Fiber orientation and cell-cell coupling influence ventricular fibrillation dynamics.
Cell Coupling Influences VF Dynamics.


BACKGROUND
The structure of ventricular fibrillation (VF) is influenced by regional differences in action potential durations and perhaps restitution kinetics and fiber anisotropy. The spatial organization of VF was investigated by measuring the cross-correlation (CC) and mutual information (MI) of membrane potential (Vm) oscillations recorded from multiple sites.


RESULTS
Rabbit hearts (n = 6) were retrogradely perfused and stained with di-4-ANEPPS, and VF was elicited by burst pacing. Vm oscillations were recorded optically from multiple locations on the epicardium using a 16 x 16 photodiode array or a 72 x 78 CCD camera. The spatial organization of VF was investigated by calculating the maximum CC (CCmax) and MI (MImax) that can be obtained between any two sites. CCmax and MImax were extended to all pixels and served as indices of the similarities between Vm transients at a reference pixel and all other pixels on the map. We found that maps of CCmax and MImax did not contain discrete regions with high CC or MI. However, CCmax and MImax decreased monotonically with increasing distance between any arbitrarily chosen reference pixel and all other pixels. In VF, maps of CCmax and MImax revealed elliptical gradients of CC and MI that were closely aligned with fiber orientation, with major axis at 127 degrees +/- 8 degrees on the left ventricles.


CONCLUSIONS
CC and MI analysis in fibrillation provides new evidence that anisotropy of fiber orientation and cell-cell coupling have a direct influence on VF dynamics.
Choi
Bum-Rak
BR
Liu
Tong
T
Lavasani
Mitra
M
Salama
Guy
G
D000200:Action Potentials; D000818:Animals; D016880:Anisotropy; D018780:Body Surface Potential Mapping / Q000379:methods*; D002450:Cell Communication; D016764:Cell Polarity; D005260:Female; D006329:Heart Conduction System / Q000187:drug effects / Q000473:pathology* / Q000503:physiopathology*; D006352:Heart Ventricles / Q000187:drug effects / Q000473:pathology / Q000503:physiopathology; D019850:Heptanol / Q000494:pharmacology; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D032383:Myocytes, Cardiac / Q000473:pathology; D011817:Rabbits; D013050:Spectrometry, Fluorescence / Q000379:methods; D013223:Statistics as Topic; D014693:Ventricular Fibrillation / Q000473:pathology* / Q000503:physiopathology*
D019850:Heptanol