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Thrombolysis is a treatment that allows blood flow to be restored by dissolving clots. Intravenous drugs are used for this purpose. It is worth finding out in which cases the thrombolysis is used and what it works. It is important because the sudden inhibition of blood flow through the artery can be very serious, causing ischemia of vital organs, such as the brain or the heart.
Thrombolysis , as a causal therapy that allows the dissolution of the clot that closes the cerebral vessel, has become an effective standard in the treatment of acute ischemic stroke. Unfortunately, late admission to the hospital due to failure to recognize the symptoms of a stroke or delaying seeking medical help, as well as contacting a general practitioner instead of calling an ambulance, are still obstacles in the use of the drug.
Sudden ischemic conditions, such as stroke, heart attack, and pulmonary embolism, are life-threatening and require immediate action. The immediate cause of these diseases is embolism, i.e. a material that inhibits blood flow.
The emboli can be blood clots, broken plaques, fat particles or gas bubbles. The vast majority of these are clots, i.e. plugs made of conglomerates of platelets and coagulation factors. This material is produced in various locations in the circulatory system, most often in the atria of the heart of people with atrial fibrillation.
If a thrombus is displaced from where it was formed, it flows downstream to various vessels in the body and closes them.
Less frequent embolism is caused by the fragmentation of the atherosclerotic plaque and its closure of the artery. The embolic material does not have to block the blood flow at the site of its inception, unfortunately you never know where it will go.
In many locations the embolism can be completely harmless due to the functioning of the so-called collateral circulation, which supplies the same areas of the body with other arteries. However, if it reaches a large artery supplying a large area of the body (e.g. the femoral artery supplying the lower limb) or an organ artery that requires a large amount of blood (the brain and heart), acute ischemia occurs.organ. Congestion is responsible for such diseases as:
- ischemic stroke
- heart attack
- acute lower limb ischemia
- acute intestinal ischemia
- pulmonary embolism
Thrombolysis is one of the few causal treatments for this state of affairs. This treatment is based on the intravenous administration of a drug - recombinant tissue plasminogen activator (rt-PA - alteplase).
It is a protein obtained by genetic engineering, when activated in the body, it causes the formation of plasmin, which in turn breaks down the blood proteins contained in the clot. As a result, the process of dissolution of the thrombus is significantly accelerated and it is possible to restore blood flow in the blocked vessel.
Timely administration of the drug is crucial, for the best treatment results, it must be initiated before ischemia causes irreversible changes in the damaged organ. This is why it is so important to act immediately when symptoms appear:
- stroke: sudden speech disorders, visual disturbances or paresis
- heart attack: chest pain
- limb ischemia: limb pain, pallor, tingling
Thrombolysis: indications
All indications for thrombolysis are conditions caused by embolism. These include:
- heart attack
- pulmonary embolism
- acute limb ischemia
- stroke
In the case of the former, thrombolysis is selected if it is not possible to perform coronary angioplasty (stenting) in a timely manner. The most common reason is the distance from the hospital where the procedures are performed.
In the case of pulmonary embolism, thrombolytic treatment is undertaken in the most advanced cases and in patients with shock.
In the case of acute limb ischemia - most often of the legs, as well as acute intestinal ischemia, such treatment is rarely used, and immediate surgery is much more common.
Thrombolysis is most widely used in ischemic strokes. This drug has been used in the United States and Canada since 1996, it has been available in Poland since 2003, but it has been reimbursed by the National He alth Fund since 2009, thanks to which the number of patients treated with this method is constantly increasing.
It has been proven that if thrombolytic therapy is started in a timely manner - optimally up to 4.5 hours after the onset of symptoms, in many cases it is possible to obtain adequate blood flow and improve the patient's condition. Often it is possible to reduce the severity of symptoms,less often their complete resignation. In addition, the use of thrombolysis increases the likelihood of improvement in the long term after a stroke, not only in fitness and everyday functioning, but it has also been proven that this treatment has a positive effect on the effects of post-stroke rehabilitation.
It is also believed that early administration of the drug may lead to the restoration of the vessel and prevent the development of a permanent neurological deficit. So it is obvious that the sooner this treatment is started, the greater the chance of improvement. Thrombolytic treatment is currently the standard treatment of ischemic stroke, provided that the patient comes to the hospital in time.
Complement to this method, a chance in the absence of rt-PA effects is mechanical thrombectomy, i.e. intravascular treatment.
Thrombolysis: contraindications
Thrombolysis is an aggressive treatment with a risk of complications, therefore its use should be carefully considered, taking into account the possibility of contraindications. Due to the fact that rt-PA strongly inhibits blood clotting and "thins the blood", this drug should not be administered if there is current bleeding or its risk is increased.
If this treatment is nevertheless taken, life-threatening haemorrhages (brain, gastrointestinal, and wound) may occur. Before administering thrombolysis, it is first of all necessary to exclude a hemorrhagic stroke that has the same symptoms but a completely different cause.
In this case, the cause of the stroke is not an obstruction of blood flow through the embolus, but bleeding into the brain from the damaged vessel. The conclusive examination is computed tomography or magnetic resonance imaging.
Other conditions associated with a greater risk of bleeding and therefore a contraindication to thrombolysis include:
- head injuries and previous bleeding into the brain
- High blood pressure not responding to treatment
- coagulation disorders, including e.g. a shortage of platelets
- active bleeding or bleeding in the period of several days before the stroke
- surgery in the weeks before the stroke
- cancer
- aortic dissection
- very extensive stroke
The list of contraindications is very long, some of them are so-called relative contraindications, that is, contraindications for which thrombolysis may be administered if the possibility of improvement is greater than the risk of complications.
Thrombolysis: complications
The occurrence of many complications can be prevented by careful consideration of contraindications andconsidering the risk of thrombolysis, on the other hand, it is one of the few effective therapeutic methods and often the only one available. Therefore, the decision to use it is often very difficult and ambiguous.
The most common complications of thrombolysis are bleeding, they occur in about 5% of patients, but usually harmless, they include: hematomas, bleeding from injection sites and the associated decreases in hemoglobin and hematocrit.
More serious complications are less common: bleeding into the brain, respiratory tract, gastrointestinal tract or urinary tract, if they are massive, may lead to a drop in pressure, shock and sometimes even cardiac arrest.
A small percentage of patients develop an allergic reaction to alteplase.
The incidence of strokes is gradually declining with effective prophylaxis, such as anticoagulation, in people with atrial fibrillation. Unfortunately, around 15 million people worldwide still experience a stroke each year, some of them die as a result of this disease, and many remain unfit and require assistance, hence the need for appropriate stroke treatment.
About the author
Bow. Maciej GrymuzaA graduate of the Faculty of Medicine at the Medical University of K. Marcinkowski in Poznań. He graduated from university with an over good result. Currently, he is a doctor in the field of cardiology and a doctoral student. He is particularly interested in invasive cardiology and implantable devices (stimulators).
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