We demonstrate that a shift of the vulnerable window caused by tissue inhomogeneity can play a role in the generation of re-entrant excitation. The Earm-Hilgemann-Noble equations were incorporated into one- and two-dimensional inhomogeneous partial differential equation models of atrial tissue. Inhomogeneity was produced by a reduction of ḡ(Na) over part of the medium and the vulnerable window for initiating re-entrant activity in homogeneous models determined from numerical integrations. Forty percent reduction of ḡ(Na) produced little effect on the width of the vulnerable window, but the onset of the vulnerable window was delayed. The delay of the vulnerable window facilitates the initiation of re-entry at junctions between tissue with normal and reduced excitability, even though there is hardly any change in action potential duration.
ASJC Scopus subject areas
- Statistics and Probability
- Modeling and Simulation
- Biochemistry, Genetics and Molecular Biology(all)
- Immunology and Microbiology(all)
- Agricultural and Biological Sciences(all)
- Applied Mathematics