Nuclear Cardiology Nuclear Stress Test A nuclear stress test is similar to a stress echocardiogram because you walk or run on a treadmill to make your heart beat fast and pump hard. The patient is injected with a radioisotope or imaging tracer to create pictures of the blood flow to your heart. Resting and stress images are obtained under a nuclear scanner or camera to identify areas of poor blood flow to the heart muscle. If you are unable to exercise, a pharmacologic stress test can be performed. During this test, a small amount of medicine is administered to make the coronary arteries dilate similar to when you perform exercise. A small amount of imaging tracer is injected into a vein at rest and following the medication. The medication does not increase your heart rate. The medication dilates blood vessels leading into the heart, increasing blood flow, therefore simulating exercise for patients unable to exercise on a treadmill. Nuclear or echocardiography imaging is obtained to identify areas of poor blood flow to the heart muscle.