Venous thromboembolism Flashcards

1
Q

What is the difference between a venous and an arterial thrombus?

A

Venous thrombus: red cells trapped in a fibrin meshwork

Arterial thrombus: platelets trapped in fibrin meshwork

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2
Q

Where do the majority of DVTs arise? What complications are associated with DVT?

A

Majority arise in calf venous sinuses
Can result in PEs
20% of DVTs are fatal

Other complications:

  • extension of clot
  • recurrent VTE
  • post thrombotic syndrome: recurrent pain + swelling
  • –> result of venous hypertension
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3
Q

What is Virchow’s triad?

A

3 factors that cause VTE:

  1. reduced blood flow (stasis)
  2. vessel wall disorder
  3. hypercoagulability
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4
Q

What are the risk factors for VTE?

A
  1. Genetic:
    - antithrombin deficiency
    - protein C+S deficiency
    - Factor V leiden
    - Elevated factor VII, IX and XI
  2. Environmental:
    - surgery
    - trauma
    - immobilisation
    - pregnancy
    - hormonal therapy
    - travel
  3. Acquired:
    - age
    - cancer
    - antiphospholipid
    - infections
    - obesity
    - smoking
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5
Q

Describe how DVTs usually present.

A
  • Usually unilateral*
  • Pain
  • erythema
  • tenderness
  • swelling
  • palpable cord (thrombosed vein)
  • warmth
  • ipsilateral oedema
  • superficial venous dilation
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6
Q

What are the differential diagnoses for DVT?

A
  • Musculotendinous: trauma, haematoma
  • Congestive heart failure
  • Compression of iliac veins
  • Lymphoedema
  • Acute arterial occlusion
  • Post-thrombotic syndrome
  • Ruptured baker’s cyst
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7
Q

How is DVT diagnosed? (besides clinical presentation)

A
  • D-dimer test: increased value = increased thrombolysis = clot present
  • radiological assessment: compression US, venography (gold standard), CT can be used
  • Wells Score (>2 = DVT likely)
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8
Q

State the criteria in Wells score for DVT.

A
  • active cancer (<6 months) = +1
  • paralysis, paresis = +1
  • bedridden >3 days = +1
  • localised tenderness along deep veins = +1
  • entire leg swollen = +1
  • calf swelling >3cm = +1
  • pitting oedema = +1
  • collateral superficial vein = +1
  • previous DVT = +1
  • alternative diagnosis just as likely = -2
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9
Q

How does pulmonary embolism present/what are the signs?

A

Presentation:

  • pulmonary infarct/haemorrhage –> breathlessness, pleuritic chest pain, haemoptysis
  • isolated breathlessness
  • collapse, syncope

Signs:

  • tachypnoea
  • tachycardia
  • crepitations
  • pleural rub
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10
Q

What might a PE look like on an ECG?

A
  • sinus tachycardia
  • right heart strain
  • t wave inversion (anterior leads, V4 + V4)
  • S1Q3T3 pattern
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11
Q

What might a PE look like on a CXR?

A

Often normal

  • focal oligaemia
  • small pleural effusion
  • wedge shaped density above diaphragm
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12
Q

What would material blood gases in PE show?

A

Hypoxia

Hypercapnia

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13
Q

What are the differential diagnoses for PE?

A
  • COPD exacerbation
  • Pneumonia/bronchitis
  • Acute coronary syndrome
  • Pneumothorax
  • Musculoskeletal pain/rib fracture
  • Pulmonary hypertension
  • Lung cancer
  • Pericaridal tamponade
  • Dissection of aorta
  • Anxiety
  • Asthma
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14
Q

How is PE diagnosed? (besides clinical presentation)

A
  • CT pulmonary angiogram
  • Isotope lung scan (normal lung scan will exclude PE)
  • Echocardiogram
  • Leg US if symptomatic
  • D-dimer
  • Wells Score (>/=4 = PE likely)
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15
Q

State the criteria for Wells Score in PE.

A
  • Clinical signs of DVT = +3
  • Alternative diagnosis is less likely = +3
  • Pulse >100 = +1.5
  • Immobilisation or surgery = +1.5
  • Previous DVT or PE = +1.5
  • Haemoptysis = +1
  • Cancer (last 6 months) = +1
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16
Q

What is the prognosis for PE?

A
  • untreated = 10% mortality within 1 hour
  • treated = 5% mortaility within 1 hour
  • 30% mortality within 2 weeks
17
Q

What is the usual treatment plan for VTE?

A

Acute (5-10 days):

  • IV heparin
  • LMWH
  • Fondaparinux
  • DOAC

Short-term (3-6 months):

  • Warfarin
  • LMWH
  • DOAC

Long-term (>3-6 months):

  • Warfarin
  • LMWH
  • DOAC
  • ASA
18
Q

In treating VTE, how long should heparin be given for?

A

Stop heparin after a minimum of 5 days and when INR is in the therapeutic range (2.0-3.0) for 2 consecutive days

19
Q

When should LMWH be monitored?

A

renal failure
pregnant
obese

20
Q

How is unfractionated heparin (UFH) monitored?

A

By measuring APPT

21
Q

When is fondaparinux unsuitable as a treatment for VTE?

A

Renal impairment