Finite-element based optimization of left ventricular passive stiffness in normal volunteers and patients after myocardial infarction: Utility of an inverse deformation gradient calculation of regional diastolic strain.

ABSTRACT

INTRODUCTION: Left ventricular (LV) diastolic dysfunction (DD) is common after myocardial infarction (MI). Whereas current clinical assessment of DD relies on indirect markers including LV filling, finite element (FE) -based computational modeling directly measures regional diastolic stiffness. We hypothesized that an inverse deformation gradient (DG) method calculation of diastolic strain (IDGDS) allows the FE model-based calculation of regional diastolic stiffness (material parameters; MP) in post-MI patients with DD. METHODS: Cardiac magnetic resonance (CMR) with tags (CSPAMM) and late gadolinium enhancement (LGE) was performed in 10 patients with post-MI DD and 10 healthy volunteers. The 3-dimensional (3D) LV DG from end-diastole (ED) to early diastolic filling (EDF; DGED→EDF) was calculated from CSPAMM. Diastolic strain was calculated from DGEDF→ED by inverting the DGED→EDF. FE models were created with MI and non-MI (remote; RM) regions determined by LGE. Guccione MPs C, and exponential fiber, bf, and transverse, bt , terms were optimized with IDGDS strain. RESULTS: 3D circumferential and longitudinal diastolic strain (Ecc;Ell) calculated using IDGDS in CSPAMM obtained in volunteers and MI patients were [Formula see text]  = 0.27 ± 0.01, [Formula see text]  = 0.24 ± 0.03 and [Formula see text]  = 0.21 ± 0.02, and [Formula see text]  = 0.15 ± 0.02, respectively. MPs in the volunteer group were CH = 0.013 [0.001, 0.235] kPa, [Formula see text]  = 20.280 ± 4.994, and [Formula see text]  = 7.460 ± 2.171 and CRM = 0.0105 [0.010, 0.011] kPa, [Formula see text]  = 50.786 ± 13.511 (p = 0.0846), and [Formula see text]  = 17.355 ± 2.743 (p = 0.0208) in the remote myocardium of post-MI patients. CONCLUSION: Diastolic strain, calculated from CSPAMM with IDGDS, enables calculation of FE model-based regional diastolic material parameters. Transverse stiffness of the remote myocardium, , may be a valuable new metric for determination of DD in patients after MI.