Lecture 7: Thrombosis Flashcards
(42 cards)
What are the deep veins of the leg?
Illiac, femoral, popliteal and tibial
What are the superficial veins of the leg?
Greater and lesser saphenous veins
What are the three components of virchows triad?
Circulatory stasis, hyper-coagulable state and endothelial injury
What are the symptoms of a DVT?
Can be asymptomatic
Unilateral calf swelling, heat, pain, redness, hardness
What could be the differential diagnoses of a DVT?
Cellulitis, Bakers cyst, muscular pain
What is shown by doppler ultrasound in presence of DVT?
Shows velocity and direction of blood flow
In DVT the veins will be non-compressible by U/S probe
What do D-dimers indicate?
Activation of the clotting cascade
What can be used to assess the likelihood of having a DVT?
Wells risk score and D-dimer test
What is the initial treatment for a DVT?
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
What is the subsequent treatment for a DVT?
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
What are the symptoms of a PE?
Microemboli - asymptomatic
Classic symptoms:
- Pleuritic pain
- Dyspnoea
- Haemoptysis
Massive: syncope, death
Also:
- Tachycardia
- Tachypnoeic
- Hypotensive
What can be used to investigate a possible PE?
CTPA
V/Q scan (limitation: underlying lung disease)
ECG (sinus tachycardia, AF, right heart strain)
CXR (usually normal)
How would you treat a massive PE?
Thrombolysis and IV heparin
How would you treat a standard PE?
LMW heparin injections, warfarin for 6 months
Consider DOAC as alternative
What is a thrombophillia screen?
Done in younger patients with VTE
Inherited: prothrombin gene variant, anti-thrombin deficiency, protein C deficiency, protein S deficiency
Acquired: anti-phospholipid syndrome
Which drugs are anti-coagulants?
Warfarin
Heparin (LMW or unfractionated)
DOACS (dabigatran - thrombin inhibitor; rivaroxaban - factor Xa inhibitor)
Anti-platelet drugs
Anti-fibrinolytic
What is warfarin?
Vitamin K antagonist - prevents gamma-carboxylation of factors II, VII, IX and X
Prolongs the extrinsic pathway (PT time)
Monitored by INR
What is the target INR for DVT, PE and AF?
2.5
What is the target INR for VTE or metal heart valves?
3.5
What are the half lives of the clotting factors associated with warfarin - II, VII, IX, X
VII - 6 hours
IX - 24 hours
X - 40 hours
II - 60 hours
How long can it take warfarin to reach therapeutic levels?
> 3 days
What drug can also inhibit protein C and protein S?
Warfarin
How would you prescribe warfarin?
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
Which clinical states have an INR target of 2.5?
DVT, PE, AF, recurrent DVT off warfarin, thrombophilia, cardiomyopathy
