Cardiac Stress Test

Cardiac nuclear medicine tests are indicated for individuals with unexplained chest pain or chest pain brought on by exercise (called angina) to permit the early detection of heart disease.

The most common cardiac nuclear medicine procedure, called myocardial perfusion imaging, enables the visualization of blood-flow patterns to the heart walls. The test is important for evaluating the presence of suspected or known coronary artery disease (blockages) as well as the results of previous injury to the heart from a heart attack (myocardial infarction). It also can be done to evaluate the results of bypass surgery or other revascularization procedures designed to restore the blood supply to the heart. Heart-wall movement and overall heart function can be also be evaluated.

What to expect with your procedure

You should avoid caffeine (coffee, tea, etc.) and smoking for 48 hours before the examination. You should not eat or drink anything after midnight before the procedure, but continue taking medications with small amounts of water unless your physician says otherwise. Wear comfortable, walking shoes and loose-fitting clothes for your procedure. Tell the technologist and supervising physician if you have asthma or a chronic lung disease or have problems with your knees, hips or keeping your balance, which may limit your ability to perform the exercise needed for this procedure.

Preparing for your procedure

For the stress part of the examination, you will exercise by either walking on a treadmill or pedaling a stationary bicycle for a few minutes. While you exercise, the electrical activity of your heart will be monitored by electrocardiography (ECG) and your blood pressure will be measured frequently. Before you stop exercising, you will be given the radiopharmaceutical through an IV leading into a vein in your arm. The compound is given when the blood flow to the heart is at its peak because of your exercising. This provides the best opportunity to identify regions of the heart that are not receiving adequate blood flow.

One minute later, you will stop exercising. Approximately one half-hour later, as you lay on an examining table, the compound will have collected in your heart. The gamma camera will then be used to obtain images. The gamma camera likely will move slowly and automatically in an arc over the front of your chest after it is positioned initially by the technologist.

The images obtained after exercise must usually be compared with images of your heart obtained after injection of the same radiopharmaceutical while you are resting. This may be performed before or after the exercise part of the examination, depending on the protocol used. Comparison of the exercise and resting images is done to determine whether coronary blood flow has changed once you have rested and to check for coronary artery disease.

If you are unable to use a treadmill or bicycle, you will not exercise, but you will be given a drug that will cause your heart to work as hard as if you had exercised. You will then be given the radiopharmaceutical.

Immediately after the procedure, a diagnostic radiologist and cardiologist with specialized training in nuclear medicine will check the quality of the images to ensure that an optimal diagnostic study has been performed.