Thrombolysis for arterial vascular conditions

Thrombolysis means breaking up blood clots. Once a clot starts to form in a blood vessel, it might continue to get bigger until the whole vessel is blocked. Although an operation might be needed to remove the clot, it is sometimes possible to dissolve it by injecting a thrombolytic (clot-busting) medicine directly into the clot. This can lead to a great improvement in blood flow, and mean surgery is unnecessary. 

Why thrombolysis is recommended for you

Your doctors know that there is a problem with part of your circulation. You are likely to have had an angiogram (special X-ray of the blood vessels), which has shown a blockage in an artery. If nothing is done about this, you could have severe and permanent damage. While the blockage might need to be treated with surgery, in your case it has been decided that thrombolysis is the best way of proceeding.

Giving your permission (consent)

We want to involve you in decisions about your care and treatment. If you decide to go ahead, you will be asked to sign a consent form. This says that you understand what is involved and agree to have the treatment.  

You can read more about our consent process.

During thrombolysis

The procedure is done by the radiologist and under a local anaesthetic. This means that a specific part of your body will be numb, so that you will not feel any pain, but you are not asleep.

The radiologist will use X-ray equipment and small amounts of contrast (dye) to position a catheter (thin tube) close to the blockage in your artery. This catheter is passed to the blockage in your artery through a cut (incision) in your groin. The thrombolytic medicine is then injected into the blood clot. The radiologist will check the clot’s progress by injecting more contrast to show how much of it has dissolved. 

In some people, the whole clot is dissolved at the first attempt. More commonly, the catheter will need to be left in the artery and attached to an infusion pump, so that the thrombolytic medicine can continue to be given over the next few hours or overnight.  


Some discomfort might be felt in the skin and deeper tissues during injection of the local anaesthetic. After this, the procedure should not be painful. The radiologist and other staff looking after you can give you more painkillers if necessary. 

You will be awake during the procedure, and can tell the radiologist if you feel any pain or become uncomfortable in any other way. As the contrast passes around your body you might get a warm feeling, which some people can find a little unpleasant. 

After thrombolysis

You will be taken back to the ward where the nurses will carry out routine observations (such as blood pressure and pulse), to make sure that there are no adverse effects. They will also look at the puncture site to make sure there is no bleeding. 

You need to stay in bed for as long as the catheter is in the artery. The radiologist will need to check the progress of the clot and will arrange for you to go back to the X-ray department later in the day or the next day. 

By injecting a small amount of contrast dye in the catheter, it is possible to tell how much of the clot has dissolved. The radiologist might also use a special balloon attached to a different catheter, to try and open up a narrowed artery and improve your blood flow even more. Your radiologist will tell you how long you need to stay in hospital, but it might be for a few days. 

What happens next

This depends on where the blockage was and how successful the thrombolysis has been. For many people, no more procedures are necessary. However, in some people the artery might be so narrow that an operation is still needed to permanently improve the blood supply.

After thrombolysis, most people will be started on aspirin or an anticoagulant (a medicine to thin the blood). This medicine is to improve blood flow in the arteries and to reduce the chance of a similar condition happening again. When you go home you should continue with all your usual medicines. If you are taking metformin, this should be stopped for 48 hours after your procedure and then continued as usual.

Risks of thrombolysis


Sometimes there might be a small bruise around the site where the needle has been inserted and this is quite normal. If this becomes a large bruise, there is a risk of it getting infected, and this might require treatment with antibiotics or surgery.

Bruising can occur under the skin (where the catheter is inserted in the groin). This is known as a haematoma and is very common, and can take 1 or 2 weeks to disappear.

Internal bleeding

The most common side effect of thrombolytic medicines is bleeding (haemorrhage). This is most commonly seen at the site of the injection but can also occur elsewhere in the body.  

On average: 

  • a minor haemorrhage (bleed that does not need surgery or blood transfusion) happens in 15 out of every 100 people having the treatment
  • a major bleed (requiring surgery or a blood transfusion) happens in 5 out of every 100 people
  • in 1 in 100 people, there is a risk of the treatment causing a stroke

The risks of not treating your blocked artery are felt to be greater than the risks of bleeding elsewhere. 

The treatment might not work

Sometimes the blood clot is so large that the thrombolytic medicine simply cannot dissolve it all. In these cases, surgery will be required to relieve the blockage. 

Allergic reactions

Some patients have an allergic reaction to the thrombolytic medicine. Please tell your nurse or doctor if you have had a previous allergic reaction.

Some patients have an allergic reaction to the contrast dye used to obtain the X-ray pictures. This reaction is usually minor, for example a skin rash which will clear up on its own. Rarely, it can be a more serious reaction, which can be treated with steroids. Please tell your nurse or doctor if you have had a previous allergic reaction.


The iodine in the contrast dye can affect the kidneys, particularly if there is already some kidney damage. Intravenous fluids and medicine can be given before and after the procedure to try to reduce this risk. A routine pre-procedure blood test will always be done to check your renal function (whether your kidneys are working properly).

Tear in the artery

Occasionally the artery can be damaged during the procedure. This can sometimes be treated in the same department by putting a stent with a covering around it (stent-graft) into the artery to seal the tear. If this is not possible, an operation might be required to repair the artery. This happens in less than 1 in 100 people.

Around 1 in 10 people will need to have a smaller operation in the future, if a leak is detected around the stent at your follow-up appointment.


The most common complications are groin wound infections, which can usually be managed by a course of oral antibiotics.

Other complications

General complications of this type of surgery include a heart attack and chest infection, but these are very rare.

How you can help yourself


If you are a smoker, the most important thing you can do to help yourself is to give up smoking. This will also help to protect all of your arteries, making it less likely that you will suffer from heart attacks or strokes.

Giving up is not easy but there is a smoking cessation service and support groups that can help. Your vascular specialist nurse or GP practice nurse can advise you about these. If you would like to stop smoking, please speak to your nurse or call our stop smoking service phone: 020 7188 0995, or call the NHS Smoking Helpline phone: 0300 123 1044.

Keeping active

Gentle exercise, such as walking or cycling, are recommended to help improve your overall fitness. Exercise helps your body to produce healthy cholesterol and this helps to protect your arteries against bad cholesterol.

Blood pressure

It is very important that you have your blood pressure checked regularly, at least every 6 months. If you have been prescribed medicines for high blood pressure, you must make sure that you take it according to the instructions given.


If you have diabetes it is important that your blood sugar levels are well-controlled.

Blood cholesterol (fatty substance in your blood) levels

You should eat a healthy, balanced diet and try to reduce any excess weight. It is important to reduce the level of cholesterol in your blood. Your vascular nurse can refer you to a dietitian if needed. You might be prescribed medicine to help lower your cholesterol (for instance, a statin), and low dose aspirin to help prevent blood clots from forming.

Resource number: 3731/VER4
Published date: February 2024
Review date: February 2027

Contact us

If you have any questions or concerns before or after you have left hospital, please refer to your after visit summary for contact details, Monday to Friday, 8am to 4pm.

Out of hours, please leave a message and a member of staff will call you back in working hours.

Alternatively, please contact your GP or NHS 111.

You can also contact your ward 24 hours a day, to speak to the ward sister, or nurse in charge.

Do you have any comments or concerns about your care?

Contact our Patient Advice and Liaison Service (PALS)

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