Pharmacologic treatment of portal hypertension.

Variceal formation and rupture are dreaded complications of chronic liver disease and portal hypertension. The pharmacologic treatment of portal hypertension should be able to stop as well as to prevent variceal hemorrhage. There are two principal types of vasoactive drugs in the treatment of portal hypertension: vasoconstrictors and vasodilators. Vasoconstrictors reduce the splanchnic blood flow, thereby decreasing the portal blood flow and portal pressure. Vasodilators act by different mechanisms, including by relaxation of myofibroblasts in the fibrous septa and presinusoidal areas of the liver and by direct vasodilation of the collateral circulation. In addition, paradoxically, they could decrease portal flow and pressure by inducing a baroreflex-mediated mesenteric arterial vasoconstriction. A miscellaneous group of drugs is also available. These drugs reduce the blood flow and pressure in the gastroesophageal variceal system by mechanisms other than vasoconstriction or vasodilation. The success of these pharmacologic agents is limited once the varices have ruptured. The use of beta-blockers in the prophylaxis of the first variceal bleeding has been proven of benefit in this respect. Future research should be aimed at elucidating the role that humoral and endothelial factors play in development of the hyperdynamic circulatory state that characterizes patients with portal hypertension. Once these etiologic factors have been identified and new knowledge is acquired about their role in the complications of chronic liver disease, the challenge will rest on developing novel pharmacologic therapies specifically targeting these factors.