Just like every other part of the body, the heart itself needs a blood supply; in fact it needs a very good one in view of the constant and vital work it does throughout our lives. The coronary arteries are the blood vessels that lie on the surface of the heart and supply it with the blood it needs. Frequently these arteries become narrowed or 'furred up' with fatty deposits. This means that less blood is able to get through to the part of the heart supplied by that particular coronary artery and this is particularly a problem when the heart needs a lot of blood, for example during exercise. This usually causes pain from the heart called angina.
If the artery blocks completely, no blood is able to get through, causing an area of the heart muscle to die. This is called a myocardial infarction or heart attack.
A coronary artery bypass graft (CABG) is an operation which uses a blood vessel from another part of the body to bypass the narrowing, thereby relieving the angina pains and reducing the risk of a heart attack.
A CABG is usually suggested when someone is suffering from angina that is not controlled by medication.
In this situation a CABG will aim to relieve the angina and may prevent a heart attack from occurring.
The operation is also sometimes done after someone has had a heart attack in order to prevent another one or to treat remaining angina.
In these circumstances the specialist will usually arrange further investigations to assess how many coronary arteries are narrowed and by how much.
These investigations usually include an exercise ECG (a heart trace performed while the person is exercising on a treadmill) and an angiogram (a special x-ray of the arteries of the heart).
The results of these tests help the doctor to decide if a CABG would be beneficial.
A CABG is a major operation but these days it is quite a common one. The patient's chest is opened via a cut down the middle of the breastbone extending into the upper part of the abdomen. At the same time a second surgeon removes a length of vein from the patient's leg, which will be used to bypass the narrowed section of coronary artery. A heart-lung machine is then used to take over the work of the heart and lungs so that the heart can be stopped whilst the surgeon operates on it.
The surgeon then uses the vein removed from the leg, or an artery called the internal mammary artery from inside the chest wall, to form new coronary arteries where they are needed to bypass the furred up ones. The patient is then taken off the heart-lung machine and blood is then able to flow through the newly-formed arteries to supply the parts of the heart which were previously starved of blood. The operation usually lasts between three and five hours.
After the operation, the patient is taken to the Intensive Care Unit (ICU) until their condition has stabilised enough to allow them back to the ward.
Generally speaking, most CABG operations are very successful, leading to a relief of symptoms for at least five years in 80 per cent of people.
They have been shown to improve the life expectation in some groups of patients. However, like any major operation there are possible complications. These include irregularities of the heartbeat, infection of the chest or leg wound, and post-operative bleeding, requiring a return to the operating theatre.
A day or two after the operation the patient is usually taken from ICU to the ward and is usually discharged home a week or so later. An out-patient follow-up appointment will usually be arranged for them, but the timing of this varies between hospitals. They will be advised by the consultant about resuming activities. Normally it is suggested that they gradually increase what they do over the next three months after which all normal activities should resume. The timing of return to work will vary from one person to another but on average someone will need between two to three months off work following a CABG.
Driving is not allowed for one month after a CABG but it may be sensible to leave it until about six weeks after the operation before driving again depending on how the individual feels. One of the most troublesome symptoms afterwards tends to be pain at the site where the chest was opened in the middle of the breastbone, but this will gradually subside.
Many people who have this operation will come out of hospital on less medication than they went in with. This is because they may have needed tablets to control their angina, which they will not need after bypass surgery. However, they may still need to remain on some medication according to the specialist's instructions. This often includes having to take a certain amount of aspirin each day and medication to lower the level of cholesterol (a type of fat) in the blood to help to prevent further narrowing of the arteries.
It is difficult to answer how long the new blood vessels will last for because the useful life of the newly formed coronary arteries is very variable. As mentioned above 80 per cent of people who have this operation are symptom free for at least five years and many of those will have no trouble for a lot longer than this. Some people do need a repeat operation after a few years and this depends to some extent on whether or not they look after themselves and their new arteries by following the advice of the doctors.
Probably the most important measure for the person to take from the moment they know that they are going to have the operation is to give up smoking for the rest of their lives. This will not only reduce their chances of having a complication following surgery but will also help to stop the new arteries from furring up, thereby preventing the need for a repeat operation, which tends to be riskier than the first. Stopping smoking will also significantly reduce the chances of a heart attack.
Another worthwhile measure to take is to start a food diet, which is low in fat, because this will also help to keep the new heart vessels healthy and open. The patient's physician or specialist will probably measure the level of fat (called cholesterol) in the blood so that they can advise on how best to keep this down to a safe level. As mentioned above, this may involve taking medication to reduce the cholesterol level. Regular exercise is recommended, as is routine blood pressure measurement since high blood pressure contributes to narrowing of the arteries. A positive attitude and a determination to return to a normal life after the operation are also important factors in speeding recovery.
Surgeons in certain specialised hospital units have begun pioneering CABG operations via keyhole surgery. Delicate instruments allow them to work inside the body through small holes in the skin, enabling them to view their surgery through special narrow telescopes. This method allows patients to leave hospital after only three days although it is not yet widely available.
In cases where bypass surgery is not thought to be suitable, a procedure called an angioplasty may be recommended. This involves the insertion of a special catheter (thin tube) into the narrowed artery at the end of which is a balloon that is inflated, thereby opening up the narrowing. This is not a new development in itself but it has recently been shown that the placing of a tube called a 'stent' (which is left inside the constriction in the artery) during the angioplasty procedure frequently prevents the narrowing from returning and may be in some cases a more suitable procedure for the patient.