Clinical aspects of thrombosis Flashcards

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1
Q

What is thrombosis

A

Blood in BVs should be fluid

Inappropriate blood coagulation within a vessel is called thrombosis

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2
Q

Appropriate blood coagulation occurs when

A

Blood escapes from a vessel

-failure of this results in bleeding

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3
Q

Types of thrombosis and properties

A
In the arterial circulation
-high pressure system
-platelet rich
In the venous circulation
-low pressure system
-fibrin rich
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4
Q

Arterial thrombosis can cause

A

MI

Thrombotic stroke

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5
Q

Venous thrombosis can cause

A
Leg deep vein thrombosis (MI)
Pulmonary embolism (PE)
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6
Q

Treatment for arterial thrombosis

A

Antiplatelet drugs

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7
Q

Treatment for venous thrombosis

A

Anticoagulant drugs

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8
Q

Formation of arterial thrombosis

A

Atherosclerotic plaque

  • initial fatty streak
  • plaque enlargement
  • turbulence due to protrusion into lumen
  • loss of endothelium and collagen exposure
  • platelet activation and adherence
  • fibrin meshwork deposition and red cell entrapment
  • more turbulence, more platelet and fibrin deposition
  • thrombus of layers of platelets, fibrin and red cells
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9
Q

Main risk factors for arterial thrombosis

A
Family history
Diabetes mellitus
Hypertension
Hyperlipidaemia
Smoking
Atrial fibrillation for stroke
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10
Q

Other risk factors for arterial thrombosis

A

Male sex
Polycythaemia, gout
Collagen vascular disease
Lupus anticoagulant, high FVIII, high fibrinogen

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11
Q

Management of arterial thrombosis

A

Stroke and MI are in the top 5 of causes of death.
Lifestyle
-quit smoking
-exercise
-diet
-weight control
Antithrombotics: primary prevention in pts with atrial fibrillation.

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12
Q

Treatment options for arterial thrombosis

A
Antiplatelet agents: start acutely, continue long term
Thombolysis
Invasive
Rehabilitation in all cases
Secondary prevention
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13
Q

Antiplatelet agents for arterial thrombosis

A

Aspirin

Copidogrel

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14
Q

Aspirin

A

Irreversible inhibitor of cyclooxygenase (COX1), inhibiting the production of thromboxane.
Inhibition lasts for the lifespan of platelet: ≈ 1 week.
Risk reduction of non fatal vascular event by 30%.
Risk reduction of fatal vascular event by 15%.

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15
Q

Clopidogrel

A

Irreversible ADP mediated platelet inhibition.
Inhibition lasts for the lifespan of platelet: ≈ 1 week.
Decreases the risk of MI 18%,
Risk of coronary stent thrombosis/recurrent stroke by 30%

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16
Q

Thrombolysis indications

A

MI
stroke within 3 hours,
Life-threatening PE

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17
Q

Thombolysis drugs

A

ALTEPLASE (rt-PA, tissue-type plasminogen activator)
STREPTOKINASE
Others
Main side effect: bleeding

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18
Q

Invasive arterial thrombosis treatment

A

Percutaneous coronary intervention (cardiac stenting)
Combined with 3 – 12 months aspirin + clopidogrel
Coronary artery bypass grafting
Carotid endarterectomy

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19
Q

Rehabilitation for arterial thrombosis

A

Stroke: swallowing, malnutrition, mobilisation

20
Q

Secondary prevention of arterial thrombosis

A

Lifestyle
-exercise, stop smoking, diet, weight control, safe alcohol use.
Blood pressure control
Cholesterol lowering
Diabetic control
Antithrombotic therapy in stroke associated with atrial fibrillation

21
Q

Atrial fibrillation

A
Irregularly irregular heart rhythm
4% in >60years, 8% in >80years
Left atrial thrombus
Embolisation leads to stroke
Impaired cardiac output
22
Q

Treatment for atrial fibrillation

A

DC cardioversion
Heart rate control: Beta blockers, Ca channel blocker, Digoxin, AV junction ablation
Anticoagulation

23
Q

How does atrial fibrillation cause stroke?

