Authored by Darlene Zagata in Medical Science 
Published on 07-04-2009

A nuclear stress test is a non-invasive technique used to measure blood flow to the heart while at rest and during stress. A nuclear stress test can detect the presence of conditions such as coronary artery disease in which blockage or narrowing of the blood vessels that supply blood to the heart may occur. Although a nuclear stress test is similar to a routine stress test, a radioactive substance is injected into the bloodstream which travels to the heart. A scanner then detects the radioactive material and creates an image of the heart allowing blockages to be viewed. The image shows how well blood is flowing to the heart muscle.

The nuclear stress test is usually done in conjunction with a form of exercise such as the treadmill. Measuring the heart’s pumping action during exercise induced stress helps determine blockages that may limit blood flow and impede the action of the heart. A small amount of the radioactive solution can also be injected into a vein to monitor the heart’s action during rest. A gamma camera then detects energy emitted from the radioactive material to monitor the blood flow while the patient is lying down at rest.

It is normally required that the patient does not eat or drink anything three to four hours before the scheduled test. The patient should consult with the physician about any prescription medications that he may be taking. It is advisable to dress in comfortable clothing and shoes since the patient will be on a treadmill.

Several small electrodes are placed on the patient’s chest which are then connected to a machine known as an electrocardiograph that monitors the heart’s electrical activity. An intravenous line (IV) will be inserted into a vein in the patient’s arm. The patient will then be asked to begin the exercise and will continue until the radioactive substance is injected into the IV. The patient will then exercise for approximately one minute more. If at any time during the test, the patient feels chest pain, dizziness or shortness of breath, he should immediately tell the physician. In the next portion of the test, the patient will lie down beneath a scanning camera. The images will show the flow of blood to the heart while the patient is at rest. The test may take approximately 30 to 60 minutes.

Patients who undergo a nuclear stress test are often concerned about the effects of the radioactive compound. Although the majority of patients suffer no ill effects from the substance, a small percentage may experience side effects such as a metallic taste in their mouths, headache or rash. Rare side effects that may occur in association with the radioactive compound include joint pain, shortness of breath, vomiting, slow heart rate or seizure. There may also be side effects of the treadmill test which may include chest pain or irregular heart rate. Patients are often asked to remain for a length of time following a nuclear stress test in the advent that side effects may occur.