Frequency analysis of ventricular fibrillation in Swine ventricles.
It has been suggested from frequency analysis that cardiac fibrillation is driven by stable intramural reentry, with wavebreak occurring due to failure of 1:1 propagation. We tested this hypothesis with a combined experimental and theoretical approach. Optical mapping was performed on epicardial, endocardial, and transmural cut surfaces of fibrillating swine ventricles. Wavelets were characterized, the frequency content of optical signals analyzed, and space-time plots (STPs) constructed to detect Wenckebach-like conduction. The findings were compared with simulations in 2D and 3D cardiac tissue using the Luo-Rudy action potential model. The incidence of reentry in the cut transmural surface (11.8% in right ventricle, 14.3% in left ventricle) was similar to that on the endocardial surface (13.1%, P=NS) but greater than on the epicardial surface (7.7%, P<0.01). Frequency spectra of optically recorded membrane voltage were organized into spatial domains with the same dominant frequency, but these domains were nonstationary. In STPs, pseudo-2:1 conduction block was caused by double potentials arising when reentry occurred on the recording site rather than true Wenckebach conduction. The latter was observed in 11 of 166 STPs but did not occur at borders of high-to-low frequency domains. In simulations, similar findings were obtained when action potential duration (APD) restitution slope was steep. Stationary dominant frequency domains with Wenckebach conduction patterns were observed only in the presence of shallow APD restitution slope and marked nonuniform tissue heterogeneity. In conclusion, stable intramural reentry as the engine of fibrillation was not observed. Our findings support the idea that dynamic wavebreak plays a fundamental role in the generation and maintenance of ventricular fibrillation.
Valderrábano
Miguel
M
Division of Cardiology, Department of Medicine, Cedars-Sinai Medical Center, Los Angeles, CA, USA.
Yang
Junzhong
J
Omichi
Chikaya
C
Kil
John
J
Lamp
Scott T
ST
Qu
Zhilin
Z
Lin
Shien-Fong
SF
Karagueuzian
Hrayr S
HS
Garfinkel
Alan
A
Chen
Peng-Sheng
PS
Weiss
James N
JN
D000200:Action Potentials; D000818:Animals; D018780:Body Surface Potential Mapping; D003198:Computer Simulation; D004699:Endocardium / Q000503:physiopathology; D005260:Female; D005583:Fourier Analysis; D006329:Heart Conduction System / Q000503:physiopathology*; D006352:Heart Ventricles / Q000503:physiopathology*; D066298:In Vitro Techniques; D008297:Male; D008564:Membrane Potentials; D008955:Models, Cardiovascular; D055095:Optics and Photonics; D010496:Pericardium / Q000503:physiopathology; D012815:Signal Processing, Computer-Assisted; D013552:Swine; D014693:Ventricular Fibrillation / Q000503:physiopathology*