HISTOPATHOLOGIC ANALYSIS OF TRANSJUGULAR INTRAHEPATIC PORTOSYSTEMIC SHUNTS

This prospective study was undertaken in 17 patients treated with 22 t ransjugular intrahepatic portosystemic shunt (TIPS) procedures and aim ed to evaluate the nature and causes of short- and long-term shunt abn ormalities, Specimens were collected after autopsy in 6 patients and a fter liver transplantation in 11 patients; the time from shunting rang ing from 4 to 385 days. During the first 2 weeks the shunt surface was covered by poorly organized fibrin platelet clots that were mixed wit h inflammatory and red blood cells. Thereafter, a pseudo-intima develo ped, initially made of loose granulation tissue that was formed by ede ma, myofibroblasts, neo capillaries, collagen fibers, and inflammatory cells, This pseudo-intima extended with time as the myofibroblasts in creased in number, as the collagen fibers thickened, and as the inflam matory cells grew more scarce, Its thickness ranged from 50 to 3,500 m u m, the maximal values being observed in the middle of the shunt, The shunt was obstructed by a clot in 3 patients (18%). In 7 shunts (31.8 %) the pseudo-intima was thicker than 1,000 mu m and was referred to a s hyperplastic pseudo-intima, It showed more dense inflammatory infilt rate and anarchic deposition of more scarce collagen fibers, Pseudo-in tima hyperplasia was associated with previously diagnosed thrombosis, which had been treated by dilatation in 2 cases and by biliary deposit s in 3 cases, while it remained unexplained in 2 cases, Accordingly, t his study confirms the following: 1) that early TIPS obstruction resul ts from thrombosis; 2) that 2 weeks after insertion, the stent is cove red by a smooth pseudo intima; 3) that thereafter, pseudo intimal hype rplasia is the main cause of TIPS stenosis or occlusion; and 4) that b iliary secretions and previous thrombosis could be important triggerin g mechanisms for this pseudo-intima overgrowth.