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Period-doubling instability and memory in cardiac tissue
Jeffrey J Fox1, Eberhard Bodenschatz, Robert F Gilmour
1Department of Biomedical Sciences and Laboratory of Atomic and Solid State Physics, Cornell University, Ithaca, New York 14853, USA.
Physical Review Letters
|September 13, 2002
Summary
Alternans, a cardiac instability, may not depend on the restitution slope as previously thought. A new memory model explains alternans dynamics beyond simple restitution properties, challenging prior assumptions in cardiac electrophysiology.
Area of Science:
- Cardiac Electrophysiology
- Computational Biology
- Nonlinear Dynamics
Background:
- Alternans, or period-doubling instability of action potential duration, has been theoretically linked to restitution relation slopes greater than or equal to one.
- Recent experimental data challenge the predictive power of the restitution slope for alternans onset.
Purpose of the Study:
- To investigate the mechanisms underlying alternans beyond the traditional restitution theory.
- To compare a return map memory model with action potential data from an ionic model.
Main Methods:
- Developed and analyzed a return map memory model.
- Compared model dynamics to action potential data from a detailed ionic model.
- Employed linear stability analysis to determine the onset of alternans in the memory model.
Main Results:
- The memory model reproduced cardiac dynamics not explained by a unidimensional restitution relation.
- Linear stability analysis confirmed that the slope of the restitution curve was not predictive of alternans onset in the memory model.
- Demonstrated that memory effects are crucial for understanding alternans dynamics.
Conclusions:
- Alternans can arise from mechanisms not captured by the restitution slope alone.
- A return map memory model provides a more comprehensive explanation for alternans.
- Findings challenge the established view of restitution slope as the sole predictor of cardiac alternans.