A cardiac PET stress test is a specialized imaging procedure that provides detailed insights into blood flow to your heart muscle, both at rest and under conditions of increased demand. It helps healthcare providers understand the heart’s performance and identify potential issues that might affect its ability to pump blood effectively.
Understanding the Cardiac PET Stress Test
A cardiac PET (Positron Emission Tomography) scan involves injecting a small amount of radioactive tracer into the bloodstream, which then travels to the heart. A special camera detects the emitted energy, creating detailed images that show areas of good blood flow and areas where flow might be reduced or absent.
The “stress” component of the test evaluates the heart’s function when it is working harder. This increased demand can be simulated through physical exercise, such as walking on a treadmill, or by administering a medication that mimics the effects of exercise on the heart. By comparing blood flow images taken at rest with those taken during stress, doctors can identify differences that indicate impaired blood supply.
This diagnostic tool helps identify conditions like coronary artery disease (CAD), which occurs when the arteries supplying blood to the heart become narrowed or blocked. It can also assess the extent of heart muscle damage after a heart attack or determine if a previous bypass surgery or stent placement has been effective.
Preparing for Your Test
You will likely be instructed to avoid caffeine for at least 12 to 24 hours prior to the test, as caffeine can interfere with the stress portion. This includes coffee, tea, soda, chocolate, and certain medications that contain caffeine. You may also be asked to fast for four to six hours before the test, avoiding food and drink except water.
Discuss all current medications with your doctor or the testing facility in advance. Some medications, particularly those for heart conditions or asthma, may need to be temporarily stopped or adjusted before the test. Never discontinue any medication without specific instructions from your healthcare provider. Inform them about any allergies, especially to medications or dyes.
Wearing comfortable, loose-fitting clothing and walking shoes is recommended for the test, especially if you will be performing physical exercise. Avoid wearing jewelry or clothing with metal fasteners, as these can interfere with the imaging equipment. Bringing a list of all your medications, including over-the-counter drugs and supplements, is also helpful for the medical staff.
What Happens During the Test
Upon arrival, an intravenous (IV) line will be inserted into a vein, usually in your arm. This IV line will be used to administer the radioactive tracer and, if necessary, the stress medication. Electrodes will be placed on your chest to monitor your heart’s electrical activity throughout the procedure, and a blood pressure cuff will be applied to your arm.
The first set of images, known as rest images, will be taken after the initial tracer injection while you lie still on a scanning bed. You will need to remain very still during this imaging period, which usually lasts about 15 to 30 minutes.
Following the rest images, the stress portion of the test will begin. If you are able to exercise, you will walk on a treadmill or pedal a stationary bike, gradually increasing the intensity until your heart reaches a target rate or you experience symptoms. If exercise is not possible, a medication such as Regadenoson or Dipyridamole will be administered through the IV to simulate the effects of exercise on your heart. You might feel a temporary flush, shortness of breath, or chest discomfort, which is a normal response to these medications and is closely monitored.
Immediately after the stress phase, a second dose of the radioactive tracer will be injected, and another set of images will be taken while you lie on the scanning bed. The entire imaging process, including both rest and stress phases, takes between one and three hours to complete.
After Your Test
Once both the rest and stress imaging phases are complete, the IV line will be removed. You can resume your normal diet and activities immediately after the test, unless otherwise instructed by the medical staff. Drinking plenty of fluids helps flush the small amount of radioactive tracer from your system.
The images captured during your cardiac PET stress test will be analyzed by a nuclear cardiologist or radiologist. The interpretation involves looking for areas where blood flow is reduced during stress but normal at rest, which could indicate a blockage, or areas where flow is reduced in both states, suggesting heart muscle damage.
Results are available within a few days to a week after your test. Your referring physician will then discuss the findings with you during a follow-up appointment. Based on the results, your doctor will explain what the findings mean for your heart health and discuss next steps, which could include medication adjustments, lifestyle changes, or further diagnostic tests or treatments.