Thromboembolic disease Flashcards
Coenzymes of clotting
Factors V & VIII
Cofactors of clotting
Calcium
Phospholipids
Tissue factor of clotting
VIIa
Classification of thrombotic diseases
venous thromboembolism arterial thrombosis (mostly to atherosclerosis) capillary thrombosis (mainly due to microangiopathic hemolytic anemias)
Venous thromboembolism (VTE) diseases: definitions
- superficial vein thrombosis (IV, catheters, complications rare)
- Migratory SVT (can be a sign of malignancy)
- DVT
- DVT complications: PE, postphlebitic syndrome
DVT/PE epidemiology
DVT relatively common (~70/100,000/yr), more frequent among inpatients 1/20 will develop a DVT over time 50% of DVT patients have occult PE 30% of PE patients have demonstrable DVT 1-8% PE patients die 40% DVT - postphlebtic syndrome 20% DVT recurrence
Acquired risks for VTE
Immobility age pregnancy obesity trauma surgery malignancy meds - OCP inflammation hyperviscosity Antiphospholipid antibody syndrome (APLAS)
Hereditary risks for VTE
Factor V Leiden (Resistant to breakdown) Prothrombin gene mutation Protein C deficiency Protein S deficiency Antitrombin-3 deficiency Increased factor 8 Increased homocysteine
Virchow’s triad
Stasis
Vascular injury
Hypercoagulation
Accumulative risks of VTE
> 2 risk factors is supra-additive
Dx of VTE
Clinical aspects (DVT, PE, postphlebitic syndrome) Radiologic tests - US (doppler vs compression) - spiral CT (vs V/Q scan and angiography) Lab tests - D-dimers, etiology testing
Sx of DVT
painful, swelling
red and warm
Sx of PE
Typical: SOB, chest pain, hemoptysis
Atypical: abdominal pain, syncope, fever, cough, seizure
Sx of post-phlebitic syndrome
Swelling, pain
Ulcers, rash
US for VTE
High sens & spec for proximal DVT but not for distal DVT
Compression US +/- doppler US in symptomatic patient
Spiral CT
High accuracy and less radiation than V/Q scan
Non-invasive (unlike angiography)
D-dimer testing
High sensitivity
Low specificity - could be thrombosis, trauma, surgery, etc.
Etiologic testing of VTE (types)
Hereditary: AT-3, protein C&S, factor V leiden, prothrombin gene mutation, Factor VIII, and homocysteine
Acquired: lupus inhibitor, antiphospholipid antibodies
Indications for etiologic testing of VTE
Unprovoked +/- recurrent VTE (50% with first, unprovoked VTE has an underlying hereditary disorder)
Strong family hx
Purpura fulminans in neonates and children (urgent protein C&S testing)
Only test if the results will change management!
- change anticoagulant duration
- prophylaxis
- alternatives to OCP or HRT required
DON’T TEST IF:
- provoked
- not recurrent
- arterial thrombosis
Approach to Dx of VTE
Moderate to high clinical suspicion for testing to be of value
–> determine pre-test probability (prevalence, clinical s&s)
Treatment regimen
Heparin + Coumadin (warfarin)
~5 day overlap
Typically 6 months on coumadin (3 months - indefinite)
Heparin acts more rapidly (increases AT-3 activity) but is given iv
Coumadin is po but acts slower and has a potential, transient procoagulant state (inhibits vit-K dependent factors + Protein C&S)
How to monitor VTE treatment
Heparin: PTT (50-75)
Coumadin: INR (2-3)
