Thrombosis & Embolism PDF

Thrombosis & Embolism Dr. Hanan Hosny Objective: Thrombosis: Defintion Causes Types Microscopic picture Fate Embolism Definition Types Thrombosis : Formation of solid (clotted) mass of blood within blood vessel - (Thrombus) Predisposing factors : Genetic : Deficiency of A...

Thrombosis & Embolism Dr. Hanan Hosny Objective: Thrombosis: Defintion Causes Types Microscopic picture Fate Embolism Definition Types Thrombosis : Formation of solid (clotted) mass of blood within blood vessel - (Thrombus) Predisposing factors : Genetic : Deficiency of Antithrombin, Protein C & S, Fibrinolysis Acquired : -Old age -Prolonged Bed rest or Immobilization - Oral contraceptives -Smoking - Burns - Atherosclerosis, - Varicose veins Microscopic picture: Virchow’s triad: Three main factors which predispose to thrombosis Endothelial injury. Alteration in the Blood flow. Hypercoagulability of the Blood. Arterial Thrombus: 1-Causes of Endothelial injury Injury to endothelium exposes subendothelial collagen Platelets & WBC’s comes in contact with endothelial cells which initiate clotting mechanism to form thrombus. Examples of endothelial injuries: Traumatic Inflammatory injury Hypertension Bacterial infection Autoimmune diseases Smoking 2-Alteration in the Blood flow Turbulence: Disruption of normal laminar flow (arterial) Stasis: Slowing of blood flow is the major factor (venous). Examples: Atherosclerosis Aneurysm: abnormal aortic and arterial dilation Cardiac failure Long term use of contraception Sever burn or trauma 3-Hypercoagulability of the Blood Any alteration of coagulation pathway that predispose to thrombosis. Factors (causes): Increased coagulation factors Increased Platelet Count and their adhesiveness. Decreased coagulation inhibitotrs; Antithrombin III Microscopic Picture of Thrombus : lines of Zahn: Thrombus formation occurred over time, Some layers of the thrombus will be richer in fibrin and RBCS, others will be richer in platelets, thus the different layers of color. Morphological Types: Arterial thrombi : White(pale) and mural Venous thrombi : Red and occlusive Arterial thrombi (Pale) They are dry ,easily breakable Composed mainly of platelets and fibrin and little RBC They are attached to blood wall Venous thrombi( Red) Composed of platelets, fibrin, and large number of RBC. Typically develop in venous system Slow blood flow in veins encourages entrapment of red cells Sites: Deep calf veins Femoral veins Iliac vein Low power view of thrombosed coronary artery. Note previous narrowing of the lumen by atherosclerosis Clinical finding in deep venous thrombosis: Patient may be asymptomatic Edema of ankle and foot Calf pain when ankle is dorsiflexion Investigation: Doppler Ultrasound Venography Fates of Thrombi Resolution Propagation (leading to obstruction of vessel) Embolism Potential Outcomes Of Venous Thrombosis Embolism Definition A detached intravascular solid, liquid, or gaseous mass carried by blood away from the point of origin Pathogenesis: About 99% of emboli are from dislodged thrombus → thromboembolus If Lodge in too-small vessels to permit further passage → complete or partial occlusion → infarction (ischemic necrosis) Causes - 90% Deep veins thrombosis(DVT) of lower extremities Others -Pelvic venous plexus -Right side of heart Types Pulmonary thromboembolism Systemic thromboembolism Fat embolism Air embolism Amniotic fluid embolism Pulmonary Embolism