ELECTROCARDIOGRAM (ECG)
An ECG is the most commonly performed cardiac investigation. It is a 10 second tracing of the heart’s electrical activity displayed on single page. Cables are attached to the body using sticker electrodes and allow the heart’s electrical activity to be viewed from multiple different vectors.
An ECG is essential in the diagnosis of heart rhythm abnormalities and unstable cardiac conditions like acute myocardial infarction (heart attack). It also contributes to the investigation of chronic diseases like high blood pressure, and structural heart abnormalities.
STRESS ECG
A stress ECG uses similar technology to a resting ECG, however the heart’s electrical activity is measured during gradually increasing exercise intensity. This is usually done on a treadmill but a stationary bicycle can also be used. Established exercise protocols are used to standardise performance and interpretation of the test.
A stress ECG is most useful in the assessment of chest pain syndromes, and in particular suspected coronary heart disease. It can also be used to aid decision-making in the management of cardiac arrhythmias and valvular heart disease.
ECHOCARDIOGRAM
An echocardiogram is a detailed ultrasound assessment of the heart using multiple imaging positions and modalities, including 2-dimensional ultrasound, M-Mode, continuous- and pulsed wave doppler and colour doppler. A well performed echocardiogram gives detailed analysis of the structure and function of each of the heart chambers, valves and major vessels, as well as the lining of the heart (pericardium).
Echocardiography is essential in the assessment and management of chest pain syndromes, unexplained shortness of breath, established coronary heart disease, heart failure, heart rhythm abnormalities, heart valve abnormalities, heart muscle disease and pericardial disease, amongst others.
Similar to stress ECG, stress echocardiography can also be used to assess the response of the heart muscle and valves to exercise, which contributes to the management strategy of these conditions.
Echocardiography has led to a better understanding and improved diagnosis of previously difficult to diagnose conditions, such as diastolic heart failure and pericardial constriction.
CORONARY ANGIOGRAPHY
Coronary angiography is a procedure performed to allow direct visualisation of the coronary arteries (blood vessels supplying blood to the surface of the heart) by advancing a thin tube (‘catheter’) into these arteries and injecting dye (‘contrast’) while recording the moving image using X-ray technology. This is the most accurate way of assessing for narrowings or blockages of the coronary arteries.
Coronary angiography is typically required in one of three scenarios: unstable coronary disease (unstable angina or heart attack), stable coronary disease (stable angina or ischaemic heart failure) or before major cardiac surgery to assess for narrowings in the coronary arteries that may require coronary bypass grafting at the time of surgery.
Implantation of a coronary stent can be performed at the same time if deemed necessary. A stent is a metal scaffold that is implanted directly into the coronary artery and is used to open narrowings or blockages to restore normal blood flow. Other advanced technology can be used to aid stent implantation, such a physiological interrogation (FFR.iFR), cutting balloons and rotablation.