Blood Clots Flashcards
What is the difference between hemostatic and pathologic?
H: form rapidly and remain localized
P: Form slowly, impair blood flow and cause complete vessel occlusion
What factor allows crosslinking of fibrin?
XIIIa creates a meshwork of fibrin
What are Vitamin K dependent factors?
II, VII, IX, and X
What are the contact activation factors?
XI, XII, prekallikrein, HMW kininogen
What are the thrombin sensitive factors?
V, VIII, XIII, fibrinogen
What are the antithrombic substances?
- Thrombomodulin/Protein C and S
- Antithrombin
- Heparin sulfate
What are the components of the fibrinolytic system?
Plasminogen –(tPA)–> Plasmin → fibrin degradation products (D-dimer)
Regulated by plasminogen activator inhibitor-1 (tPA) andα2-antiplasmin (plasmin)
What is Virchows triad?
Thrombus is caused by:
1. Endothelial injury
2. Venous stasis
3. Hypercoagulability
What is blood stasis?
Decrease or cessation of blood flow
What are examples of blood stasis?
- Acute med inllness
- Surgery
- Paralysis
- Immobility
- Obesity
What is vascular injury?
Intact vascular endothelium separates flowing blood from sub endothelial vessel wall → preventing blood loss through clot formation
What are examples of vascular injury?
- Orthopedic surgery
- Trauma
- Indwelling venous catheters
What is hypercoagulabilty?
Increased tendency to form blood clots
Examples of hypercoagbulabilty?
- Lupus anticoags
- Pregnancy
- Drugs therapy
What are the drugs associated with hypercoagulabilty?
- Estrogen contain contraceptives and replacement therapies
- Tamoxifen
- Raloxifene
- Cancer therapy
- HIT
What are the OACs?
- Warfarin (Coumadin)
- Dabigatran (Pradaxa)
- Apixaban (Eliquis)
- Edoxaban (Savaysa)
- Rivaroxaban (Xarelto)
What are the PACs?
- Heparin
- Low molecular weight heparin: Enoxaparin (Lovenox); Tinzaparin (Innohep); Dalteparin (Fragmin)
- Fondaparinux (Arixtra)
- Argatroban (Acova)
- Bivalirudin (Angiomax)
ADRs of UFH? Dosing? Indications?
ADRS; bleeding, HIT, osteopenia
Round to the nearest 100 units
IV or SQ ideal for CrCl<30 or unstable patients
What is the most common complication of HIT?
VTE
How do you prevent and manage HIT?
Confirm heparin antibody testing
D/C all heparin sources, if on warfarin temporary interrupt and reverse vitamin K
Initiate DTI
What is considered thrombocytopenia?
Alt <150 or decrease of 30050%
What are the 4 T score? How are they scored?
- Thrombocytopenia
- Timing
- Thrombosis
- Other potential causes of Thrombocytopenia
Low (3 or less) – no further workup
Moderate (4-5) or high (6-8) – further workup (heparin antibodies)
What is the onset of HIT usually?
5-10 days after first dose
What are the DDIs of DOACS?
PgP
Rivaroxaban and apixaban (CYP3A4)