Acute Coronary Syndrome

Description

Acute coronary syndrome (ACS) is the term used to describe a sudden reduction in blood supply to the heart muscle, usually as a result of partial or complete blockage of a coronary artery.The main subtypes of ACS include angina and myocardial infarction (MI) more commonly known as heart attack.
The heart muscles require an adequate and consistent supply of nutrients and oxygen to function properly and this is mostly supplied by blood from the coronary artery. The heart muscle's demand for oxygen varies depending on the physical or emotional requirements of the body. Anything that impairs the flow of blood through the coronary artery is likely to reduce the oxygen supply to the heart muscles with varying consequences.

Reduced blood flow through a coronary artery is usually caused by plaque deposition. Plaques, known as atheroscleroma, are lesions that form on the walls of arteries in response to some initial injury, caused by infection, increased blood pressure or other factors. The initial inflammatory response is followed by the development of a lesion consisting of a fibrous outer layer and a sticky lipid inner core. As these lesions grow they reduce the blood flow through the affected artery. This may cause oxygen starvation to the heart muscle if there is increased demand due to exertion or stress, and may result in heart muscle pain and other symptoms which are relieved by rest. This condition is known as stable angina.
In some cases the fibrous outer layer of plaque may rupture exposing the sticky inner layer of lipids. Red blood cells stick to this lipid layer and form a clot which causes further blockage of the artery. Symptoms of angina may become more severe and occur at rest. This is known as unstable angina.
If there is significant reduction in blood flow, part of the heart muscle may be starved of oxygen and suffer necrosis and permanent damage. Complete obstruction can result in rapid muscle and heart failure. This is known as myocardial infarct.

Signs & Symptoms

The main symptom of decreased blood flow to the heart is chest pain, experienced as tightness around the chest and radiating to the left arm and the left angle of the jaw. This may be associated with sweating, nausea and vomiting, as well as shortness of breath. In many cases, the symptoms are unusual, with pain experienced in different ways or even being completely absent. Some patients may report palpitations, anxiety or a sense of impending doom and a feeling of being acutely ill.

Treatment

Treatment depends on ECG findings, blood test results and time lapsed between symptoms and presentation.
The main objective is to reduce or remove blockage to coronary artery. This may be achieved with medications which inhibit platelet aggregation (aspirin clopidogel) or coagulation (heparin) and prevent or reduce clotting. Oxygen starvation of muscle may be relieved with nitrates or beta blockers.
Blockages may have to be removed or reduced by insertion of a catheter into the coronary artery and dilation with a balloon. A more permanent effect may be achieved by inserting a stent (a device like a coiled spring which maintains an open passage in the artery).

Patient Management

Patients who have experienced ACS should be on permanent aspirin therapy unless contraindicated. Patients should reduce lipid intake, maintain a healthy diet and exercise regularly. Patients should not smoke as this will greatly increase the likelihood of further problems.