A cardiac nuclear stress test is a two part test whereby the cardiologist assesses first the effect of exercise or stress on your heart and second, with nuclear imaging, the adequacy of blood flow to your heart muscle.    

What is the stress portion of the test?  

The stress portion of the test can be performed either by the patient walking on a treadmill or by the cardiologist administering a medicine intravenously called adenosine which mimics stress to the heart. The cardiologist will employ continuous ECG monitoring and frequent blood pressure measurements to assess your heart rate and blood pressure response to exercise, potential causes of chest pain or shortness of breath, and your exercise tolerance, as well as observe for any abnormal heart rhythms called arrhythmias.    

What is the nuclear portion of the test?  

The nuclear portion of the test is the imaging portion of the test and involves injecting a tracer nuclear medicine through an IV both before and during the stress portion of the test. A camera is then employed to take pictures of your heart by detecting minute amounts of the radionucleide tracer as it flows through your coronary arteries. Pictures are taken both before and after the stress portion of the test.  

When put together, the results of the stress test and nuclear imaging of the heart give your doctor the ability to rule in or out any major blockages of the coronary arteries, assess extent of prior heart attack damage as well as check the effectiveness of prior bypass surgery or coronary stenting.