Clinical implications of hemodynamic analysis for the three-dimension iliac vein model with different stenosis.

Background: The aim of this study was to perform hemodynamic simulations of a three-dimension ideal inferior vena cava-iliac vein model with artificial stenosis to determine the degree of stenosis that requires clinical intervention. Methods: Four three-dimension stenosis models (30%, 50%, 70%, and 90% stenosis) were constructed using commercial software (Solidworks). The inlet flow rates were acquired from previous literatures to perform the hemodynamic simulations. Changes in the old blood volume fraction, as well conventional hemodynamic parameters including pressure, differential pressure, wall shear stress, and flow patterns, over time were recorded. The pressure at the telecentric region of the stenosis increased with increasing degree of stenosis. Results: For the 70% stenosis model, the pressure at the telecentric region of the stenosis reached 341 Pa, and the differential pressure between the two ends of the stenosis was 363 Pa (approximately 2.7 mmHg). Moreover, in the 70% and 90% stenosis models, there was a marked change in wall shear stress in the stenosis and the proximal end region, and the flow patterns began to show the phenomenon of flow separation. Blood stasis analysis showed that the 70% stenosis model had the slowest decrease in old blood volume fraction, while the proximal end region had the largest blood residue (15%). Conclusion: Iliac vein stenosis of approximately 70% is associated with clinically relevant hemodynamic changes, and is more closely related to DVT than other degrees of stenosis.