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MBBS IV - Junior Clerkship WCS > JC50 (Medicine) - DVT, PE, Thrombophilia > Flashcards

JC50 (Medicine) - DVT, PE, Thrombophilia Flashcards

1
Q

Virchow’s triad of thrombosis

A

Stasis
Coagulability
Endothelial injury

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2
Q

Risk factors of vascular stasis

A 
Heart failure 
Stroke 
Surgery 
Pelvic obstruction 
Varicose veins
Prolonged immobolization
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3
Q

Risk factors of hypercoagulability

A 
Inherited and acquired thrombophilia 
Malignancy, esp. haematological 
Nephrotic syndrome 
Myeloproliferative neoplasm 
Pregnancy/ Estrogen therapy 
Dehydration 
Paroxysmal Nocturnal Haemoglobinuria
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4
Q

Risk factors of endothelial injury

A

Surgery
Radiation
Tourniquet and Indwelling catheter
Sepsis

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5
Q

General risk factors of thrombosis (arterial and venous) (8)

Risk factors of arterial thrombosis only (5)

A 
Both arterial and venous thrombosis:
Age 
Family history of thrombosis 
Smoking 
Obesity 
Antiphospholipid syndrome 
Hyperhomocysteinaemia 
MPN
PNH
Arterial thrombosis only: 
Male sex
Hypercholesterolemia
Diabetes Mellitus 
Hypertension 
Chronic renal impairment
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6
Q

List inherited thrombophilia

A
  1. Antithrombin, Protein C, Protein S deficiency
  2. Factor V Leiden
  3. Hyperhomocysteinemia
  4. Prothrombin G20210A mutation
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7
Q

Anti-thrombin deficiency

  • Inheritance pattern
  • Antithrombin function and synthesis
  • Drug C/I
  • Treatment
A

Inheritance: AD

Antithrombin: most thrombogenic inherited cause

  • Synthesis in liver
  • Function: neutralize thrombin, factor IXa, Xa, XIa, XIIa

C/I:
Heparin is ineffective without antithrombin, heparin-resistant

Tx:
Higher dose of LMWH
Antithrombin concentrate in refractory VTE
Prophylaxis in pregnancy, surgery or post-VTE

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8
Q

Protein C deficiency

  • Inheritance pattern
  • Physiological Synthesis and function
  • Tx
A

AD inheritance

Synthesis in liver
Function: Vitamin K dependent anticoagulant, need activation by thrombin, Inactivates factor Va and VIIIa

Tx:

Anticoagulation in VTE → should continue indefinitely
Prophylactic anticoagulation in pregnancy, surgery or post-VTE

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9
Q

Protein S deficiency

  • Inheritance pattern
  • Synthesis and function
  • Tx
A

AD inheritance

Synthesis in Liver, Endothelial cells, Megakaryocytes and Brain cells

Function:
Co-factor of activated protein C to inactivate Factor Va and VIIIa
Vitamin K dependent anticoagulant

Tx:
Anticoagulation in VTE → individualize decision for indefinite anticoagulation
Prophylactic anticoagulation in pregnancy, surgery

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10
Q

Common ACQUIRED causes of anticoagulant deficiency (Anti-thrombin, Protein C and S)

A

Depletes all 3 of anti-thrombin, Protein C and Protein S:

  • Neonatal period
  • Liver disease
  • Sepsis
  • Acute thrombosis
  • DIC
  • L-asparaginase

Pregnancy and Estrogen, Nephrotic syndrome:
- Depletes Antithrombin and Protein S

Warfarin:
- Depletes Protein C and Protein S (both vit. K dependent)

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11
Q

Factor V Leiden
Prothrombin G2021A mutation
Hyperhomocysterinemia

A

check SN

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12
Q

Antiphospholipid syndrome

Cause
Manifestations
Confounding factors for positive result
Treatment

A

Cause:
Generation of auto-antibodies against phospholipid-binding proteins
- Anti-cardiolipin antibodies (IgG or IgM)
- Anti-B2 glycoprotein I
- Lupus anticoagulant (actually prothrombotic)

