ST elevation myocardial infarction: Large trials have shown that mortality can be reduced using thrombolysis in treating heart attacks. It works by stimulating secondary fibrinolysis by plasmin through infusion of analogs of tissue plasminogen activator, the protein that normally activates plasmin.
Stroke: Thrombolysis reduces major disability or death when given within 3 hours of ischaemic stroke onset when there are no contraindications to treatment.
Massive pulmonary embolism. For the treatment of a massive pulmonary embolism, catheter-directed therapy is a safer and more effective alternative to systemic thrombolysis. This involves the injecting of drugs directly into the clot.
Apart from streptokinase, all thrombolytic drugs are administered together with heparin, usually for 24 to 48 hours. Thrombolysis is usually intravenous. It may also be used directly into the affected blood vessel during an angiogram, e.g. when patients present with stroke beyond three hours or in severe deep vein thrombosis. Thrombolysis is performed by many types of medical specialists, including interventional radiologists, vascular surgeons, cardiologists, interventional neuroradiologists, and neurosurgeons. In some countries such as the United States of America, emergency medical technicians may administer thrombolytics for heart attacks in prehospital settings, by on-line medical direction. In countries with more extensive and independent qualifications, prehospital thrombolysis may be initiated by the emergency care practitioner. Other countries which employ ECP's include, South Africa, the United Kingdom, and New Zealand. Prehospital thrombolysis is always the result of a risk-benefit calculation of the heart attack, thrombolysis risks, and primary percutaneous coronary intervention availability.
Contraindications
Thrombolysis is not without risks. Therefore, clinicians must select patients who are to be best suited for the procedure, and those who have the least risk of having a fatal complication. An absolute contraindication is in itself enough to avoid thrombolysis, while a relative contraindication needs to be considered in relation to the overall clinical situation.
Myocardial infarction
Absolute contraindications:
Any previous history of hemorrhagic stroke, ischemic stroke within 3 months.
Stroke or serious head trauma within the past three months where the risks of bleeding are considered to outweigh the benefits of therapy.
Major surgery within the last 14 days.
Patient has a known history of intracranial haemorrhage, subarachnoid haemorrhage, known intracranial arteriovenous malformation or previously known intracranial neoplasm
Suspected recent myocardial infarction.
Recent biopsy of a parenchymal organ or surgery that, in the opinion of the responsible clinician, would increase the risk of unmanageable bleeding.
Recent trauma with internal injuries or ulcerative wounds.
Gastrointestinal or urinary tract haemorrhage within the last 30 days or any active or recent haemorrhage that, in the opinion of the responsible clinician, would increase the risk of unmanageable bleeding.
Arterial puncture at non-compressible site within the last 7 days.
Concomitant serious, advanced or terminal illness or any other condition that, in the opinion of the responsible clinician would pose an unacceptable risk.
Minor or Rapidly improving deficit.
Seizure: If the presenting neurological deficit is deemed due to a seizure.
Pregnancy is not an absolute contraindication. Consider intra-arterial thrombolysis.
Side-effects
Hemorrhagic stroke is a rare but serious complication of thrombolytic therapy. If a patient has had thrombolysis before, an allergy against the thrombolytic drug may have developed. If the symptoms are mild, the infusion is stopped and the patient is commenced on an antihistamine before infusion is recommenced. Anaphylaxis generally requires immediate cessation of thrombolysis.
Agents
Thrombolysis therapy uses thrombolytic drugs that dissolve blood clots. Most of these drugs target fibrin and are therefore called fibrinolytics. All currently approved thrombolytic drugs are biologics, either derived from Streptococcus species, or, more recently, using recombinantbiotechnology whereby tPA is manufactured using cell culture, resulting in a recombinant tissue plasminogen activator or rtPA. Some fibrinolytics are:
In people who receive thrombolytic therapy delivered through a catheter, there is a risk of hemorrhage as a side effect. Scientists have studied whether measuring fibrinogen in blood can be used as a biomarker to predict hemorrhage. As of 2017 it was not known if this works or not.
