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.
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
Tsu-Juey
TJ
Wu
Shien-Fong
SF
Lin
Ali
A
Baher
Zhilin
Z
Qu
Alan
A
Garfinkel
James N
JN
Weiss
Chih-Tai
CT
Ting
Peng-Sheng
PS
Chen
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