Stable angina is the main symptom of coronary heart disease. It usually feels like a tightness or heaviness in the chest, but the feeling might spread further, say to the arms, neck or stomach. The pain usually goes away within ten to 15 minutes.

Angina is caused by insufficient oxygen reaching the heart muscle, because of the blockages in the coronary arteries. Physical exertion is likely to bring on an angina attack, as the heart must work harder and will therefore need more oxygen. Angina becomes more common once we're over the age of 50.

Unstable angina is where many small blood clots narrow the artery and suddenly reduce the amount of blood reaching the heart. Variant angina is due to spasm of a coronary artery and there can be irregularities in the heart's normal rhythm during an attack. This type of angina may not be caused by fatty athersclerotic deposits.

There is a wide range of treatments for angina, including a small daily dose of aspirin, which reduces the risk of a heart attack.

Glyceryl trinitrate (GTN) is prescribed to ease the pain of an angina attack. It is available in many forms, including tablets, sprays, patches and injections. These treatments won't clear the blockages once they have formed.

Several surgical procedures have been developed to clear blocked arteries. These include angioplasty and coronary artery bypass graft. For detailed information on the tests and treatments for coronary heart disease see the British Heart Foundation website.

Heart attack or myocardial infarction occurs when the blood supply to a part of the heart muscle is interrupted or stops, usually because of a blood clot in the coronary artery. Without oxygen the heart begins to shut down. The symptoms are usually, but not always, a crushing pain in the chest, which may spread to both arms (particularly the left), and up into the throat and jaw. If this does not go away within 15 minutes, help should be sought immediately by phoning 999 for an ambulance.

Cardiac arrest is the term used to describe potentially fatal, abnormal heart rhythms. Damage to the heart muscle (caused by a heart attack) can lead to the lower chambers quivering or wobbling rather than beating in time with the rest of the heart. This is called ventricular fibrillation, which leads onto cardiac arrest, when blood stops being delivered to the rest of the body. If cardiac arrest occurs, the heart will only survive if given a jolt of electricity to defibrillate it.