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Haematology Y3 > Thrombotic events > Flashcards

Thrombotic events Flashcards

1
Q

What are the types of thrombotic events?

A

Arterial
- Coronary, cerebral, peripheral

Venous
- Deep venous thromboses
- Pulmonary Embolism

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2
Q

What is arterial thrombosis?

A

A blood clot which forms in the artery.

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3
Q

Risk factors for arterial thrombosis?

A

Factors that can cause damage to the endothelium, increase in foamy macrophages and platelet activation:

  • Hypertension
  • Smoking
  • High cholesterol
  • Diabetes mellitus
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4
Q

What is the pathophysiology of atherosclerosis?

A

Damage to endothelium causes recruitment of “foamy” macrophages rich in cholesterol, resulting in the formation of cholesterol-rich plaques.

STABLE plaques result in stable angina and intermittent claudication.

UNSTABLE plaques result in stroke, unstable angina or myocardial infarction.
- Plaques rupture, platelets are recruited and cause acute thrombosis leading to sudden symptom onset.
- Leads to acute organ ischemia and infarction

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5
Q

Pathophysiology of platelets in arterial thrombosis?

A
  1. Plaque ruptures - more likely in the high pressure environment of the arteries.
  2. Exposed endothelium and release of Von Willebrand factor and other proteins for which platelets have receptors for leads to platelet adhesion to the site of injury.
  3. Platelets become activated - releases granules that activate coagulation and recruit other platelets to develop a platelet plug (e.g. ADP, thrombin and thromboxane A2).
  4. Platelet aggregation via membrane glycoproteins (fibrinogen)
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6
Q

Management of arterial thrombosis?

A

Basic principles of management:

  • Aspirin and other anti-platelet drugs
  • Modify risk factors for atherosclerosis
    - Stop smoking, treat hypertension, treat diabetes and lower cholesterol.
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7
Q

What is deep vein thrombosis?

A

Refers to the intra-luminal occlusion of any vein within the deep system of a limb (either arm or leg) or the pelvis

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8
Q

Aetiology of venous thrombosis?

A

Venous thrombosis is considered to arise from the interplay between the three factors that make up Virchow’s triad

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9
Q

What are the components of Virchow’s triad?

A

Hypercoagulable state

Endothelial injury

Circulatory stasis

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10
Q

What are all the causes of hypercoagulable states?

A
  • Malignancy
  • Pregnancy and peripartum
  • Oestrogen therapy
  • IBD
  • Sepsis
  • Thrombophilia (abnormal tendancy to form blood clots)
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11
Q

What are all the causes of endothelial injury?

A
  • Venous disorders
  • Venous valvular damage (e.g. from previous DVT/PE - very strong RF)
  • Trauma or surgery
  • Indwelling catheters
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12
Q

What are all the causes of circulatory stasis?

A
  • Left ventricular dysfunction
  • Immobility or paralysis
  • Venous insufficiency/varicose veins
  • Venous obstruction - tumour, obesity, pregnancy
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13
Q

Pathophysiology of venous thrombosis?

A

The venous system is a low pressure system so platelets are not activated, this activates coagulation cascade which leads to clot rich in fibrin

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14
Q

What is the difference between DVT and PVT?

A
  • Distal vein thrombosis: refers to DVT of the calves
  • Proximal vein thrombosis: DVT of the popliteal or femoral vein, more likely to embolise
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15
Q

Symptoms for venous thrombosis?

A
  • Calf - warmth, tenderness, swelling, erythema (unilateral)
  • Mild fever
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16
Q

Signs of venous thrombosis?

A
  • Pitting oedema
  • Pain on palpation of deep veins
  • Distention of superficial veins
17
Q

Investigations for venous thrombosis?

A
  • D-dimer: rule out test for patients considered unlikely to have a DVT based on the Wells score
  • US Doppler leg scan: diagnostic, indicated if patient has raised D-dimers, or if they have a Wells score of 2 or more (in which case US would be first line)
18
Q

Acute management for venous thrombosis?

