Department of Mechanical Engineering and Materials Science, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America.
Physiol Meas. 2018 Feb 1;39(1):015006. doi: 10.1088/1361-6579/aa9f46.
Blood flow waveforms-essential data for hemodynamic modeling-are often in practice unavailable to researchers. The objectives of this work were to assess the variability among the waveforms for a clinically relevant older population, and develop data-based methods for addressing the missing waveform data for hemodynamic studies.
We analyzed 272 flow waveforms from the internal carotid arteries of older patients (73 ± 13 yr) with moderate cardiovascular disease, and used these data to develop methods to guide new approaches for hemodynamic studies.
Profound variations in waveform parameters were found within the aged population that were not seen in published data for young subjects. Common features in the aged population relative to the young included a larger systole-to-diastole flow rate ratio, increased flow during late systole, and absence of a dicrotic notch. Eight waveforms were identified that collectively represent the range of waveforms in the older population. A relationship between waveform shape and flow rate was obtained that, in conjunction with equations relating flow rate to diameter, can be used to provide individualized waveforms for patient-specific geometries. The dependence of flow rate on diameter was statistically different between male and female patients.
It was shown that a single archetypal waveform cannot well-represent the diverse waveforms found within an aged population, although this approach is frequently used in studies of flow in the cerebral vasculature. Motivated by these results, we provided a set of eight waveforms that can be used to assess the hemodynamic uncertainty associated with the lack of patient-specific waveform data. We also provided a methodology for generating individualized waveforms when patient gender, age, and cardiovascular disease state are known. These data-driven approaches can be used to devise more relevant in vitro or in silico intra-cranial hemodynamic studies for older patients.
血流波形是血流动力学建模的基本数据，但在实践中，研究人员往往无法获得这些数据。本研究旨在评估临床相关老年人群的波形变异性，并开发基于数据的方法来解决血流动力学研究中缺失的波形数据。
我们分析了 272 名患有中度心血管疾病的老年患者（73±13 岁）颈内动脉的血流波形，并利用这些数据开发了方法，为血流动力学研究提供新的指导思路。
在老年人群中发现了波形参数的显著变化，这些变化在年轻受试者的文献数据中并未出现。与年轻人群相比，老年人群的常见特征包括收缩期到舒张期流量比增大、收缩后期流量增加以及没有二尖切迹。确定了 8 个波形，它们共同代表了老年人群的波形范围。获得了波形形状与流量之间的关系，结合将流量与直径相关联的方程，可以用于为特定患者的几何形状提供个性化的波形。流量对直径的依赖性在男性和女性患者之间存在统计学差异。
结果表明，尽管在大脑血管血流研究中经常使用单一的典型波形来表示，但这种方法不能很好地代表老年人群中发现的多样化波形。受这些结果的启发，我们提供了一组 8 个波形，可以用来评估缺乏特定患者波形数据所带来的血流动力学不确定性。我们还提供了一种在已知患者性别、年龄和心血管疾病状态的情况下生成个性化波形的方法。这些基于数据的方法可以用于设计更相关的针对老年患者的体外或体内颅内血流动力学研究。
