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This Article Full Text Full Text (PDF) All Versions of this Article: 297/3/H1058    most recent 01334.2008v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Google Scholar Articles by Bovendeerd, P. H. M. Articles by Delhaas, T. PubMed PubMed Citation Articles by Bovendeerd, P. H. M. Articles by Delhaas, T.

Determinants of left ventricular shear strain

¹Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven; and ²Cardiovascular Research Institute Maastricht, Maastricht University, Maastricht, The Netherlands

Submitted 28 December 2008 ; accepted in final form 8 July 2009

Mathematical models of cardiac mechanics can potentially be used to relate abnormal cardiac deformation, as measured noninvasively by ultrasound strain rate imaging or magnetic resonance tagging (MRT), to the underlying pathology. However, with current models, the correct prediction of wall shear strain has proven to be difficult, even for the normal healthy heart. Discrepancies between simulated and measured strains have been attributed to 1) inadequate modeling of passive tissue behavior, 2) neglecting active stress development perpendicular to the myofiber direction, or 3) neglecting crossover of myofibers in between subendocardial and subepicardial layers. In this study, we used a finite-element model of left ventricular (LV) mechanics to investigate the sensitivity of midwall circumferential-radial shear strain (E_cr) to settings of parameters determining passive shear stiffness, cross-fiber active stress development, and transmural crossover of myofibers. Simulated time courses of midwall LV E_cr were compared with time courses obtained in three healthy volunteers using MRT. E_cr as measured in the volunteers during the cardiac cycle was characterized by an amplitude of 0.1. In the simulations, a realistic amplitude of the E_cr signal could be obtained by tuning either of the three model components mentioned above. However, a realistic time course of E_cr, with virtually no change of E_cr during isovolumic contraction and a correct base-to-apex gradient of E_cr during ejection, could only be obtained by including transmural crossover of myofibers. Thus, accounting for this crossover seems to be essential for a realistic model of LV wall mechanics.

magnetic resonance tagging; finite-element model; cardiac mechanics; myofiber angle