Thrombolysis

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Thrombolysis

Thrombolysis is the breakdown (lysis) of blood clots

Thrombosis

Thrombosis is the formation of a blood clot inside a blood vessel, obstructing the flow of blood through the circulatory system. When a blood vessel is injured, the body uses platelets and fibrin to form a blood clot, because the first step in repairing it is to prevent loss of blood....
by pharmacological

Pharmacology

Pharmacology is the study of drug action. More specifically it is the study of the interactions that occur between a living organism and exogenous chemicals that alter normal biochemical function....
means. It is colloquially referred to as clot busting for this reason. It works by stimulating fibrinolysis

Fibrinolysis

Fibrinolysis is the process wherein a fibrin thrombus, the product of coagulation, is broken down. Its main enzyme plasmin cuts the fibrin mesh at various places, leading to the production of circulating fragments that are cleared by other proteases or by the kidney and liver....
by plasmin

Plasmin

Plasmin is an important enzyme present in blood that degrades many blood plasma proteins, most notable, fibrin thrombuss. The degradation of fibrin is termed fibrinolysis....
through infusion of analogs of tissue plasminogen activator

Tissue plasminogen activator

Tissue plasminogen activator is a protein involved in the breakdown of blood clots. Specifically, it is a serine protease found on endothelial cells, the cells that line the blood vessels....
, the protein that normally activates plasmin.

mbolysis requires the use of thrombolytic drug

Thrombolytic drug

Thrombolytic drugs are used in medicine to dissolve thrombus in a procedure termed thrombolysis. They limit the damage caused by the blockage of the blood vessel....
s, which are either derived from Streptomyces spp. or (more recently) the effect of recombinant

Recombinant

Recombinant may refer to :* Recombinant DNA - a form of artificial DNA* , offers healthcare providers and academic medical centers proven, leading-edge data warehousing and clinical intelligence solutions to deliver higher quality outcomes, accelerate personalized medicine, and lower costs....
technology, where human activators of plasminogen (e.g.

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Encyclopedia

Thrombolysis is the breakdown (lysis) of blood clots

Thrombosis

Pharmacology

Fibrinolysis

Plasmin

Tissue plasminogen activator

Agents

Thrombolysis requires the use of thrombolytic drug

Thrombolytic drug

Recombinant

streptokinase
Streptokinase

Streptokinase is a protein produced by beta-haemolytic streptococcus and is used as an effective and inexpensive clot-dissolving medication in some cases of myocardial infarction and pulmonary embolism....
urokinase
Urokinase

Urokinase , also called urokinase-type Plasminogen Activator , is a serine protease . Urokinase was originally isolated from human urine, but is present in several physiological locations, such as blood stream and the extracellular matrix....
alteplase (recombinant tissue plasminogen activator or rtPA).
reteplase
Reteplase

Reteplase is a thrombolytic drug, used to treat myocardial infarction by breaking up the clots that cause them.Reteplase is a recombinant non-glycosylated form of human tissue plasminogen activator, which has been modified to contain 357 of the 527 amino acids of the original protein....
tenecteplase
Tenecteplase

Tenecteplase is an enzyme used as a thrombolytic drug.Tenecteplase is a tissue plasminogen activator produced by recombinant DNA technology using an established mammalian cell line ....

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 anticoagulant

Anticoagulant

An anticoagulant is a substance that prevents blood coagulation; that is, it stops blood from clotting. A group of pharmaceuticals called anticoagulants can be used in vivo as a medication for thrombosis disorders....
s (such as heparin

Heparin

Heparin, a highly-sulfated glycosaminoglycan, is widely used as an injectable anticoagulant and has the highest negative charge density of any known biomolecule....
) 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

Fibrin

Fibrin is a fibrous protein involved in the clotting of blood, and is non globular. It is a fibrillar protein that is Polymerization to form a "mesh" that forms a hemostasis plug or clot over a wound site....
mesh (the backbone of a clot). This makes the clot soluble and subject to further proteolysis

Proteolysis

Proteolysis is the directed degradation of proteins by cellular enzymes called proteases or by intramolecular digestion....
by other enzymes, and restores blood flow over occluded blood vessel

Blood vessel

The blood vessels are the part of the circulatory system that transport blood throughout the body. There are three major types of blood vessels: the artery, which carry the blood away from the heart, the capillary, which enable the actual exchange of water and chemicals between the blood and the tissues; and the veins, which carry blood from...
s.

