Nuclear cardiology studies use techniques to assess blood flow to the heart muscle, evaluate the pumping function of the heart as well as visualize the size and location of heart muscle damage due to blockages in coronary arteries. Myocardial perfusion imaging (examination of blood flow to the heart muscle) is the most widely used nuclear cardiology technique.
Myocardial perfusion images are combined with exercise to assess the blood flow to the heart muscle. Exercise is in the form of walking on a treadmill. In the event that a person cannot exercise on the treadmill, a chemical stress test is performed using the drug dipyridamole, adenosine or dobutamine.
A small amount of imaging agent (Cardiolite or Thallium) is injected into the blood stream through a vein in the arm during rest and during exercise or chemical stress. A scanning device is used to measure the uptake of the imaging agent by the heart. If there is a significant blockage of a coronary artery, a decrease in blood flow will be detected and subsequently demonstrated by abnormalities of the images (pictures) obtained by scanning the heart.
Nuclear cardiology studies also evaluate how well the heart muscle pumps. In patients with coronary artery disease and in those who have had a heart attack, the assessment of the pumping function of the heart (also known as the ejection fraction) is essential in the prediction of both long term and short- term survival.