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A cardiac perfusion scan measures the amount of blood in your heart muscle at rest and after it has been stressed. It is often done to find out what may be causing symptoms like angina (such as chest pain or pressure). It may be done after a heart attack to see if areas of the heart are not getting enough blood or to find out how much heart muscle has been damaged from the heart attack.
During the scan, a camera takes pictures of the heart after a special test medicine (radioactive tracer) is given through an IV. The tracer travels through the blood and into the heart muscle. As the tracer moves through the heart muscle, areas that have good blood flow absorb the tracer. Areas that do not absorb tracer may not be getting enough blood or may have been damaged by a heart attack.
A set of pictures will be made when you are at rest and after your heart has been stressed, either by exercise or after you have been given a medicine. The resting pictures are then compared with the stress images.
This test is also known by other names including myocardial perfusion scan, myocardial perfusion imaging, thallium scan, sestamibi cardiac scan, and nuclear stress test.
A cardiac perfusion scan is done to:
Tell your doctor ALL the medicines and natural health products you take. Some may increase the risk of problems during your test. Your doctor will tell you if you should stop taking any of them before the test and how soon to do it.
If you take aspirin or some other blood thinner, ask your doctor if you should stop taking it before your test. Make sure that you understand exactly what your doctor wants you to do. These medicines increase the risk of bleeding.
You may be told not to eat or drink for several hours before the scan. You may be told to avoid alcohol, tobacco, and drinks that have caffeine for at least 24 hours before the test.
Wear comfortable shoes, such as running shoes, and loose shorts or pants. Don't wear jewellery to the test.
If you are breastfeeding, you may want to pump enough breast milk before the test to get through 1 to 2 days of feeding. The radioactive tracer used in this test can get into your breast milk and is not good for the baby.
A cardiac perfusion scan is usually done in a hospital radiology or nuclear medicine department, in a doctor's office, or at an outpatient clinic.
For resting scans, in which you do not exercise, you will be asked to remove your clothing above the waist. You will be given a hospital gown to wear. Electrodes might be attached to your chest to keep track of your heartbeats.
You will have a very thin tube, called an IV, going into your arm or hand. A small amount of the radioactive tracer will be put in the IV.
You will lie on your back on a table with a large camera above your chest. The camera records the tracer that has moved from your blood into your heart muscle.
You will be asked to remain very still during each scan. The camera will move to take more pictures at different angles. Several scans will be taken.
The stress scan is done in two parts. In many hospitals, the first images are taken while the person is at rest. Then a second set of images is taken after the person is given a medicine such as dipyridamole. It makes the heart respond like it would to exercise. Exercise and the medicine increase the amount of blood that your heart needs. Sometimes the stress scan is done first and the resting scan might be done the next day. Sometimes only a stress scan is done.
A stress test with medicine is often combined with a low-level exercise stress test. Medicine is also used when a person can't exercise for some reason.
For this test, you will be asked to sit or lie on the examining table. You will be given a routine electrocardiogram (EKG or ECG).
Then you will be given the medicine through your IV. More EKGs and blood pressure measurements are often taken. After the medicine takes effect, a small amount of radioactive tracer is given through your IV.
You will wait about 30 to 60 minutes. You might be asked to eat or drink something. Then you will lie down on a table for a set of scans. The camera records the tracer that has moved from your blood into your heart muscle.
Sometimes more pictures are taken after you rest for 2 to 4 hours, or even the next day.
For stress scans using exercise, your heart rate will be checked with an EKG. Because EKG electrodes need to be attached to the chest, men are usually bare-chested and women usually wear a bra, gown, or loose shirt.
The exercise stress scan is done in two parts. First a set of resting images is taken. Then a set of stress images is taken right after exercise. Sometimes the stress scan is done first and the resting scan might be done the next day.
In many hospitals, first resting pictures are taken using one type of tracer. More pictures are taken using a different tracer after your heart has been stressed by exercise.
In this stress test, you exercise on a treadmill or stationary bike. Your heart rate and blood pressure will be checked during the test and for 5 to 10 minutes after the test.
You will start by walking or pedalling slowly and easily. Every few minutes, the speed or incline of the treadmill or resistance of the bike may be increased. You will exercise until you need to stop or until you reach a suitable heart rate. At that point, you will be given a tracer medicine through your IV.
You will then lie down on a table for scanning.
Sometimes more pictures are taken after you rest for 30 minutes to 4 hours.
The cardiac scanning test itself is painless.
Cardiac perfusion scans are usually safe.
Anytime you're exposed to radiation, there's a small chance of damage to cells or tissue. That's the case even with the low-level radioactive tracer used for this test. But the chance of damage is very low compared with the benefits of the test.
There will be some risks when the test uses exercise or medicine to stress your heart. The amount of risk depends on the condition of your heart and your general level of health. The risks include:
Test results are usually available within 1 to 3 days.
Current as of: August 31, 2020
Author: Healthwise StaffMedical Review: Rakesh K. Pai MD, FACC - Cardiology, ElectrophysiologyE. Gregory Thompson MD - Internal MedicineMartin J. Gabica MD - Family MedicineAdam Husney MD - Family MedicineGeorge Philippides MD - Cardiology
Current as of: August 31, 2020
Author: Healthwise Staff
Medical Review:Rakesh K. Pai MD, FACC - Cardiology, Electrophysiology & E. Gregory Thompson MD - Internal Medicine & Martin J. Gabica MD - Family Medicine & Adam Husney MD - Family Medicine & George Philippides MD - Cardiology
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