Thrombolytic therapy: indications, results
The dissolution and cleavage of a blood clot is carried out using a process such as thrombolysis. It is carried out naturally or artificially (medication). In the first case, blood enzymes break down small clots. Large blood clots can dissolve only under the influence of thrombolytics. Medicines for thrombolysis are prescribed by the attending physician in the relief of the consequences of myocardial infarction, ischemic stroke, in the treatment of cardiovascular diseases.
Content:
- Thrombolytics - what are they?
- Indications and contraindications
- Classification of thrombolytics
- Evaluation of effectiveness and complications
- List of thrombolytic drugs
Thrombolytics - what are they?
Thrombolytic drugs are drugs that dissolve blood clots. They are made up of filaments of fibrin, which are coagulated protein. Thrombus formation is part of the natural defense of the human body, designed to clog mechanical damage to blood vessels in case of injury. In a patient with a predisposition to thrombus formation, or with a combination of negative factors, thrombi are formed in intact vessels. Constantly increasing, the thrombus partially blocks the lumen of the vessel, disrupts blood circulation in it.
If a thrombus completely blocks the main artery, doctors have only a few hours to perform the operation and thereby save the patient's life.
Thrombolytics should be distinguished from drugs with a similar effect aimed at preventing the progression of cardiovascular diseases. These drugs are intended for the urgent dissolution of a blood clot; they are injected directly into the vascular system.
Fibrinolytic drugs are used for thrombolysis of large clots, as well as for dissolving blood clots in debilitated patients or in the elderly, when the body cannot split the clot on its own. Due to thrombosis, ischemia occurs - a condition of circulatory disorders of various organs and oxygen starvation of tissues. When a blood clot is separated, it breaks off and clogs the vessels leading to vital organs. As a result, embolism or thromboembolism occurs.
Indications and contraindications
The appointment of thrombolytics is the prerogative of the attending physician, who will certainly take into account the indications and contraindications for their use. Most often, drugs with thrombolytic action are used in the treatment of thrombosis and thromboembolism.
Indications for thrombolytic therapy:
- Cerebrovascular stroke;
- Myocardial infarction;
- Thrombophlebitis;
- Thromboembolism of the pulmonary artery (tela);
- Thrombosis of great vessels in pathologies of the cardiovascular system.
A blood clot can form even after successful surgery, or after a severe injury. With complications of varicose veins, thrombophlebitis develops - an inflammatory process of the vessel wall followed by the formation of a thrombus. The insidiousness of a blood clot is that for a long time they do not show noticeable symptoms. The patient discovers that he is seriously ill only with a complete blockage of the vessel and a sharp deterioration in his condition.
Absolute contraindications to the use of thrombolytics:
- Severe nasal, gastrointestinal, urogenital bleeding that occurred at the time of treatment, as well as within 2 previous weeks before it.
- Injuries, traumas, operations that occurred within the previous 10 days, if these cases concern the spinal cord or the brain, the period is increased to 2 months.
- Hemorrhagic stroke that occurred during the last six months..
- Pathologies of the circulatory system related to blood clotting.
- Increased blood pressure, not controlled by drugs.
- Low blood platelet count.
- Allergy, individual intolerance to thrombolytics and their components.
- High risk of developing aortic aneurysm, its dissection, pericarditis.
-
Suspected pancreatitis.
Thrombolytics are prescribed with caution for the following diseases and conditions:
- Over 75 years old;
- Pregnancy;
- A history of diabetes mellitus;
- Chronic pathologies of the heart, liver, kidneys;
- Large area burns;
- Recent bone fractures;
- not nine months have passed since the last thrombolysis.
If you have allergies and somatic diseases, you should definitely tell your doctor about this.
Classification of thrombolytics
Currently there are 4 generations of fibrinolytic drugs. Despite the fact that a lot of time has passed since the invention of the first generation drugs in the middle of the last century, these drugs are still used with considerable efficiency.
- Systemic drugs of the first generation (Streptodecase, Fibrinolysin, Streptokinase, Urocanase) are natural enzymes that activate the natural response to blood clots. The risk of their use is that the foreign proteins in them can cause anaphylactic shock. In addition, these drugs can provoke bleeding due to the activation of a quantitative blood enzyme.
