central problem in biomechanical studies of personalized human left ventricular (LV) modelling is to\nestimate material properties from in vivo clinical measurements. In this work we evaluate the passive myocardial\nmechanical properties inversely from the in vivo LV chamber pressureââ?¬â??volume and strain data. The LV myocardium\nis described using a structure-based orthotropic Holzapfelââ?¬â??Ogden constitutive law with eight parameters. In the\nfirst part of the paper we demonstrate how to use a multi-step non-linear least-squares optimization procedure to\ninversely estimate the parameters from the pressureââ?¬â??volume and strain data obtained from a synthetic LV model\nin diastole. In the second part, we show that to apply this procedure to clinical situations with limited in vivo\ndata, additional constraints are required in the optimization procedure. Our study, based on three different healthy\nvolunteers, demonstrates that the parameters of the Holzapfelââ?¬â??Ogden law could be extracted from pressureââ?¬â??volume\nand strain data with a suitable multi-step optimization procedure. Although the uniqueness of the solution cannot\nbe addressed using our approaches, the material response is shown to be robustly determined.
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