What is the role of dobutamine in stress echocardiography, and what constitutes a positive test?

• A. Dobutamine increases contractility and heart rate, simulating exercise; a positive test shows inducible wall motion abnormalities.
• B. Dobutamine decreases heart rate and reduces contractility.
• C. Dobutamine increases preload only.
• D. Dobutamine is contraindicated in stress testing.

Answer: (A)