Phase response curve based model of the SA node: simulation by two-dimensional array of pacemaker cells with randomly...

Area of Science:

• Computational biology
• Cardiac electrophysiology
• Mathematical modeling

Background:

• The sinoatrial (SA) node governs heart rhythm through the coordinated activity of pacemaker cells.
• Understanding SA node dynamics is crucial for diagnosing and treating cardiac arrhythmias.

Purpose of the Study:

• To simulate the SA node's electrical activity using a 2D array model.
• To investigate the impact of pacemaker cell properties and their interactions on SA node function.

Main Methods:

• A 15x15 2D array model of randomly distributed pacemaker cells was developed.
• The model incorporated intrinsic cycle length and phase response curves (PRC) to simulate cell interactions.
• The simulation analyzed global dynamics, conduction velocity, and responses to perturbations like vagal stimulation.

Main Results:

• SA node global dynamics and disorder are significantly affected by cycle length distribution and spatial inhomogeneity in electrical coupling (PRC).
• These factors determine conduction velocity and can explain anisotropic conduction within the SA node.
• Model perturbations, such as a vagal pulse, correctly induced pacemaker site shifts and transient heart rate changes.

Conclusions:

• Pacemaker cell properties and their spatial arrangement are critical determinants of SA node rhythm and electrical propagation.
• The simulation model provides insights into the mechanisms underlying normal SA node function and anisotropic conduction.
• This computational approach can help elucidate the basis of cardiac arrhythmias originating from SA node dysfunction.