Portal hypertension

Portal pressure can be derived using the hydraulic analogy to Ohm’s law: P (pressure) = Q (flow) × R (resistance), wherein, portal venous pressure (PVP) is equal to the product of portal blood flow (PBF) and the resistance to that flow (intrahepatic venous resistance [IHVR]): PVP = PBF × IHVR. Portal hypertension is caused by increased resistance and/or increased blood flow in the portal prehepatic, hepatic, or posthepatic circulation. The clinical consequences of portal hypertension, which include the development of acquired portosystemic shunts, ascites, hepatic encephalopathy, or some combination of these, cause significant morbidity and mortality.