Abstract：
BACKGROUND: Nutcracker syndrome is a disease characterized by complex symptoms, making its diagnosis challenging and often delayed, often resulting in a painful experience for the patients.
OBJECTIVE: This study aimed to investigate the pathogenesis of nutcracker syndrome through the perspective of hemodynamics by simulating blood flow with varying compression degrees of the left renal vein.
METHODS: 3D patient-specific vascular models of the abdominal aorta, superior mesenteric artery and left renal vein were constructed based on CT images of patients suspected of having nutcracker syndrome. A hemodynamic simulation was then conducted using computational fluid dynamics to identify the correlation between alterations in hemodynamic parameters and varying degrees of compression.
RESULTS: The study indicated the presence of an evident gradient in velocity distribution over the left renal vein with relatively high degrees of stenosis (α ≤ 50°), with maximum velocity in the central region of the stenosis. Additionally, when the compression degree of the left renal vein increases, the pressure distribution of the left renal vein presents an increasing number of gradient layers. Furthermore, the wall shear stress shows a correlation with the variation of blood flow velocity, i.e., the increase of wall shear stress correlates with the acceleration of the blood flow velocity.
CONCLUSIONS: Using computational fluid dynamics as a non-invasive instrument to obtain the hemodynamic characteristics of nutcracker syndrome is feasible and could provide insights into the pathological mechanisms of the nutcracker syndrome supporting clinicians in diagnosis.
OBJECTIVE: This study aimed to investigate the pathogenesis of nutcracker syndrome through the perspective of hemodynamics by simulating blood flow with varying compression degrees of the left renal vein.
METHODS: 3D patient-specific vascular models of the abdominal aorta, superior mesenteric artery and left renal vein were constructed based on CT images of patients suspected of having nutcracker syndrome. A hemodynamic simulation was then conducted using computational fluid dynamics to identify the correlation between alterations in hemodynamic parameters and varying degrees of compression.
RESULTS: The study indicated the presence of an evident gradient in velocity distribution over the left renal vein with relatively high degrees of stenosis (α ≤ 50°), with maximum velocity in the central region of the stenosis. Additionally, when the compression degree of the left renal vein increases, the pressure distribution of the left renal vein presents an increasing number of gradient layers. Furthermore, the wall shear stress shows a correlation with the variation of blood flow velocity, i.e., the increase of wall shear stress correlates with the acceleration of the blood flow velocity.
CONCLUSIONS: Using computational fluid dynamics as a non-invasive instrument to obtain the hemodynamic characteristics of nutcracker syndrome is feasible and could provide insights into the pathological mechanisms of the nutcracker syndrome supporting clinicians in diagnosis.
摘要：
背景：胡桃夹综合征是一种以复杂症状为特征的疾病，使其诊断具有挑战性并且经常延迟，通常会给患者带来痛苦的经历。
目的：本研究通过模拟左肾静脉不同受压程度的血流，从血流动力学的角度探讨胡桃夹综合征的发病机制。
方法：腹主动脉的3D患者特异性血管模型，根据疑似胡桃夹综合征患者的CT图像构建肠系膜上动脉和左肾静脉。然后使用计算流体动力学进行血液动力学模拟，以确定血液动力学参数的变化与不同程度的压缩之间的相关性。
结果：研究表明，左肾静脉上存在明显的速度分布梯度，狭窄程度相对较高（α≤50°），在狭窄的中央区域具有最大速度。此外,当左肾静脉的压缩程度增加时，左肾静脉的压力分布呈现增加的梯度层数量。此外，壁面剪应力与血流速度的变化具有相关性,即，壁面剪应力的增加与血流速度的加速有关。
结论：使用计算流体动力学作为一种非侵入性工具来获得胡桃夹综合征的血流动力学特征是可行的，可以提供对胡桃夹综合征的病理机制的见解，支持临床医生的诊断。
目的：本研究通过模拟左肾静脉不同受压程度的血流，从血流动力学的角度探讨胡桃夹综合征的发病机制。
方法：腹主动脉的3D患者特异性血管模型，根据疑似胡桃夹综合征患者的CT图像构建肠系膜上动脉和左肾静脉。然后使用计算流体动力学进行血液动力学模拟，以确定血液动力学参数的变化与不同程度的压缩之间的相关性。
结果：研究表明，左肾静脉上存在明显的速度分布梯度，狭窄程度相对较高（α≤50°），在狭窄的中央区域具有最大速度。此外,当左肾静脉的压缩程度增加时，左肾静脉的压力分布呈现增加的梯度层数量。此外，壁面剪应力与血流速度的变化具有相关性,即，壁面剪应力的增加与血流速度的加速有关。
结论：使用计算流体动力学作为一种非侵入性工具来获得胡桃夹综合征的血流动力学特征是可行的，可以提供对胡桃夹综合征的病理机制的见解，支持临床医生的诊断。