A
  • Anticoagulation: apixaban or rivaroxaban (DOACs) first line
    • May be outpatient if patient considered low-risk
    • If neither apixaban or rivaroxaban are suitable then either LMWH followed by dabigatran or edoxaban

OR LMWH followed by a vitamin K antagonist (i.e. warfarin)

  • Percutaneous mechanical thrombectomy: used in massive DVTs
  • IVC filter: does not actually treat the DVT but reduces the risk DVT embolising into the pulmonary arteries causing a PE, used in patients where anticoagulation is contraindicated
19
Q

What type of drug is warfarin?

A

Vitamin K antagonist

20
Q

Secondary prevention of venous thrombosis?

A
  • The options for long term anticoagulation are warfarin, a DOAC or LMWH
  • Treatment with a should be continued for at least three months
    • Provoked DVT with reversible factors - 3 months
    • Provoked DVT with irreversible factors, or unprovoked DVT - 3-6 months, potentially life-long depending on patient factors (e.g. genetic clotting disorder)
21
Q

What are hereditary thrombophilias?

A

A group of genetic defects in which affected individuals have an increased tendancy to develop premature, unusual and recurrent thromboses

22
Q

Aetiology of hereditary thrombophilias?

A
  • Factor V Leiden
  • Prothrombin 20210 mutation
  • Antithrombin deficiency
  • Protein C deficiency
  • Protein S deficiency
23
Q

Are there any symptoms with hereditary thrombophilias?

A

Usually does not have any symptoms, only becomes apparent when patient develops a thrombosis

24
Q

When should a hereditary thrombophilia screening be considered?

A
  • Venous thrombosis <45 years old
  • Recurrent venous thrombosis
  • Unusual venous thrombosis
  • Family history of venous thrombosis
  • Family history of thrombophilia
25
Q

Management of hereditary thrombophilia?

A
  • Advice on avoiding risk
  • Short term prophylaxis to prevent thrombotic events during periods of known risk
  • Short term anticoagulation to treat thrombotic events
  • Long term anticoagulation if recurrent thrombotic events
26
Q

What is anti-phospholipid syndrome?

A

An autoimmune disorder characterised by arterial and venous thrombosis, adverse pregnancy outcomes (for mother and foetus), and raised levels of antiphospholipid antibodies.

27
Q

Aetiology of antiphospholipid syndrome?

A

Genetic predisposition

More common in females

While it can occur as a primary condition, it often occurs secondary to SLE (or another rheumatic or autoimmune disorder).

28
Q

Pathophysiology of antiphospholipid syndrome?

A

Reacts against proteins that bind to anionic phospholipids on plasma membranes.

29
Q

Venous features in antiphospholipid syndrome?

A

DVT/PE

Recurrent pulmonary emboli or thrombosis can lead to life-threatening pulmonary hypertension.

Livedo reticularis - blood clots in capillaries lead to swelling of venules, causing purplish, net-like discolouration of the ski n.

30
Q

Arterial features in antiphospholipid syndrome?

A

May contribute to an increased frequency of stroke or MI, especially in younger individuals

  • Strokes may develop secondary to in situ thrombosis or embolisation that originates from the valvular lesions of endocarditis.
31
Q

Other features in antiphospholipid syndrome?

A

Catastrophic APS (rare) - multiorgan infarctions over a period of days to weeks, often fatal.

Miscarriage
- Late spontaneous foetal loss (second or third trimester) is common; however, can occur any time during pregnancy.
- Recurrent early foetal loss (< 10 weeks gestation) is also possible.

Many patients have migraines

32
Q

Investigations for antiphospholipid syndrome?

A

Bloods
- One or more of three positive blood tests are needed on 2 occasions, 12 weeks apart to diagnose APS:

  1. Anticardiolipin antibodies
  2. Anti beta-2-GPI antibodies
  3. Positive lupus anticoagulant assay

FBC: thrombocytopaenia

Clotting screen: prolongation of aPTT

33
Q

Management of antiphospholipid syndrome?

A

Anticoagulation for those with an episode of thrombosis - acute LMWH then warfarin or aspirin prophylaxis.

  • Patients who are found to have positive antibodies but who have never had an episode of thrombosis DO NOT require anticoagulation.

LMWH and aspirin used during pregnancy for patients with recurrent pregnancy loss.

Haematology Y3 (39 decks)

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