Heart Rhythm Insights Into Structural Remodeling in Atrial Tissue: Timed Automata Approach

Abstract

The heart rhythm of a person following heart transplantation (HTX) is assumed to display an intrinsic cardiac rhythm because it is significantly less influenced by the autonomic nervous system—the main source of heart rate variability in healthy people. Therefore, such a rhythm provides evidence for arrhythmogenic processes developing, usually silently, in the cardiac tissue. A model is proposed to simulate alterations in the cardiac tissue and to observe the effects of these changes on the resulting heart rhythm. The hybrid automata framework used makes it possible to represent reliably and simulate efficiently both the electrophysiology of a cardiac cell and the tissue organization. The curve fitting method used in the design of the hybrid automaton cycle follows the well-recognized physiological phases of the atrial myocyte membrane excitation. Moreover, knowledge of the complex architecture of the right atrium, the ability of the almost free design of intercellular connections makes the automata approach the only one possible. Two particular aspects are investigated: impairment of the impulse transmission between cells and structural changes in intercellular connections. The first aspect models the observed fatigue of cells due to specific cardiac tissue diseases. The second aspect simulates the increase in collagen deposition with aging. Finally, heart rhythms arising from the model are validated with the sinus heart rhythms recorded in HTX patients. The modulation in the impairment of the impulse transmission between cells reveals qualitatively the abnormally high heart rate variability observed in patients living long after HTX.

The Reversal Effect of Sigma-1 Receptor (S1R) Agonist, SA4503, on Atrial Fibrillation After Depression and Its Underlying Mechanism

“…Wavelength theory suggests that reentry can be disrupted by increasing either the CV or the tissue refractory properties (Igarashi et al, 2012). Electrical and structural remodeling severely interfere with impulse transmission (Makowiec et al, 2018), contributing to abnormal electrical signal propagation. The lack of electrical connection contributes to desynchronized cardiac activation and contraction, as in connexins 40 and 43, the principle atrial gap junction proteins (Davis et al, 1994).…”

Patterns of Heart Rate Dynamics in Healthy Aging Population: Insights from Machine Learning Methods

“…Therefore, the abnormal levels of short term HRV indices observed are supposed to be related to so-called erratic rhythms, i.e., rhythms probably resulting from remodeling of the cardiac tissue [ 10 , 21 , 53 , 54 , 55 ]. Accordingly, the higher HRV values cannot be attributed solely to the better organization of the feedback reflexes driving the organism’s response to the actual body needs, but rather, the characteristics of the cardiac cells and the structure of their interconnections should be taken into account [ 56 ].…”

Unified mechanism of local drivers in a percolation model of atrial fibrillation

“…Discrete models of cardiac tissue are well established historically and have recently regained popularity [23,[25][26][27][28][29][30][31][32]. In these models, the onset of reentry has been associated with the approach from above of the bond occupation probability to the percolation threshold [29].…”