Myocardial Perfusion Imaging (MPI) Test - More information on Nuclear Heart Scans

What is a myocardial perfusion imaging test?

Myocardial perfusion imaging (MPI) is a non-invasive imaging test that shows how well blood flows through (perfuses) your heart muscle. It can show areas of the heart muscle that aren’t getting enough blood flow. This test is often called a nuclear stress test.  It can also show how well the heart muscle is pumping.

There are 2 techniques for MPI:  single photon emission computed tomography (SPECT) and positron emission tomography (PET).

MPI is useful in patients with chest discomfort to see if the discomfort comes from lack of blood flow to the heart muscle caused by narrowed or blocked heart arteries (angina).  Myocardial perfusion imaging doesn’t show the heart arteries themselves, but can tell your doctor with good certainty if any heart arteries are blocked and how many.  MPI can also show if you’ve previously had a heart attack.

Depending on circumstances, for example if you have chest pain and an abnormal MPI study, the next step may be performing a coronary angiogram.  On the other hand, if the MPI study is normal, your doctor can confidently look into other causes of chest pain that aren’t related to the heart.

Quick facts

• An MPI test examines blood flow through your heart during exercise on a treadmill or exercise bicycle (“physical stress”) and while you rest. If you can’t exercise well, you’ll get a medicine (“chemical/pharmacologic stress”) to increase the blood flow to your heart muscle as if you were exercising.
• The test uses radioactive material called tracers. Tracers mix with your blood and are taken up by your heart muscle as the blood flows through your heart arteries.
• A special “gamma” camera takes pictures of your heart to show how well your heart muscle is perfused (supplied with blood)
• The pictures will help your doctor see if your heart muscle is getting enough blood, or if blood flow is reduced to parts of the heart muscle because of narrowed arteries. MPI can also tell if there are areas of dead cells (scars) from a past heart attack.  Some  forms of MPI can also tell your doctor if portion of the heart muscle that aren’t working well after a heart attack have a chance of going back to normal if a coronary stent is place or bypass surgery is done (“viability imaging”)
• The amount of radiation you get from an MPI test is small.

Why do people have MPI tests?
An MPI test shows how well blood flows through your heart muscle. If the test shows a lack of blood flow during exercise or stress, but is normal at rest, it could mean that an artery that carries blood to your heart is narrowed or blocked. If the test shows a lack of blood flow to a portion of the heart muscle during exercise or stress and at rest, it could mean that your heart muscle is scarred, possibly from a past heart attack.

MPI tests can help your doctor:

• Find out if there are narrowings or blockages in your coronary (heart) arteries if you have chest discomfort
• If you have heart damage from a heart attack if your heart is not working normally
• Determine if you should undergo a coronary angiogram 
• Decide whether you would benefit from coronary stent or bypass surgery to treat your chest discomfort or help a abnormal pumping fuction go back to normal
• If a heart procedure you had to improve blood flow (stent, bypass) is working
• How well your heart can handle physical activity

What are the risks of an MPI test?
MPI tests are generally safe for most people. MPI studies expose you to a low dose of X-rays. Experts disagree if X-rays at such low doses can cause cancer, but the possibility exists that no dose of X-rays, however low, is completely safe.  Don’t take the test if your risk for a heart attack is low, or if there is no other reason (chest discomfort) to think that you have heart trouble. If you’re pregnant or think you might be pregnant, or if you’re a nursing mother, tell your doctor before you have this test. It could harm your baby.

How do I prepare for my MPI test?

• Tell your doctor about any medicines you take, including over-the-counter medicines, herbs and vitamins. He or she may ask you not to take them before the test. Don’t stop taking your medicine until your doctor tells you to.
• Your doctor may also ask you not to eat certain foods, such as caffeine-containing beverages (i.e. coffee, tea, soft drinks) or chocolate, for 24 hours before your test. The test may have to be postponed or cancelled if you did drink caffeine.
• Don’t eat, and drink only water for 4 to 6 hours before your test.
• Wear comfortable, loose-fitting clothing and comfortable shoes to exercise in.

What happens during my MPI test?

Specially trained technicians usually perform the test in a hospital or clinic with special equipment.

