HEART INVESTIGATIONS
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There are a number of investigations that can be used to provide information about the heart's underlying rhythm, structure and function.
The most appropriate tests for an individual will vary depending on numerous clinical factors including the patient's symptoms, examination findings and any underlying conditions that they may have.
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ELECTROCARDIOGRAPHY AND CARDIAC MONITORING
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There are a variety of non-invasive tests designed to specifically look at the heart’s rhythm and identify the risk of developing an arrhythmia. The humble electrocardiogram (ECG) is a very useful tool that provides a snapshot of the heart's rhythm, as well useful information about the underlying structure and function of the heart. It forms part of the basic cardiovascular review in clinic.
There are a number of devices that can be used to assess the heart over a longer period of time. An ECG can be adapted so that it can be used during your normal day to day activities to assess the heart for 24 hours, or in some cases up to several days. This is useful as it enables an abnormal heart rhythm to be 'captured' if it is episodic and not picked up during a standard ECG.
There are also devices that can be taken home and can be triggered by the click of a button to record the heart rhythm when a patient experiences symptoms such as palpitations (this is known as a event recorder). The device can be taken home for several days and can be useful when a patient experiences symptoms that happen infrequently. Finally, if the patients symptoms warrant and then a very small implantable loop recorder can be inserted under the skin of the chest. This can monitor your heart rhythm over several months (often the device battery can last up to 2 years) and heart arrhythmia information can be uploaded remotely and analysed remotely.
A tilt table test is a non-invasive test whereby a person's ECG is monitored whilst he/she is tilted at differing angles. This test is useful to identify certain causes of blackouts or near faints such as simple faints (vasovagal syncope).
Last but not least, one's blood pressure can also be monitored for a 24 hour period during your regular daily activities. This allows an average BP to be derived and therefore a better understanding of blood pressure control during a normal day, rather than simply one off readings in a clinic, which may be made worse by 'white coat' hypertension.
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EXERCISE TOLERANCE TEST
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An Exercise tolerance test, or exercise ECG, is a series of ECGs taken at several standardised stages of increasing levels of exertion (normally on a treadmill). It is usually performed when it is important to gain an idea of your exercise tolerance. Also looks for ECG changes which may be suggestive of angina or underlying heart rhythm problems.
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ECHOCARDIOGRAM ASSESSMENTS
An Echocardiogram is a non-invasive test that uses ultrasound to assess the structure and function of the heart. It looks at the pumping efficiency of the heart and can give important information about the function of the heart valves. Furthermore, important information about the pressures in the heart chambers can be derived.
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A stress echocardiogram is a non-invasive assessment of the blood supply to the heart and that may be used to investigate chest pain. ‘Stress’ is achieved in a controlled environment by gradually increasing the intensity of exercise (either on a treadmill or on a static bicycle). If patients are unable to exercise, then heart ‘stress’ can also be achieved by an intravenous infusion of a drug.
CT CORONARY ANGIOGRAPHY
A CT coronary angiogram is an x-ray based test that looks at the coronary arteries in a non-invasive way. This test can give information about narrowings of the coronary arteries, assess bypass grafts and help understand other important factors in cardiac anatomy. For this reason it may be used to investigate chest pains. It is also a good way of looking for the amount of heart artery calcium which can be an indicator of coronary disease and future cardiac risk.
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CATHETER LABORATORY ASSESSMENTS
A coronary angiogram is an invasive procedure that allows an accurate assessment of the coronary arteries. This involves the insertion of a long, thin flexible tube called a catheter into a blood vessel (normally in the groin or wrist) and this is then guided by x-ray up to the heart and coronary arteries. A special type of dye is then injected into the catheter and x-rays are taken which allow the arteries to be clearly visualised. This can show up any arteries that may be narrowed or blocked allowing us to investigate angina (chest pain).
Other tests that may be performed during the angiogram to help assess the functional significance of heart artery disease including a pressure wire study (an accurate assessment of coronary blood flow) and/or intravascular imaging to look at the arteries with thin ultrasound and light telescopes(eg IVUS or OCT). These additional tests are described on the cardiac procedures page.
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CARDIAC MRI
A cardiac MRI is a state of the art test that gives a detailed assessment of heart structure and function without the need for radiation. It can also give information about any underlying heart muscle abnormalities and any muscle injury/scarring. Furthermore, it can be used in the investigation of chest pain when the scan is also performed during an intravenous infusion of a short-lived drug that induces heart ‘stress’ in a controlled environment.
MYOCARDIAL PERFUSION IMAGING​
Myocardial perfusion imaging is nuclear medicine non-invasive assessment of the blood flow to the heart muscle that may be used in the assessment of chest pain. A radioisotope is injected to find areas of the heart muscle that do not have adequate blood supply at rest and this is compared with images taken during the infusion of an intravenous 'stress' agent.
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