Manifestations:

  • DVT, PE
  • Arterial thrombosis: MI, Stroke
  • Thrombocytopenia
  • Pregnancy complications, Recurrent fetal loss
  • Livedo reticularis

Confounding factors: Marginal and transient increase concentration, with prolong aPTT

  • Viral infections
  • Drugs

Tx:

  • Life-long LMWH or Warfarin for VTE, Add aspirin for Arterial thrombosis
  • Target INR between 2 to 3
  • DOAC not recommended
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13
Q

Malignancy- associated VTE

A

Malignancy is prothrombotic state
Immobolization causes stasis
Drugs can cause thrombosis

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14
Q

MPN associated thrombosis

  • Risk for arterial or venous thrombosis?
  • High risk of thrombosis in which organ?
  • Cause?
A

Risk of both arterial and venous thrombotic risk

Mesenteric thrombosis

Acquired vWD in extreme thrombocytosis

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15
Q

Pregnancy and Estrogen associated VTE

  • High risk in which pregnancy period?
  • Maternal risk factors
A

Highest risk in post-partum period

Higher risk:

  • Multiple pregnancies
  • Maternal obesity
  • Maternal DM or HT
  • Thrombophilia
  • High maternal age
  • Hospitalization and C-section
  • Eclampsia
  • Post-partum hemorrhage
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16
Q

Nephrotic syndrome associated VTE

  • Pathogenesis
  • Increase risk of arterial or venous thrombosis
A

Pathogenesis:
- Renal vein thrombosis and nephrotic syndrome cause proteinuria&raquo_space; Loss of natural anticoagulants through kidneys

Risk:
- Arterial and venous thrombosis

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17
Q

Clinical presentation of venous thromboembolism (5 main sites in body with S/S) **

A
  1. Lower limb DVT
    - asymmetrical lower limb swelling/ bilateral calf girth difference
    - Dilated superficial veins
    - pain, warmth, erythema
  2. Pulmonary embolism
    - Pleuritic chest pain/ central/ crushing
    - Hemoptysis
    - Acute cough, dyspnea, syncope
    - Shock, sudden death
  3. Cerebral venous thrombosis:
    - Increase ICP: headache, papilloedema, impaired consciousness
    - Seizures, focal deficit
  4. Mesenteric venous thrombosis
    - Portal vein thrombosis
    - Acute abdominal pain +/- fever, diarrhea
  5. Axillary vein thrombosis
    - UL pain, swelling, heat
    - Venous thoracic outlet syndrome
    - Young, athletic male with prior strenuous UL exercise
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18
Q

Outline history taking for suspected thrombosis

A
  1. Onset of manifestations: DVT/ PE/ Cerebral thrombosis/ Mesenteric thrombosis
  2. Screen underlying causes:
    - Recent operations
    - Trauma
    - Immobility
    - Pregnancy and obstetric history, high estrogen exposure
    - Inherited/ acquired thrombophilia conditions
    - Underlying malignancies and constitutional symptoms
  3. Family of inherited thrombophilia/ Malignancies
  4. Social history: risk factors of venous and arterial thrombosis
19
Q

First-line investigations for VTE

Second-line screening

A

Blood tests:

  • CBC with diff.
  • Full clotting profile, D-dimer
  • Troponin

Physical exam: DVT Well’s score

Radiological

  • USG doppler: DVT, Mesenteric thrombosis
  • CT pulmonary angiogram* or V-Q scan
  • Echocardiogram

ECG

Second line - Thrombophilia screening
Do not perform during acute thrombosis

20
Q

Practical function of D-dimer test

A

D-dimer: in low pre-test probability
Sensitive but not specific
If +ve, offer duplex USG in 4h (or else start anticoagulant first)

