Characterizing Intracranial Hemodynamics in Sickle Cell Anemia: Impact of Patient-Specific Viscosity,Cardiovascular Engineering and Technology

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Characterizing Intracranial Hemodynamics in Sickle Cell Anemia: Impact of Patient-Specific Viscosity
Cardiovascular Engineering and Technology ( IF 1.8 ) Pub Date : 2021-07-20 , DOI: 10.1007/s13239-021-00559-2
Sara B Keller ₁ , Jacob M Bumpus _{2,

3} , J Christopher Gatenby ₄ , Elizabeth Yang ₅ , Adetola A Kassim ₆ , Carlton Dampier ₇ , John C Gore _{2,

8,

9} , Amanda K W Buck _{2,

8,

10}

Affiliation

Department of Bioengineering, University of Washington, Seattle, WA, USA.
Department of Biomedical Engineering, Vanderbilt University, Nashville, TN, USA.
Northgate Technologies, Inc, Elgin, IL, USA.
Department of Radiology, University of Washington, Seattle, WA, USA.
Center for Cancer and Blood Disorders, Pediatric Specialists of Virginia, Fairfax, VA, USA.
Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA.
Department of Pediatrics, Emory University and Aflac Cancer and Blood Disorders Center, Children's Healthcare of Atlanta, Atlanta, GA, USA.
Vanderbilt University Institute of Imaging Science, Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, TN, USA.
Department of Physics and Astronomy, Vanderbilt University, Nashville, TN, USA.
Vanderbilt University Medical Center, 1161 21st Avenue South, Medical Center North, AA-1105, Nashville, TN, 37232-2310, USA.

Purpose

Pediatric and adult patients with sickle cell anemia (SCA) are at increased risk of stroke and cerebrovascular accident. In the general adult population, there is a relationship between arterial hemodynamics and pathology; however, this relationship in SCA patients remains to be elucidated. The aim of this work was to characterize circle of Willis hemodynamics in patients with SCA and quantify the impact of viscosity choice on pathophysiologically-relevant hemodynamics measures.

Methods

Based on measured vascular geometries, time-varying flow rates, and blood parameters, detailed patient-specific simulations of the circle of Willis were conducted for SCA patients (n = 6). Simulations quantified the impact of patient-specific and standard blood viscosities on wall shear stress (WSS).

Results

These results demonstrated that use of a standard blood viscosity introduces large errors into the estimation of pathophysiologically-relevant hemodynamic parameters. Standard viscosity models overpredicted peak WSS by 55% and 49% for steady and pulsatile flow, respectively. Moreover, these results demonstrated non-uniform, spatial patterns of positive and negative WSS errors related to viscosity, and standard viscosity simulations overpredicted the time-averaged WSS by 32% (standard deviation = 7.1%). Finally, differences in shear rate demonstrated that the viscosity choice alters the simulated near-wall flow field, impacting hemodynamics measures.

Conclusions

This work presents simulations of circle of Willis arterial flow in SCA patients and demonstrates the importance and feasibility of using a patient-specific viscosity in these simulations. Accurately characterizing cerebrovascular hemodynamics in SCA populations has potential for elucidating the pathophysiology of large-vessel occlusion, aneurysms, and tissue damage in these patients.

中文翻译：

表征镰状细胞性贫血的颅内血流动力学：患者特定粘度的影响

目的

患有镰状细胞性贫血 (SCA) 的儿科和成人患者中风和脑血管意外的风险增加。在一般成年人群中，动脉血流动力学和病理学之间存在关系；然而，SCA 患者中的这种关系仍有待阐明。这项工作的目的是描述 SCA 患者的 Willis 循环血流动力学特征，并量化粘度选择对病理生理学相关血流动力学测量的影响。

方法

根据测量的血管几何形状、随时间变化的流速和血液参数，对 SCA 患者 ( n = 6) 进行了详细的患者特异性 Willis 环模拟。模拟量化了患者特定和标准血液粘度对壁剪切应力 (WSS) 的影响。

结果

这些结果表明，使用标准血液粘度会给与病理生理学相关的血流动力学参数的估计带来很大的误差。对于稳定和脉动流，标准粘度模型分别高估了峰值 WSS 55% 和 49%。此外，这些结果表明与粘度相关的正负 WSS 误差的非均匀空间模式，并且标准粘度模拟将时间平均 WSS 高估了 32%（标准偏差 = 7.1%）。最后，剪切速率的差异表明粘度选择会改变模拟的近壁流场，从而影响血流动力学测量。