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

中文翻译：

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健康心肌的 Holzapfel-Ogden 定律中的参数估计

个性化人类左心室 (LV) 建模的生物力学研究的一个核心问题是从体内临床测量中估计材料特性。在这项工作中，我们从体内 LV 室压力-容积和应变数据反向评估被动心肌机械特性。LV 心肌使用基于结构的正交各向异性 Holzapfel-Ogden 本构定律和八个参数进行描述。在本文的第一部分中，我们演示了如何使用多步非线性最小二乘优化程序从舒张期合成 LV 模型中获得的压力-体积和应变数据中反向估计参数。在第二部分中，我们展示了将该程序应用于体内数据有限的临床情况，优化程序中需要额外的约束。我们的学习，基于三个不同的健康志愿者，证明可以通过合适的多步优化程序从压力-体积和应变数据中提取 Holzapfel-Ogden 定律的参数。尽管使用我们的方法无法解决解决方案的独特性，但材料响应已被证明是可靠确定的。