Patient Information – heart tests

There are many different heart tests we can do to see how the heart is functioning. Which test we recommend depends on what your symptoms are. The British Heart Foundation website ( is a good source of information for more details, but here are some of the commonly performed heart tests.

Stress Echocardiography

One heart test we do is called stress echocardiography (often called ‘stress echo’) is a widely used test to assess how well the heart is working. An ultrasound machine is used to take pictures of the heart at rest and after the heart rate has been increased (the ‘stress’), either after exercise (walking on a treadmill) or after a drug has been given to increase the heart rate in a gradual and controlled manner. The ultrasound images of the heart at rest and at stress are then compared with one another to see how well the heart copes with the extra workload. The test is safe, painless, doesn’t involve exposure to any radiation and takes about 30 minutes.

Why do this heart test?

Stress echo is most commonly used in patients experiencing chest pain to look for coronary heart disease. The chest pain may be a sign that the heart is not getting enough blood when it needs it – often referred to as angina – and stress echo can detect this. Stress echo can also be used to check how well the heart works in patients with valve disease (e.g. narrow or leaky heart valves) and in patients with heart failure also.

How many of these heart tests do you do?

Northwick Park Hospital performs more than 2000 stress echo tests each year and this is more than any other hospital in the country.

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Another common heart test is an echocardiogram (or “echo”. This is a non-invasive and diagnostic test that uses sound waves (ultrasound) to create video pictures of the heart so that the structure, movement and function of the heart’s chambers and valves can be assessed. The technology is similar to that used to assess a baby’s health during pregnancy.

This enables the doctor or technician to diagnose many types of heart muscle and valve disease. They can also follow the progress of disease over time, to plan medical and surgical treatment. In addition they can evaluate the success of this treatment.

There are two main types of echocardiogram:

1) Transthoracic echocardiogram: this is the most common type of echo where the hand held ultrasound device is placed over several parts of the chest. This is safe and painless with the entire procedure taking less than 30 minutes.

2) Trans-oesophageal echocardiogram (TOE): this involves placing a small ultrasound probe into the gullet. The gullet is located very close to the heart. This means that the heart can be viewed and assessed in even greater detail.

The latest technology allows us to view the heart in three-dimension (3D) using echo. It’s almost as if the doctor is looking at the heart with his own eyes!

We perform around 6000 scans a year making this department one of the busiest in the country.

ECG & Exercise ECG


An ECG (Electrocardiograph) is a recording of the electrical activity of the heart and gives us a picture of the rhythm of the heart and is useful in helping diagnose a heart condition. You will have 4 electrodes attached to your arms and legs and 6 placed on your chest. These will be attached to an ECG machine and a recording of your heart beat will be taken. This is a painless procedure and the electrodes are sticky to attach on the skin. People with a hairy chest may need to have some hair shaved away in order for the recording to work.

What does the ECG show?

The ECG gives us a snapshot of the electrical activity of the heart. It is the starting point for most cardiology investigations. You can see things like a heart attack, an old heart attack, rhythm problems and heart conduction problems. You can also see if the heart is being strained by high blood pressure.

What is an exercise ECG?

As frequently heart symptoms first start to show initially when exercising, it will sometimes be helpful to record this when exercising on a treadmill or exercise bike. It may be that this will show changes as the heart has to work harder. To do this you will be asked to walk or run on a treadmill or cycle on a bike while we record the ECG. This will take about 10 minutes and your blood pressure will be checked regularly during this time. If you are unable to exercise, this test will not be offered to you.

Angiography & Angioplasty with Stenting

What is this heart test?

An angiogram is when an image of the arteries supplying the heart muscle itself is taken. A small tube is inserted into the heart via an artery in the arm or leg. Dye is then injected and using X-ray the outline of the artery is recorded. If a narrowing is found, if possible a wire is placed across the narrowing and then a balloon is passed over this wire and inflated to re open the artery. Finally, a stent, which is a scaffold, is inserted to help keep the artery open.

Is an angiogram painful?

A local anaesthetic is injected into the skin around where the catheter will be placed. This can sting a little, but the skin quickly goes numb and is not painful. You may feel some pressure in the area. Occasionally if one of the heart arteries is narrow, during the test you may experience your angina chest pain. The doctor will quickly be able to give you medicine to relieve this.

What happens afterwards?

Tablets have to be taken for a year after this procedure to reduce the clotting mechanism of the blood and prevent the stent becoming blocked. If there are numerous narrowings or if this procedure is unable to be performed, patients may be referred for a bypass operation.

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