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Figure 3 Transmural unipolar recording of the left ventricle in the long QT syndrome type 2 (LQT2) model. The activation-recovery interval (ARI) and its transmural dispersion are presented during pacing at basic cycle lengths (BCLs) of 600 ms (A), 400 ms (B) and 600 ms after nicorandil (C). The ARI measurements are shown with each electrogram. The thin vertical line in each electrogram represents the point of the maximal derivative of the T-wave. (A) The mid-myocardial (Mid) site shows greater ARI prolongation than the epicardial (Epi) or endocardial (Endo) sites, resulting in a 43- to 44-ms ARI dispersion across the ventricular wall. Faster pacing at a 400-ms BCL shortened ARI at all sites, and transmural ARI dispersion was reduced to 30 to 31 ms (B). Compared with faster pacing, the magnitude of ARI shortening was significantly greater when nicorandil was administrated during 600-ms BCL pacing, and transmural ARI dispersion decreased to 25 to 26 ms (C).
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