Portal Hypertension

Question 1

what is it

Answer 1

portal vein pressure above the normal range (5-8mmHg) or hepatic pressure gradient >5mmHg

Question 2

what causes the increased pressure

Answer 2

ΔP = Q x R
increased resistance to portal flow (R)
increased portal venous inflow (Q)

Question 3

what is prehepatic cause

Answer 3

blockage of portal vein and thus liver

due to portal vein thrombosis or occlusion secondary to congenital portal venous abnormalities

Question 4

what is intrahepatic cause

Answer 4

due to distortion of the liver architecture, either

1) presinusodial (eg schistosomiasis or non cirrhotic portal hypertension)
2) postsinusoidal (cirrhosis) causes are cirrhosis, alcoholic hepatitis, congenital hepatic fibrosis
3) budd chiari syndrome and veno-occlusie disease

Question 5

what is concequence

Answer 5

cirrhosis and PH leads to hepatocellular dysfunction and portosystemic shunting

this causes increased production of vasodilators

this leads to splanchnic arteriolar vasodilation which leads to activation of arteriolar baroreceptors (decreased MAP)

this decreased MAP leads to activation of SNS and RAAS - renal vasoconstriction and sodium and water retention