On CPB, which drug is a beta blocker that can cause vasodilation?

• A. Inderal/propranolol
• B. Esmolol
• C. Metoprolol
• D. Isoproterenol

Answer: (A)

Beta blockade during CPB changes how the circulation responds to circulating catecholamines and intrathoracic pressures. Propranolol is a nonselective beta blocker, meaning it blocks both beta-1 receptors (heart) and beta-2 receptors (vascular smooth muscle and elsewhere). In the CPB setting, blocking beta-2–mediated vasodilatory signals can, in combination with the circuit physiology and other drugs in use, contribute to a net vasodilatory effect in some patients or situations. The other options are beta-1 selective blockers, which mainly reduce heart rate and contractility with less direct impact on vascular tone, and a beta-agonist (isoproterenol) that causes vasodilation via its receptor stimulation, not blockade. So propranolol is the beta blocker among these choices most associated with broader vascular effects that can include vasodilation in CPB contexts.