portal hypertension Humans Hypertension, Portal Non-alcoholic Fatty Liver Disease Prognosis Review Severity of Illness Index Weights and Measures cirrhosis complication devices diagnostic accuracy disease exacerbation endoscopic ultrasonography hepatic vein catheterization hepatic vein pressure gradient hepatic venous pressure gradient human liver cirrhosis liver fibrosis mechanocrine signaling mechanotransduction microbiome nonalcoholic fatty liver nonalcoholic fatty liver disease nonalcoholic steatohepatitis pathophysiology portal pressure gradient portal vein blood pressure pressure measurement