Clinical approach to venous thromboembolism

Question 1

DVT - proximal veins

Answer 1

iliac
femoral
greater saphenous
popliteal

Question 2

DVT - distal veins

Answer 2

tibial

lesser saphenous

Question 3

DVT - Sx

Answer 3

Unilateral pain and swelling

Question 4

DVT - DDx

Answer 4

Ruptured Baker's cyst
Muscle or tendon
Joint
Peripheral edema
Superficial thrombophlebitis (due to rerouting)

Question 5

Well’s criteria - DVT

Answer 5

active cancer
paralysis/casting
bedridden > 3 days or surgery within 3 months
Hx of DVT
Likely alternative diagnosis (-2)
Calf swelling >3 cm (circumference)
Superficial veins
Unilateral edema
Swelling of entire leg
Localized pain over deep venous system

Low risk: 0
Moderate: 1-2
High >2

Question 6

Dx workup for DVT

Answer 6

low/moderate probability of DVT –> D-dimer

• negative: rule out DVT
• positive: imaging required

Question 7

Imaging for DVT

Answer 7

High clinical probability
Low/moderate probability with positive d-dimer
Proximal doppler US
- positive: diagnosis confirmed
- negative: low probability - excluded; mod/high probability - repeat in 5-7 days

Distal DVT harder to identify with doppler US

Question 8

PE - Sx

Answer 8

SOB (new onset)

Chest pain - classicaly pleuritic

Question 9

Well’s criteria - PE

Answer 9

Symptoms of DVT 3
Other dx less likely 3
HR > 100 1.5
Immobilization/surgery 1.5 (within 4 weeks)
Previous DVT/PE 1.5
Hemoptysis 1
Malignancy 1
PE unlikely 4

Question 10

Dx workup - PE

Answer 10

Low probability

D-dimer: negative (rule out PE), positive (imaging required)

Question 11

Imaging for PE

Answer 11

Low probability with positive d-dimer
High clinical probability
CT scan - PE protocol
VQ scan (patients with renal insufficiency, can get a lot of indeterminate results)

Question 12

Interpretation of PE imaging

Answer 12

Normal: PE unlikely
Positive: treat for PE
Indeterminate: further testing
- serial doppler US
- pulmonary angiography
- d-dimer

Question 13

Post-thrombotic syndrome

Answer 13

chronic venous insufficiency due to residual thrombus or damage to valves
chronic limb aching and swelling
skin ulceration
can be confused with acute recurrence
compression stockings for prevention and treatment

Question 14

Treatment approaches to PE

Answer 14

Anticoagulants
Thrombolytic therapy
Surgical thrombectomy
IVC interruption

Question 15

Treatment of VTE

Answer 15

Initial treatment:
LMWH or UFH - min 5 days, INR>2 for two days
Long-term therapy: warfarin (INR 2-3) >= 3 months

OR
Rivaroxiban >=3 months

Question 16

Standard unfractionated heparin

Answer 16

Continuous iv 
Requires monitoring (PTT)
More HIT, osteopenia
Short half-life
Rapidly reversible with protamine sulfate
safe in renal failure
post-op and critical care areas

Question 17

LMWH

Answer 17

sc administration
no monitoring
outpatient & inpatient
less osteopenia
less HIT
longer half-life
less readily reversible
accumulate in renal failure

Question 18

Indications for UFH vs LMWH

Answer 18

UFH:
sick inpatient, concern re:bleeding risk, need for invasive procedures, renal failure

LMWH:
outpatients, stable inpatients

Question 19

Adverse effects of heparins

Answer 19

Bleeding

Heparin-induced thrombocytopenia (HIT)

Question 20

Definition of HIT

Answer 20

Drug-induced, immune-mediated
Antibodies against heparin/PF-4 complex
Thrombocytopenia +/- thrombosis
5-10 days after starting heparin
Occurs in up to 5% patients receiving UH and <1% receiving LMWH

Question 21

Dx of HIT

Answer 21

4T score:
- thrombocytopenia
- timing
- thrombosis
- alternative cause
low risk - unlikely HIT
High or intermediate risk - HIT assay
- stop heparin and start alternative anticoagulant pending results

Question 22

HIT assays

Answer 22

gel assay (false positive and negatives)
ELIZA (false positives)
Serotonin release assay - GOLD STANDARD

Question 23

Treatment for HIT

Answer 23

Alternative anticoagulant 
- argatroban
- fondaparinux
- danaparoid
- lepirudin
NO HEPARIN EVER AGAIN!

Question 24

Warfarin

Answer 24

Vitamin K antagonist

• po - inhibit synthesis of vitamin K-dependent clotting factors (II, VII, IX, and X)
• delayed acting (5-7 days)
• many drug and food interactions
• requires monitoring with PT measured as INR
  
  • normal INR: 0.8-1.2
  • aim to prolong INR to 2-3

Question 25

Complications of warfarin

Answer 25

Bleeding: directly proportional to INR
major bleeding 1-2% / year
can be reversed with vitamin K and/or plasma

Question 26

Rivaroxiban

Answer 26

new oral anticoagulant
Xa inhibitor
immediate acting, no need for heparin
fixed dose, no INR monitoring
not reversible
costs about $3/day

Question 27

Dabigatran

Answer 27

Direct thrombin inhibitor

Question 28

Apixaban

Answer 28

Factor xa inhibitor

Question 29

Duration of VTE therapy

Answer 29

First episode of unprovoked >=3 months
Provoked DVT with transient risk factor (surgery, estrogen, pregnancy): 3 months
Recurrent VTE: indefinite
VTE with cancer: indefinite, initial 3-6 months LMWH

Question 30

Indications for thrombolytic therapy

Answer 30

Submassive PE: hypotension, severe hypoxemia, R. heart failure
Selected cases of severe DVT

Question 31

Thrombolytic therapy

Answer 31

Plasminogen activators: tPA (tissue plasminogen activator)

Catheter directed or systemic (bleeding risk 3x greater than with anticoagulant therapy, especially intracranial bleeding)

Question 32

Surgical thrombectomy

Answer 32

rarely used
acute massive PE
chronic thromboembolic disease complicated by pulmonary HTN

Question 33

IVC filter indications

Answer 33

Absolute CI to anticoagulant therapy - i.e. bleeding, requiring urgent surgery
Recurrent PE despite adequate anticoagulant therapy

Question 34

Pulmonary angiography

Answer 34

High sens and spec for PE but high morbidity

Question 35

Most common cardiac rhythm with PE patients

Answer 35

sinus tachycardia

Question 36

Common findings in patients with DVT confirmed on venous studies

Answer 36

Erythema and swelling of the calf
calf tenderness
normal exam of legs