Abstract
The heart is an elastic excitable medium, in which mechanical contraction is triggered by nonlinear waves of electrical excitation, which diffuse rapidly through the heart tissue and subsequently activate the cardiac muscle cells to contract. These highly dynamic excitation wave phenomena have yet to be fully observed within the depths of the heart muscle, as imaging technology is unable to penetrate the tissue and provide panoramic, three-dimensional visualizations necessary for adequate study. As a result, the electrophysiological mechanisms that are associated with the onset and progression of severe heart rhythm disorders such as atrial or ventricular fibrillation remain insufficiently understood. Here, we present a novel synchronization-based data assimilation approach with which it is possible to reconstruct excitation wave dynamics within the volume of elastic excitable media by observing spatiotemporal deformation patterns, which occur in response to excitation. The mechanical data are assimilated in a numerical replication of the measured elastic excitable system, and within this replication, the data drive the intrinsic excitable dynamics, which then coevolve and correspond to a reconstruction of the original dynamics. We provide a numerical proof-of-principle and demonstrate the performance of the approach by recovering even complicated three-dimensional scroll wave patterns, including vortex filaments of electrical excitation from within a deformable bulk tissue with fiber anisotropy. In the future, the reconstruction approach could be combined with high-speed imaging of the heart's mechanical contractions to estimate its electrophysiological activity for diagnostic purposes.
Highlights
The beating of the heart is orchestrated by nonlinear waves of electrical excitation, which propagate rapidly through the heart muscle and trigger a release of intracellular calcium, which in turn fuels the contractions of cardiac muscle cells
We performed more than 10 000 simulations and coupled elastic excitable system 2 to the dynamics that evolved in system 1 as described in Sec
We provided a numerical proof-of-principle, which shows that it is possible to reconstruct various electrical excitation wave dynamics evolving in two- and three-dimensional anisotropic elastic excitable media, from elementary focal and planar waves to spiral and scroll waves, to even complicated spatiotemporal chaos, solely by observing soft-tissue mechanics
Summary
The beating of the heart is orchestrated by nonlinear waves of electrical excitation, which propagate rapidly through the heart muscle and trigger a release of intracellular calcium, which in turn fuels the contractions of cardiac muscle cells. During severe heart rhythm disorders such as atrial or ventricular brillation, the electrical excitation degenerates into complex, unorganized wave patterns, which scitation.org/journal/cha cause highly irregular mechanical activations of the heart muscle. To date, no imaging technique exists, which can provide adequate in-depth visualizations of the three-dimensional, intracardiac electrical wave phenomena, in particular, during cardiac brillation. The electrical activation can be measured noninvasively, but rather indirectly, on the heart surface of patients using inverse electrocardiography.. Inverse electrocardiographic techniques provide indirect measurements, the electrical activation patterns are calculated from a plurality of electrocardiograms measured on the body surface, and the technique’s accuracy and ability to resolve arrhythmias are under debate.. The only way to measure the electrical activity directly within the heart muscle is to use plunge needle electrodes or needle catheters.. In addition to direct measurement techniques, inverse computational approaches have been proposed to estimate the electrical activity within the cardiac muscle, from super cial or sparse electrical measurement data as well as from mechanical deformation data.
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