Recent research on nutcracker syndrome has focused mainly on exploring the value and criteria of various imaging modalities for the diagnosis of the disease. Providing more quantitative parameters related to the lesion through non-invasive modalities has been a focus of studies on clinical diagnosis and treatment of nutcracker syndrome. However, no relevant data are available on pressure changes in left renal vein and inferior vena cava and hemodynamic parameters in left renal due to different degrees of stenosis in the left renal vein.

To develop acomputational fluid dynamics (CFD) model to obtain the hemodynamics of individuals with nutcracker syndrome, to explore the relationship of blood flow velocity, wall static pressure, and wall shear stress with the change of vessel disease.

70 patients with nutcracker syndrome were sampled from the Affiliated Hospital of Xuzhou Medical University from September 2019 to March 2021. CFD was used to simulate the intravascular blood flow in the left renal vein of real-world patients with nutcracker syndrome based on CT enhanced images. The hemodynamic characteristics, including vascular diameter and flow velocity, were obtained and compared with those measured by ultrasound.

The left renal vein's intake pressure was high, but the stenosis and exit pressures were low. From the inlet to the outlet, the pressure successively dropped. Except for the narrow region, the wall shear stress was smaller, and the closer to the center of the stenosis, the higher the shear stress. The blood flow velocity in the stenosis was significantly higher than that in other areas of the left renal vein, which was consistent with the result of ultrasonography.

The successfully developed vascular model, The hemodynamic change rules of nutcracker syndrome patients include that the inner diameter of the left renal vein becomes smaller and the flow velocity increases at the stenosis.

目前胡桃夹综合征的研究主要集中在探讨各种影像学方法对该病的诊断价值及其诊断标准方面。通过无创方式提供更多与病变相关的量化参数，是胡桃夹综合征临床诊断、治疗依据研究的重点。然而，对左肾静脉不同狭窄程度引起左肾静脉与下腔静脉压力差值、左肾静脉血流动力学参数的变化未见相关的数据资料。

通过计算流体力学（CFD）的方法对胡桃夹综合征患者进行血流动力学数值的模拟，探讨血液流速、静压力、壁面切应力与血管狭窄程度的关系。

选择2019年9月至2021年3月在徐州医科大学附属医院就诊的70例胡桃夹综合征患者为研究对象。以真实患者的左肾静脉CT增强图像为基础，应用CFD方法对胡桃夹综合征患者左肾静脉进行血管内血流模拟计算，获得患者的血流动力学特征，并与超声测得的血管内径及流速比较。

左肾静脉血流入口处的压力显示为高压，狭窄处与出口处显示为低压，从入口到出口呈现压力递减的特点。壁面切应力除狭窄处外均呈现较低的壁面切应力，越靠近狭窄中心位置，切应力越高，狭窄处的血流速度明显高于左肾静脉其他区域，与超声检查结果一致。

本研究成功建立了胡桃夹综合征患者的血管模型，胡桃夹综合征患者血流动力学变化规律为狭窄处左肾静脉内径变小，流速增快。