Thrombotic disorders Flashcards
Contrast arterial and venous thrombi
arterial thrombi: platelet rich white clots formed under high shear stress, generally occlusive and lead to infarction
venous thrombi: fibrin rich red clots that occur in areas of venous stasis and lead to edema, swelling, pain, and inflammation
What is a paradoxical embolus?
embolus originating in a vein that bypasses the lung and enters the arterial circulation via a patent ductus arteriosis or atrial septal defect
In the formation of arterial atherosclerotic plaques, increased endothelial expression of VCAM has three major effects:
- recruits inflammatory cells
- stimulates cytokine release, lipid oxidation, uptake by macrophages
- stimulates SMC proliferation
List risk factors for both venous and arterial thrombosis
hyperhomocysteinemia, heparin-induced thrombocytopenia, and antiphospholipid syndrome/lupus anticoagulants
List the three factors in Virchow’s triad (risks for venous thrombi)
- venous stasis
- endothelial abnormalities
- intrinsic hypercoagulability of blood (ex factor V Leiden, AT3 deficeincey, SLE, DIC)
Lupus anticoagulants are phospholipid-dependent antibodies that inhibit
in vitro coagulation but are associated with ______ in vitro
arterial and venous thrombi- NOT bleeding
List two examples of targets of anti-phospholipid antibodies:
cardiolipin, B2 glycoprotein I
Describe antiphospholipid syndrome
the presence of persistent antiphospholipid antibodies in association with a syndrome of arterial and/or venous thrombosis, recurrent fetal wastage, and autoimmune thrombocytopenia
Describe the mechanism of HIT
moderate to severe, late
onset thrombocytopenia due to development of a heparin-dependent antibody that is associated with an increased risk of thrombosis
mechanism: PF4 binds heparin, forming neoantigens that cause Fc dependent platelet activation and release of platelet granules
What is appropriate treatment of HIT?
stop all heparin
give fondaparinux or argatroban
List five genetic syndromes associated with increased risk of VTE
- AT3 deficiency
- Protein C deficiency
- Protein S deficiency
- Factor V Leiden- most common
- Prothrombin G20210A polymorphism (autosomal dominant, increased levels of prothrombin antigen in plasma)
Increased levels of _______ is a risk factor for both arterial and venous thrombosis
homocysteine
What is standard therapy for uncomplicated DVT/PE?
5 days of heparin, transition to warfarin (or alternatively oral thrombin or Xa inhibitors)
3-6 months of therapy
Patients with ______ DVT are treated for longer periods of time due to increased risk of recurrence
idiopathic
List some therapies used for prophylaxis of VTE (as in hospitalized patients)
heparins
dabigatran, rivaroxaban
mechanical prophylaxis- compression stockings etc
