Blood clotting

Question 1

What is DVT?

Answer 1

Deep vein thrombosis is when a thrombus forms in venous circulation

Question 2

Risk factors for DVT?

Answer 2

Virchow’s triad:

1. blood vessel injury eg fractures, hip/knee surgery
2. Altered blood flow eg bedbound, pregnancy, MI, AF ec
3. hyper coagulation - heparin

Question 3

DVT treatment in good vs bad renal function

Answer 3

Good renal function: dalteparin/enoxaparin

Bad: UFH

Question 4

Heparin
Dalteparin 
Enoxaparin 
MOA
-difference between heparin and LMWH

Answer 4

High affinity for ATIII

• natural anti-coagulant (inhibiting Xa and IIa)
• preventing conversion of fibrinogen to fibrin

LMWH = acts on Xa only better for prevention

Question 5

Factor Xa inhibitors

MOA

Answer 5

Rivaroxaban/ Apixaban
Fonaparinux
-blocks conversion of fibrinogen to fibrin

Question 6

Bivalirudin
Dabigatran
MOA

Answer 6

Direct thrombin inhibitors

Question 7

What is the recommended renal clearances for Xa inhibitors?

Answer 7

Rivaroxaban = >15ml/min Crcl
Apixaban = 30ml/min
dabagatrian 50ml/min

Question 8

Outline the treatment of DVT

Answer 8

1. DOACS
   - Rivaroxaban 15mg bd for 21 days THEN 20mg daily for 3months (proximal ) or 6months (distal - below the knee)
   - apixaban 10mg bd for 7 days THEN 5mg bd for 3/6months

2.

• LMWH or UFH for 5 days THEN dabigatran 150mg bd
• LMWH or UFH for 5 days THEN warfarin (2-3INR)

Question 9

Outline the prevention of DVT after Knee or hip replacement

Answer 9

-Must check crCl
DOAC
-rivaroxaban  10mg daily
-apixaban 2.5mg bd 
dabigatran 110mg stat then 220mg daily