Which statement best reflects propranolol's effect relevant to portal hypertension?

• A. Reduces heart rate
• B. Lowers blood pressure
• C. Decreases portal blood flow
• D. Improves renal perfusion

Answer: (C)

In portal hypertension, the important therapeutic goal is to reduce portal venous inflow, which lowers the pressure in the portal system. Propranolol, a nonselective beta-blocker, accomplishes this through two actions. Blocking beta-1 receptors decreases heart rate and cardiac output, reducing the amount of blood entering the systemic and splanchnic circulation. More crucial for portal hypertension is the blockade of beta-2 receptors on splanchnic vessels, which removes beta-2–mediated vasodilation and allows unopposed alpha-adrenergic vasoconstriction. This constricts the mesenteric vessels and lowers portal venous inflow to the liver. The net result is decreased portal blood flow, which is the effect most relevant to managing portal hypertension. While a drop in heart rate or blood pressure can occur, and renal perfusion may be variably affected in cirrhosis, the key mechanism by which propranolol benefits portal hypertension is the reduction of portal venous inflow.