Hemodynamic analysis of the juxtahepatic inferior vena cava

Abstract

Objective To establish a digital model of the juxtahepatic inferior vena cava (IVC) by analyzing the blood flow and the flow type,and to determine the minimal diameter of the retrohepatic IVC which maintained a normal blood flow through the retrohepatic inferior vena cava.Methods Firstly,120 patients' data,including CT images,were collected to establish a digital model of the juxtahepatic IVC.Secondly,an in vitro model of the juxtahepatic IVC was built,using pig's blood to determine the pressure differences on the two ends.Water was then used as control.Finally,ANSYS13.0 was used to simulate the blood flow through the juxtahepatic IVC.Results As the juxtahepatic IVC was a 3-dimensional cylinder,the pressure difference at the 2 ends of the juxtahepatic IVC was higher for blood than water when the diameter was bigger,and the flow was low.On the contrary,the pressure difference for blood was lower than water when the diameter was small and the flow was high.When the blood flow in the juxtabepatic IVC was 3 000 ml/min,the minimal diameter of the retrohepatic IVC was 10 mm to maintain a pressure difference of less than 5 cmH2O (500 kPa).When the blood flow was 5 000 ml/min,the diameter required 12 mm.In most cases the blood flow in the retrohepatic IVC was laminar,but transitional flow was observed in some cases.However,no turbulence was observed in the blood flow.On the other hand,much more turbulence or transitional flow was observed for water flow.Conclusions To maintain a normal blood flow in the juxtahepatic IVC,and an effective preload was required.The minimal diameter of the retrohepatic IVC was found to be 10 mm.The bigger the diameter,the safer it would be for patients with liver and retrohepatic vena cava injury. Key words: Juxtahepatic vena cava; Retrohepatic vena cava; Fluid dynamic analysis; Digital model