A finite element model-based optimization method successfully estimated regional myocardial contractility in vivo in under 5 hours, with depressed borderzone contractility confirmed ex vivo.
A computationally efficient FE model-based method using tagged MRI and catheterization pressures can accurately estimate regional myocardial contractility in vivo in under 5 hours.
A non-invasive method for estimating regional myocardial contractility in vivo would be of great value in the design and evaluation of new surgical and medical strategies to treat and/or prevent infarction-induced heart failure. As a first step towards developing such a method, an explicit finite element (FE) model-based formal optimization of regional myocardial contractility in a sheep with left ventricular (LV) aneurysm was performed using tagged magnetic resonance (MR) images and cardiac catheterization pressures. From the tagged MR images, 3-dimensional (3D) myocardial strains, LV volumes and geometry for the animal-specific 3D FE model of the LV were calculated, while the LV pressures provided physiological loading conditions. Active material parameters (T (maxB) and T (maxR) ) in the non-infarcted myocardium adjacent to the aneurysm (borderzone) and in myocardium remote from the aneurysm were estimated by minimizing the errors between FE model-predicted and measured systolic strains and LV volumes using the successive response surface method for optimization. The significant depression in optimized T (maxB) relative to T (maxR) was confirmed by direct ex vivo force measurements from skinned fiber preparations. The optimized values of T (maxB) and T (maxR) were not overly sensitive to the passive material parameters specified. The computation time of less than 5 hours associated with our proposed method for estimating regional myocardial contractility in vivo makes it a potentially very useful clinical tool.
Sun et al. (2009) studied Left ventricular aneurysm (n=1). Finite element model-based formal optimization using tagged MR images and cardiac catheterization pressures vs. Direct ex vivo force measurements was evaluated on Regional myocardial contractility (active material parameters T(max_B) and T(max_R)). A finite element model-based optimization method successfully estimated regional myocardial contractility in vivo in under 5 hours, with depressed borderzone contractility confirmed ex vivo.