D-dimer positive = many confounding factors, does not rule in acute thrombosis
D-dimer negative = chance of acute thrombosis is almost zero &raquo_space; rule out acute thrombosis

21
Q

Practical function of thrombophilia screening

A

Prophylaxis during at-risk periods: Pregnancy, operation

Identify family members at risk: screen first-degree relatives

22
Q

Treatment options for acute thrombosis

Indication for each option

A

Anti-coagulants: for proximal DVT and PE

  • LMWH
  • DOAC
  • Warfarin (if renal impairment)

Catheter-directed thrombolysis:

  • for haemodynamically unstable, persistent hypotension, venous gangrene of limbs
  • massive iliofemoral DVT failing anticoagulation

Surgical embolectomy

IVC Filter insertion:

  • temporary placement, stop embolism from reaching lungs
  • If C/I anticoagulants or failed anticoagulants
23
Q

Duration of anticoagulant treatment

  • Provoked
  • Unprovoked
  • Recurrent
  • Malignancy
  • APS
  • Pregnancy
A

Provoked = 3 months

Unprovoked = 6 months or long-term

Recurrent = Long-term

Malignancy-cause = LMWH (or DOAC), continue >6mo if active cancer

Anti-phospholipid syndrome = heparin followed by indefinite warfarin

Pregnancy: LMWH in 1st and 3rd trimester, Warfarin in 2nd trimester, cover 6 weeks post-partum

24
Q

Treatment of lower limb DVT

- Proximal clot vs distal clot

A

** Superficial femoral vein is a DEEP VEIN**

Treatment of Proximal clot: NSAID, LMWH or DOAC for 45 days

Treatment of distal clot: Anticoagulants for 90 days/ optional since low risk of embolization

25
Q

S/S after treatment of DVT
Cause?
Management?

A

Post-thrombotic syndrome (30%)

  • Persistent swelling, pain, skin pigmentation, ulcer in affected limb after DVT
  • Caused by chronic venous insufficiency and damage to venous valve
  • Manage by compression therapy
26
Q

Surgical conditions that increase risk of VTE

A

Long, major surgery >30 mins

Abdominal or pelvic surgery, especially for cancer

Major lower limb orthopedic surgery, e.g. hip fracture or knee replacement

27
Q

Summarize Patient factors that increase risk of VTE

A 
Old age 
Obesity 
Varicose veins 
Previous DVT 
Family history, esp. young VTE 
Pregnancy and high estrogen exposure 
Prolonged immobility 
IV drug use in femoral vein
28
Q

Summarize Haematological disorders that increase risk of VTE

A

MPN:
Polycythemia vera
Essential thrombocythaemia
Myelofibrosis

Anticoagulant deficiency: Antithrombin, Protein C, Protein S

PNH

Gain-of-function mutations: Factor V Leiden, Prothrombin G20210A mutation

29
Q

Summarize medical conditions that increase risk of VTE

A 
MI/ Heart failure 
Pneumonia 
Inflammatory bowel disease 
Nephrotic syndrome 
Neurological diseases and immobility 
Malignancies
30
Q

Ddx of Lower limb DVT

A

Cellulitis
Ruptured Baker’s cyst
Lymphedema
Haematoma

31
Q

Ddx mesenteric thrombosis

A

Malignant infiltration of portal vein esp HCC

Extrinsic compression by abdominal tumours

All causes of scute generalised abdominal pain e.g. ruptured viscus, ruptured aaa, acute pancreatitis or appendicitis, ischemic colitis…

32
Q

Ddx cerebral venous thrombosis

A

Haemorrhagic stroke
SAH
Seizure of other origin

33
Q

Ddx pulmonary embolism

A 
Stable angina or ACS
Pneumothorax
Aortic dissection
Gastrointestinal causes
Musculoskeletal causes
34
Q

Drugs used for acute anticoagulation

A

Subcutaneous LMWH or fondaparinux for most pt.

