Information for patients
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What is a Pulmonary Embolus?
A pulmonary embolus is a blood clot which has become lodged in the veins of your lungs.
What is Thrombolysis?
Thrombolysis is a treatment which involves a clot busting drug being injected to one of your veins to try and dissolve the pulmonary embolus.
Why do I need this treatment?
You have suffered a serious and life threatening pulmonary embolus. This blood clot is causing significant strain on your heart and lungs and is affecting your blood and oxygen supply to the rest of your body.
When the pulmonary embolus is causing such serious effect on your body, the risk of dying or having long-term complications is much higher. Using blood thinners alone is less effective in this situation.
What tests will I have before this treatment?
You will normally have a combination of the following:
Pulse, Blood Pressure, Blood Oxygen Levels and Temperature
The combination action of these are known as your ‘vital signs’. These will be checked frequently before, during and after the treatment.
You will have had blood tests checked including your blood count, blood clotting, kidney and liver tests and also blood markers to check for heart strain (troponin).
This is known as an Electrocardiogram or ‘ECG’. This is a simple bedside test which records the electrical conditions through your heart. This can provide evidence as to whether the pulmonary embolus is placing strain on your heart.
CT Scans of your chest
A CT scan is a three dimensional X-ray scan. A specialised scan called a CT Pulmonary Angiogram is usually performed. This creates a map of the veins running through your lungs. This shows where the blood clot is.
This scan can also show whether the blood clot is placing strain on your heart. Most patients will have this test, however if a patient is extremely unwell and unable to go to the CT scanner, they may have thrombolysis before having the CT scan.
This is known as an Echocardiogram. An ultrasound is a test which uses sound waves to create a picture of the inside of your body. You may have an ultrasound of your heart to try and work out whether your heart is causing any strain because of the pulmonary embolus.
Where will I have this treatment?
You will need to be monitored closely while you are having thrombolysis. You will usually be moved to the high dependency unit. This allows the medical tram to insert different monitors into your arteries or veins.
How is the treatment given?
The treatment is normally given as an injection through a vein. You will usually receive a small dose through an injection (known as a ‘loading dose’) followed by an infusion through a drip over 45 minutes to an hour.
After the thrombolysis is given, you will then normally be put on a different drip called ‘heparin’. This will run continuously for 1-2 days.
This treatment helps to keep your blood thin and stop any more blood clots forming.
What are the risks of this treatment?
As in any treatment, there are potential side effects. The risk of side effects is balanced against the risk of harm from your Pulmonary Embolus.
There are 3 potential types of bleeding:
- Intracranial haemorrhage – this is bleeding within your brain of skull. This is very serious and can result in death or severe disability. Approximately 1 in 50 patients who have thrombolysis will have this. The risk in older patients of a severe complication (those who are 75 or older) is higher at approximately 1 in 10 patients (these risks are detailed in the additional references at the end of this leaflet).
- Severe bleeding – this is bleeding which either needs a procedure to stop it or a blood transfusion or includes intracranial haemorrhage. This could also be bleeding inside your gut, bladder, vagina or severe bleeding from your nose. Approximately 1 in 11 patients will have some form of severe bleeding during thrombolysis.
- Minor bleeding – it is common to develop bruising after thrombolysis. This does not cause any lasting problems.
Any drugs can cause allergic reactions. This can manifest as skin rashes, lip or face swelling and in the most serious circumstances as shock and collapse. The risk of an allergic reaction during thrombolysis is very low.
Failure of thrombolysis
There is a small risk that the thrombolysis will have no effect on the blood clot.
Low blood pressure
There is a small chance that the thrombolysis medicine can cause your blood pressure to drop during the treatment. You will be closely monitored during the treatment and if this happens, the team may administer further medicines to support your blood pressure.
What are the benefits of this treatment?
The potential benefits of this treatment are dissolving the blood clot which will allow:
- Your blood pressure to return to normal and the ‘shock’ to get better.
- Your oxygen level to return to normal.
- The strain on your other organs to be relieved.
The combination of these things will reduce the chance of you dying from this pulmonary embolus and hopefully speed up your recovery.
