Coronary angioplasty (PCI)

In the majority of cases, narrowings or blockages of the coronary arteries can be treated by a procedure called angioplasty (PCI) . The usual technique for this is similar to Coronary Angiography from the patient’s point of view and may well follow on from a Coronary Angiography procedure. In the same position, a further tube with a special shape is passed up the femoral or radial artery and sighted at the mouth of the coronary artery, which is narrowed. Through this tube, a very fine steel wire, 1/14,000 of an inch in diameter is navigated across the narrowing. When the steel wire tip is safely positioned at the far end of the artery, a tiny balloon is slid over the steel wire. When this balloon is in the position of the narrowing artery, it is inflated to high pressure using a special hydraulic inflation device. The pressure delivered to the balloon is transmitted to the arterial wall. The pressure cracks and stretches the plaque of cholesterol. A variety of different balloons may be used, depending on the length of the narrowing and how tight it is. When the balloon has been deployed and a further picture is taken, the Cardiologist will usually decide to deploy a stent.

A narrowed right coronary artery (a) treated with rotablation or drill (b) and then stent (c and d) to open it up successfully.

Once the coronary artery has been successfully treated, the access pipe in the wrist or leg is removed and the hole closed by pressure or a plug. It is customary to keep patients in overnight and repeat an Electrocardiogram and a blood test the following morning. If there are no complications, you will be allowed home early the next day.

What is a Stent?

A Stent is a highly specialised piece of steel, in the form of a slotted tube, which is mounted and laser bonded onto a balloon. It is advanced over the narrowing, which may well have already been pre-dilated with a balloon. When it is in position, the Cardiologist inflates this to high pressure. A slotted metal tube then takes on a form of a helical spiral and the metal mesh braces against the artery wall, pushing back any plaque or torn segments of artery lining.

What are the risks of Angioplasty (PCI)?

The risks of Angioplasty are broadly similar to those of Coronary Angiography, however, there are more specific risks associated with the Angioplasty procedure itself. These tend to be damage to the coronary artery wall, the provocation of a heart rhythm disturbance or damage to the artery such that the patient may require a bypass operation. This tends to occur in less than 1:200 patients treated.

What are the long term consequences of stent delivery?

The major downside of stent delivery is the risk of “re-stenosis”. When the artery wall has been stretched and injured by the balloon and stent procedure, there is a rapid response of the cells in the arterial wall, proliferate and to heal the injury. This is very similar to the response that is seen if you cut yourself and there is formation of a scab. However, sometimes this process can be very pronounced and can lead to the new tissue encroaching into the arterial lumen. This is called re-stenosis. It happens at a greater or lesser extent with all patients. However, in certain individuals the response may be so brisk that it causes significant narrowing. In this situation, some 4-6 weeks after the procedure, the patient may become aware of the symptoms returning again. If this is the case, they should immediately inform the cardiologist, who will evaluate them, either with a stress echocardiogram or with a further angiogram.

What types of stents are there?

Broadly speaking, there are two types of stent. The first type of stent is the bare metal stent (BMS). These were the type originally developed and are made from a variety of steel alloys, containing greater or lesser percentages of Cobalt and other transition metals. They have different properties, but their overall principle is to prevent encroachment of the vessel wall again. However, as we have seen in large clinical trials, there is a significant percentage of patients who will experience re-stenosis.

This is where the second type of stent comes in. The second type of stent is broadly termed a “drug eluting” stent (DES). This is a stent which is specially designed and has a polymer coated on the side of the stent which faces the arterial wall. Within that polymer, is a timed release drug. There are a variety of drugs available, but they all have the same goal. They affect the local development of rapid cell growth and diminish the likelihood of re-stenosis and the return of symptoms. These types of stents are best used in very long or particularly narrow arteries. The cardiologist will decide which specific stent is best for you during the procedure.

Is there any downside to the use of drug eluting stents?

One of the downsides with eluting stents is that the drug, which prevents in-growth of the vessel wall, also slows down the re-lining or “reendothelialization” of the inside of the stent. This can lead to a risk of blood clotting inside the stent. Continuing research is directed at identifying the patient types, who will benefit most from drug eluting stents, with least risk of thrombosis.

Clopidogrel is vital!

The two most important parts of your treatment following stent implantation are the tablets which stop the blood clots forming. These normally are Aspirin and Clopidogrel (also known as Plavix). The cardiologist will advise you precisely how long you should continue with these medications and you can discuss their use and the duration of prescription with him. They should be taken at least for 4 weeks. If you have a drug-eluting stent, then you will need both drugs for 1 year.

Instead of Clopidogrel, Prasugrel may be used. This is a new, more powerful agent, reserved for patients at very high risk of coronary problems.