• The technician places small metal disks (electrodes) on your chest, arms and legs. The disks have wires that hook up to a machine to record your electrocardiogram (ECG). The ECG keeps track of your heartbeat during your test and is used to tell the camera when to take a picture.
• You’ll wear a cuff around your arm to keep track of your blood pressure.
• The technician will put an intravenous line (IV) in your arm. 
• You’ll exercise on either a treadmill or exercise bicycle
• If you cannot exercise, your IV line will be connected to a bag that has a medicine to increase the blood flow to your heart, similar to when you exercise, or make your heart go faster. This is called a chemical or pharmacologic stress test. These medicines may include adenosine, dipyridamole (Persantine) or dobutamine.
• When you reach your peak activity level, you’ll stop and receive a small amount of radioactive material (tracer) through the IV line.
• You’ll lie still on a table for 10- 30 minutes while the gamma camera takes pictures of your heart. Several scans are done during that time to provide pictures of thin slices of your entire heart from all angles. It’s very important to hold completely still with your arms above your head while the pictures are being taken.
• During the resting part of the test, you’ll receive more tracer and another set of pictures will be taken. This set of images will be compared to the images taken after exercise or stress. 
• Some forms of the test do not use stress or exercise, but take 2 sets of rest images with 2 different tracers.

The test takes between 3 and 4 hours. Some labs may do the resting part of the test first, or do the resting and exercise tests on different days.

What happens after my MPI test?

• You can usually go back to your normal activities right away.
• Drink plenty of water to flush the radioactive material from your body.
• Make an appointment with your doctor to discuss the test results and next steps.

“My doctor showed me the pictures from my test and I could see where I had a lack of blood supply in my heart.”  Mitch, age 49.

How can I learn more about a MPI test?

Talk with your doctor. Here are some good questions to ask:

• Why are you doing this test rather than a different one without radiation?
• Do you think the small possible risk of cancer related to X-rays is justified compared to my condition and my risk of having heart trouble?
• What do I need to do to get ready for this test?
• When will I get the results of my test?
• Will I need to have more tests after this?
• What if I get chest pain or shortness of breath during the test?

Courtesy: http://www.heart.org/HEARTORG/Conditions/HeartAttack/SymptomsDiagnosisofHeartAttack/Myocardial-Perfusion-Imaging-MPI-Test_UCM_446352_Article.jsp

Nuclear Heart Scan

The question of Nuclear Heart Scans and associated tests comes up from time to time on different heart support groups I am a member of on Facebook and came again overnight on one of these groups.

With this in mind I thought it relevant to post some information on these tests.

Types of Nuclear Heart Scans

The two main types of nuclear heart scans are single photon emission computed tomography (SPECT) and cardiac positron emission tomography (PET).

Single Photon Emission Computed Tomography

Doctors use SPECT to help diagnose coronary heart disease (CHD). Combining SPECT with a stress test can show problems with blood flow to the heart. Sometimes doctors can detect these problems only when the heart is working hard and beating fast.

Doctors also use SPECT to look for areas of damaged or dead heart muscle tissue. These areas might be the result of a previous heart attack or other cause.

SPECT also can show how well the heart's lower left chamber (left ventricle) pumps blood to the body. Weak pumping ability might be the result of a heart attack, heart failure, and other causes.

Tracers commonly used during SPECT include thallium-201, technetium-99m sestamibi (Cardiolite^®), and technetium-99m tetrofosmin (Myoview™).

SPECT is a noninvasive nuclear imaging test. It uses radioactive tracers that are

injected into the blood to produce pictures of the heart.

Positron Emission Tomography

Doctors can use PET for the same purposes as SPECT—to diagnose CHD, check for damaged or dead heart muscle tissue, and check the heart's pumping strength.

Compared with SPECT, PET takes a clearer picture through thick layers of tissue (such as abdominal or breast tissue). PET also is better at showing whether CHD is affecting more than one of your heart's blood vessels.

Right now, however, there's no clear advantage of using one scan over the other in all situations. Research into advances in both SPECT and PET is ongoing.

PET uses different tracers than SPECT.

PET is a noninvasive nuclear imaging test that uses radioactive tracers to produce pictures of 

your heart. Doctors use cardiac PET scans to diagnose

Courtesy: http://www.nhlbi.nih.gov/health/health-topics/topics/nscan/types

Coronary Calcium Scan - The Heart Test You May Need—but Likely Haven’t Heard of

This topic has come up a few times on Facebook groups I am a member of and I thought it is worth posting about here:

Coronary Calcium Scan - The Heart Test You May Need

Meet the coronary calcium scan, an accurate test that can help determine your future risk of heart attack or cardiovascular disease. Johns Hopkins experts explain why this test may be best for you.

How's your coronary artery calcium? What's that, you ask? Like the more familiar tests used to assess your risk of future heart problems—cholesterol, blood pressure and blood sugar tests, for example—coronary artery calcium (CAC) testing helps reveal your risk of heart disease, often before other warning signs appear.

