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FLUID AND HEMODYNAMIC DERANGEMENTS - PART II. SOCORRO CRUZ – YANEZ MD, FPSP. THROMBOSIS. Definition : Formation of a solid clotted mass ( thrombus ) derived from blood elements ( vessel , platelets , CF) intravascularly in a living person.
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FLUID ANDHEMODYNAMIC DERANGEMENTS- PART II SOCORRO CRUZ – YANEZ MD, FPSP
THROMBOSIS Definition : Formation of a solid clotted mass ( thrombus ) derived from blood elements ( vessel , platelets , CF) intravascularly in a living person. A.K.A antemortem clot
ENDOTHELIAL ATTACHMENT LINESOF ZAHN THROMBUS
POSTMORTEM CLOT • Formed extravascularly • Postmortem ( clotting after death ) • Involves only clotting factors • “ currant jelly “ or “ chicken fat “ clot
Rubbery, gelatinous • Forms perfect cast • on vessel wall • No attachment to • endothelium POST- MORTEM CLOTS
NORMAL HEMOSTASIS Functions : 1. Maintenance of blood in a fluid, clot free state 2. Ability to produce hemostatic plug at site of vascular injury
FACTORS OF NORMAL HEMOSTASIS • Blood vessel/ endothelium • Platelets • Coagulation system
SEQUENCE OF EVENTS IN HEMOSTASIS • Vasoconstriction • Primary hemostatic plug • Secondary hemostatic plug • Thrombosis and anti-thrombotic events
NORMAL HEMOSTASIS :A. VASOCONSTRICTION • Stimulated by vascular injury • Mediated by : a . sympathetic NS b. Endothelin secretion
BLOOD VESSEL WALL CONTRIBUTION 1. Elaboration of prothrombotic factors / substances : a. vWF- platelet binding co-factor b. extrinsic tissue factor- activates extrinsic clotting pathway c. Plasminogen activators inhibitors – inhibits fibrinolysis • Insulation of platelets from subendothelial collagen
BLD VESSEL CONTRIBUTION Cont… • Elaboration of humoral factors ( endothelin) vasoconstriction 4. Role of subendothelial collagen
BLOOD VESSEL WALL CONTRIBUTION (Cont..) • Elaboration of anti-thrombotic substance a. Plt aggregator inhibitors: prostacyclin , ADPase , NO b. Anti-thrombin inhibitors : thrombomodulin, heparin like molecule c. Fibrinolytic : t-PA
PLATELET ROLE IN HEMOSTASIS: • Formation of Io hemostatic plug A. Platelet adhesion - attachment to site of injury and exposed collagen - needs vWF to bridge platelet and collagen
PLATELET ROLE (cont..) • Platelet secretion and release Alpha granules Dense bodies - fibrinogen - ADP - fibronectin - Ca - PDGF - histamine - PF4 - serotonin
PLATELET ROLE (cont..) • Platelet aggregation ( platelet to platelet interaction ) - formation of temporary ( primary ) hemostatic plug - stimulated by ADP, TXA2 thrombin
PLATELET ROLE (cont..) 4. Platelet contraction • viscous metamorphosis • formation of secondary hemostatic plug • mediated by octomyosin
ROLE OF COAGULATION SYSTEM IN HEMOSTASIS • conversion of thrombin to fibrinogen and formation of fibrin thrombus • may be stimulated by extrinsic and intrinsic pathway
ANTI-CLOTTING MECHANISM • Depletion of clotting factors • Clearance of CF by liver • Fibrinolysis : plasmin and plasminogen • Proteases • Anti-thrombin
THROMBOSIS : PREDISPOSING FACTORS • INJURY TO ENDOTHELIUM • ALTERATION IN NORMAL BLOOD FLOW • ALTERATION IN THE BLOOD ( hypercoagulable state )
Endothelial Injury : • Acute Myocardial Infarction • Atherosclerosis • Cigarette smoking • Vasculitis • Hypertension • Hypercholesterolemia
Alterations in blood flow • Stasis • Aneurysm • Valvular stenosis / regurgitation • Vascular obstructions
Hypercoagulability • Immobilization • Malignancy • APAS • DIC • Nephrotic syndrome • Oral contraceptive use
THROMBUS : Morphology • Endothelial wall attachments • Gross and microscopic laminations ( LINES OF ZAHN ) • Compositions : laminated platelets, fibrin, RBC and WBC
ENDOTHELIAL ATTACHMENT THROMBUS
2 1 LINES OF ZAHN
THROMBUS : COMPONENTS OF LAYERS 1 – Pale areas( fibrin/platelets ) 2- Red areas ( RBC,WBC , fibrin )
THROMBUS : COMPONENTS OF LAYERS 1 – Pale areas( fibrin/platelets ) 2- Red areas ( RBC,WBC , fibrin )
THROMBUS : Morphology TYPES OF THROMBI : • Mural thrombus • Vegetations • Arterial / occlusive / white or conglutination thrombi • Venous/phlebothrombosi/ red or coagulative thrombi
THROMBUS VALVE