In cardiogenic shock, how does dobutamine primarily affect cardiac function?

• A. Increases contractility via beta-1 agonism, with modest vasodilation
• B. Decreases heart rate and contractility
• C. Causes strong vasoconstriction
• D. Only reduces preload without changing contractility

Answer: (A)

In cardiogenic shock, the priority is to boost the heart’s output by making it contract more forcefully. Dobutamine achieves this mainly through stimulating beta-1 receptors on cardiac muscle. This increases cAMP, which raises intracellular calcium during systole, producing stronger contractions (positive inotropy) and a higher stroke volume. Because there is some beta-2 activity as well, there is mild vasodilation, which lowers afterload a bit and helps the weakened ventricle eject blood more easily. It does not primarily slow the heart, reduce contractility, cause strong vasoconstriction, or act only to reduce preload. So the key effect is increased contractility with modest vasodilation.