Clinical aspects of thrombosis

Question 1

What is thrombosis?

Answer 1

Inappropriate blood coagulation within a vessel

Question 2

When does appropriate blood coagulation occur?

Answer 2

When blood escapes from a vessel

Question 3

What are the types of thrombosis?

Answer 3

In the arterial circulation:

• High pressure system
• Platelet rich

In the venous circulation:

• Low pressure system
• Fibrin rich

Question 4

What can arterial thrombosis cause?

Answer 4

MII

Thrombotic stroke

Question 5

When can venous thrombosis cause?

Answer 5

Leg deep vein thrombosis (MI)
Pulmonary embolism (PE)

Question 6

How to treat thrombosis?

Answer 6

Arterial thrombosis - anti-platelet drugs

Venous thrombosis - anticoagulant thrombosis

Question 7

How does arterial thrombosis form?

Answer 7

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 deposotion and red cell entrapment
• More turbulence, more platelet and fibrin deposition
• Thrombus of layers of platelets, fibrin and red cells

Question 8

Risk factors for arterial thrombosis?

Answer 8

Main risk factors:
Family history
Diabetes mellitus
Hypertension
Hyperlipidaemia
Smoking
Atrial fibrillation for stroke

Other risk factors:
Male sex 
Polycythaemia, gout
Collagen vascular disease
Lupus anticoagulant, high FVIII, high fibrinogen

Question 9

How to manage arterial thrombosis?

Answer 9

Lifestyle:
Quit smoking
Exercise
Diet
Weight control

Antithrombotics: primary prevention in pts with atrial fibrillation

Question 10

Treatment options for arterial thrombosis?

Answer 10

Antiplatelet agents: start acutely, continue long term
Aspirin:
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%.
Dose: 75-300mg/day

Clopidogrel:
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%.
Dose 75mg/day

Thrombolysis
Indications:
MI, stroke within 3 hours, life-threatening PE

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

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

Rehabilitation in all cases
Stroke: swallowing, malnutrition, mobilisation

Question 11

Secondary prevention of arterial thrombosis (treatment)?

Answer 11

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

Question 12

What is atrial fibrillation?

Answer 12

Irregular heart rhythm
Embolisation leads to stroke
Impaired cardiac output

Question 13

Treatment of atrial fibrillation?

Answer 13

DC cardioversion
HR control: B blockers, Ca channel blocker, digoxin, AV junction ablation
Anticoagulation

Question 14

How does atrial fibrillation cause stroke?

Answer 14

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

Question 15

What can a deep vein thrombosis cause?

Answer 15

Pulmonary embolism = death OR pulmonary hypertension = chronic PE = death

Deep vein insufficiency = post-thrombotic syndrome = leg ulcers

Question 16

How does a venous thrombosis form? (what are the risk factors)

Answer 16

Hypercoagulability - inherited, acquired

Vascular damage - acquired

Stasis - acquired

Question 17

Risk factors of venous thrombosis?

Answer 17

Heritable:

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

Acquired:

• Age
• Previous VTE
• Antiphospholipid syndrome
• Paralysis
• Major trauma
• Pregnancy
• Chemo
• Obesity
• Contraceptive pill

Mixed:

• Raised FVIII
• Raised FIX
• Raised XI
• Raised fibrinogen

Question 18

Heritable thrombophilias

Answer 18

TABLE…. SLide 21

Question 19

List the types of heritable thrombophilias?

Answer 19

Factor V Leiden
Prothrombin gene mutation
Protein C deficiency
Protein S deficiency
Antithrombin deficiency

Question 20

Name the most common heritable thrombophilia

Answer 20

Factor V leiden

Question 21

What is the incidence of venous thrombosis?

50% of pts with a strong family history have heritable thrombophilia - thrombophilic defect is identifiable

Answer 21

1 in 1000 overall
Higher in older age
3 in 10.000 age 40
26 in 10.000 age 80

Question 22

How to prevent a venous thrombosis?

Answer 22

Adequate hydration
Early mobilisation

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

Chemical prophylaxis prevents 50 – 70% of VTE:

• Low molecular weight heparin
• Direct oral anticoagulants

Question 23

Risk assessment of VTE and dental surgery - what to do?

Answer 23

Do not routinely offer pharmacological or mechanical VTE prophylaxis to pts undergoing a surgical procedure with LA by infiltration with no limitation of mobility
Risk assess on admin and reassessed within 24hrs

Question 24

VTE treatment?

Answer 24

Acute:
- Anticoagulation
- Thrombolysis
- Thrombectomy
Inferior vena cava filter

Long term:

• Anticoagulation
• Stockings

Question 25

How long does VTE treatment last?

Answer 25

3 months after 1st event
Provoked events do not need anticoagulation >3 months
Distal DVT do not need anticoagulation >3 months
Consider long term anticoagulation after 1st unprovoked thrombosis