Mother rotors and the mechanisms of D600-induced type 2 ventricular fibrillation.
BACKGROUND
Two types of ventricular fibrillation (VF) have been demonstrated in isolated rabbit hearts during D600 infusion. Type 1 VF is characterized by the presence of multiple, wandering wavelets, whereas type 2 VF shows local spatiotemporal periodicity. We hypothesized that a single mother rotor underlies type 2 VF.


RESULTS
One (protocol I) or 2 (protocol II) cameras were used to map the epicardial ventricular activations in Langendorff-perfused rabbit hearts. Multiple episodes of type 2 VF were induced in 22 hearts by high-concentration (> or =2.5 mg/L) D600 (protocol I). During type 2 VF, a single spiral wave (n=19) and/or an epicardial breakthrough pattern (n=11) was present in 14 hearts. These spiral waves either slowly drifted or intermittently anchored on the papillary muscle (PM) of the left ventricle. Dominant-frequency (DF) analyses showed that the highest local DF was near the PM (12.5+/-1.1 Hz). There was an excellent correlation between the highest local DF of these spiral waves and breakthroughs (11.8+/-1.7 Hz) and the DF of simultaneously obtained global pseudo-ECG (11.2+/-1.8 Hz, r=0.97, P<0.0001) during type 2 VF. We also successfully reproduced the major features of type 2 VF by using the Luo-Rudy action-potential model in a simulated, 3-dimensional tissue slab, under conditions of reduced excitability and flat action-potential duration restitution.


CONCLUSIONS
Either a stationary or a slowly drifting mother rotor can result in type 2 VF. Colocalization of the stationary mother rotors with the PM suggests the importance of underlying anatomic structures in mother rotor formation.
Wu
Tsu-Juey
TJ
Cardiovascular Center, Taichung Veterans General Hospital and Institute of Clinical Medicine, National Yang-Ming University School of Medicine, Taipei, Taiwan. tjwu@vghtc.vghtc.gov.tw
Lin
Shien-Fong
SF
Baher
Ali
A
Qu
Zhilin
Z
Garfinkel
Alan
A
Weiss
James N
JN
Ting
Chih-Tai
CT
Chen
Peng-Sheng
PS
D000200:Action Potentials; D000818:Animals; D003198:Computer Simulation; D003952:Diagnostic Imaging / Q000295:instrumentation / Q000379:methods; D004594:Electrophysiology / Q000295:instrumentation / Q000379:methods; D005583:Fourier Analysis; D005711:Gallopamil / Q000633:toxicity*; D006329:Heart Conduction System / Q000503:physiopathology*; D008955:Models, Cardiovascular; D010210:Papillary Muscles / Q000473:pathology; D010496:Pericardium / Q000503:physiopathology*; D011817:Rabbits; D015222:Sodium Channels / Q000502:physiology; D014693:Ventricular Fibrillation / Q000139:chemically induced / Q000145:classification / Q000503:physiopathology*
D015222:Sodium Channels; D005711:Gallopamil