A
  1. Blood pools in atria
  2. Blood clot forms
  3. Blood clot breaks off
  4. Blood clot travels to brain and blocks a cerebral artery causing a stroke
24
Q

Venous thromboembolism

A

DVT –> PE –> pulmonary hypertension (or death) –> chronic PE (can lead to death)
DVT –> deep vein insufficiency –> post-thrombotic syndrome –> leg ulcers

25
Q

Formation of venous thrombosis

A
*Virchow's triad*
Clotting factors and blood
-hypercoagulability (inherited or acquired)
Vessel wall 
-vascular damage (acquired)
Flow
-stasis (acquired)
26
Q

Risk factors for venous thrombosis

A

Heritable
Aquired
Mixed

27
Q

Heritable risk factors for venous thrombosis

A
Antithrombin deficiency
Protein C deficiency
Protein S deficiency
Factor V Leiden
Prothrombin mutation         20210 A
Dysfibrinogenaemia
Homocysteinuria
28
Q

Acquired risk factors for venous thrombosis

A
Age
Previous VTE
Antiphospholipid syndrome
Paralysis/ immobility
Major trauma/ surgery
Malignancy
Pregnancy
Chemotherapy
HRT
Combined oral contraceptive pill
Obesity
Paroxysmal nocturnal haemoglobinuria
Heparin induced thrombocytopenia
29
Q

Mixed risk factors for venous thrombosis

A
Raised FVIII
Raised FIX
Raised XI
Raised fibrinogen
Hyperhomocysteinaemia
30
Q

Heritable thrombophilias typically associated with

A

idiopathic VTE at young age

31
Q

Incidence of venous thrombosis

A
1 in 1000 overall
Higher in older age 
3 in 10.000 age 40
26 in 10.000 age 80
-therefore, presence of a heritable thrombophilia only gives a small increase in absolute risk
32
Q

How many pts with a strong family history is a thrombophilic defect identified

A

Only 50%

33
Q

Risk factors for venous thrombosis

A
COCP
Increases with age
Pregnancy
FV Leiden
Immobilisation without prophylaxis
Hospitilisation
-multifactorial disorder occurring through the interplay of one or more genetic and/or environmental risk factors when a critical thrombotic threshold is reached
34
Q

Assessing risk for venous thrombosis in pts

A

risk for each patient must be assessed by looking for individual risk factors present

35
Q

Hospitilisation as risk factor for venous thrombosis

A

150 fold increased risk compared to community

36
Q

Epidemiology hospitalised pts and venous thrombosis

A

Venous thromboembolism in hospitalised patients causes 25,000 – 32,000 deaths each year in the UK
Many of these deaths are preventable with thromboprophylaxis
5 times the number of deaths of acquired hospital infections

37
Q

Reducing risk of venous thromboembolism in hospital

A

Undergo assessment of VTE and bleeding risk using criteria in the ‘national tool’
Be offered verbal and written information on VTE prevention as part of admissions process
Have VTE and bleeding risk reassessed with 24hrs of admission to hospital
If at risk of VTE, be offered prophylaxis in accordance with NICE guidance
Be offered verbal and written information on VTE prevention as part of discharge process
Where appropriate be offered extended prophylaxis in accordance with NICE guidance

38
Q

Venous thombosis prevention strategies

A

Adequate hydration
Early mobilisation
Mechanical prophylaxis
Chemical prophylaxis prevents 50 – 70% of VTE

39
Q

Mechanical prophylaxis (venous thrombosis prevention)

A

All surgical patients at risk of VTE
Graduated elastic compression hosiery
Intermittent pneumatic compression (flowtron boots or foot pumps)

40
Q

Chemical prophylaxis (venous thrombosis prevention)

A

Low molecular weight heparin

Direct oral anticoagulants

41
Q

Risk assessment and dental surgery

A

NICE guidance for adults (18 years and older) admitted to hospital as inpatients or formally admitted to a hospital bed for day-case procedures.

Do not routinely offer pharmacological or mechanical VTE prophylaxis to patients undergoing a surgical procedure with local anaesthesia by local infiltration with no limitation of mobility.
All other patients must be risk assessed on admission (or at pre-assessment clinic) and reassessed within 24 hours

42
Q

Acute VTE - treatment options

A

Anticoagulation
Thrombolysis
Thrombectomy
Inferior vena cava (IVC) filter

43
Q

Long-term VTE - treatment options

A

Anticoagulation

Stockings

44
Q

Duration of treatment of VTE

A

3 months after provoked event
Long term after 2nd idiopathic thrombosis
Long term after 1st life threatening PE
Consider long term after 1st idiopathic thrombosis depending on risk factors for recurrence and bleeding

45
Q

Duration of treatment of VTE

A

3 months after provoked event
Long term after 2nd idiopathic thrombosis
Long term after 1st life threatening PE
Consider long term after 1st idiopathic thrombosis depending on risk factors for recurrence and bleeding

46
Q

Summary - venous thrombosis

A

Multifactorial disease
Associated with significant mortality/morbidity
Prevention essential, especially in hospital setting
Treatment mainly with anticoagulants
-optimum duration debated
-associated with increased risk of bleeding

47
Q

Summary of thrombosis

A

Both venous and arterial thrombosis have high morbidity and mortality.
Prevention is essential in both
Treatment is with systemic anticoagulation in venous thrombosis and antiplatelet agents in arterial thrombosis