Blood tests
These can pick up abnormalities that influence how well the heart is working. For example, they can detect raised levels of cholesterol (which may lead to coronary artery disease), abnormal levels of thyroid hormones (which can affect the heart's strength and rhythm) and the presence of cardiac enzymes (chemicals released when heart muscle cells are damaged in a heart attack).
Cardiac enzyme tests
Blood samples taken over a series of days can reveal the level of enzymes - proteins that help with chemical actions in the body and are released after a heart attack - in the blood.
Cerebral arteriography
This is used to show the extent and location of hardening of the arteries in the brain in order to diagnose patients at risk of stroke. The test takes between 20 minutes and an hour and is often done as day case, though some patients may have a short stay in hospital. There is a very small risk - one in 700 - that the test will cause a heart attack.
Chest x-ray
This shows abnormalities in the size or shape of the heart, and whether fluid is building up in the lungs because the heart isn't working efficiently as a pump.
Coronary angiogram
This is often used to assess whether people with angina require surgery. The test gives vital information about:
- Blood pressure within the heart
- How much oxygen is in the blood
- The function of the pumping chambers and valves
- The exact severity and positioning of any narrowings in the coronary arteries
A catheter is inserted into a vein or artery in the groin or arm, under a local anaesthetic, and dye is injected into the coronary arteries. Obstructions in the arteries can be identified by tracing the liquid's passage though the veins.
Coronary angiography
This is a more complex test. Under the guidance of an x-ray camera, a long, thin tube is threaded into the coronary arteries via a blood vessel in the groin or arm and a dye, which can be seen on the x-ray screen, is then injected, showing the pattern of the coronary arteries.
CT scan
High resolution images of the heart, brain and blood vessels are given by X-ray computed tomography (CT) or computerised axial tomographic (CAT) scans. It's useful to evaluate disease of the aorta - the largest artery in the body and involves little potential risk to patients. In stroke patients, it gives valuable information about the location and extent of brain injury.
Doppler studies and echocardiography
Blood samples taken over a series of days can reveal the level of enzymes - proteins that help with chemical actions in the body and are released after a heart attack - in the blood.
Echocardiogram
This scan uses sound waves to create an image of the heart as it beats. It shows the structure of the heart, how the walls of the heart move, and how well the heart valves are working.
Echocardiography
A pulse of high frequency, inaudible sound is transmitted through the skin by placing a recorder or probe on the chest wall. The probe picks up the echoes reflected from various parts of the heart and displays them as an echocardiogram - a picture on a screen. The recorded waves show the shape, texture and movement of the valves and the size and function of the heart muscle and chambers. The test can take up to an hour and is painless. It provides information about disease of the heart muscle for those who have suffered a heart attack or heart failure and to assess people with disease of the heart valves.
Electrocardiogram (ECG)
This shows electrical activity in the heart. It can reveal the thickness of the heart muscle (this may indicate long-term strain due to high blood pressure), areas of damage after a heart attack, and whether the blood supply to the heart muscle is adequate.
Exercise stress test (or treadmill test)
This monitors the heart during exercise and shows how well it responds when the demands on it are increased. It's a good way to detect blockages in the blood flow through the coronary arteries to the muscle of the heart (coronary artery disease).
Holter monitoring
Also known as 24-hour ECG, involves electrocardiogram recordings taken over 24 hours and can help diagnose palpitations, which occur infrequently and can easily be missed in a short test. The electrodes are placed on the chest and attached with wires to a small portable tape recorder which is worn on a belt around the waist. The recorder - the Holter monitor - takes constant or intermittent readings.
MRI scan
A magnetic resonance imaging (MRI) scan produces detailed pictures of internal organs, including the heart and brain. Patients lie in a short tunnel-like machine which contains a cylindrical magnet. Short bursts of magnetic fields and radio waves create images of parts of the body as required.
MRI can measure the flow of blood through some of the major arteries and can detect abnormal heart function in disorders such as cardiomyopathy (heart muscle disease), coronary heart disease, and congenital heart defects and help define the location and extent of brain injury in stroke patients.
Nuclear imaging
A very small and harmless quantity of radioactive substance, called an isotope, is injected into the blood, often while exercising. Gamma rays emitted by the isotope - usually technetium or thallium - are picked up by a "camera" positioned close to the chest and tests the size and pumping function of the heart chambers, taking pictures of the inside of the heart as it empties and fills. Blood flow to the heart muscleis also studied, taking pictures of the flow of blood to the muscular walls of the heart.
Thallium scan
Radioactive dye is injected during exercise to demonstrate the amount of blood reaching different parts of the heart's muscular walls.
When the results of these and other tests are available, it's possible to build a picture of what is going wrong with the heart, reach a diagnosis and consider appropriate treatment.
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