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T2: Theme 2: Blood > Lecture 7: Thrombosis > Flashcards

Lecture 7: Thrombosis Flashcards

1
Q

What are the deep veins of the leg?

A

Illiac, femoral, popliteal and tibial

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2
Q

What are the superficial veins of the leg?

A

Greater and lesser saphenous veins

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3
Q

What are the three components of virchows triad?

A

Circulatory stasis, hyper-coagulable state and endothelial injury

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4
Q

What are the symptoms of a DVT?

A

Can be asymptomatic

Unilateral calf swelling, heat, pain, redness, hardness

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5
Q

What could be the differential diagnoses of a DVT?

A

Cellulitis, Bakers cyst, muscular pain

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6
Q

What is shown by doppler ultrasound in presence of DVT?

A

Shows velocity and direction of blood flow

In DVT the veins will be non-compressible by U/S probe

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7
Q

What do D-dimers indicate?

A

Activation of the clotting cascade

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8
Q

What can be used to assess the likelihood of having a DVT?

A

Wells risk score and D-dimer test

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9
Q

What is the initial treatment for a DVT?

A

Therapeutic anti-coagulation using sub-cut LMW heparin

Dosing according to patients weight

If the patient has renal impairment (creatinine clearance less than 30ml/min) then anti-coagulant with IV unfractionated heparin instead

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10
Q

What is the subsequent treatment for a DVT?

A

Load with oral warfarin for 3-5 days, stop LMW weight once INR>2.0 for 2 days

1st DVT = 6 months warfarin

2nd DVT/PE = lifelong warfarin

Maintain INR between 2-3

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11
Q

What are the symptoms of a PE?

A

Microemboli - asymptomatic

Classic symptoms:

  • Pleuritic pain
  • Dyspnoea
  • Haemoptysis

Massive: syncope, death

Also:

  • Tachycardia
  • Tachypnoeic
  • Hypotensive
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12
Q

What can be used to investigate a possible PE?

A

CTPA

V/Q scan (limitation: underlying lung disease)

ECG (sinus tachycardia, AF, right heart strain)

CXR (usually normal)

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13
Q

How would you treat a massive PE?

A

Thrombolysis and IV heparin

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14
Q

How would you treat a standard PE?

A

LMW heparin injections, warfarin for 6 months

Consider DOAC as alternative

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15
Q

What is a thrombophillia screen?

A

Done in younger patients with VTE

Inherited: prothrombin gene variant, anti-thrombin deficiency, protein C deficiency, protein S deficiency

Acquired: anti-phospholipid syndrome

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16
Q

Which drugs are anti-coagulants?

A

Warfarin

Heparin (LMW or unfractionated)

DOACS (dabigatran - thrombin inhibitor; rivaroxaban - factor Xa inhibitor)

Anti-platelet drugs

Anti-fibrinolytic

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17
Q

What is warfarin?

A

Vitamin K antagonist - prevents gamma-carboxylation of factors II, VII, IX and X

Prolongs the extrinsic pathway (PT time)

Monitored by INR

18
Q

What is the target INR for DVT, PE and AF?

A

2.5

19
Q

What is the target INR for VTE or metal heart valves?

A

3.5

20
Q

What are the half lives of the clotting factors associated with warfarin - II, VII, IX, X

A

VII - 6 hours
IX - 24 hours
X - 40 hours
II - 60 hours

21
Q

How long can it take warfarin to reach therapeutic levels?

A

> 3 days

22
Q

What drug can also inhibit protein C and protein S?

A

Warfarin

23
Q

How would you prescribe warfarin?

A

Load patient with LMW heparin (10mg, 10mg, 5mg) - bc of fall is protein C and protein S

Patients have different sensitivity to warfarin

LMW continued until the INR is >2 for 2 days

24
Q

Which clinical states have an INR target of 2.5?

A

DVT, PE, AF, recurrent DVT off warfarin, thrombophilia, cardiomyopathy

25
Q

Which clinical states have an INR target of 3.0?

A

Recurrent DVT while on warfarin, mechanical heart valves, anti-phospholipid syndrome

26
Q

Which drug is metabolised by CYTP450?

A

Warfarin

Inhibitors of this enzyme potentiate warfarin and vv

27
Q

What are the side effects of warfarin?

A

Teratogenic (use LMW heparin in pregnancy)

Significant haemorrhage risk (1%)

Minor bleeding (20%)

Skin necrosis

Alopecia

28
Q

How can you reverse warfarin?

A

Give vitamin K 2-10mg IV/PO depending on INR level

If life threatening bleed can give activated prothrombin complex (octaplex) containing FII, VII, IX and X

Can also give FFP

29
Q

What is heparin?

A

A mucopolysaccharide that potentiates anti-thrombin 3

Irreversibly inactivates factors IIa (thrombin) and Xa

30
Q

How is unfractionated heparin given?

A

IV infusion

5000U bolus and ~1000U/hour infusion

Monitored by APTT with target range of 1.5-2.5x normal

Safe in renal failure

31
Q

How is LMW heparin given?

A

SC injection

Prescribed acc to patients weight

Not usually monitored but patient have to have creatinine clearance of over 30ml/min

32
Q

What drug can be partially reversed with protamine sulphate?

A

Unfractionated heparin

33
Q

Which drug is used for thromboprophylaxis for hospital in-patients?

A

LMW heparin

34
Q

What are NOACs?

A

Alternative to warfarin

Oral

Dont require monitoring

Dabigatran and rivaroxaban

Irreversible

35
Q

What is dabigatran?

A

Direct thrombin inhibitor

Used for VTE prophylaxis, treatment of DVT and PE, stroke prevention in AF

110mg bd or 150mg bd

36
Q

What is rivaroxaban?

A

Direct factor Xa inhibitor

Used for VTE prophylaxis, treatment of DVTs and Yes, stroke prevention in AF

15mg bd for 3 weeks, then 20mg od (or 15mg od if CrCl is 15-50ml/min)

37
Q

Which drug is a COX inhibitor?

A

Aspirin

38
Q

What is clopidogrel?

A

ADP receptor inhibitor (anti-platelet drug)

39
Q

How does dipyridamole work?

A

Inhibits phosphodiesterase

40
Q

How does prostacyclin work?

A

Stimulates adenylate cyclase

41
Q

What are abciximab, eptifibatide and tirofiban?

A

Glycoprotein2b3a inhibitors

42
Q

Name two fibrinolytic agents

A

tPA and streptokinase

Used to lyse fresh thrombi (arterial) by converting plasminogen to plasmin

Acute MI, thrombotic stroke, major PE, iliofemoral thrombosis

Aim to use within 6 hours

T2: Theme 2: Blood (8 decks)

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