Complex patterns of subcellular cardiac alternans.

Area of Science:

• Cardiovascular physiology
• Computational biology
• Biophysics

Background:

• Cardiac alternans precede fatal arrhythmias like sudden cardiac death.
• Microscopic alternans are early indicators, preceding fully developed alternans.
• Understanding alternans onset is crucial for preventing cardiac events.

Purpose of the Study:

• To model and investigate microscopic calcium alternans.
• To explore the impact of calcium diffusion on alternans formation.
• To identify novel mechanisms driving cardiac alternans.

Main Methods:

• Developed a computational model for intracellular calcium dynamics.
• Investigated effects of cytosolic and sarcoplasmic reticulum calcium diffusion.
• Employed semi-analytical and computational techniques to analyze stability regions.

Main Results:

• Cytosolic coupling leads to alternans via period doubling bifurcation.
• Luminal coupling results in a novel saddle-node bifurcation pathway.
• Emergent calcium patterns change abruptly at stability boundaries.

Conclusions:

• Microscopic calcium alternans exhibit complex dynamics.
• Luminal calcium plays a significant role in cardiac calcium dynamics.
• This study reveals new insights into the origins of cardiac alternans.