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)
What drugs require parenteral AC for 5 days before use?
Dabigatran and edoxaban
What DOAC requires food?
Rivaroxaban 15 mg and 20 mg tabs taken with food
ADRs of DOAcs?
Bleeding
Why doesn’t LMWH need monitoring?
More predictable dose response
ADRs of LMWH?
Bleeding, HIT, osteopenia
Types of LMWH?
- Enoxaparin (Lovenox);
- Tinzaparin (Innohep);
- Dalteparin (Fragmin)
How should LMWH be dosed? CIs?
Renal dose adjustment necessary at CrCl < 30mL/min
CI in dialysis/ESRD
What LMWH are not commonly used in practice?
Dalteparin and Tinzaparin
What kind of dosing in enoxaparin?
TBW and not adjusted for treatment dosing
Round to nearest syringe size
When would fondaparinux be used? ADRs?
CI is CrCl <30mL/min
Used in patients with HIT
ADRs: bleeding
What are the D/FDIs for warfarin?
- Fluconazole
- Amiodarone
- Bactrim
- Flagyl (Metronidazole)
What is the warning of warfarin use?
Narrow TI requiring frequent monitoring
Bleeding, purple toe syndrome, skin necrosis
Do not adjust more often than Q3 days
What are INR goals for warfarin?
2-3
2.5-3.5 for mechanical valves
Onset of warfarin?
6 days for full effect
It takes longer for warfarin to affect INR
What foods are considered high in vitamin K?
Dark leafy green veggies
Very high >200mcg
high 100-200 mcg
What should we assess when doing warfarin counseling?
- Lab monitoring
- Drug interactions
- Food interactions
- Dosing frequency
How do you evaluate non valvular AF for antithrombic therapy?
CHA2DS2-VAsc Score
HAS BLED
How do you evaluate valvular AF or mitral valve stenosis for antithrombic therapy?
- Anticoagulant indicated
- Warfarin INR 2-3 or 2.5-3.5 for mechanical mitral valves
What does the CHA2DS2-VAsc Score factor in? When would we recommended anticoagulant in A fib/flutter?
- Age
- Sex
- CHF
- HTN
- Stroke,TIA, VTE
- AS
- Diabetes
Score of ≥2 in men or ≥3 in women
What do you do if there was a Score of 1 in men and 2 in women in CHA2DS2 VASC
Oral anticoagulant to reduce thromboembolic stroke risk may be considered
What do you do if there was a Score of 0 in men and 1 in women in CHA2DS2 VASC
Omit anticoagulat therapy