This MedLibrary.org supplementary page on Thrombolysis is provided directly from the open source Wikipedia as a service to our readers. Please see the note below on authorship of this content, as well as the Wikipedia usage guidelines. To search for other content from our encyclopedia supplement, please use the form below:
Related Sponsors
Thrombolysis is the breakdown (lysis) of blood clots by pharmacological means. It is colloquially referred to as clot busting for this reason. It works by stimulating fibrinolysis by plasmin through infusion of analogs of tissue plasminogen activator, the protein that normally activates plasmin.
Contents |
Agents
Thrombolysis requires the use of thrombolytic drugs, which are either derived from Streptomyces spp. or (more recently) the effect of recombinant technology, where human activators of plasminogen (e.g. tissue plasminogen activator, tPA) are manufactured by bacteria.
Some commonly used thrombolytics are
- streptokinase
- urokinase
- alteplase (recombinant tissue plasminogen activator or rtPA).
- reteplase
- tenecteplase
Principles
Formation of blood clots lies at the basis of a number of serious diseases (see below). By breaking down the clot, the disease process can be arrested, or the complications reduced. While other anticoagulants (such as heparin) decrease the "growth" of a clot, thrombolytic agents actively reduce the size of the clot.
All thrombolytic agents work by activating the enzyme plasminogen, which clears the cross-linked fibrin mesh (the backbone of a clot). This makes the clot soluble and subject to further proteolysis by other enzymes, and restores blood flow over occluded blood vessels.
Uses
Diseases where thrombolysis is used:
- Myocardial infarction
- Stroke (ischemic stroke)
- Massive pulmonary embolism
- Acute limb ischaemia
Apart from streptokinase, all thrombolytic drugs are administered together with heparin (unfractionated or low molecular weight heparin), usually for 24-48 hours.
Thrombolysis is usually intravenous. It may also be used during an angiogram (intra-arterial thrombolysis), e.g. when patients present with stroke beyond three hours.
In some settings, emergency medical technicians may administer thrombolysis for heart attacks in prehospital settings. (Although in the UK is is more common for a Paramedic to administer thrombolysis - rather than technicians)
Contraindications
These are contraindicated in bleeding disorders, active bleeding and when there has been recent surgery. Diabetic retinopathy is a relative contraindication, as is untreated high blood pressure. Warfarin treatment increases risk of bleeding and is a relative contraindication.
Streptokinase is contraindicated in patients who have been previously treated with streptokinase, as there is a risk of anaphylaxis (life-threatening allergic reaction) due to the production of antibodies against the enzyme.
References
- Wardlaw JM, Zoppo G, Yamaguchi T, Berge E (2003). "Thrombolysis for acute ischaemic stroke". Cochrane Database Syst Rev (3): CD000213. doi:. PMID 12917889.
Wikipedia content modification information:
- This page was last modified on 6 September 2008, at 21:11.
Wikipedia Authorship and Review
Wikipedia content provided here is not reviewed directly by MedLibrary.org. Wikipedia content is authored by an open community of volunteers and is not produced by or in any way affiliated with MedLibrary.org.
Wikipedia Usage Guidelines
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article on "Thrombolysis".
The URL for this specific entry is:
All Wikipedia text is available under the terms of the GNU Free Documentation License. (See Copyrights for details). Wikipedia® is a registered trademark of the Wikimedia Foundation, Inc.