What is it?

A cardiac perfusion scan measures the amount of blood in your heart muscle at rest and after your heart has been made to work hard. Medicine or exercise can be used to increase the amount of blood that your heart needs.

During the scan, a camera takes pictures of your heart after a radioactive tracer is put into a vein in your arm. The tracer travels through the blood and into your heart. As the tracer moves through your heart, areas that have good blood flow absorb the tracer. Areas that don't absorb the tracer may not be getting enough blood or may have been damaged by a heart attack. The pictures show the difference.

Two sets of pictures may be made during the test. One set is taken while you are resting. Another set is taken after your heart has been made to work harder (called a stress test).

Why is this test done?

The test is often done to find out what may be causing chest pain or pressure. It may be done after a heart attack to see if areas of the heart aren't getting enough blood. It also may be used to find out how much your heart has been damaged from the heart attack.

How do you prepare for the test?

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 a medicine that prevents blood clots, your doctor may tell you to stop taking it before your test. Or your doctor may tell you to keep taking it. (These medicines include aspirin and other blood thinners.) Make sure that you understand exactly what your doctor wants you to do.

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.

How is the test done?

A cardiac perfusion test can be done while you're resting, after you exercise, or after you take medicine. Or you could have the test after taking medicine and exercising.

Before the scans, electrodes will be attached to your chest to help record your heartbeats. You will have a tube, called an IV, put into your arm. Radioactive tracer will be put in the IV.

• For the resting scan, you will lie on a table. A camera above your chest records the tracer that has moved from your blood into your heart muscle. Several scans will be taken. They take 10 to 30 minutes each.
• For an exercise scan, you will walk on a treadmill or pedal a stationary bike. Then you have the scan.
• For a medicine scan, you are given a medicine in your IV that increases the amount of blood that your heart needs. Then you have the scan.

How long does a cardiac perfusion scan take?

• Each scan may take about 30 to 60 minutes.
• How long the test takes will depend on how many scans you have and how long you wait between scans.

What are the risks of a cardiac perfusion scan?

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:

• Fainting.
• Chest pain.
• An irregular heartbeat.
• Heart attack. There is a slight risk that death may result if a heart attack occurs during the test.

What happens after the test?

You can go home and back to your usual activities right away, unless you are already admitted to the hospital.

How can you care for yourself at home?

• Drink plenty of fluids for the next 24 hours to help flush the tracer out of your body. If you have kidney, heart, or liver disease and have to limit fluids, talk with your doctor before you increase the amount of fluids you drink.
• Most of the tracer will leave your body through your urine or stool within a day. So be sure to flush the toilet right after you use it, and wash your hands well with soap and water. The amount of radiation in the tracer is very small. This means it isn't a risk for people to be around you after the test.
• Do not breastfeed your baby for 1 or 2 days after this test. During this time, you can give your baby breast milk you stored before the test, or you can give formula.

When should you call for help?

Call 911 anytime you think you may need emergency care. For example, call if:

• You passed out (lost consciousness).
• You have been diagnosed with angina, and you have angina symptoms that do not go away with rest or are not getting better within 5 minutes after you take a dose of nitroglycerin.
• You have symptoms of a heart attack. These may include:
  • Chest pain or pressure, or a strange feeling in the chest.
  • Sweating.
  • Shortness of breath.
  • Nausea or vomiting.
  • Pain, pressure, or a strange feeling in the back, neck, jaw, or upper belly or in one or both shoulders or arms.
  • Light-headedness or sudden weakness.
  • A fast or irregular heartbeat.
  After you call 911, the operator may tell you to chew 1 adult-strength or 2 to 4 low-dose aspirin. Wait for an ambulance. Do not try to drive yourself.

Watch closely for changes in your health, and be sure to contact your doctor or nurse advice line if you have any problems.