Cardiac excitation mechanisms, wavefront dynamics and strength–interval curves predicted by 3D orthotropic bidomain simulations

► We compute anodal and cathodal strength–interval curves by 3D bidomain simulations. ► The results show detailed excitation patterns elicited by break and make responses. ► We identify novel excitation mechanisms at the break/make transition of the S–I curves. ► The model includes intramural fiber...

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Published inMathematical biosciences Vol. 235; no. 1; pp. 66 - 84
Main Authors Colli Franzone, P., Pavarino, L.F., Scacchi, S.
Format Journal Article
LanguageEnglish
Published United States Elsevier Inc 01.01.2012
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Summary:► We compute anodal and cathodal strength–interval curves by 3D bidomain simulations. ► The results show detailed excitation patterns elicited by break and make responses. ► We identify novel excitation mechanisms at the break/make transition of the S–I curves. ► The model includes intramural fiber rotation and orthotropic anisotropy. ► The LRd model is augmented with the electroporation, outward, and funny currents. The assessment and understanding of cardiac excitation mechanisms is very important for the development and improvement of implantable cardiac devices, pacing protocols, and arrhythmia treatments. Previous bidomain simulation studies have investigated cathodal and anodal make/break mechanisms of cardiac excitation and strength–interval (S–I) curves in two-dimensional sheets or cylindrical domains, that by symmetry reduce to the two-dimensional case. In this work, cathodal and anodal S–I curves are studied by means of detailed bidomain simulations which include: (i) three-dimensional cardiac slabs; (ii) transmural fiber rotation; (iii) unequal orthotropic anisotropy of the conducting media; (iv) incorporation of funny and electroporation currents in the ventricular membrane model. The predicted shape of cathodal and anodal S–I curves exhibit the same features of the S–I curves observed experimentally and the break/make transition coincides with the final descending phase of the S–I curves. Away from the break/make transition, only the break or make excitation mechanism is observed independently of the stimulus strength, whereas within an interval at the break/make transition, new paradoxical excitation behaviors are observed that depend on the stimulus strength.
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ISSN:0025-5564
1879-3134
DOI:10.1016/j.mbs.2011.10.008