- Second-generation drugs (Alteplase, Actilise, Remombinant Prourokinase) are created using biotechnology by introducing the necessary genes to E. coli bacteria. The drug is devoid of the side effects of the first generation drugs, since its enzymes act locally, directly in the focus of thrombosis.
- Third-generation drugs (Tenecteplaza, Reteplaza, Lanoteplaza) - selectively and long-term act on a blood clot with the help of active components.
- Combined preparations of the fourth generation (Urokinase-Plasminogen) - have an even faster, more accurate and long-lasting effect.
The most actively prescribed drugs are second-generation drugs with predictable effects and studied side effects. The effect of modern drugs has not yet been fully understood.
Thrombolysis for heart attacks, strokes is performed systemically or locally. In the first case, the drug is injected into a vein, and its enzymes take too long to reach the blood clot. When administered locally, the drug is delivered to the thrombus using a catheter; thrombolysis occurs quickly.
Evaluation of effectiveness and complications
Evaluation of the effectiveness of the use of thrombolytics is carried out using instrumental examination methods:
- CT scan;
- Magnetic resonance imaging;
- Coronary angiography.
The study of the coronary arteries is carried out 1-2 hours after the start of thrombolysis using X-ray with the introduction of a contrast agent.
Performance criteria:
- 0 - the contrast agent does not move along the vessel;
- 1 - a small part of the contrast passed through the thrombus;
- 2 - half of the contrast has passed through the area thrombosed by a blood clot;
- 3 - the passability of the section is restored.
As a result of thrombolysis, complications may occur - hyperthermia, lowering blood pressure, allergy to the drug, bleeding. In case of complications, you should immediately consult a doctor, do not self-medicate.
List of thrombolytic drugs
There are two methods of thrombolysis - delivery of activated plasmin to the thrombus, and activation of plasminogen, which enhances the formation of plasmin.
Classification of drugs by the mechanism of action:
- Direct drugs of plasma origin, directly acting on fibrin;
- Indirect drugs-agents that activate the formation of plasmin from plasminogen;
- Combined drugs that combine the qualities of the first two groups.
Thrombolytics:
- Fibrinolysin (Plasmin). The main active ingredient is profibrinolysin, isolated from human plasma. Slowly dissolves arterial blood clots, therefore it is considered insufficiently effective. They are used in the absence of other effective drugs.
- Streptokinase. Analogs: Kabikinaza, Celiasa, Avelizin. The complex effect of the drug with plasminogen stimulates the formation of plasmin. The medicine is produced from the culture of streptococcus, so the patient's body can develop antibodies to it within 1-6 months. This property of streptokinase is stopped by the use of vitamins or corticosteroids before its use.
- Urokinase. Analogs: Urokidan, Abbokinase. The drug activates plasminogen, converting it into plasmin, produced from kidney cells. Does not cause allergies, does not provoke the formation of antibodies.
- Prokinaza. It is produced from the DNA of human embryonic kidney cells in glycosylated and non-glycosylated forms, activates plasminogen.
- APSAK. The combination of streptokinase with plasminogen is supplemented in this case with acetyl components for accelerated action on a thrombus. Analogs: Eminaza, Anistreplaza.
- Tissue plasminogen activator. Made from DNA recombinant materials. The protease of the drug dissolves a thrombus when interacting with fibrin, without causing an allergic reaction, the formation of antibodies, or hemodynamic disturbances. The drug is more effective than Urocanase and Streptokinase.
- Staphylokinase. An extremely effective drug synthesized from strains of Staphylococcus aureus is non-allergenic. In patients using the drug, there are no deaths.
It is advisable to use thrombolytics for the treatment of thrombosis in any pathology of the heart and blood vessels. They are able to save the patient's life, restore his ability to work. To prevent recurrence of thrombosis, the patient is prescribed anticoagulants and antiplatelet agents.
The author of the article: Volkov Dmitry Sergeevich | c. m. n. surgeon, phlebologist
Education: Moscow State University of Medicine and Dentistry (1996). In 2003, he received a diploma from the Educational and Scientific Medical Center of the Presidential Administration of the Russian Federation.
