Cardiac Nuclear Medicine Scan Content from the guide to life, the universe and everything

Cardiac Nuclear Medicine Scan

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Your doctor would like you to attend the hospital's radiology department for a cardiac nuclear medicine scan.

Scary stuff. Especially if you've never had a scan before, and even more so if this is your first 'health scare'.

The scan is requested when a patient has chest pain and the doctors are not sure if it is coming from the heart or not. The scan displays in real time whether there's any ischaemia (lack of blood supply) in a particular area of the heart. It is usually done if a regular treadmill ECG (electrocardiograph) test is inconclusive, or the patient is unable to use a treadmill.

This Entry gives a brief explanation of what is involved and answers some questions you may have before you attend. The information is taken from an actual appointment letter to a prospective patient after she had been recommended for a scan by her own GP. A technician or staff nurse will explain the procedure in detail when you arrive at the hospital department; the procedure may vary by hospital or circumstances. Although you will have to fast before the procedure unless otherwise instructed, diabetic patients will receive special instructions and should ensure the Nuclear Medicine Department knows they are diabetic.

What is a Scan?

Different types of scans are used for different things. Ultrasound is one type and MRI (magnetic resonance imaging) is another. The cardiac nuclear medicine scan that you will have is not like these. It is a test in which a small amount of radioactivity (called a tracer) is used to obtain pictures that will help the doctor understand your illness. This scan is also called a technetium heart scan, technetium (99mTc) pyrophosphate scintigraphy, hot-spot myocardial imaging, infarct avid imaging or a myocardial infarction scan. (Any other names will be similar to these.)

What Does it Involve?

The procedure usually takes place over two days. On the first day you will be given a small injection of radioactive technetium-99 (99mTc)1. The injection will feel like having a blood test. It will not cause you to feel ill or have any other adverse effects. After the injection you will be able to have a drink.

After 45 minutes you will be given a further drink and a sandwich. This is part of the test, and improves the quality of the pictures. After another 15 minutes they'll begin to take the first set of photos. These will take about 30 minutes to complete. A special camera - called a gamma camera - takes the pictures. You will have to lie on a bed during this process. You will not normally need to undress for the pictures.

After they have finished taking the pictures you will be free to leave the department. You will need to return another day for the second part of the test.

For the second test, they'll make your heart pump harder. For some patients, this can be achieved simply by the act of walking on a treadmill. In other patients they may stimulate the heart by injecting a chemical into the back of the hand through a small needle (called a cannula). There is a small chance that the chemical will cause you to feel sick or suffer a mild headache. After the chemical has been administered, they'll inject the radioactive material through the cannula. You will then be able to have a drink. While all this is happening, you will be attached to a heart monitor. After another 45 minutes, you'll be given a further drink and a sandwich. After another 15 minutes, they'll begin the second set of pictures. These also take about 30 minutes to complete. After they have finished taking the pictures the test is complete and you will be free to go home.

A Researcher's Personal Experience

First Scan

As my scan was due to take place in the afternoon, my letter said I was permitted to have a slice of toast and a glass of orange juice for breakfast, but definitely no tea or coffee.

Tip: If you need to take tablets, water is fine too. You should bring a list of the medications you are taking to the hospital.

Upon attending the right department, I sat down and waited.

Tip: Bring along a book or magazine.

Eventually, I was called to have my personal details checked and then to be weighed, as the medicine is administered in proportion to the patient's weight. Then I was sent back to the waiting area. After a bit, someone else called my name and I was taken to the room where the injection is given.

Tip: Offer your right arm for the injection, because you will be required to raise your left arm for around 15 to 20 minutes during the scan itself.

After the injection, I had to wait an hour for my scan. However, they did bring me a cup of tea and a choice of sandwiches about 45 minutes into the wait. When you are taken for the scan you have to lie on a bed about a quarter of the size of the one you're used to sleeping on. They lower the bed for you to climb on, and then ask you to raise your left arm and put it behind your head. I was told there was a handle to grasp, which I declined to do; instead I placed my hand under my head as it felt comfortable. This turned out to be a big mistake.
The scanner itself is a large photo machine. It was lowered to the area just above me (quite alarmingly close), and my nurse gave it a 'trial run' over my chest and back again before starting the scan properly. She then asked me to remain as still as I could, as the scanner was going to take 32 pictures of my heart from different angles. As she started it off, I was told it would take about 15 minutes to complete (it was nearer 20). After a few minutes, the pressure on my shoulder intensified and I started to sweat. I couldn't take my mind off the pain that was building in my arm, and the scanner moving and clicking above me seemed to be taking forever. The piped music of 'Lovely Day' that bizarrely played over and over again only added to my torture.

Finally, a little bell sounded and an attendant moved forward to extract me from the scan bed. The first nurse had disappeared, and the attendant offering to help me off the bed was the same young man who had given me the injection. I gratefully accepted, as I was quite disoriented. My arm felt like it had been sawn off and reattached with a rusty needle and barbed wire. I felt quite dizzy and barely heard him telling me to return next week (which I knew) at a later time (which I didn't) and not to take my atenolol - a beta blocker - from Sunday until after the second test. Luckily, someone had written it all down for me. I was allowed to leave the hospital, and was grateful to get home for an afternoon spent sipping cups of tea and looking forward to the second scan with relish.

Tip: Keep away from babies and small children for the rest of the day.

Please be aware that for 24 hours after the test you are radioactive, so don't go snail-hunting after dark.

Second Scan

The second procedure went exactly as the first, except that I received the chemical injection through the cannula in the back of my hand while lying on a bed and attached to a heart monitor. The chemical gave me a headache, but I was told the antidote is caffeine. Therefore, the next cup of tea was also for medicinal purposes.
This time, I remembered to grasp the handle provided, so I was quite comfortable throughout the scan, and it wasn't as scary as the first one had been. After the scan, I was dismissed home to wait for an appointment with the heart specialist.
BBC Factfiles: The Heart
1Actually technetium Tc-99m tin (II) pyrophosphate, usually referred to just as 'technetium'.

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