Patho of Venous Thromboembolism Flashcards
Define Thrombosis
Obstruction of a blood vessel by a clot
Completely cut off = necrosis of tissue
Define embolus
Blood clot becomes unlodged and free floating
Define venous thromboembolism
Clot formation with the venous circulation
DVT or PE
Define DVT
Venous thrombosis which can break off and become a PE
Incidence of VTE?
Double in each decade over 50
Risk Factors for VTE
Virchow’s Triad
Endothelial injury
Abnormal blood flow
Hypercoagulability
Hypercoagulability
Balance between anticoagulant, pro-coagulant, fibrinolytic factors, so a shift = intravascular thrombosis (thrombophilia)
Define thrombophilia
Any alteration of the coag pathway that predisposes to thrombosis
Primary/Genetic Hypercoagulability
Mutation in Factor V gene so it can’t be broken down by protein C
Genetic deficiencies in anticoags
Excess of factor VIII, IX, XI and fibrinogen
Acquired Diseases
Pregnancy Malignancy Trauma Heparin induced Thrombocytopenia Antiphospholipid syndrome
Pregnancy + 2 months after has what changes?
Increased factor synthesis
Increased platelet count
Decreased Protein C and antithrombin
Inhibit of fibrinolytic system
Malignancy has what changes?
Disseminated cancers = release of procoagulant tumor products
Suppressed levels of protein C and antithrombin
Endothelial damage does what?
Exposes ECM –> platelets adhere and coag cascade begins
Endothelial dysfunction does what?
Change the balance between pro and anti
Abnormal Blood flow
Disrupts laminar flow, platelets come in contact with the endothelium
No dilution of clotting factors
No inflow of clot inhibitors
Enhanced pro-coagulant activity
Turbulence and stasis contribute to thrombosis via?
Plaques
Aneurysms
Hyperviscocity
Sickle cell anemia
Thrombus occurred, next 4 events?
Propagation (obstruction)
Embolization
Dissolution/Resolution
Organization and recanalization (flow is regained)
Arterial thrombi
Site of turbulence or injury
Coronary, cerebral and femoral
Occlusive
Can lead to MI or stroke
Venous thrombosis
Site of stasis
Lower extremities 90%
Can lead to DVT or PE
DVT is what?
Observed at or above the knee
Can become a PE
Predisposing factors: bed rest, CHF
Asymptomatic until embolization
PE is what?
Blockade of the main pulmonary artery
Most are clinically silent and with time can become part of the wall
Signs of PE
Sudden difficulty breathing Chest pain Palpitation Bloody cough Hypoxia, dyspnea, tachypnea (rapid breathing), tachycardia
PE Patho
Increases pulmonary vascular resistance –> right ventricular outflow obstruction –> decrease preload
Increase pressure in excess of 50 mmHG
If the heart can’t increase the pressure enough, what happens?
Right Heart Failure
