Activation delay in healed myocardial infarction: a comparison between model and experiment

Area of Science:

• Cardiac Electrophysiology
• Computational Biology
• Myocardial Infarction Research

Background:

• Conduction delay in healed myocardial infarction can facilitate reentry arrhythmias.
• This delay is often due to increased path length in surviving myocardial bundles.
• Bundle bifurcations represent critical sites for additional conduction delay.

Purpose of the Study:

• To investigate and characterize conduction delay at sites where cardiac bundles bifurcate.
• To model the electrophysiological behavior of activation spread in a simplified myocardial structure.

Main Methods:

• Development of a two-dimensional computer model simulating activation spread in excitable elements.
• Modeling a structure of merging and diverging bundles, specifically focusing on bifurcation points.
• Comparison of simulated extracellular electrograms with experimental data from a superfused infarcted papillary muscle model.

Main Results:

• Identification of a zone of local conduction delay (crowded isochrones) at bundle bifurcation sites.
• Observation that the positioning of isochrones was dependent on activation time determination methods.
• Demonstration that lines of activation delay were predominantly oriented perpendicular to the fiber direction.

Conclusions:

• The study enhances understanding of extracellular electrograms at critical "pivoting points" in the cardiac tissue.
• Activation sequences at a microscopic level are best reconstructed using Laplacian signals.
• Findings contribute to a better comprehension of arrhythmogenesis in infarcted myocardium.