Department of Aerospace & Mechanical Engineering, University of Southern California, Los Angeles, USA.
Department of Aerospace & Mechanical Engineering, University of Southern California, Los Angeles, USA; Division of Cardiovascular Medicine, Department of Medicine, Keck School of Medicine, University of Southern California, Los Angeles, USA.
J Biomech. 2021 Dec 2;129:110852. doi: 10.1016/j.jbiomech.2021.110852. Epub 2021 Oct 31.
Intrinsic Frequency (IF) is a systems-based approach that provides valuable information for hemodynamic monitoring of the left ventricle (LV), the arterial system, and their coupling. Recent clinical studies have demonstrated the clinical significance of this method for prognosis and diagnosis of cardiovascular diseases. In IF analysis, two dominant instantaneous frequencies (ω and ω) are extracted from arterial pressure waveforms. The value of ω is related to the dynamics of the LV and the value of ω is related to the dynamics of vascular function. This work investigates the effects of vessel wall mechanics on the accuracy and applicability of IFs extracted from vessel wall displacement waveforms compared to IFs extracted from pressure waveforms. In this study, we used a computational approach employing a fluid-structure interaction finite element method for various wall mechanics governed by linearly elastic, hyperelastic, and viscoelastic models. Results show that for vessels with elastic wall behavior, the error between displacement-based and pressure-based IFs is negligible. In the presence of stenosis or aneurysm in elastic arteries, the maximum errors associated with displacement-based IFs is less than 2%. For non-linear elastic and viscoelastic arteries, errors are more pronounced (where the former reaches up to 11% and the latter up to 27%). Our results ultimately suggest that displacement-based computations of ω and ω are accurate in vessels that exhibit elastic behavior (such as carotid arteries) and are suitable surrogates for pressure-based IFs. This is clinically significant because displacement-based IFs can be measured non-invasively.
固有频率（IF）是一种基于系统的方法，可为左心室（LV）、动脉系统及其耦合的血液动力学监测提供有价值的信息。最近的临床研究表明，该方法对心血管疾病的预后和诊断具有临床意义。在 IF 分析中，从动脉压力波形中提取两个主要的瞬时频率（ω 和 ω）。ω 的值与 LV 的动力学有关，而 ω 的值与血管功能的动力学有关。这项工作研究了血管壁力学对从血管壁位移波形中提取的 IF 与从压力波形中提取的 IF 的准确性和适用性的影响。在这项研究中，我们使用了一种计算方法，采用流体-结构相互作用有限元法，对由线弹性、超弹性和粘弹性模型控制的各种壁力学进行了研究。结果表明，对于具有弹性壁行为的血管，基于位移的 IF 与基于压力的 IF 之间的误差可以忽略不计。在弹性动脉存在狭窄或动脉瘤的情况下，基于位移的 IF 最大误差小于 2%。对于非线性弹性和粘弹性动脉，误差更为明显（前者最高可达 11%，后者最高可达 27%）。我们的结果最终表明，在表现出弹性行为的血管（如颈动脉）中，基于位移的 ω 和 ω 的计算是准确的，并且可以作为基于压力的 IF 的合适替代品。这在临床上具有重要意义，因为基于位移的 IF 可以进行非侵入性测量。
