You will usually have an appointment to assess your health a few days before having a coronary angioplasty. This will give you an opportunity to discuss any concerns with your cardiologist (heart specialist).

Before the procedure is carried out, the arteries near your heart need to be examined to make sure the operation is technically possible. This is done using a test called coronary angiography.

During coronary angiography, a long, flexible plastic tube called a catheter (about the width of the lead in a pencil) is inserted into a blood vessel, either in your groin or arm.

The tip of the catheter is guided to your heart, or the arteries supplying your heart, using an X-ray. A special fluid that shows up on X-rays, known as contrast medium, is injected through the catheter. The resulting pictures are called angiograms.

During your pre-operative assessment, you may also have blood tests and a general health check to ensure you are suitable for surgery.

You will be asked not to eat or drink anything for four to six hours before a coronary angioplasty.

You will usually be able to take most medications as normal up to the day of the procedure, with the exception of blood-thinning medication (anticoagulants), such as warfarin, dabigatran, rivaroxaban and apixaban. You may also need to alter the timing of any diabetes medication you take. Your medical team can give you more information about this.

Read more about preparing for an operation.

The operation

A coronary angioplasty usually takes place in a room called a catheterisation laboratory, rather than in an operating theatre. This is a room fitted with X-ray video to allow the doctor to monitor the procedure on a screen.

Coronary angioplasty usually takes between 30 minutes and two hours, although it can take longer.

You will be asked to lie on your back on an X-ray table. You will be linked up to a heart monitor and given a local anaesthetic to numb your skin. An intravenous (IV) line will also be inserted into a vein, in case you need to have painkillers or a sedative.

The cardiologist (heart specialist) will make a small incision in the skin of your groin, wrist or arm – over an artery where your pulse can be felt. They will then insert a small tube called a sheath into the artery to keep it open during the procedure.

A catheter will then be passed through the sheath and guided along the artery into the opening of your left or right coronary artery.

A thin, flexible wire is then passed down the inside of the catheter to beyond the narrowed area. A small, sausage-shaped balloon is passed over the wire to the narrowed area and inflated for about 20-30 seconds. This squashes the fatty material on the inside walls of the artery to widen it. This may be done several times.

While the balloon is inflated, the artery will be completely blocked and you may have some chest pain. However, this is normal and is nothing to worry about. The pain should go away when the balloon is deflated. Ask your cardiologist for pain medication if you find it uncomfortable.

You should not feel anything else as the catheter moves through the artery, but you may feel an occasional missed or extra heartbeat. This is nothing to worry about and is completely normal.

If you are having a stent inserted (see below), it will be delivered already fitted onto a balloon and will open up as the balloon is inflated. The stent will be left inside your artery after the balloon is deflated and removed.

When the operation is finished, the cardiologist will check that your artery is wide enough to allow blood to flow through more easily. This is done by monitoring a small amount of contrast dye as it flows through the artery.

The balloon, wire, catheter and sheath are then removed and any bleeding is stopped with a dissolvable plug or firm pressure. In some cases, the sheath is left in place for a few hours or overnight before being removed.

Going home

A coronary angioplasty often involves an overnight stay in hospital, but many people can go home on the same day if the procedure is straightforward.

After the operation, you will not be able to drive for one week, so you will need to arrange for someone to drive you home from hospital.

Read more about recovering from a coronary angioplasty.

Stents

A stent is a short, wire-mesh tube that acts like a scaffold to help keep your artery open. There are two main types of stent:

• bare metal (uncoated) stent
• drug-eluting stent – which is coated with medication that reduces the risk of the artery becoming blocked again

The biggest drawback of using bare metal stents is that, in around a third of cases, the arteries begin to narrow again. This is because the immune system sees the stent as a foreign body and attacks it, causing swelling and excessive tissue growth around the stent.

It is possible to avoid this problem by using drug-eluting stents. These are coated with medication that reduces the body’s abnormal response and tissue growth. However, this also delays the healing of the coronary artery around the stent and means it is vitally important to keep taking blood thinning treatment (see below) for up to one year after the procedure to help reduce the risk of a blood clot blocking the stent suddenly and causing a heart attack.

Once a drug-eluting stent is in place, the medication is released over time into the area most likely to become blocked again. The two most researched types of medication are:

• "-limus" medications (such as sirolimus, everolimus and zotarolimus) – which have previously been used to prevent rejection in organ transplants
• paclitaxel – which inhibits cell growth and is commonly used in chemotherapy 

The use of drug-eluting stents has reduced the rate of arteries re-narrowing from around one third to less than one in 10 and they are now used in more than 70% of stent procedures.

The National Institute for Health and Care Excellence (NICE) recommends that drug-eluting stents should be considered if the artery being treated is less than 3mm in diameter or the affected section of the artery is longer than 15mm, because evidence suggests the risk of re-narrowing is highest in these cases.

Before your procedure, discuss the benefits and risks of each type of stent with your cardiologist.

If you have a stent, you’ll also need to take certain medications to help reduce the risk of blood clots forming around the stent. These include:

• aspirin, taken every morning for life
• clopidogrel, taken for one to 12 months depending on whether you have had a bare metal or drug-eluting stent, or whether you have had a heart attack
• prasugrel or ticagrelor, which are used as alternatives to clopidogrel in some hospitals