Spiral Wave Initiation in an Electromechanical Model for Human Cardiac Tissue
Statistical Physics, Nonlinear Dynamics, Complex Systems, Soft and Fluid Matter, Biological Physics
Final Report Abstract
Heart failure due to cardiac arrhythmias is a major cause of death in the industrialized world. One of the main mechanisms for the onset of cardiac arrhythmia is due to reentrant electrical activity ”spiral waves” in the cardiac muscle. It is known that the deformation of cardiac tissue plays an important role in the onset of cardiac arrhythmias. However, the underlying mechanisms are not well understood. The aim of this project was to use a novel discrete mechanical model for human cardiac tissue to identify and study mechanisms of mechanical spiral wave initiation in cardiac tissue. The research resulted in two novel mechanisms for mechanical spiral wave initiation in the cardiac muscle. The first mechanism explains how an external mechanical load can induce wavebreak and spiral activity in cardiac tissue. We show that wavebreak can occur due to front-back collisions and wave front dissipation due to the effect of stretch on wave velocity. This result may be very important, as it is known for more than onehundred years that a punch on the chest of a healthy individual can induce severe cardiac arrhythmias. However, the underlying mechanisms of mechanical spiral wave initiation in cardiac tissue are not fully understood. The second mechanism of spiral wave initiation which was found in this project is due a so-called ”dynamical instability” - where a repeated stimulation of the cardiac tissue results in wavebreak and spiral initiation. So far only one type of dynamical instability of waves in cardiac tissue was studied in details, so called alternans phenomena. Here we identified for the first time that dynamical instability can emerge from mechanical determinants and is not related to the alternans phenomenon. It also occurs due to the effect of deformation on the velocity of a wave, however, compared to the first mechanism it does not require external stretch of the tissue. We show that this ”mechanically caused dynamical instability” causes wavebreak and spiral wave activity for much lower stimulation frequencies than the classical alternans phenomenon. Our fundamental findings on the theory of mechanical spiral wave initiation may have substantial long-term implications. Once an instability is understood, possible targets for drug development can be identified (for instance ion channel blockers). Thus, the results achieved in this project may lead to a better treatment and prevention of cardiac arrhythmias in the future.
Publications
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(2015) A theory for spiral wave drift under mechano-electrical feedback. New Journal of Physics 17: 043055
Dierckx H, Arens S, Li B, Weise LD, Panfilov AV
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Discrete Mechanical Modeling of Mechanoelectrical Feedback in Cardiac Tissue: Novel Mechanisms of Spiral Wave Initiation. In: Modeling the Heart and the Circulatory System 14 (Ed. Quarteroni A), chapter 2 (pp. 29-50). Springer International Publishing. 2015
Weise LD, Panfilov AV
