Final answer:
Propranolol is not used in stress echocardiography because, as a β-blocker, it decreases heart rate and blood pressure, which is counterproductive to the test's objectives.
Step-by-step explanation:
Stress echocardiography involves inducing cardiovascular stress to assess heart function. Adenosine, Dipyridamole, and Dobutamine are commonly employed for this purpose, increasing heart rate and workload to simulate exercise during the echocardiogram. In contrast, Propranolol, a β-blocker, is not used for stress echocardiography. By blocking β-receptors, Propranolol decreases heart rate and blood pressure, providing therapeutic benefits in conditions like hypertension. However, its mechanism opposes the goal of stress testing, which aims to evaluate the heart's response under increased demand. Propranolol's role lies in managing cardiovascular conditions rather than inducing stress, making it unsuitable for stress echocardiography protocols.