Thrombolysis, also called fibrinolytic therapy, is the breakdown (lysis) of blood clots formed in blood vessels, using medication. It is used in ST elevation myocardial infarction, stroke, and in cases of severe venous thromboembolism (massive pulmonary embolism or extensive deep vein thrombosis). Thrombolytic medications pose a risk of serious bleeding, and in some situations thrombolysis may therefore be unsuitable. Thrombolysis can also play an important part in reperfusion therapy in blocked arteries.
Medical uses Diseases where thrombolysis is used:
ST elevation myocardial infarction: Large trials have shown that mortality can be reduced using thrombolysis (particularly fibrinolysis) in treating heart attacks. It works by stimulating secondary fibrinolysis by plasmin through infusion of analogs of tissue plasminogen activator (tPA), the protein that normally activates plasmin. Percutaneous coronary intervention (PCI), a minimally invasive procedure in which coronary stents are deployed to open obstructed arteries is superior to fibrinolytic therapy, but fibrinolysis is still recommended for use in healthcare settings where PCI is not available in a timely manner. Stroke: Thrombolysis reduces major disability or death when given within 3 hours (or perhaps even 6 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. Severe deep vein thrombosis (DVT), such as phlegmasia cerulea dolens, which threatens limb loss, or iliofemoral DVT, where clots involve at a minimum the common iliac vein Acute limb ischemia Clotted hemothorax Thrombolysis is usually intravenous. It may also be used directly into the affected blood vessel during an angiogram (intra-arterial thrombolysis), e.g. when patients present with stroke beyond three hours or in severe deep vein thrombosis (catheter-directed thrombolysis). 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, 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 (fibrinolysis) may be initiated by the emergency care practitioner (ECP). 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 (pPCI) 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. History of ischemic stroke within 3 months. History of stroke, dementia, or central nervous system damage within 1 year Head trauma within 3 weeks or brain surgery within 6 months Known intracranial neoplasm (primary or metastatic) Suspected aortic dissection Internal bleeding within 6 weeks Active bleeding or known bleeding disorder Traumatic cardiopulmonary resuscitation within 3 weeks Relative contraindications:
Prior ischemic stroke not within past 3 months. Oral anticoagulant therapy Acute pancreatitis Pregnancy or within 1 week postpartum Active peptic ulceration Transient ischemic attack within 6 months Dementia Infective endocarditis Active cavitating pulmonary tuberculosis Advanced liver disease Intracardiac thrombi Uncontrolled hypertension (systolic blood pressure >180 mm Hg, diastolic blood pressure >110 mm Hg) Puncture of noncompressible blood vessel within 2 weeks Previous streptokinase therapy Major surgery, trauma, or bleeding within 2 weeks
Stroke Absolute contraindications:
Uncertainty about time of stroke onset (e.g. patients awakening from sleep). Coma or severe obtundation with fixed eye deviation and complete hemiplegia. Hypertension: systolic blood pressure ≥ 185mmHg; or diastolic blood pressure >110mmHg on repeated measures prior to study (if reversed, patient can be treated). Clinical presentation suggestive of subarachnoid haemorrhage even if the CT scan is normal. Presumed septic embolus. Patient having received a heparin medication within the last 48 hours and has an elevated Activated Prothrombin Time (APTT) or has a known hereditary or acquired haemorrhagic diathesis INR >1.7 Known advanced liver disease, advanced right heart failure, or anticoagulation, and INR > 1.5 (no need to wait for INR result in the absence of the former three conditions). Known platelet count <100,000 uL. Serum glucose is < 2.8 mmol/L or >22.0 mmol/L. Relative contraindications:
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