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CARDIOVASCULAR > Clinical aspects of thrombosis > Flashcards

Clinical aspects of thrombosis Flashcards

1
Q

What is thrombosis?

A

inappropriate blood coagulation within a blood vessel.

Blood in blood vessels should be fluid ideally.

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2
Q

When does appropriate blood coagulation occur?

A

When blood escapes from a vessel (if it didnt happen it would result in excessive bleeding)

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3
Q

What are the 2 types of circulations thrombosis can occur in and their pressures?

What is each type rich in?

A

In the arterial circulation: a high pressure system which is platelet-rich

In the venous circulation: a low pressure system which is fibrin-rich

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4
Q

What can arterial thrombosis lead to? (2)

A

myocardial infarction

thrombotic stroke

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5
Q

What can venous thrombosis lead to?

A

leg deep vein thrombosis (MI)

pulmonary embolism (PE)

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6
Q

Which type of drugs are used to treat arterial thrombosis?

A

antiplatelet drugs

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7
Q

Which type of drugs are used to treat venous thrombosis?

A

anticoagulant drugs

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8
Q

How does the formation of arterial thrombosis occur involving atherosclerotic plaque?

A
  • initial fatty streak
  • plaque enlargement
  • turbulence due to protrusion into the 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

What are the main risk factors for arterial thrombosis? (6)

List other risk factors too?

A
  • family history
  • diabetes mellitus
  • hypertension
  • hyperlipidaemia
  • smoking
  • atrial fibrillation for stroke

OTHERS: males more likely, polycythaemia, gout, collagen vascular disease, high fibrinogen, high FVIII, lupus anticoagulant

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10
Q

How can we manage arterial thrombosis?

A

lifestyle: quit smoking, exercise, diet, weight control

antithrombotics: primary prevention in patients with atrial fibrillation

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11
Q

Which antiplatelet agents can be taken for arterial thrombosis? (2)

A

aspirin

clopidogrel

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12
Q

How does aspirin work as an antiplatelet agent?

By what % does it reduce the risk of vascular events happening?

A

It is an 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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13
Q

How does clopidogrel work as an antiplatelet agent?

By what % does it reduce the risk of MI and coronary stent thrombosis/recurrent stroke?

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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14
Q

Aside from antiplatelet drugs, what other drugs can be used to treat arterial thrombosis?

What would be the indications for this?

A

Drugs that induce thrombolysis (the dissolution of a clot)

including: Alteplase, streptokinase, others

INDICATIONS: stroke within 3hrs, MI, life-threatening pulmonary embolism

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15
Q

What is the main side effect of thrombolysis-causing drugs?

A

bleeding

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16
Q

What are some invasive treatment options for arterial thrombosis?

A
  • Percutaneous coronary intervention (cardiac stenting) combined with 3 – 12 months aspirin + clopidogrel
  • Coronary artery bypass grafting
  • Carotid endarterectomy
17
Q

In all cases, regardless of treatment, what should be done?

A

rehabilitation

especially for stroke patients - swallowing, malnutrition, mobilisation

18
Q

What secondary prevention methods can be used for arterial thrombosis?

A

Lifestyle - exercise, diet, stop smoking, weight, safe alcohol use

BP control

Cholesterol lowering

Diabetic control

Antithrombotic therapy in stroke associated with atrial fibrilation

19
Q

What is atrial fibrillation?

What is its incidence in older people?

How can it be treated?

A

An irregular heart rhythm. Can cause a left atrial thrombus and impaired cardiac output.

Embolisation would lead to stroke.

4% of over 60s affected, 8% of over 80s

treatment:

  • DC cardioversion
  • Heart rate control: Beta blockers, Ca channel blocker, Digoxin, AV junction ablation
  • Anticoagulation
20
Q

How does atrial fibrillation cause stroke? (4 steps)

A
  • blood pools in atria
  • blood clot forms
  • blood clot breaks off
  • blood clot travels to brain and blocks a cerebral artery, causing a stroke.
21
Q

How can deep vein thrombosis lead to death?

A
22
Q

What are the 3 factors contributing to the formation of venous thrombosis?

A

Hypercoagulability - inherited or acquired

Stasis - acquired

Vascular damage - acquired

23
Q

What are the heritable risk factors for venous thrombosis?

A
  • antithrombin deficiency
  • Protein C deficiency
  • protein S deficiency
  • Factor V Leiden
  • prothrombin mutation 20210 A
  • dysfibrinogenaemia
  • Homocysteinuria
24
Q

What are the acquired risk factors for venous thrombosis?

A
  • age
  • previous VTE
  • antiphospholipid syndrome
  • paralysis/immobility
  • major trauma/surgery
  • malignancy
  • pregnancy
  • chemotherapy
  • Hormone replacement therapy
  • Combined oral contraceptive pill
  • obesity
  • Paroxysmal nocturnal haemoglobinuria
  • Heparin induced thrombocytopenia
25
Q

Is raised FVIII / FIX / XI / fibrinogen levels an acquired or inherited risk factor for venous thrombosis?

A

Mixed

26
Q

What are the different types of heritable thrombophilias?

A
27
Q

What is the incidence of venous thrombosis?

A

1 in 1000 overall

3 in 10000 age 40

26 in 10000 age 80

28
Q

What is thrombophilia typically associated with at a young age?

A

idiopathic VTE (venous thromboembolism)

29
Q

How does the presence of heritable thrombophilia increase the risk?

A

It only gives a small increase in absolute risk

Altogether in only 50% of patients with a strong family history a thrombophilic defect is identified

30
Q

What is VTE?

A

Venous thromboembolism - a blood clot that forms in a vein.

It is a multifactorial disorder occurring through the interplay of one or more genetic and/or environmental risk factors when a critical thrombotic threshold is reached.

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

VTE is a risk factor of venous thrombosis

31
Q

What is the NICE guidance for VTEs and reducing the risk of venous thrombosis:

A

All patients admitted to hospital must:

  • 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
32
Q

What are some venous thrombosis prevention strategies?

Think about mechanical and chemical prophylaxis and what they involve

A
  • Adequate hydration
  • Early mobilisation
  • Mechanical prophylaxis: for 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

33
Q

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

A
  • 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.
34
Q

What are the acute treatment options for VTE? (4)

A
  • Anticoagulation
  • thrombolysis
  • thrombectomy
  • inferior vena cava (IVC) filter
35
Q

what are the long term treatment options for VTE? (2)

A
  • anticoagulation
  • stockings
36
Q

What is the duration of treatment of VTE?

A

3 months after a first event

Provoked events do not need anticoagulation >3 months

Distal DVT do not need anticoagulation > 3 months

Consider long term anticoagulation after first unprovoked thrombosis

CARDIOVASCULAR (3 decks)

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