i. ACS Acute Coronary Syndrome
Acute Coronary Syndrome (ACS) is an umbrella term for all ischaemic heart diseases that are caused by reduced blood flow to the heart (Roebuck A and Farrer M 2005). It includes the following conditions:
- unstable angina pectoris (UA),
- non-ST-elevation myocardial infarction (NSTEMI), and
- ST-elevation myocardial infarction (STEMI) (NICE, 2014.)
A diagnosis of ASC is based on the presenting symptoms and a comprehensive clinical history. The symptoms are commonly associated with a rupture of an arteriosclerotic plaque within the coronary arteries. This leads to the formation of a thrombus (blood clot) in the effected vessel by a process of platelet activation, adhesion and aggregation.
In unstable angina and non ST elevated myocardial infarction there is partial occlusion of the affected coronary artery by the thrombus which reduces the oxygen supply to the myocardium. It is this reduced blood supply that causes the ischaemic chest pain. Changes can be seen on ECG, but changes are not necessarily always present. There will be raised cardiac enzymes which will be indicated in blood tests.
If the blood vessel is totally occluded by the thrombus this is known as ST elevated myocardial infarction there will ST elevation present on the ECG and raised cardiac enzymes. The myocardium is starved of oxygen and nutrients resulting in death of the affected heart muscle.
Risk factors for development of coronary diseases are divided into modifiable and non-modifiable factors. Modifiable risk factors are physical activity, hypertension, hyperlipidemia, diabetes, smoking, obesity and stress. Non-modifiable risk factors are age, family history and gender. (NICE, 2014).