Computer models of depolarization alterations induced by myocardial ischemia: The effect of superimposed ischemic inhomogeneities on propagation in space and time-frequency domains

Research output: Contribution to journalArticle

Abstract

A two-dimensional modified Luo-Rudy model was created to represent a 40 mm by 40 mm slab of myocardial tissue. An inhomogeneity was introduced to simulate acute myocardial ischemia, with components of hyperkalemia, acidosis and anoxia. Simulations were carried out for various degrees of ischemia, to study both the interaction of the propagation front with the inhomogeneity, and the reconstructed signals. The simulations utilized a modified LR model, with a realistic anisotropy of myocardial tissue. Each cluster (.4 mm × .4 mm) was given bulk electric properties, Rx and Ry (25Ω and 250Ω, respectively). The slab was stimulated and the 2D depolarization pattern was computed by numerical integration. To study ischemia, a circular inhomogeneity with concentric regions (ro = 12.8 mm {bord er zone, BZ}, ri = 11.2 mm {extreme zone, EZ}) regions was introduced in the model. From the 2D simulations and the regional action potentials (AP), unipolar and bipolar lead potentials were reconstructed. Time-frequency decomposition was performed on the lead signals by wavelet analysis. Isochrone and (dV/dt)max maps were obtained to study depolarization. Our results indicate that spatial inhomogeneities yield dramatic spatial dispersion of the wavefront and are the origin of mid-frequency intra-QRS components In cardiac signals. Severe APD shortening and spatial distortion of the isochrone and upstroke maps are also observed.

Original languageEnglish (US)
Pages (from-to)553-574
Number of pages22
JournalJournal of Biological Systems
Volume7
Issue number4
DOIs
StatePublished - Jan 1 1999

Keywords

  • Cardiac modeling
  • Cellular networks
  • Depolarization
  • Myocardial ischemia
  • Time-frequency analysis

ASJC Scopus subject areas

  • Ecology
  • Agricultural and Biological Sciences (miscellaneous)
  • Applied Mathematics

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