Abstract
Spiral waves of excitation in cardiac tissue are associated with life-threatening cardiac arrhythmias. It is, therefore, important to study the electrophysiological factors that affect the dynamics of these spiral waves. By using an electrophysiologically detailed mathematical model of a myocyte (cardiac cell), we study the effects of cellular parameters, such as membrane-ion-channel conductances, on the properties of the action-potential (AP) of a myocyte. We then investigate how changes in these properties, specifically the upstroke velocity and the AP duration (APD), affect the frequency ω of a spiral wave in the mathematical model that we use for human-ventricular tissue. We find that an increase (decrease) in this upstroke-velocity or a decrease (increase) in the AP duration increases (decreases) ω. We also study how other intercellular factors, such as the fibroblast-myocyte coupling, diffusive coupling strength, and the effective number of neighboring myocytes and fibroblasts, modulate ω. Finally, we demonstrate how a spiral wave can drift to a region with a high density of fibroblasts. Our results provide a natural explanation for the anchoring of spiral waves in highly fibrotic regions in fibrotic hearts.
Highlights
Nonlinear waves in the form of rotating spirals are ubiquitous spatiotemporal patterns that occur in a variety of biological or physical systems; these include chemical-reaction waves in the BelousovZhabotansky system [1,2,3,4,5], oxidation waves of carbon monoxide on the surface of platinum [6,7,8], calcium-signalling waves in Xenopus oocytes [9], cyclic-AMP signalling waves in the aggregration process of Dictyostelium discoideum [10, 11], and, notably, action-potential (AP) waves that mediate muscle contraction in cardiac tissue
The cell membrane of a myocyte is embedded with various ion channels, which we list in Table 1; Vm depends on the currents through these ion channels (Eq 1), so, if we vary the conductances of these channels, we can modulate the AP of the myocyte
We find that increasing GCaL (GKr) increases the AP duration (APD), whereas GNa has no significant effect on the APD (Figure 1B)
Summary
Nonlinear waves in the form of rotating spirals are ubiquitous spatiotemporal patterns that occur in a variety of biological or physical systems; these include chemical-reaction waves in the BelousovZhabotansky system [1,2,3,4,5], oxidation waves of carbon monoxide on the surface of platinum [6,7,8], calcium-signalling waves in Xenopus oocytes [9], cyclic-AMP signalling waves in the aggregration process of Dictyostelium discoideum [10, 11], and, notably, action-potential (AP) waves that mediate muscle contraction in cardiac tissue The organization of these AP waves in the form of spirals or scrolls in cardiac tissue is associated with abnormal and life-threatening heart rhythms known as arrhythmias. There are multiple mechanisms through which spiral waves can occur in cardiac tissue [12,13,14,15,16,17,18]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
