Background:Accumulating studies on computational fluid dynamics (CFD) support the involvement of hemodynamic factors in artery stenosis.Based on a patient-specific CFD model,the present study aimed to investigate the hemodynamic characteristics of transplant renal artery stenosis (TRAS) and its alteration after stent treatment.Methods:Computed tomography angiography (CTA) data of kidney transplant recipients in a single transplant center from April 2013 to November 2014 were reviewed.The three-dimensional geometry of transplant renal artery (TRA) was reconstructed from the qualified CTA images and categorized into three groups:the normal,stenotic,and stented groups.Hemodynamic parameters including pressure distribution,velocity,wall shear stress (WSS),and mass flow rate (MFR) were extracted.The data of hemodynamic parameters were expressed as median (interquartile range),and Mann-Whitney U-test was used for analysis.Results:Totally,6 normal,12 stenotic,and 6 stented TRAs were included in the analysis.TRAS presented nonuniform pressure distribution,adverse pressure gradient across stenosis throat,flow vortex,and a separation zone at downstream stenosis.Stenotic arteries had higher maximal velocity and maximal WSS (2.94 [2.14,3.30] vs.1.06 [0.89,1.15] m/s,256.5 [149.8,349.4] vs.41.7 [37.8,45.3] Pa at end diastole,P =0.001;3.25 [2.67,3.56] vs.1.65 [1.18,1.72] m/s,281.3 [184.3,3 64.7] vs.65.8 [61.2,71.9] Pa at peak systole,P =0.001) and lower minimal WSS and MFRs (0.07 [0.03,0.13] vs.0.52 [0.45,0.67] Pa,1.5 [1.0,3.0] vs.11.0 [8.0,11.3] g/s at end diastole,P =0.001;0.08 [0.03,0.19] vs.0.70 [0.60,0.81] Pa,2.0 [1.3,3.3] vs.16.5 [13.0,20.3] g/s at peak systole,P =0.001) as compared to normal arteries.Stent implantation ameliorated all the alterations of the above hemodynamic factors except low WSS.Conclusions:Hemodynamic factors were significantly changed in severe TRAS.Stent implantation can restore or ameliorate deleterious change of hemodynamic factors except low WSS at stent regions.