Monday November 9, 2009

Q: What is the mechanism of action of B-blockers in reducing portal hypertension which ultimately help in reducing variceal bleeding?

Answer: Nonselective beta-blockers like propranolol and nadolol, reduce portal pressure through both local and systemic effects by 9% to 31%.

Local: In the splanchnic circulation, blockade of the vasodilating beta2 adrenoreceptors results in unrestricted alpha-adrenergic activity, splanchnic arteriolar vasoconstriction, and decreased portal inflow.

Systemic: Blockade of the cardiac beta1 receptors decreases the heart rate and cardiac output and secondarily decreases portal inflow.