Cardiovascular: warfarin and heparins

Question 1

What is duration of treatment for:
Isolated Calf DVT
Provoked VTE
Unprovoked VTE

Answer 1

Isolated calf dvt = 6 weeks
provoked = 3 months
unprovoked= 3 plus months (long term)

Question 2

What is target INR for:

• VTE/AF/MI/cardioversion/ biprosthetic mitral valve?
• Mechanical valve
• recurrent DVT in pts receiving anticoagulation

Answer 2

VTE/AF most indications= 2.5
Mechanical valve= 3-3.5
Recurrent=3.5

Question 3

What are INR targets for
biprosthetic mitral valve
mechanical valve

Answer 3

Biprosthetic mitral valve is 2.5

but mechanical valve is 3.5

Question 4

how often is INR monitored

Answer 4

1-2 weeks until stable then 3 monthly

Question 5

if a patient on warfarin presents with a painful skin rash - what is most appt action?

Answer 5

MHRA warning regarding risk of calciphylaxis - refer to GP asap
Risk increased if have renal diseas

Question 6

what are interactions of warfarin

Answer 6

Enzyme inhibitors as thy can increase warfarin levels in body and increase bleeding risk (increased INR)

Question 7

For elective surgery, what is the process with warfarin?

Answer 7

stop 5 days before elective
If INR >1.5 the day before then give oral phytomenadione
re-start warfarin on evening of or next day

Question 8

If a patient is on warfarin but requires emergency surgery what is done?

Answer 8

delay 6-12hrs

If cannot delay - IV phytomenadione and dried prothrombin complex

Question 9

If pt is at high risk of VTE e.g. had in last 3 months, previous stroke/TIA or mechanical valve, how would you manage warfarin pre surgery?

Answer 9

still stop 5 days prior but bridge with LMWH and stop these 24hrs prior

Question 10

if there is ANY BLEEDING (minor or major) with warfarin, regardless of INR (e.g. if 5-8 or >8), what is the process

Answer 10

STOP
IV phyto
restart when INR <5

Question 11

if INR is between 5-8 but no bleeding what is done?

Answer 11

Omit 1-2 doses
reduce maintenance dose
measure INR in 2-3 days

Question 12

if IN 5-8 but minor bleeding?

Answer 12

omit
IV phyto
repeat if INR still high in 24hr
re-start <5

Question 13

if INR >8 but no bleeding?

Answer 13

omit
ORAL phyto
repeat if INR still high in 24h
re-start <5

Question 14

What are 3 MHRA warnings re; warfarin

Answer 14

1. Risk calciphylaxis -painful skin rash
2. antiretrovirals for hep C can affect INR
3. Miconazole OTC daktarin c/i - increases wafarin and risk of bleeding

Question 15

how long does wafarin take to work

Answer 15

48-72hrs hence need bridging with LMWH

Question 16

what are some counselling points of warfarin

Answer 16

Alert card, yellow book
bleeding signs 
skin rash
no drastic changes in diet with greens 
reducing alcohol 
informing dentist and soft toothbrush,care when shaving
avoiding pomegranate/gfruit

Question 17

Which patients are at increased risk of VTE

Answer 17

immobility
obesity
malignancy 
older >60
clotting disordeers 
HRT/contraception
pregnancy 
co-morbdities

Question 18

how would you treat a VTE

Answer 18

LMWH or UF for 5 days until INR >2 for at least 24hrs
then initiate DOAC
(or warfarin-bridge)

Question 19

What is the preferred choice for VTE proph and treatment in pregnancy and why

Answer 19

LMWH - dont cross placenta, reduced risk of osteoporosis and HIT

Question 20

What are key risks/sid effects of heparins

Answer 20

1. heparin induced thrombocytopenia occurring 5-10 days after ~30% reduction in platelets and skin rash
2. Haemorrhagee
3. Hyperkalaemia
4. osteoprosis (higher in heparin rather than lmwh)

Question 21

Why arent LMWH used in renal impairment

Answer 21

Longer duration of action

Question 22

When are LMWH preferred

Answer 22

if risk of osteoporosis
pregnant
if at risk of Heparin induced thrombocytopnia (have a reduced risk with lmwh)

Question 23

What bloods would you measure with heparins

Answer 23

platelets
APTT
K+

Question 24

How long would you continue VTE prophylaxis in

• surgery
• major abdominal cancer surgery or pelvic
• Knee/hip

Answer 24

general surg 5-7 days
major cancer abdomen/pelvic= 28 days
replacement= extended