Ventricular repolarization sequences on the epicardium and endocardium. Monophasic action potential mapping in healthy pigs
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To investigate repolarization sequence, monophasic action potentials were recorded from a mean of 153 +/- 54 left and right ventricular epicardial and endocardial sites in 10 pigs using the CARTO mapping system (Biosense Webster, Waterloo, Belgium). The activation time and end-of-repolarization (EOR) time were measured and 3-dimensional maps of activation and repolarization sequences constructed. Results: In 8 of 9 pigs, both the activation and EOR times appeared first in the septum and last in the latero-basal areas on the endocardium, not on the epicardium. The EOR followed the activation sequence, both on the epicardium (in 8/9 pigs) and endocardium (in 8/8 pigs). The maximal EOR differences were 84 +/- 20 ms, whereas the local EOR differences between paired sites against each other on the tell ventricular epicardium and endocardium were 11 +/- 9 ms in the apex and 12 +/- 12 ms in the anterior wall. Conclusion: The EOR follows the activation sequence both on the epicardium and endocardium. The apico-basal gradients are predominant repolarization gradients, as compared with the epicardial-endocardial gradients. (C) 2012 Elsevier Inc. All rights reserved.