Uses

Diseases where thrombolysis is used:

Myocardial infarction
Myocardial infarction

Myocardial infarction , commonly known as a heart attack, occurs when the Blood flow to part of the heart is interrupted. This is most commonly due to occlusion of a coronary artery following the rupture of a Vulnerable plaque, which is an unstable collection of lipids and white blood cells in the wall of an artery....
Stroke
Stroke

A stroke is the rapidly developing loss of brain function due to a disturbance in the blood supply to the brain. According to the National Stroke Association, a "stroke" occurs when a blood clot blocks and artery or a blood vessel breaks, interrupting blood flow to an area of the brain....
(ischemic stroke)
Massive pulmonary embolism
Pulmonary embolism

Pulmonary embolism is a blockage of the pulmonary artery or one of its branches, usually occurring when a deep vein thrombosis becomes dislodged from its site of formation and travels, or embolism, to the pulmonary artery blood supply of one of the lungs....
Acute limb ischaemia

Apart from streptokinase, all thrombolytic drugs are administered together with heparin

Heparin

Heparin, a highly-sulfated glycosaminoglycan, is widely used as an injectable anticoagulant and has the highest negative charge density of any known biomolecule....
(unfractionated or low molecular weight heparin

Low molecular weight heparin

In medicine, low-molecular-weight heparin is a class of medication used as an anticoagulant in diseases that feature thrombosis, as well as for prophylaxis in situations that lead to a high risk of thrombosis....
), usually for 24-48 hours.

Thrombolysis is usually intravenous. It may also be used during an angiogram

Angiogram

Angiography or arteriography is a medical imaging technique used to visualize the inside, or lumen , of blood vessels and organs of the body, with particular interest in the artery, veins and the heart chambers....
(intra-arterial thrombolysis), e.g. when patients present with stroke beyond three hours.

In some settings, emergency medical technician

Emergency medical technician

Emergency medical technician is a term used in various countries to denote a healthcare provider trained to provide pre-hospital emergency medical services....
s may administer thrombolysis for heart attacks in prehospital settings. (Although in the UK it is more common for a Paramedic

Paramedic

A paramedic is a medical professional, usually a member of the emergency medical services, who primarily provides pre-hospital advanced Medical emergency and Physical trauma care....
to administer thrombolysis - rather than technicians)

Contraindications

These are contraindicated in bleeding disorders, active bleeding and when there has been recent surgery. Diabetic retinopathy

Diabetic retinopathy

Diabetic retinopathy is retinopathy caused by complications of diabetes mellitus, which can eventually lead to blindness.It is an ocular manifestation of systemic disease which affects up to 80% of all patients who have had diabetes for 10 years or more....
is a relative contraindication, as is untreated high blood pressure

Hypertension

Hypertension, also referred to as high blood pressure, HTN or HPN, is a medical condition in which the blood pressure is chronically elevated....
. Warfarin

Warfarin

Warfarin is an anticoagulant. It was initially marketed as a pesticide against rats and mice, and is still popular for this purpose, although more potent poisons such as brodifacoum have since been developed....
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

Anaphylaxis

Anaphylaxis is an acute Circulatory system and very severe Type I hypersensitivity allergy reaction in humans and other mammals. The term comes from the Greek words a?a ana and f??a??? phylaxis ....
(life-threatening allergic reaction) due to the production of antibodies

Antibody

Antibodies are gamma globulin proteins that are found in blood or other bodily fluids of vertebrates, and are used by the immune system to identify and neutralize foreign objects, such as bacterium and viruses....
against the enzyme.