Narrowing of the coronary arteries by atherosclerosis (fatty deposits, calcium, cholesterol and blood clots) is known as coronary artery disease. This may be chronic and cause symptoms such as chest pain (angina) and breathlessness on exertion; or acute, causing acute myocardial infarction (heart attack).

Coronary artery bypass grafting restores blood flow to the heart muscle by adding a bypass graft (vein or artery) to bypass the blocked area. This surgery is usually done through an incision down the middle of the breastbone, called a median sternotomy, but can occasionally be done through an incision below the nipple on the left side, called a thoracotomy.

You may be connected to a heart lung machine (cardiopulmonary bypass) to maintain blood flow to the rest of the body while your heart is stopped to allow the bypass grafts to be sewn onto the coronary arteries. Alternatively, the bypass grafts may be constructed by stabilising the heart with special instruments while it is still functioning (beating heart surgery). Your surgeon will decide which is the most appropriate technique for you.

There are four valves inside the heart to allow blood to pass in one direction only. Occasionally these valves may become narrowed, causing obstruction to the flow of blood (stenosis) or may leak, allowing blood to flow backwards within the heart (insufficiency). This affects the efficiency of the heart's function. Occasionally these valves may be damaged by infection (endocarditis). The two most commonly involved valves are the aortic and the mitral valves. The aortic valve will usually be replaced. The mitral valve is frequently suitable for repair but, if this is not possible, a replacement will be undertaken.

There are two types of replacement valves. One is a tissue valve (bioprosthesis) made from the aortic valve of a pig or the sack around the heart of a cow (pericardium). The other type is a mechanical valve that is made from a very durable material called pyrolytic carbon. Your surgeon will decide with you the type of valve that is most suited to your requirements.

It is essential to use the heart lung machine (cardiopulmonary bypass) for heart valve surgery.

The aorta is the main blood vessel that runs from the heart supplying blood to every organ in the body. Occasionally the aorta can become diseased by dilating or enlarging (aneurysm) or by splitting, separating into an inner and outer layer (dissection). Surgery is then undertaken to replace the segment of diseased aorta. The approach may be through the sternum or through an incision in the left chest (thoracotomy). The heart lung machine (cardiopulmonary bypass) is usually required for this type of surgery. Your surgeon will discuss this in greater detail with you. Preparation for and recovery is similar to that of coronary artery bypass or valve surgery.