2 less appreciated factor in Variceal bleed beside obstruction 


Obstruction of portal venous flow, whatever the etiology, results in a rise in portal venous pressure. This is a well know documented etiology. But there are 2 other factors which may play part in increase portal pressure and variceal bleed. 

1. Increase Endothelin-1 (ET-1) which is a powerful vasoconstrictor synthesized by sinusoidal endothelial cells and causes increased hepatic vascular resistance of cirrhosis and the development of liver fibrosis. 

2. Nitric Oxide (NO) is a known vasodilator substance that is synthesized by sinusoidal endothelial cells. In the cirrhotic liver, the production of NO is decreased. 


 Gupta TK, Toruner M, Chung MK, Groszmann RJ. Endothelial dysfunction and decreased production of nitric oxide in the intrahepatic microcirculation of cirrhotic rats. Hepatology. Oct 1998;28(4):926-31.