What is Nuclear cardiology?
Nuclear Cardiology consists of various diagnostic tests to evaluate the function of an individual's heart muscle. These tests generally involve evaluating the blood flow in the coronary arteries, which supply blood to the heart, or measuring the amount of blood pumped by the heart with each beat (called ejection fraction). You may have heard these tests referred to as "nuclear treadmill test," "cardiolite stress test," "thallium stress test," "multigated acquisition (MUGA)", or "rest/exercise ejection fraction (REEF)."

What will these tests show the physician?
The heart is the hardest-working muscle in the body. Each day, it beats about 100,000 times and PUMPS more than 1,900 gallons of blood. Therefore, it's a muscle that requires plenty of oxygen. The heart receives oxygen from blood flowing through the coronary arteries, and nuclear cardiology tests can evaluate the condition of these vessels and analyze the movement of the heart muscle.

If the coronary arteries around the heart become partially blocked or narrowed by the accumulation of fatty materials (plaque), the heart muscle may not receive the blood and oxygen it needs to function properly. This narrowing or clogging of the coronary arteries is called coronary atherosclerosis or coronary artery disease (CAD). Some people with CAD may experience chest pain called angina pectoris, while others may have no outward physical signs of the disease. In fact, about one person in three with clogged arteries has no warning sign of chest pain. For them, the first sign of trouble is a heart attack. Nuclear cardiology tests can provide the physician with detailed information about the blood flow through the coronary arteries of your heart, the amount of coronary artery disease, and your heart's pumping ability.
The nuclear cardiology physician can determine if the heart muscle is getting the blood supply it needs and categorize the test results as:

Normal - This means you have adequate blood supply and heart muscle movement at rest and during exercise. These donut shaped images demonstrate blood flow to a portion of the heart muscle. A normal, healthy heart has an identical pattern of blood supply at rest and under "stress."

Ischemia - This means you do not get adequate blood supply under exercise conditions to some areas of the heart muscle, often due to narrowing clogging in the coronary arteries. Under "stress" conditions, the blood supply to the heart muscle should increase. The "break" in the donut in the stress image indicates a diminished blood supply to that portion of the heart muscle, which indicates blockage in the coronary arteries that carry blood to the heart.

Scar - This means that there may be some areas of the heart muscle which may be damaged from a lack of blood supply. The blood supply to the heart muscle is decreased at rest and under "stress." This indicates permanent damage to the heart muscle.

What will happen to me during the test?
The nuclear cardiology test usually consists of two parts, rest imaging and stress imaging. These two tests allow the physician to compare the amount of blood flowing through the heart muscle while at rest and during exercise, by taking pictures or "images" of the nuclear material as it moves through the blood vessels.

Rest Imaging
For the "resting" portion of the test, a small amount of a radionuclide (a nuclear tracing element that shows the blood flow) will be administered through an IV line. An electrocardiogram (also called an EKG or ECG), which monitors your heart rate and rhythm, is sometimes used for this portion of the test. After the radionuclide is injected, a special gamma camera that can detect radiation will take a picture of the radionuclide as it flows through your heart while you are at rest.

The gamma camera revolves around the patient's chest to create a picture of the nuclear material as it flows through the heart

Stress Imaging
The "stress" portion of the test will show your physician how the blood flow to your heart looks during exercise. It is then compared to the same images of your heart during rest. There are various methods of stress testing, including:

» Treadmill which exercises your heart by walking
» Bicycle, which exercises your heart by pedaling a stationary bike
» Pharmacologic stress, which uses medications to make your heart act as it would during exercise.Pharmacologic stress is used for patients who, due to medical conditions or injuries,cannot exercise on the treadmill or bicycle. It is also used for patients who are taking medications that keep their heart rate from increasing during exercise.

During stress testing, an electrocardiogram (also know as an EKG or ECG) will be used to monitor your heart rate and rhythm throughout the exercise part of the test. Several small pads, called electrodes, will be placed on your chest. These electrodes transmit information to a computer monitor, so that your heart rhythm can be watched closely throughout the stress test. This information can help the physician determine if there are any changes or abnormalities with your heart rhythm.

If the stress test involves exercise on a treadmill or stationary bicycle, the rate of exercise will start slowly and gradually increase. If you walk on a treadmill, it will move very slowly at first, then increase in speed. If you pedal a stationary bicycle, it will feel easy to pedal at first, and will gradually get harder. As you exercise, your heart rate, rhythm and blood pressure will be closely monitored.

You will be encouraged to keep exercising throughout the stress exam. If you experience symptoms such as chest pain, shortness of breath, or lightheadedness, immediately tell the person monitoring the test. To increase the effectiveness of the test, it is important to exercise as long as possible.

If you have a pharmacologic stress test, medications will be used to make your heart react as it would during exercise. Again, if you experience symptoms such as chest pain, shortness of breath, or lightheadedness, immediately tell the person monitoring the test.

As with "rest imaging," during "stress imaging" a small amount of a radionuclide (a nuclear tracing element that shows the blood flow) will be administered through an IV fine. The radionuclide will be injected during the exercise or the pharmacologic part of the test. After the radionuclide is injected, a special gamma camera that can detect radiation will take a picture of the radionuclide as it flows through your heart.

Precautionary Information
A nuclear medicine exam with radionuclides involves the injection of a small amount of a radioactive material which is cleared from the body by natural processes. The amount of radiation you will be exposed to is comparable to that from an X-ray or CAT (CT) scan. Millions of nuclear medicine exams of various types are performed each year. However, if you are pregnant, suspect you may be, or are a nursing mother, discuss this with your physician before undergoing a nuclear procedure.