Coronary Artery Disease

Your heart is the organ which pumps the oxygen-filled blood to all parts of your body. Your heart, which is about the size of your fist, has a wall which consists mostly of muscle. The contraction of the muscle in combination with the opening and closing of the valves results in the flow of blood around the body.

Like any muscle, your heart requires oxygen to work. Oxygen-rich blood is fed to the heart via the coronary arteries, which branch off from the aorta. These vessels lie on the surface of the heart and distribute blood to all areas of the heart muscle through a complex network of small vessels.

Coronary artery disease causes the blood supply to the heart muscle to become restricted by a coronary artery blockage called a stenosis. The stenosis is caused by a build up of fatty plaque or cholesterol, which is deposited inside the vessel wall. The stenosis results in insufficient flow of blood to the heart muscle, and results in a lack of oxygen.
If the build up of plaque is only mild you may not experience any noticeable symptoms at rest, and possibly only mild chest pressure or pain during exercise. However, if the blockage is more severe the disease leads to insufficient blood supply of the heart muscle which may result in chest pain (angina.), heart attack (myocardial infarction), or rhythm disturbances (arrhythmia). A heart attack results from a completely blocked vessel and may damage the heart muscle.
 

Reaching a Diagnosis

If your physician suspects that you have coronary artery disease, or you are experiencing the symptoms of it, several tests can be undertaken to make a diagnosis. Initially the cardiologist would undertake an electrocardiogram (ECG), first while you are resting and then again while you are walking or running on a treadmill.

If the ECG suggests that your heart is not getting the oxygen it requires, the next step would be to undertake an angiogram. This procedure involves the injection of a dye, which is visible by x-ray, into the coronary arteries. The dye is injected by means of a catheter, which is introduced into the groin or to the arm. The x-ray is in the form of a video allowing the cardiologist to see the arteries and the presence of any narrowing or blockages. Using this information the physician will recommend a course of treatment.

The cardiologist will discuss with you the various treatment options. If medication therapy or bypass surgery is not recommended at this stage, then angioplasty and possible stenting are the most likely alternatives. These procedures involve the widening of the blocked vessels in order to restore the flow of blood.
 

Angioplasty & Stenting

Percutaneous Transluminal Coronary Angioplasty (PTCA) is a non-surgical technique used to open the narrowed vessels by expanding a balloon within the constricted section. This procedure is undertaken in a catheterisation laboratory (cathlab), which is a cross between an x-ray room and an operating theatre.

The catheter is introduced under a local anaesthetic through a small puncture in the groin or the arm. A small sheath is inserted into the opening and this makes possible the placement of a guiding catheter, which is fed through the sheath to the coronary arteries. A dye is injected into the guide catheter, which allows the physician to visualise the coronary arteries on a continuous x-ray machine (fluoroscope).

During the procedure you will not be under general anaesthetic, but may be given a mild sedative to help you to relax. You are kept awake as most people find that they can cope fairly well with the procedure. In addition the physician may ask you to move or breath deeply to improve the quality of the x-ray pictures.

If during the angiography procedure your cardiologist sees a blockage in your coronary arteries he or she may choose to open the blockage with a balloon catheter and then keep the blockage open by implanting a small scaffold-like device called a “stent”.
The tiny balloon and stent are manoeuvred through the coronary arteries to the site of the narrowed vessel. Once in place the balloon is inflated which expands the stent to form an open support structure. The balloon is then deflated and withdrawn, leaving behind the stent, which holds the vessel open and thereby improves blood flow to the heart, thus relieving the symptoms of heart disease.

The procedure usually takes approximately 1½ hours, during which time you will need to remain quite still. For the most part you will be perfectly comfortable. However, when the balloon is inflated you may experience some pressure or chest pain. This will quickly fade away when the balloon is deflated.
 

You and Your Stent

There are currently two types of stents available: bare metal and drug eluting. As the name implies bare metal stents have no coating and are made of sophisticated materials like cobalt-chromium. Drug-eluting stents have a very thin coating into which a small amount of drug is impregnated, which is then released into the vessel wall. The doctor will choose one of these devices and this choice will have important implications for you.

When a stent is implanted the process of pushing back the vessel to open the blockage causes an injury to the vessel wall. In the majority of cases this injury heals with no negative effects. However, in a small percentage of cases (depending on a number of factors such as the length and diameter of the blockage), the healing of the injury may cause excessive scar tissue which re-blocks the vessel. This is called restenosis (re-blockage). Restenosis is not fatal but it may result in you having a repeat procedure within the next year.

Drug-eluting stents were developed to prevent restenosis by delivering a tiny quantity of drug into the surrounding tissue that limits the healing response. These devices have been shown to be very effective in most cases. However the drugs are very powerful and can sometimes prevent any healing for a long period. This places the stent at risk of clotting with blood (like a fresh cut on your skin). In a very small percentage of cases this can lead to a heart attack. To overcome this risk the doctor will get you to take an anti-platelet (blood thinning) drug, normally Plavix together with Aspirin. This drug is normally prescribed for a period of six months to one year, during which time you would be advised not to undergo any form of surgery, as you would need to stop the drug to avoid excessive bleeding.

Research has shown that once you stop the drug there is an increased risk – when compared to a bare metal stent – of a clot forming in the vessel. It is important that you understand the risks and benefits of each of these products and discuss them with your cardiologist before the procedure.
 

Recovery

After the PTCA procedure you will be returned to your room or ward, after which your heart will be carefully monitored. This will be done by frequent blood pressure tests, and you may also be attached to an ECG machine for constant monitoring of your heart function.
If the insertion point was in the groin area you can expect to stay in bed for several hours. The introducer sheath is normally removed after the procedure and when it is removed a nurse will apply pressure to the puncture site for 20 to 30 minutes, or until there is no bleeding. Bleeding is unlikely after this time, however if you do experience sharp pain or bleeding, call the nurse at once. Stay laying flat and press on the puncture site with your fingers. You will be asked to walk within 12 to 24 hours of the procedure.

The dye, which was used to visualise your arteries, ends up in your kidneys, and you will need to urinate frequently to get rid of the dye. You will also be asked to drink lots of fluids to help your kidneys get rid of the dye more easily.

Mild chest pain is common after the procedure, but this should gradually disappear within a couple of hours. If your chest pain increases, additional x-rays may have to be taken.
After a successful PTCA and stenting procedure you should be sent home from hospital within one or two days. It is likely that the physician will advise you to avoid strenuous activity for at least a week.

For more information on heart health please see: www.heartfoundation.co.za