Over the longer term, this can reduce the risk of scar tissue forming in the veins of your lungs. This can lower the chance of you developing high blood pressure in your lungs which is known as pulmonary hypertension.
Is there anything that would stop me from having this treatment?
Yes, there are some things which would mean we could definitely not give you the treatment. Your team will check carefully to make sure these do not apply to you.
- Having had a previous stroke caused by bleeding into your brain.
- If you have a cancer affecting your brain or nervous system.
- Having had a stroke caused by a blood clot in the arteries of your brain within the last 6 months.
- Bleeding from your gut within the last 1 month.
- Any major trauma, surgery or head injury within the last 3 weeks.
- Any other condition which makes you more likely to bleed.
There are also come conditions which may make you likely to have serious bleeding with this treatment. Your team would have to think very carefully about whether thrombolysis was right for you in these circumstances.
- If you have a TIA (also known as ‘Transient Ischaemic Attack’ or ‘mini-stroke’) within the last 6 months.
- If you are pregnant.
- If you are taking blood thinning treatment.
- If you have known peptic or stomach ulcer disease.
- If you have had a biopsy or other procedure to your body, which could potentially bleed.
- If you have an infection in your heart.
- If your blood pressure is very high and is not responding to the treatment.
- If you have severe liver disease.
How will you monitor me during and after the treatment?
You will be monitored closely with a combination of the following:
You will have your blood oxygen level monitored continuously with a small probe attached to your finger. You may also have a plastic tube inserted in one of your arteries of your wrist to allow constant monitoring of your blood pressure.
Your pulse and heart rhythm will be monitored continuously by means of small sticky pads attached to your chest.
You will have regular blood tests to check your oxygen level, kidney and liver functions, blood clotting and blood count. These will help the team work out if the treatment has worked.
How will you know if the treatment has worked?
The most important sign that the treatment has worked will be if your blood pressure and pulse return to normal or improve. Other signs will include your oxygen level improving and whether your blood tests show that the strain on your other organs has improved.
What are the alternatives to Thrombolysis?
The possible alternative to Thrombolysis are:
Blood thinning treatment or anticoagulation is the normal treatment for a pulmonary embolus. This is usually given in tablet form but may be given by daily injections under the skin while you recover in hospital.
While you are unwell you would also receive oxygen therapy, fluid through a drip and other treatments felt necessary. Blood-thinning treatment does not dissolve the pulmonary embolus.
Your body’s own mechanisms will do this, in the same manner that it heals bruises. Blood-thinning treatment reduces the risk of you having further emboli while your body heals from this one.
An operation to remove the blood clot can be performed. This is an extremely serious operation and requires going on heart bypass and your heart being stopped.
What will you do if this treatment does not work?
If the treatment does not work then the team will consider 3 options, these include:
The team may opt to accept that the treatment has not been successful and then proceed with the normal treatment for a pulmonary embolus. This would mean starting on blood thinning treatment and supporting your body with oxygen treatment, fluids and any other treatment required.
The team may feel that a further attempt at Thrombolysis may be successful.
The team may feel that an operation to remove the clot known as an ’embolectomy’ may be the best option. This is a very serious, invasive operation which would require you to be transferred to the Cardiothoracic Surgeons at James Cook University Hospital.
It is important to understand that there have been no large studies performed to understand what the best treatment is for patients in whom thrombolysis has not been successful.
There is no ‘one size fits all’ answer, the team will carefully consider how your body is coping with the pulmonary embolus and your health before you become unwell to try and come to an agreement on the best option for you.
If the Thrombolysis is successful, will I need any other treatment for my Pulmonary Embolus?
Yes, you will normally be commenced on blood thinning treatment known as anticoagulation. This is usually in the form of tablets although very occasionally may be given as daily injections under the skin.
This is a life threatening illness. The team will normally recommend that you stay on this treatment indefinitely unless you suffer a side effect.
We will give you a more detailed information leaflet on ‘Anticoagulation’ to further explain this.
Will I need to change any of my usual medicines because of this treatment?
If you are taking other medications that potentially thin your bloods then your team may need to change these.
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Diagnosis and Management of Acute Pulmonary Embolism
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Leaflet reference: PIL1389
Date for Review: November 2025