Review Question - QID 100623

Dobutamine increases myocardial oxygen consumption by its activity on Beta-1-adrenergic receptors, resulting in positive inotropic effects, increased heart rate, and cardiac conduction velocities.

Dobutamine exhibits much more Beta-1 activity than Beta-2, and is a relatively mild alpha-1 agonist. Dobutamine is utilized in the treatment of cardiogenic shock and acute heart failure due to its ability to increase cardiac output. It is less useful in ischemic heart disease, as the positive inotropic effect often results in increased myocardial oxygen demand. Dobutamine is also a commonly used agent in pharmacologic cardiac stress testing.

Incorrect Answers:
Answer 1: Dobutamine's Beta-1 agonist action results in increased cardiac conduction velocities through the AV node.
Answer 3: The Beta-1 positive chronotropic effect leads to increased heart rate in the SA node. This contributes to the increased cardiac output seen with dobutamine therapy.
Answer 4: The mild Alpha-1 agonist effect of dobutamine, leading to vasoconstriction is overpowered by the more potent Beta-2 agonist effect, resulting in net vasodilation and therefore decreased resistance of the systemic vasculature.
Answer 5: The Beta-1 positive inotropic effect leads to increased cardiac contractility, which, along with net vasodilation, contributes to the increased cardiac output seen with dobutamine therapy.