| Sumario: | Cell Coupling Influences VF Dynamics. Introduction: 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 (V[sub m]) oscillations recorded from multiple sites. Methods and Results: Rabbit hearts (n = 6) were retrogradely perfused and stained with di-4-ANEPPS, and VF was elicited by burst pacing. V[sub m] 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 (CC[sub max]) and MI (MI[sub max]) that can be obtained between any two sites. CC[sub max] and MI[sub max] were extended to all pixels and served as indices of the similarities between V[sub m] transients at a reference pixel and all other pixels on the map. We found that maps of CC[sub max] and MI[sub max] did not contain discrete regions with high CC or MI. However, CC[sub max] and MI[sub max] decreased monotonically with increasing distance between any arbitrarily chosen reference pixel and all other pixels. In VF, maps of CC[sub max] and MI[sub max] revealed elliptical gradients of CC and MI that were closely aligned with fiber orientation, with major axis at 127°± 8° on the left ventricles. Conclusion: 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. (J Cardiovasc Electrophysiol, Vol. 14, pp. 851-860, August 2003).
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