Clinical approach to venous thromboembolism Flashcards
DVT - proximal veins
iliac
femoral
greater saphenous
popliteal
DVT - distal veins
tibial
lesser saphenous
DVT - Sx
Unilateral pain and swelling
DVT - DDx
Ruptured Baker's cyst Muscle or tendon Joint Peripheral edema Superficial thrombophlebitis (due to rerouting)
Well’s criteria - DVT
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
Dx workup for DVT
low/moderate probability of DVT –> D-dimer
- negative: rule out DVT
- positive: imaging required
Imaging for DVT
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
PE - Sx
SOB (new onset)
Chest pain - classicaly pleuritic
Well’s criteria - PE
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
Dx workup - PE
Low probability
D-dimer: negative (rule out PE), positive (imaging required)
Imaging for PE
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)
Interpretation of PE imaging
Normal: PE unlikely Positive: treat for PE Indeterminate: further testing - serial doppler US - pulmonary angiography - d-dimer
Post-thrombotic syndrome
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
Treatment approaches to PE
Anticoagulants
Thrombolytic therapy
Surgical thrombectomy
IVC interruption
Treatment of VTE
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
Standard unfractionated heparin
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
LMWH
sc administration no monitoring outpatient & inpatient less osteopenia less HIT longer half-life less readily reversible accumulate in renal failure
Indications for UFH vs LMWH
UFH:
sick inpatient, concern re:bleeding risk, need for invasive procedures, renal failure
LMWH:
outpatients, stable inpatients
Adverse effects of heparins
Bleeding
Heparin-induced thrombocytopenia (HIT)
Definition of HIT
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
Dx of HIT
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
HIT assays
gel assay (false positive and negatives) ELIZA (false positives) Serotonin release assay - GOLD STANDARD
Treatment for HIT
Alternative anticoagulant - argatroban - fondaparinux - danaparoid - lepirudin NO HEPARIN EVER AGAIN!
Warfarin
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
Complications of warfarin
Bleeding: directly proportional to INR
major bleeding 1-2% / year
can be reversed with vitamin K and/or plasma
Rivaroxiban
new oral anticoagulant Xa inhibitor immediate acting, no need for heparin fixed dose, no INR monitoring not reversible costs about $3/day
Dabigatran
Direct thrombin inhibitor
Apixaban
Factor xa inhibitor
Duration of VTE therapy
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
Indications for thrombolytic therapy
Submassive PE: hypotension, severe hypoxemia, R. heart failure
Selected cases of severe DVT
Thrombolytic therapy
Plasminogen activators: tPA (tissue plasminogen activator)
Catheter directed or systemic (bleeding risk 3x greater than with anticoagulant therapy, especially intracranial bleeding)
Surgical thrombectomy
rarely used
acute massive PE
chronic thromboembolic disease complicated by pulmonary HTN
IVC filter indications
Absolute CI to anticoagulant therapy - i.e. bleeding, requiring urgent surgery
Recurrent PE despite adequate anticoagulant therapy
Pulmonary angiography
High sens and spec for PE but high morbidity
Most common cardiac rhythm with PE patients
sinus tachycardia
Common findings in patients with DVT confirmed on venous studies
Erythema and swelling of the calf
calf tenderness
normal exam of legs
