Thrombolysis
How does thrombolysis work?
What are the benefits of thrombolysis?
What are the risks of thrombolysis?
How should I prepare for thrombolysis?
What will I experience during the thrombolysis procedure?
What do I have to do after the procedure?
What is thrombolysis?
Thrombolysis means dissolving blood clots. Once a clot starts to form in a blood vessel it may carry on getting bigger until the whole vessel is blocked. Although the blood clot can be removed by an operation, it is also possible to dissolve the clot by injecting a special clot-dissolving drug into the artery directly into the blood clot. This can lead to a marked improvement in blood flow and may avoid the need for an operation.
What medical conditions does thrombolysis treat?
Your doctors have found that there is a problem with part of your circulation. You may have had an ultrasound scan or an angiogram (a special x-ray examination of the blood vessels), which has shown a blockage in an artery, which is believed to be due to a fresh blood clot. If nothing is done to remove the blood clot, then severe and permanent damage with possible loss of your limb may result.
The exact technique may vary slightly depending on the location of the blood clot and the practice at your local hospital.
The procedure starts off in exactly the same way as an angiogram. You will be lying flat on an x-ray table. The radiology doctor will inject local anaesthetic into the skin at the site where he intends to puncture the artery. This will generally be in one of your groins.
After the skin has been numbed with local anaesthetic, the doctor will insert a needle into the artery. Once the needle is in the artery, he will pass a guide wire followed by a small tube into the vessel. He will probably inject x-ray dye to outline the course of the vessel. He will then advance a guide wire and catheter into the blood clot. After advancing the catheter into the blood clot, the guide wire will be removed and the clot-busting, or thrombolytic drug will be injected down the catheter and into the blood clot. The radiology doctor will check progress of the treatment by injecting x-ray dye to show how much of the clot has dissolved. This procedure often takes time to work.
The radiology doctor may decide to leave the catheter in place for a few hours or overnight while you are taken back to the ward. The radiology doctor will bring you back to the x-ray department to check the progress of the treatment from time to time. If the clot dissolving medicine dissolves the blood clot, the radiologist may find an underlying narrowing of the vessel which may have contributed to the blockage. In most cases, the radiology doctor will be able to treat this problem at the same time by a process called angioplasty.
The aims of the treatment are to dissolve the blood clot in your artery. This will generally have the benefit of improving the circulation to the limb beyond the blockage. If your symptoms before the treatment were severe, the treatment may result in saving your limb from amputation.
Although thrombolysis is a relatively safe procedure, the treatment is associated with risks and complications. These are often due to the fragile health of some patients who have to undergo this treatment. Unfortunately, some patients who have this treatment die during their hospital stay. This occurs in 4-13% of patients and the risk increases in patients who are over the age of 80 years.
Clot busting drugs have to be very powerful in order to work and consequently there is a risk that bleeding will occur elsewhere. For example, if you have had a recent stroke, you may be at risk of having a further stroke. For this reason, patients who have had a stroke in the recent past are not suitable for thrombolysis. Similarly, if you have a duodenal ulcer, it is possible that this might start bleeding. If this happens, it would be necessary to treat it in the usual way, perhaps with a blood transfusion. However, similar to the previous paragraph, patients with ulcers of the duodenum or stomach are not generally treated with thrombolysis.
In most patients, bleeding occurs around the puncture site, which may result in a bruise. Sometimes the bruise will be large. Major bleeding which requires some form of intervention, which usually means stopping the thrombolysis treatment and/or having a blood transfusion, occurs in 9% of patients. In most cases, the risks associated with not treating your blocked artery are felt to be greater than the risks of bleeding elsewhere (except for patients with stroke and ulcers of the stomach and duodenum).
Minor bruising is unfortunately common and occurs in around 40% of cases.
Very rarely, some damage can be caused to the artery by the catheter and this may need to be treated by surgery or another radiological procedure. If the vessel blocked is a graft made of plastic, there is a small risk of the graft becoming infected during the procedure.
Sometimes, the blood clot may be so extensive that the clot-busting drug simply cannot dissolve it away. Similarly, if the blood clot has been in the vessel for a long period of time (over two weeks) the clot-busting drug may not be effective in dissolving the blood clot. In these cases, it may be necessary for surgery to relieve the blockage.
You need to be an in-patient in the hospital. You will probably be asked not to eat for 4 hours beforehand though you may be allowed to drink some water. You may receive a sedative to relieve anxiety. During the procedure, you will be wearing a hospital gown. Before the procedure, you may be asked to shave one or both of your groin areas to enable the radiology doctor to pass a tube into the vessel at the groin.
Some discomfort will generally be experienced in the skin when the radiology doctor places the local anaesthetic into the skin with a needle. This will usually wear off after a few minutes. When the clot dissolving medicine starts to work, you may experience increased pain in the limb beyond the blood clot. This is a normal part of the procedure and is due to small blood clots breaking off from the larger blood clot and passing into the vessels beyond the blockage. If these cause severe pain, you should ask the doctors or nurses on the ward for pain relief which they will administer. In time, as the clot dissolving medicine continues to work, all of the blood clot should be dissolved therefore relieving your pain.
After about an hour, the effects of the local anaesthetic injection at the skin puncture site will unfortunately wear off. You may experience discomfort due to the presence of the catheter entering the artery through the skin at this point. Similar to the above, you should ask your doctors or nurses for pain relief to counteract this discomfort.
When the doctors inject x-ray dye or contrast medium into your blood vessels, you may feel a transient warm feeling, which some people may find a little unpleasant. However this soon passes off and should not concern you.
In general, after the doctors stop giving you the clot-busting dissolving drug, they may need to wait a little while before they remove the catheter, to allow for the effects of the drug to wear off. You may be taken back to the ward while this interval occurs. A doctor will then remove the tube and press on the puncture site for 10-30 minutes to prevent a bruise from occurring. In some hospitals, the doctors may decide to close the puncture site with a special device, which removes the necessity to press on the artery.
by Dr. Robert Morgan
May 2005