Action potential duration dispersion and alternans in simulated heterogeneous cardiac tissue with a structural barrier. Academic Article uri icon

Overview

abstract

  • Structural barriers to wave propagation in cardiac tissue are associated with a decreased threshold for repolarization alternans both experimentally and clinically. Using computer simulations, we investigated the effects of a structural barrier on the onset of spatially concordant and discordant alternans. We used two-dimensional tissue geometry with heterogeneity in selected potassium conductances to mimic known apex-base gradients. Although we found that the actual onset of alternans was similar with and without the structural barrier, the increase in alternans magnitude with faster pacing was steeper with the barrier--giving the appearance of an earlier alternans onset in its presence. This is consistent with both experimental structural barrier findings and the clinical observation of T-wave alternans occurring at slower pacing rates in patients with structural heart disease. In ionically homogeneous tissue, discordant alternans induced by the presence of the structural barrier arose at intermediate pacing rates due to a source-sink mismatch behind the barrier. In heterogeneous tissue, discordant alternans occurred during fast pacing due to a barrier-induced decoupling of tissue with different restitution properties. Our results demonstrate a causal relationship between the presence of a structural barrier and increased alternans magnitude and action potential duration dispersion, which may contribute to why patients with structural heart disease are at higher risk for ventricular tachyarrhythmias.

publication date

  • November 17, 2006

Research

keywords

  • Action Potentials
  • Computer Simulation
  • Heart
  • Heart Conduction System
  • Models, Cardiovascular

Identity

PubMed Central ID

  • PMC1783878

Scopus Document Identifier

  • 33846829659

PubMed ID

  • 17114216

Additional Document Info

volume

  • 92

issue

  • 4