Section 6 Flashcards
Define Thrombosis
Formation, development, or presences of a clot in a blood vessel
Define Thrombus
In vivo blood clot causing vascular occlusion and tissue ischemia
Define Thrombi
The plural of thrombus, a clot of blood formed with a blood vessel and remaining attached to its place of origin compare embolus.
Define Embolus
a blockage or plug that obstructs a blood vessel;
an abnormal particle like an air bubble circulating in the blood compare thrombus.
Define Emboli
plural; something that travels through the bloodstream, lodges in a blood vessel and blocks it.
What is the therapeutic purpose of anti-thrombotics?
- is to limit or prevent clotting by suppressing the synthesis or function of various hemostatic constituents
The goal is to prevent thrombosis without causing hemorrhage.
Describes the GENERAL process of DIC and resultant secondary fibrinolysis.
- A primary condition such as septicemia, obstetric complication, severe burns, or trauma causes.
- Starts with Extensive endothelial damage or release of tissue thromboplastin that imitate the clotting process.
- The next step happens at the same time: thrombi form and plasmin is activate.
Many Thrombi form:
- Through the microocuiculation
- platelets collect
- clotting factors are being used up
- decreased serum fibrinogen
- thrombocytopenia happens
- and ultimately we hav ischemia and multiple infections that lead to organ failure.
Activated plasmin:
- will stimulate fibrinolysis
- In collaboration with decreased serum fibrinogen and thrombocytopenia, there is excessive bleeding and hemorrhage happening that leads to organ failure.
Secondary fibrinolysis is the breakdown of blood clots due to a medical disorder, medicine, or other cause. This may cause severe bleeding.
Describes the GENERAL process of DIC and resultant secondary fibrinolysis.
Whenever there is overwheming stimulation of overwhelmong coagulation (tissue death), bleeding and fibrinolysis = organ failure
Saying DIC it is assumed that there is fibrinolysis too
Explain the mechanism of action and define conditions in which it is used in anti-thrombotic therapy: heparin
- Heparin causes a conformational change in the AT (antithrombin) molecule which increases its inhibitory effect.
- AT forms an irreversible complex with factors IIa, IX, Xa, XIa, XIIa, and plasmin to slowly neutralize these factors
- Heparin is not consumed in this process; thus it can dissociate and serve as a cofactor for additional AT molecules
- Heparin-like substances ( Heparin sulfate) is produced by endothelial cells
- Heparin therapy often results in a decreased level of circulating AT. These lover levels can predispose a patient to recurrent thrombosis if heparin is stopped prematurely before oral anticoagulants are fully effective.
Explain the mechanism of action and define conditions in which it is used in anti-thrombotic therapy: low molecular weight heparin
- Prepared from UFH by depolymerization, which produces heparins of more uniform molecular mass.
-Tends to have a greater impact of the inhibition of Factor Xa
-Because of difficulties with appropriate monitoring, the use of Low Molecular Weight Heparin
Explain the mechanism of action and define conditions in which it is used in anti-thrombotic therapy: warfarin (Coumadin)
- arrest vitamin k in its storage form and makes it unavailable, a second carboxyl group is added to produce complete vitamin K depends factors (II, VII, IX, and X)
–
- Warfarin and related vitamin K antagonists (VKAs) block the function of the vitamin K epoxide reductase complex in the liver, leading to the depletion of the reduced form of vitamin k and it produces nonfunctional coagulation factors ( II, VII, IX, X)
– basically by lowering the amount of active vitamin K, this prevents the activation of clotting factors.
- Arrests vitamin K in its storage form and makes it unavailable add a second carboxyl group to produce complete vitamin K dependent factors (Magic 4: II, VII, IX and X)
Explain the mechanism of action and define conditions in which it is used in anti-thrombotic therapy: direct factor Xa inhibitors
Binds to AT and increases its affinity for Factor Xa
Longer half life than UFH or LMWH
Explain the mechanism of action and define conditions in which it is used in anti-thrombotic therapy: anti-platelet agents
Asprin and other NSAIDs
* Inhibits cyclooxygenase to reduce TXA2 production (inhibits aggregation)
Clopidogrel-Plavix
* Binds Platelet membrane ADP receptor (inhibits aggregation)
Glycoprotein Inhibitors
* Abcixmab-ReoPro/ Eptifibatide-Integrilin/ Tirofiban-Aggrastat
* Binds GP IIb/IIIa (inhibits aggregation)
Protease-activated receptor-1 antagonists (PAR-1)
* Vorapaxar-Zontivity
* Inhibits thrombin related aggregation
Explain the mechanism of action and define conditions in which it is used in anti-thrombotic therapy: thrombolytic agents
Serine proteases that work by converting plasminogen to the natural fibrinolytic agent plasmin.
Plasmin lyses clot by breaking down the fibrinogen and fibrin contained in a clot.
List the most common lab test(s) to monitor: heparin
include expected therapeutic ranges or results
Lab tests: APTT or Anti-Xa assay
Therapeutic range has been: 1.5-2.5 times the upper limit of the reference range for APTT
may cause HIT
