What is Thrombolysis?
Thrombolysis is a method of dissolving clots within blood vessels to try to restore the blood supply to the part of the body affected by the clot.
How is Thrombolysis helpful in strokes?
A stroke can be due to a blood clot in part of the blood supply to the brain. This may lead to some permanent damage (infarction). Six months after a stroke about half of all patients will still have some disability, and some will have died.
We now have medicines that are promising for some types of stroke. These medicines can dissolve the blood clots and are often used to treat people with heart attacks. A clot buster called Actilyse (tissue plasminogen activator or rt-PA for short) is now licensed for the treatment of strokes
Thrombolysis, if successful, can improve the blood supply to the brain, limit the damage and improve the patient’s chances of getting better after the stroke. This treatment has to be given within 4.5 hours of the onset of the Stroke in carefully selected patients after a brain scan. The sooner the treatment is given, the better.
What are the benefits and risks of rt-PA?
Treatment with rt-PA must be thought about carefully. rt-PA can reverse the effects of some strokes, and reduce the amount of disability for some people. For every 10 people treated with rt-PA, there is at least 1 extra person who is alive and able to manage without help from others in the months following a stroke.
Unfortunately, rt-PA can have some serious side effects. Because it dissolves blood clots, there is a risk of bleeding for the first day or so after treatment. Some of the bleeding risks are minor, like a small amount of blood oozing from an injection site. The most important side effect is bleeding in the brain.
Bleeding in the brain could make the stroke worse and for a small number of people (about 2 %) the bleeding may be fatal. This type of bleeding, however, can also occur naturally in people with a stroke who have not received any rt-PA. Despite best medical care, some patients will die in the first few weeks after a stroke.
Put more simply, a person given this treatment has a 1 in 3 chance of some benefit, a 1 in 10 chance of a very good result and a 1 in 30 chance of coming to some harm from the treatment.
How is the patient assessed for suitability for this treatment?
Stroke patients are triaged by the ambulance service and on arrival in hospital and if they appear suitable for this treatment, they are 'fast tracked'. They are very quickly assessed by a relatively senior physician who is trained in stroke and thrombolysis. A history is taken and a clinical examination is made. The doctor has to be sure that patient really has a stroke and not some other condition.
The severity of the stroke is assessed using a standard scale (a patient who has either a very mild stroke or an extremely severe stroke may not be suitable for this treatment). Measurements of blood pressure, blood glucose and other observations are made. A checklist of conditions that make the treatment more dangerous is quickly run through. If eligible so far, a CT brain scan is done immediately and the result carefully assessed.
If the scan excludes a haemorrhage (or some other non stroke conditions) and the patient has no objection to receiving the treatment, the rt-PA is administered as soon as possible.
How is the treatment given?
The injection of rt-PA is given through a small tube into a vein in the arm. The dose is calculated on an estimated body weight. A small proportion is injected quickly and the rest given as an infusion via a pump over one hour.
During the treatment, the patient is observed closely and monitored in a acute treatment area. This may be a stroke unit, emergency room or other ward depending on the hospital. The blood pressure, heart and oxygen levels are monitored and neurological observations are made every few minutes.
What happens after this?
Following the treatment, the patient is monitored closely on a Stroke Unit. After about 24-48 hours, a second brain scan is done to see what the treatment has done to the stroke. Stroke rehabilitation and other routine treatments are continued as usual.