Thrombolysis

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Thrombolysis
Intervention

Thrombolysis is the breakdown (lysis) of blood clots formed in blood vessels, using drugs. Ultrasound can also be used in combination with thrombolytic drugs. One such procedure is known as ultrasound accelerated thrombolysis,[1] and another is ultrasound assisted thrombolysis. For the treatment of a massive pulmonary embolism, a review has found catheter-directed therapy to be a safer and effective alternative to systemic thrombolysis. This involves the injecting of drugs directly into the clot. The authors recommend that catheter-directed therapy be the first-line treatment for a massive pulmonary embolism.[2]

Large trials have shown that mortality can be reduced using thrombolysis (particularly fibrinolysis) in treating heart attacks.[3] It works by stimulating secondary fibrinolysis by plasmin through infusion of analogs of tissue plasminogen activator (tPA), the protein that normally activates plasmin.

It is used in conditions featuring thrombosis, particularly where this is causing major organ damage. The main complication is bleeding (which can be dangerous), and in some situations thrombolysis may therefore be unsuitable. Thrombolysis can also play an important part in reperfusion therapy that deals specifically with blocked arteries.

Agents[edit]

Thrombolysis therapy uses thrombolytic drugs that dissolve blood clots. These drugs are either derived from Streptococcus species, or, more recently, using recombinant biotechnology whereby tPA is manufactured by bacteria, resulting in a recombinant tissue plasminogen activator or rtPA.

Therapeutic ultrasound can also be employed in an ultrasound assisted thrombolysis procedure.

Some commonly used thrombolytics are:

Medical uses[edit]

Diseases where thrombolysis is used:[citation needed]

Apart from streptokinase, all thrombolytic drugs are administered together with heparin (unfractionated or low molecular weight heparin), usually for 24 to 48 hours.[citation needed]

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).[citation needed]

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 (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. As such, the prehospital practitioner will often consult with the receiving cardiologist as to treatment decisions—many cardiologists have personal preferences to available treatment options.[citation needed]

Contraindications[edit]

There are absolute and relative contraindications to thrombolysis.

Absolute[edit]

Previous intracranial bleeding at any time, stroke in less than 6 months, closed head or facial trauma within 3 months, suspected aortic dissection, ischemic stroke within 3 months (except in ischemic stroke within 3 hours time), active bleeding diathesis, uncontrolled high blood pressure (>180 systolic or >100 diastolic), known structural cerebral vascular lesion, arterio-venous malformations, thrombocytopenia, known coagulation disorders, aneurysm, brain tumors, pericardial effusion, septic embolus.[citation needed]

Relative[edit]

Current anticoagulant use, invasive or surgical procedure in the last 2 weeks, prolonged cardiopulmonary resuscitation (CPR) defined as more than 10 minutes, known bleeding diathesis, pregnancy, hemorrhagic or diabetic retinopathies, active peptic ulcer, controlled severe hypertension.[citation needed]

See also[edit]

  • TIMI – thrombolysis in myocardial infarction

References[edit]

  1. ^ Zaghlool DS1, Franz RW1, Jenkins J1.EkoSonic Thrombolysis as a Therapeutic Adjunct in Venous Occlusive Disease.Int J Angiol. 2016 Dec;25(4):203-209. Epub 2016 Apr 3.PMID:27867284
  2. ^ Kuo WT1, Gould MK, Louie JD, Rosenberg JK, Sze DY, Hofmann LV. Catheter-directed therapy for the treatment of massive pulmonary embolism: systematic review and meta-analysis of modern techniques. J Vasc Interv Radiol. 2009 Nov;20(11):1431-40. doi: 10.1016/j.jvir.2009.08.002.PMID:19875060
  3. ^ "Indications for fibrinolytic therapy in suspected acute myocardial infarction: collaborative overview of early mortality and major morbidity results from all randomised trials of more than 1000 patients. Fibrinolytic Therapy Trialists' (FTT) Collaborative Group.". Lancet (London, England). 343 (8893): 311–22. 5 February 1994. PMID 7905143. 
  4. ^ a b c d "Therapeutic Biologic Applications (BLA) > Difficulties in Obtaining Sufficient Amounts of Urokinase (Abbokinase)". US Food and Drug Administration. 10/07/2016. Retrieved 2016-12-28.  Check date values in: |date= (help)
  5. ^ a b "Therapeutic Biologics Applications (BLA)". US Food and Drug Administration. 07-10- 2016. Retrieved 2016-12-28.  Check date values in: |date= (help)
  6. ^ Wardlaw JM, Zoppo G, Yamaguchi T, Berge E (2003). Wardlaw, Joanna M, ed. "Thrombolysis for acute ischaemic stroke". Cochrane database of systematic reviews (Online) (3): CD000213. doi:10.1002/14651858.CD000213. PMID 12917889.