Page 136 - Advances in Biomechanics and Tissue Regeneration

132 7. MULTISCALE NUMERICAL SIMULATION OF HEART ELECTROPHYSIOLOGY

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FIG. 7.8 Reentrant patterns at endocardium (A) and epicardium (B) for the last recorded beat for the case [K ] o ¼ 7.0 mM and CI ¼ 260 ms. Panel
C shows the pseudo-ECG corresponding to the derivation V3; the arrows indicate the window corresponding to the patterns shown in panels
(A) and (B).

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FIG. 7.9 Transmembrane potential at t ¼ 2500 ms after initiation of earlier stimulation ([K ] o ¼ 7.0 mM and CI ¼ 260 ms). (A) Depolarization map
at the epicardium and endocardium. (B) Transmural depolarization map.

at the endocardium. The transmural map depicted in Fig. 7.9B shows how the faster endocardial conduction allows
intramural conduction, causing this wavefront to emerge at the epicardium at t ¼ 2509 ms as shown in Fig. 7.8B.
Even though, basically, one circus movement of relatively large dimensions is responsible for the sustained tachy-
cardia, the pattern of the reentrant wavefront, position, and dimensions changes from beat to beat. Fig. 7.10 shows the
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changes in the pattern from a single circus to a double circus, a figure of eight, for the case of [K ] o ¼ 7.0 mM and CI ¼
260 ms. The reentry was always observed within the ischemic region, and in all cases where sustained reentry was
found, the reentrant front was led from the endocardial surface where the pattern was clearly identified for all CIs.
Reentry patterns were not altered when the basic stimulation was maintained after delivering the extra stimulus, indi-
cating that tachycardia overrides normal stimulation.

I. BIOMECHANICS