart model