Spatially heterogeneous ionic remodelling promotes wavefront instability in simulated atrial tissue

Area of Science:

• Computational biology
• Cardiac electrophysiology
• Medical modeling

Background:

• Atrial fibrillation (AF) development is linked to electrical remodeling.
• Remodeling is typically modeled as a global change in atrial parameters.
• Spatially heterogeneous electrical remodeling is less explored computationally.

Purpose of the Study:

• To investigate the impact of spatially heterogeneous electrical remodeling on cardiac tissue.
• To explore if non-uniform remodeling can initiate or sustain fibrillatory behavior.
• To simulate AF progression using computational models.

Main Methods:

• Utilized an established human atrial action potential model.
• Incorporated parameters for both sinus rhythm and chronic atrial fibrillation.
• Simulated spatially heterogeneous remodeling using the 2D Ising model.
• Analyzed tissue behavior under various pacing frequencies.

Main Results:

• A mixture of remodeled and non-remodelled regions destabilized simulated atrial tissue at high pacing frequencies.
• Observed a window of pacing frequencies sustaining turbulent wave propagation.
• Demonstrated sustained turbulent transients when adapting from low to high pacing rates.
• Identified wavefront breakup as a mechanism for turbulent behavior.

Conclusions:

• Spatially heterogeneous remodeling can promote atrial fibrillation initiation.
• Partially remodeled tissue may represent an intermediate stage in AF progression.
• This provides a potential mechanism for 'atrial fibrillation begets atrial fibrillation'.