Unfractionated heparin

  • if rapid reversal (by protamine) may be required
  • (eg. renal failure, ↑bleeding risk, concomitant thrombolysis)

Upfront NOAC (rivaroxaban/apixaban)

35
Q

Drugs used for long-term anti-coagulation

A

Warfarin (or NOAC)

Continue LMWH for 6 months for patients with active cancer

36
Q

Unfractionated heparin

  • Indication
  • Route
  • MoA
  • Reversal
A

Indication: for acute clot only

Mechanism: binds to antithrombin → enhance affinity thrombin and factor Xa → inhibits thrombin and factor Xa

RoA: IV (bolus injection followed by continuous infusion) or deep subcutaneous

Reversal: half-life ~4 hours, can be readily reversed by protamine

37
Q

LMWH

  • Indication
  • Route
  • MoA
A
  • Indication: acute ± long-term treatment, when oral treatment not feasible
  • Route: subcutaneous
  • MoA: binds to antithrombin → Enhance affinity thrombin and factor Xa → inhibits thrombin and factor Xa
38
Q

Fondaparinux

  • Indication
  • Route
  • MoA
A
  • Indication: acute ± long-term treatment
  • Route; subcutaneously
  • MoA: retains active pentasaccharide sequence of heparin → only binds factor Xa and inhibit its function
39
Q

Warfarin

  • Indication
  • Route
  • MoA
  • Induction
  • Monitoring
  • Caution
A
  • Indication: long-term treatment only
  • Route: Oral only
  • MoA:
    inhibits vit K epoxide reductase → ↓regeneration of reduced form of vitamin K → ↓production of vitamin K-dependent factors, i.e. II, VII, IX, X → effect takes time
  • Induction: require overlap with heparin as takes time for depletion of vit K-dependent factors
  • Monitoring; INR, usually target 2-3×
  • Caution: numerous diet and drug interactions
  • Inhibitors of metabolism (↓P450): cimetidine, metronidazole
  • Inducers of metabolism (↑P450): barbiturates, rifampicin, phenytoin, griseofulvin (antifungal)
40
Q

Direct (newer) oral anticoagulants (DOAC, NOAC)

  • Examples
  • Indication
  • Route
  • Reversal methods
A

factor Xa inhibitors (apixaban, edoxaban, rivaroxaban), direct thrombin inhibitors (dabigatran)

  • Indication; short and long-term treatment
  • Route: orally
  • Reversal methods
    decoy factor Xa (andexanet α) for Xa inhibitors,
    idarucizumab for dabigatran
    prothrombin complex concentrate (PCC) if life-threatening bleeding
41
Q

Secondary prevention methods of VTE

A

□ Cancer and thrombophilia screen

□ Avoidance of precipitating factors, eg. OCP, HRT, prolonged immobilization

□ Graduated compression stockings or intermittent pneumatic compression during hospitalization

□ Prophylactic anticoagulation in hypercoagulable states, eg. pregnancy, surgery

□ Consider indefinite anticoagulation
→ Unprovoked VTE + low bleeding risk
→ Recurrent provoked VTE
→ Provoked VTE with irreversible RFs

42
Q

Indication for thrombophilia screening

A

Young patient with unprovoked venous thrombosis

Recurrent venous thrombosis or superf thrombophlebitis

Unusual sites of thrombosis (mesenteric, renal, portal veins, cerebral venous sinuses)

Warfarin-induced skin necrosis

Arterial thrombosis <40y

Recurrent miscarriage

43
Q

What conditions are checked in thrombophilia screening

A

Antiphospholipid syndrome:
Lupus anticoagulant (LA)
Anti-cardiolipin Ab (aCL)
Anti-β2-glycoprotein I Ab (anti-β2 GPI)

Inherited thrombophilias:
Protein C (PC) and S (PS)
Anti-thrombin (AT)
Activated protein C resistance (APCR)
Factor V Leiden

MBBS IV - Junior Clerkship WCS (131 decks)

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