Also known as a calcium score, it's one of the newer—and more accurate—assessment tools being used. "A coronary calcium scan isn't for everyone, but it's the finest way for those who are uncertain about their heart disease risk to make better decisions about treatment and medications," says Michael Blaha, M.D., M.P.H., director of clinical research at the Ciccarone Center for the Prevention of Heart Disease at Johns Hopkins.

What does a coronary calcium scan do?

The scan provides images of your coronary arteries that show existing calcium deposits. Called calcifications, these deposits are an early sign of coronary artery disease.

How does the coronary calcium scan work?

Pictures of your heart are taken while you lie in a scanner for about 10 minutes. This simple and painless procedure is called a computed tomography (CT) scan. A score of zero has been shown to indicate that you have a very low risk of having a heart attack within the next seven years.

How is a coronary calcium scan used?

For someone who has several risk factors for heart disease, the test can help determine how aggressive treatment should be, whether different types of medications should be started, or whether a person is at very low risk for heart events. "Unlike risk factors, which can only tell you probabilities, this information is individualized, more concrete and actionable," Blaha says.

Why doesn't everyone get a coronary calcium scan?

Because this test is relatively new, it's not part of standard guidelines for heart screenings—and not all insurance plans cover it. But it's apt to be used more in the future, as several studies comparing it with other tests have shown its effectiveness in determining the risk of cardiac events. For now, ask your doctor.

Courtesy: John Hopkin MedicineRead original article here: http://www.hopkinsmedicine.org/health/healthy_heart/know_your_risks/the-heart-test-you-may-needbut-likely-havent-heard-of

Second Cardiac Rehab Talk for 2015

On Thursday, I gave my second talk for the year to our local cardiac rehab unit with 23 people in attendance. Whilst setting up before the presentation a lady came over smiling and to say hello and introduce herself and remind me she was the person who co-ordinated a talk I gave for Heart Foundation to her local Probus group in July, 2012.

I told her I most definitely remembered that talk where she introduced me to the crowd of over 80 people who attended that day and I told her, to this day, it was one of my most satisfying talks. Apparently her husband had a bad asthma attack in December, not a heart attack, when they discovered he had some severe blockages that required a triple bypass hence here being there today with her husband. It was good to see both of them today and to see how well her husband is doing on his road to recovery.

As usually happens, people came up to me afterwards to ask questions and one was from the wife of someone who also had bypass surgery and was having issues with concentration, reading and memory. We talked a bit about this and I mentioned something called Postperfusion syndrome (also known as Pumphead) which is not unusual for someone who has had bypass surgery. She was worried, and rightly so, that it was something out of the norm and I tried to reassure her it is not unusual and it might be a good idea for both of them to have a chat with their GP or cardiologist where she could get a better explanation. I told her I am not a doctor and am not qualified to talk more about this condition but suggested she could also bring this up with one of the wonderful staff at cardiac rehab.

Another person who himself has previously had heart issues was there today with his wife who is now dealing with the after effects of a heart event and who is in denial and has a bit of dementia. He really was looking for understanding and support as I had brought up my issues dealing with depression and anxiety after my heart attack and during my recovery. Again, I referred him to the CR staff.

Still another person asked me how long it took for me to feel '100%'. My answer was simply we are all different and we all heal at a different pace after bypass surgery. I told him that I still have issues with fatigue and lack of stamina but told him I also deal with T2 diabetes, a thyroid condition, sleep apnoea and angina and that it is not unusual two or three or even four times a week for me to have an afternoon nap.

Another person brought up the question of the need for people 'like us' who have been through the process getting into schools and talking to high school kids about what has happened to us, in many cases, as a result of poor lifestyle choices - smoking, alcohol, drugs, lack of exercise, poor diet etc. This is a topic which has always been close to my heart (pun intended) and something I wanted to see implemented by a heart support group I was involved in setting up in late 2008. Unfortunately, others in the group did not see this as a priority.

Having left that group and then becoming involved in our Heart Foundation as a volunteer speaker I was asked last year to give a talk to one of our local high schools and over 70 students were in attendance. The impact of someone who has been through process of a heart attack and bypass surgery should not be underestimated on the impressionable minds of teenagers and is why I believe it is so important for 'survivors', if they are up to it, to get involved in this sort of activity as well as sharing their experience with their family, children, grandchildren, church, social and sporting clubs and work colleagues.

All in all, the day's talk went very well and I look forward to the next one in April.

Talk given in Sep, 2011