Investigations

Investigations are done to evaluate the function of the heart if heart failure is suspected. The following are the most common investigations:

• Six minute walk
• Electrocardiogram (ECG)
• Echocardiography
• Thyroid function
• Chest xray
• BNP Blood test
• 24 hour electrocardiogram
• Cardiac catherterisation and coronary angiography
• Biopsy

The Six- minute Walk Test

This is carried out in the hospital with the Specialist nurse and the Consultant in the vicinity. The patient walks for a time period of 6 minutes at their own pace with as many stops as desired. The walking distance is very indicative of the degree of heart failure. 500 metres and more in distance achieved indicates a mild level of heart failure only and a distance of 150 metres or less indicates severe heart failure. The distance reached by patients with moderate heart failure lies in between. This is regarded as a simple but important test.

ECG (Electrocardiogram)

This is an electrical tracing of heart activity. It demonstrates whether the patient has had a heart attack or has myocardial ischaemia whether the rhythm of the heart is normal, whether there is evidence of high blood pressure and whether the walls of the heart are abnormally thick.

Echocardiography

An echocardiogram is a “sound picture” of the heart and shows the heart in action, the valves, the walls and the pumping action of the heart. Abnormality of the heart structure (i.e. an area of dead muscle) will show up. It also enables the doctor to determine the ejection fraction.This shows how much blood is pumped out in each beat expressed as a percentage value. A normal left ventricle pumps out 60% of the blood, which it contains in a beat. If the ejection fraction is only 40% say, this means that the heart is not pumping normally and a significant degree of heart failure is present (if the patient has symptoms of the condition.) The ejection fraction may be normal to high in diastolic dysfunction.

Thyroid Function test and Other Blood Tests

Blood tests for thyroid function are done to demonstrate an over-active or under-active thyroid gland. Other tests include full blood count, urea and electrolytes, blood glucose (sugar) and liver function tests.

Chest X- rays

A chest x- ray shows whether a heart is enlarged, whether there is fluid in the lungs, whether there are effusions and whether there is a prominence of vessels in the lungs. Typical changes in the x- ray picture can be seen below.

BNP Blood test

BNP Blood test stands for B-type natriuretic peptide, a hormone in the blood that indicates either heart or renal failure. Higher concentrations may indicate an increased risk of death or other adverse cardiovascular events.

This test is not available in all centres.

24 hour Electrocardiogram (ECG)

This shows any abnormalities in the ECG in a 24 - hour period, when the person is going about their daily business. It may be more likely to pick up abnormalities than a one- off ECG.

Cardiac catheterisation and coronary angiography

This allows the doctor to look at the coronary arteries and assess the blood flow to the heart muscle.

Biopsy

Rarely, a biopsy may be taken of the heart muscle if inflammation or infection of the heart muscle is suspected.