Cardiac contraction induces discordant alternans and localized block

Area of Science:

• Cardiology
• Computational Biology
• Biophysics

Background:

• Cardiac alternans, alternations in action potential duration, occur at fast heart rates and are proarrhythmic.
• Excitation-contraction coupling links electrical activity to mechanical contraction in the heart.
• Understanding factors influencing alternans is crucial for preventing cardiac arrhythmias.

Purpose of the Study:

• To investigate the influence of tissue deformation on cardiac alternans dynamics using a simplified model.
• To determine how electromechanical coupling affects the transition between different types of alternans and conduction block.

Main Methods:

• Development and utilization of a simplified computational model of cardiac excitation-contraction coupling.
• Numerical simulations to observe alternans dynamics under varying conditions.
• Analytical methods to understand the underlying mechanisms of observed effects.

Main Results:

• Small stretch-activated currents can induce significant changes in alternans dynamics.
• Tissue deformation promotes a transition from in-phase (concordant) to off-phase (discordant) alternans.
• Electromechanical coupling alters the conduction velocity restitution curve, leading to conduction blocks.

Conclusions:

• Cardiac excitation-contraction coupling plays a potentially significant role in the development of arrhythmias.
• Deformation-induced changes in alternans dynamics may contribute to the initiation of reentry and fibrillation.
• The study highlights the importance of considering electromechanical interactions in cardiac electrophysiology.