Heart tests

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Blood tests help check how well your heart is working. They are also used to monitor the effects of any heart medicines you take.

The most common blood tests used to check heart health are:

• Cardiac enzyme tests (including troponin test) – These can help show whether your heart muscle has been damaged. During chemotherapy, they can help find early signs that your heart is sensitive to chemotherapy.
• Natriuretic peptide tests (BNP or NT-proBNP) – These tests can help show whether your heart is under strain. They can help find early signs that your heart may be struggling to cope with your cancer treatment. They can also show whether you need more tests to check for heart failure.
• Urea and electrolytes (U&E) tests – These give information about the levels of sodium, potassium and magnesium in your blood. These electrolytes are substances in your blood that are important to keep your heart healthy. U&Es also show how well your kidneys are working. Your kidneys may be affected by any medicines you are taking.
• Full blood count (FBC) – This test measures the number of red cells, white cells and platelets in your blood. It also measures the level of haemoglobin (Hb) in your blood. Haemoglobin carries oxygen around the body.
• Cholesterol blood tests – Having too much cholesterol in your blood increases the risk of heart problems. If your cholesterol level is high, you can make changes to your lifestyle that can help reduce it. Your doctor may also suggest that you take a medicine to lower cholesterol. These are called statins.

An angiogram:

• looks inside your coronary arteries to find out if any of them are narrowed, and how severe the narrowing is
• gives information about your risk of having a heart attack
• gives information about how effectively your heart is pumping
• gives information about the blood pressure inside your heart.

You will be asked not to eat or drink anything for several hours before your angiogram.

Having an angiogram

You have a local anaesthetic injection to numb the skin in your groin or on your wrist. The doctor then makes a small cut in the skin so they can insert a thin, flexible tube called a catheter into an artery. Using x-ray, the catheter is guided to the heart.

The doctor injects a dye into the catheter and takes x-rays. This dye is called a contrast. It is picked up on the x-rays and helps show how blood is moving through the heart. You might feel a hot, flushing sensation from the dye. Tell your doctor if you feel uncomfortable or unwell at any time.

Having a CT angiogram

A CT angiogram takes a detailed picture of the coronary arteries. It can be used to look at how blood is flowing through the heart.

You lie on a bed which is moved inside the scanner. The scanner is shaped like a large doughnut.

The scanner moves around your body and takes x-rays. These x-rays build up a picture of your heart.

A contrast dye is injected into a vein in your arm. This dye helps show certain areas of the body more clearly. It may make you feel hot all over for a few minutes. It is important to tell your doctor if you are allergic to iodine or have asthma. This is because you could have a more serious reaction.

A small amount of radiation is used during a CT scan, but this is very unlikely to harm you. It will not harm anyone you come into contact with either. If you are pregnant, talk to your doctor before having this test.

An MRI scan uses magnetism to build up detailed pictures of areas of your body. A cardiac MRI scan gives information about:

• structure of the heart
• the heart valves
• how well the heart is pumping.

Before a cardiac MRI scan

Before the scan, you will be asked to remove any metal objects, such as jewellery and hair clips.

The scanner is a powerful magnet. You may be asked to complete and sign a checklist to make sure it is safe for you. This will check whether you have:

• any metal implants, such as surgical clips, bone pins, artificial joints or artificial heart valves
• any electrical implants, such as a pacemaker, implanted defibrillators, nerve stimulators or cochlear implants.

It is safe to have an MRI if you have coronary stents in place. It would be useful to provide any records about any metal implants you have.

You should also tell your doctor if you have ever worked with metal or in the metal industry. This is because very tiny fragments of metal can sometimes lodge in the body.

Having metal in your body does not always mean you cannot have an MRI scan. Your doctor and radiographer will decide if it is safe for you. If you are not able to have an MRI scan, another type of scan can be used.

Some tattoo ink contains traces of metal. Most tattoos are safe. But tell the radiographer immediately if you feel any discomfort or heat in your tattoo during the MRI scan. You should tell the radiographer before the scan if you are pregnant or think you could be.

How is a heart MRI scan done?

For some cardiac MRIs, the doctor injects a dye into a vein in the arm. This is called a contrast. It does not usually cause discomfort. The dye helps to give a clearer picture of the heart muscle and the blood flow through and around the heart. Your doctor can tell you more about this.

During the scan, you need to lie still on a bed inside a cylinder (tube). The bed moves slowly inside the scanner. The radiographer is in a separate room, but you can hear and speak to them.

The scan can last for up to 1 hour. It is painless, but you may find it uncomfortable to lie still for that long. The scan is noisy, but you will be given earplugs or headphones. You may be able to listen to music during the scan.

After the scan, you can usually go home.

If you had a sedative, you should:

• not drive for 24 hours
• have someone to take you home
• have someone to stay with you overnight.

Some cancer drugs can cause high blood pressure. Your cancer doctor or nurse will check your blood pressure regularly. Sometimes they may want to monitor it over a longer time.

This can be done with a portable (ambulatory) blood pressure monitor.

Wearing a blood pressure monitor

You wear the monitor for 24 hours. You can still do most of your normal activities. But you should not have a bath or shower.

A blood pressure cuff (a band) is wrapped around your upper arm. A tube goes under your clothes from the cuff to a small monitor on a belt around your waist.

The cuff inflates around your arm and measures your blood pressure. It does this automatically at regular times. For example, it could happen every 30 minutes during the day and every hour at night. The monitor records your blood pressure measurements and the time they were taken.

After 24 hours, the monitor is removed by your doctor or nurse. The information is collected for your doctor to check.

Our information about heart health and cancer was developed in partnership with the British Heart Foundation.

If you have questions about your heart health, call the Heart Helpline on 0300 330 3311, Monday to Friday, 9am to 5pm, or visit bhf.org.uk.

We want everyone affected by cancer to feel our information is written for them.

We want our information to be as clear as possible. To do this, we try to:

• use plain English
• explain medical words
• use short sentences
• use illustrations to explain text
• structure the information clearly
• make sure important points are clear.

We use gender-inclusive language and talk to our readers as ‘you’ so that everyone feels included. Where clinically necessary we use the terms ‘men’ and ‘women’ or ‘male’ and ‘female’. For example, we do so when talking about parts of the body or mentioning statistics or research about who is affected.

You can read more about how we produce our information here.