Thromboembolic disease

Question 1

Coenzymes of clotting

Answer 1

Factors V & VIII

Question 2

Cofactors of clotting

Answer 2

Calcium

Phospholipids

Question 3

Tissue factor of clotting

Answer 3

VIIa

Question 4

Classification of thrombotic diseases

Answer 4

venous thromboembolism
arterial thrombosis (mostly to atherosclerosis)
capillary thrombosis (mainly due to microangiopathic hemolytic anemias)

Question 5

Venous thromboembolism (VTE) diseases: definitions

Answer 5

1. superficial vein thrombosis (IV, catheters, complications rare)
2. Migratory SVT (can be a sign of malignancy)
3. DVT
4. DVT complications: PE, postphlebitic syndrome

Question 6

DVT/PE epidemiology

Answer 6

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

Question 7

Acquired risks for VTE

Answer 7

Immobility
age
pregnancy
obesity
trauma
surgery
malignancy
meds - OCP
inflammation
hyperviscosity
Antiphospholipid antibody syndrome (APLAS)

Question 8

Hereditary risks for VTE

Answer 8

Factor V Leiden (Resistant to breakdown)
Prothrombin gene mutation
Protein C deficiency
Protein S deficiency
Antitrombin-3 deficiency
Increased factor 8 
Increased homocysteine

Question 9

Virchow’s triad

Answer 9

Stasis
Vascular injury
Hypercoagulation

Question 10

Accumulative risks of VTE

Answer 10

> 2 risk factors is supra-additive

Question 11

Dx of VTE

Answer 11

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

Question 12

Sx of DVT

Answer 12

painful, swelling

red and warm

Question 13

Sx of PE

Answer 13

Typical: SOB, chest pain, hemoptysis
Atypical: abdominal pain, syncope, fever, cough, seizure

Question 14

Sx of post-phlebitic syndrome

Answer 14

Swelling, pain

Ulcers, rash

Question 15

US for VTE

Answer 15

High sens & spec for proximal DVT but not for distal DVT

Compression US +/- doppler US in symptomatic patient

Question 16

Spiral CT

Answer 16

High accuracy and less radiation than V/Q scan

Non-invasive (unlike angiography)

Question 17

D-dimer testing

Answer 17

High sensitivity

Low specificity - could be thrombosis, trauma, surgery, etc.

Question 18

Etiologic testing of VTE (types)

Answer 18

Hereditary: AT-3, protein C&S, factor V leiden, prothrombin gene mutation, Factor VIII, and homocysteine
Acquired: lupus inhibitor, antiphospholipid antibodies

Question 19

Indications for etiologic testing of VTE

Answer 19

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

Question 20

Approach to Dx of VTE

Answer 20

Moderate to high clinical suspicion for testing to be of value
–> determine pre-test probability (prevalence, clinical s&s)

Question 21

Treatment regimen

Answer 21

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)

Question 22

How to monitor VTE treatment

Answer 22

Heparin: PTT (50-75)
Coumadin: INR (2-3)