Some protocols include light-to-moderate-intensity exercise in combination with pharmacologic infusion. These potent vasodilators enhance blood flow to normally perfused heart tissue, whereas heart muscle feed by obstructed coronary arteries demonstrates relative hypoperfusion.
Another popular pharmacologic test uses dobutamine, which in contrast to dipyridamole or adenosine stress, causes cardiac ischemia by modestly increasing heart rate and myocardial contractility. Atropine may be administered to further augment heart rate if an adequate heart rate is not achieved or other endpoints have not been reached at peak dobutamine dose. Echocardiographic images, which involve a recording sensor to bounce ultrasound waves off the heart to create an image of the muscle at work, are obtained throughout the infusion. A new or worsening wall motion abnormality suggests underlying coronary artery disease.