Congestive heart failure - Diagnosing heart failure

If you have symptoms of heart failure, your GP will ask you to describe them in detail. You will also have a physical examination.

If heart failure is suspected, a number of tests may be recommended to find out more. Some of the tests that you may have include:

• blood tests – to check whether there is anything in your blood that might indicate heart failure or some other illness
• breathing test – you may be asked to blow into a tube to check whether a lung problem is contributing to breathlessness 
• an electrocardiogram – this records the electrical activity of your heart 
• an echocardiogram – where ultrasound waves are used to examine your heart and check how well it is pumping, and whether there are valve problems (the procedure is similar to the one used to look inside the womb during pregnancy)

You should ask your doctor whether you should have these tests if you are not offered them but you are receiving treatment for heart failure.

Blood tests

Blood tests can help identify whether another condition is causing your symptoms, such as anaemia, diabetes, thyroid problems, kidney disease, or liver disease. A high blood cholesterol level is often associated with coronary heart disease, which may lead to heart failure.

Natriuretic peptide test

Your blood will be tested for a substance called natriuretic peptide (also called BNP or NTproBNP). If your heart is under high levels of stress, it will secrete BNP into your blood. The test is able to detect these increased levels.

A natriuretic peptide test can also indicate the severity of your heart failure. Higher levels of BNP/NTproBNP in your blood may indicate that you have more severe heart disease, while lower levels may indicate a milder form.

You can read more about the BNP test on the Lab Tests Online UK website. 

Echocardiogram (echo)

An echocardiogram, or echo, is a procedure that can be used to look at the structure of your heart in detail.

A pulse of harmless high-frequency sound waves is passed through the chest wall and produces a picture by "bouncing back" from the heart's structures (similar to an ultrasound scan used during pregnancy).

During the test, you will be asked to lie on your left side with your left arm behind your head. A gel will be put on your chest and an ultrasound probe (recorder) will be placed at various points on your chest between your ribs.

The probe will pick up echoes from your heart and show them on a screen as a detailed image of the structures of your heart. The image is known as an echocardiogram.

An echocardiogram provides a lot of useful information about the heart, including:

• how well your heart valves are working and whether any are damaged
• how well your heart is working as a pump (when your heart contracts, it forces blood to circulate around your body – this is known as the systolic function)
• how well your heart relaxes after pumping (the heart fills with blood when it relaxes after each contraction – this is known as the diastolic function)
• whether there are holes in the walls between the chambers of your heart that allow blood to flow from one side to the other (intracardiac shunts)

The most important finding from an echocardiogram is usually a measurement of how well one of the heart's chambers – the left ventricle – is pumping. The left ventricle pumps the blood around the body.

A measurement called the left ventricular ejection fraction (LVEF) is an estimate of how much of the blood that enters the left ventricle is pumped out when the heart muscle contracts.

In a healthy heart, about 60% of the blood entering the left ventricle is pumped out when the heart muscle contracts. A value of less than 40% indicates that your heart is definitely not pumping normally.

Sometimes different types of echocardiogram are carried out. These are outlined below.

Stress echocardiogram

A stress echocardiogram is carried out to see how well your heart functions when it has to work hard. During the test, your heart rate will be increased, either by exercising on a treadmill or exercise bike, or by using injected medication.

Transoesophageal echocardiography

Ultrasound does not travel well through lungs, which can make imaging the heart through the chest wall difficult.

However, the heart lies right in front of the oesophagus (the tube connecting your mouth to your stomach).

This makes it possible for a thin, flexible tube with a small ultrasound probe at the end to be inserted into your oesophagus to examine the structures of your heart in much greater detail. 

Before the procedure, you may be given a mild sedative to help you relax, and an anaesthetic will be sprayed on to the back of your throat.

You can read more about echocardiograms on the British Heart Foundation website.

Chest X-ray

A chest X-ray may sometimes be used to check whether your heart is bigger than it should be and whether there is fluid in your lungs, which might indicate heart failure. It can also pick up lung conditions that may be causing breathlessness.

Read more about tests for heart conditions on the British Heart Foundation website.