Thrombosis 2024 - Copy.pptx

Thrombosis  Introduction  Pathogenesis  Major forms  Consequences Learning outcomes  To understand the pathogenesis of thrombosis  To show knowledge of major forms of thrombosis  To explain the consequences of thrombosis Thrombosis  Introduction  Pathogenesis  Major forms  Consequences Ha...

Thrombosis  Introduction  Pathogenesis  Major forms  Consequences Learning outcomes  To understand the pathogenesis of thrombosis  To show knowledge of major forms of thrombosis  To explain the consequences of thrombosis Thrombosis  Introduction  Pathogenesis  Major forms  Consequences Haemostasis in the circulation Normal blood circulation Tightly regulated process  Maintain blood in a fluid, clot-free state in normal vessels  Allows rapid formation of haemostatic clot at local site of vascular injury Haemostasis Three components involved in haemostasis  Vascular wall  Platelets  The coagulation cascade Thrombosis Different from haemostasis (Pathological)  A solid mass of blood constituents formed within the vascular system in life due to inappropriate activation of haemostatic processes  Poorly attached to the vessel wall and prone to fragmentation Thrombosis  Introduction  Pathogenesis  Major forms  Consequences Pathogenesis of thrombosis Three predisposing factors: 1) Endothelial injury − Exposure of underneath ECM − Adhesion of platelet − Release of tissue factor 2) Stasis or turbulence of blood flow − Turbulence contributes to arterial and cardiac thrombosis − Stasis contributes to venous thrombosis 3) Blood hypercoagulability (also called thrombophilia) Thrombosis Arteries Cardiac chambers Veins Capillaries Normal laminar flow Atheroma Ulceration Platelet adherence Thrombosis Arterial thrombosis EC Collagen Turbulence Lipid-filled cells Loss of EC and exposure of collagen Platelet adherence and activation Thrombus formed of alternating layers of PT, fibrin, RBC Partial or complete arterial occlusion High risks for thrombosis Prolonged bed-rest or immobilization Myocardial infarction Atrial fibrillation Prosthetic cardiac valves High risks for thrombosis Tissue injury, surgery, fracture, burn Cancer Increased age Thrombosis  Introduction  Pathogenesis  Major forms  Consequences Arterial thrombosis  Usually begin at sites of turbulence or endothelial injury  Most commonly superimposed on atherosclerosis  Frequently occlusive  Common sites: coronary, cerebral and femoral arteries Venous thrombosis  Mostly occurs in superficial or deep veins of the leg  Can cause pulmonary infarction  Most commonly due to stasis  Can be rapidly offset by collateral bypass channels (~50% asymptomatic)  Can cause local pain and oedema Venous thrombosis Most venous thrombi begin at valves (turbulence) Deep venous thrombosis discussion What is the possible cause of thrombotic lesion? In class case discussion How to reduce the risk of DVT during long flight? Thrombosis  Introduction  Pathogenesis  Major forms  Consequences Fate of a thrombus  Propagation: growing bigger  Embolization: dislodging and travelling to other sites in the vasculature  Dissolution: the result of fibrinolysis (Explains why administration of fibrinolytic agents such as t-PA is effective when given