DUPLEX SONOGRAPHY AFTER TRANSJUGULAR INTRAHEPATIC PORTOSYSTEMIC SHUNTS (TIPS) - NORMAL HEMODYNAMIC-FINDINGS AND EFFICACY IN PREDICTING SHUNT PATENCY AND STENOSIS

OBJECTIVE. Portal hemodynamics are altered by placement of a transjugu lar intrahepatic portosystemic shunt (TIPS). Normal duplex sonographic findings after TIPS placement and hemodynamic alterations indicating shunt failure have not yet been well described. The purposes of this s tudy were to determine normal hemodynamic changes on duplex sonography after TIPS placement and to assess the efficacy of duplex sonography in detecting shunt dysfunction. SUBJECTS AND METHODS. Forty patients u nderwent TIPS placement and were entered into a study that included ro utine sonographic evaluation and portal venography at regular interval s. Portal venography was also performed if shunt Velocities on duplex sonography changed from the baseline, which raised the question of shu nt stenosis or occlusion, The pre-TIPS duplex sonographic study includ ed determination of patency, velocity, and flow direction in the main, right, and left portal veins and in the hepatic artery. Follow-up son ography included the pre-TIPS examination in addition to velocity dete rminations in three segments of the shunt, Correlation was made betwee n 82 concurrent sonographic and portal venographic studies, RESULTS. H igh-velocity blood flow (mean peak velocity, 135-200 cm/sec) was consi stently seen within patent, well-functioning shunts. Hepatic artery pe ak systolic velocities increased from 79 cm/sec before TIPS placement to 131 cm/sec after TIPS placement (p < .001). Main portal vein veloci ties increased from 21.8 cm/sec before TIPS placement to 41.5 cm/sec a fter TIPS placement (p < .001). When compared with portal venography, duplex sonography was 98% sensitive and 100% specific in predicting th e presence of blood flow within the stent. Sonography was highly sensi tive and specific for detecting stent stenosis. Final sonographic crit eria for shunt stenosis in angiographically documented cases were low- velocity shunt flow (less than or equal to 60 cm/sec) in the entire st ent, or low-velocity shunt flow with an associated focal velocity elev ation, CONCLUSION. Consistent changes in portal venous and hepatic art erial hemodynamics are normally seen on duplex sonography after placem ent of a TIPS. Duplex sonography accurately predicts shunt patency and dysfunction when compared with portal venography. Duplex sonography i s an effective, noninvasive method of evaluating shunt function and sh ould be considered for use as the primary imaging technique in routine follow-up after TIPS placement.