Michael J. Pentecost

OBJECTIVE: The purpose of this study was to define the pattern, rate, and interval during which stenosis develops in transjugular intrahepatic portosystemic shunts (TIPS) and to assess the effect of revision in prolonging shunt patency. MATERIALS AND METHODS: TIPS were created in 100 patients during a 34-month period. Sixty-one shunt venograms were obtained in 38 consecutive patients between 1 and 24 months after TIPS placement. Eighteen patients were examined because of recurrent symptoms, and all 38 had routine follow-up. RESULTS: Stenoses attributed to neointimal hyperplasia developed within both the TIPS stent and the outflow hepatic veins. Stenoses of greater than 50% developed in 12 patients within 6 months of TIPS placement. In addition to focal stenoses, the outflow hepatic veins diffusely shrank an average of 51% in diameter. Thirty-six shunt interventions were required: eleven balloon dilatations and 25 placements of an additional stent. Life-table analysis showed that patency of the primary shunt was 75% at 6 months, 50% at 1 year, and 32% at 2 years. The primary-assisted patency of the shunt was 85% at 12 months after shunt creation. CONCLUSION: The results indicate that TIPS are prone to significant and frequent early stenosis, warranting follow-up within 3-6 months in all cases. Stenosis of the outflow hepatic vein is the most common cause of shunt malfunction. Revision of a shunt significantly prolongs shunt patency.

The authors tested a noninvasive technique for magnetic resonance imaging of perfusion in human kidneys. Magnetic labeling (spin tagging) of aortic arterial water was performed to generate an endogenous tracer. Breath-hold renal perfusion images obtained in seven volunteers yielded average perfusion rates in cortex and medulla of 278 mL.100 g-1.min-1 +/- 55 (standard error) and 55 mL.100 g-1.min-1 +/- 25, respectively.