 Sample size The sample size will be calculated on the main study end-point: the incidence of hepatic encephalopathy. On the basis of previous studies, the post-TIPS incidence of hepatic encephalopathy is considered to be of 50 at one year. To obtain a clinically significant from 50 to 25 encephalopathy incidence reduction a 5 and b 20 it will be therefore necessary to enroll 57 patients per group. Randomization will be by sealed envelopes in blocks of ten. 