A nuclear cardiology stress test, also known as myocardial perfusion imaging, is used to determine if the heart is receiving an adequate blood supply under both stress and rest conditions. It involves injecting into the bloodstream a small amount of radioactive material that then circulates through the body, helping to evaluate the blood flow and function of the heart.
A nuclear cardiology stress test is typically given to those who have symptoms, such as shortness of breath or chest pains, that indicate coronary artery disease. It is also used to determine the risk of a heart attack, and to show if there is limited blood flow to the heart. A nuclear cardiology stress test helps to diagnose coronary artery disease, and determine the best treatment plan for serious heart conditions.
Reasons for a Nuclear Cardiology Stress Test
If a patient has symptoms that indicate coronary artery disease, or has had a previous electrocardiogram that produced abnormal results, a nuclear cardiology stress test may be recommended. It may also be an option for someone who is unable to exercise, or walk on a treadmill. Patients at high risk, such as those who smoke, or have diabetes or high blood pressure, may also be candidates for nuclear cardiology stress testing. The test is also used to help establish an appropriate treatment plan for a patient who has already been diagnosed with coronary artery disease.
The Nuclear Cardiology Stress Test
A patient may be asked to refrain from caffeine for 24 hours before taking the test, which begins with the injection of radioactive dye (either thallium or sestamibi) into the bloodstream. Electrodes are placed on different parts of the body to record the electrical signals that trigger heartbeats. Images of the heart are taken when the patient is at rest, and then again when the patient is engaging in physical activity. The images show the areas within the heart that are not receiving enough blood. Both sets of images are reviewed to compare the blood flow through the heart during different stages of rest and activity.
If a patient is unable to exercise, a medication that increases blood flow to the heart muscle may be given intravenously.
A patient may experience headache, nausea and a racing heart beat during the test, which takes, on average, 3 hours to complete.
Recovery from a Nuclear Cardiology Stress Test
The radioactive substance used in the test is naturally excreted from the body through urine, and patients are advised to drink plenty of water to help flush it through their systems. Most patients return to their normal activities immediately after testing.
Risks of a Nuclear Cardiology Stress Test
Although a nuclear cardiology stress test is generally considered safe, it does have the following risks:
- Allergic reaction to the radioactive dye
- Chest pain
- Blood-pressure surge
Although extremely rare, it is possible for a nuclear cardiology stress test to cause a heart attack.