Effectiveness of Rex Shunt for Improving the Abnormal Portal Hemodynamics and Portal Venous Pathology in EHPVO Animal Model.

PURPOSE:To investigate the feasibility of the re-patent EHPVO (r-EHPVO) as an animal model of Rex shunt and the effectiveness of Rex shunt in improving abnormal portal hemodynamics and portal venous pathology of EHPVO. METHODS:A total of 18 New Zealand white rabbits were randomly divided into three groups: normal control (NC) group, extrahepatic portal venous obstruction (EHPVO) group, and r-EHPVO group. The main portal vein was dissected only in the NC group. The main portal vein was narrowed by a cannula in the EHPVO group. The cannula narrowing the main portal vein was removed to restore the portal blood flow into the liver on day 14 in the r-EHPVO group. The portal pressure, splenic size, blood flow velocity, and diameter of the portal vein were measured on days 14 and 28. The shear stress (SS) and circumferential stress (CS) of the portal vein were calculated. The proximal end of the main portal vein was collected on day 28 for further pathological analysis, and the thickness and area of the intima and media were measured by Image J software. The portal pressure, splenic size, SS, CS, intima and media thickness, the ratio of intimal to medial area (I/M), and the ratio of intimal area to the sum of intimal and medial area (I/I + M) were compared among the three groups. The correlation between SS and intimal thickness and between CS and medial thickness were analyzed. RESULTS:On day 28, the portal pressure of the EHPVO group was significantly higher than that of the NC and r-EHPVO groups, but no significant difference was detected in the portal pressure between r-EHPVO and NC groups. The length and thickness of the spleen in the EHPVO and r-EHPVO groups were significantly higher than those in the NC group (P < 0.01) but were significantly lower in the r-EHPVO group than those in the EHPVO group (P < 0.05). The SS was significantly lower in the EHPVO group than in NC and r-EHPVO groups (P < 0.05) but was significantly higher in the NC group than in the r-EHPVO group (P = 0.003). The CS was significantly higher in the EHPVO and r-EHPVO groups than that in the NC group (P < 0.05) but was significantly lower in the r-EHPVO group than that in the EHPVO group (P < 0.001). The intimal thickness, I/M, and I/I + M of the EHPVO group were significantly higher than those of the NC and r-EHPVO groups (P < 0.05), but no significant difference was observed between the NC and r-EHPVO groups (P > 0.05). The SS is negatively related to intimal thickness (r = - 0.799, P < 0.001). CONCLUSION:The r-EHPVO model is feasible as an animal model of the Rex shunt. The Rex shunt could be beneficial to improving the abnormal portal hemodynamic and portal venous intimal hyperplasia by restoring the portal blood flow into the liver.