Journal club

1
Journal club

• Vein versus PTFE for above knee femoropopliteal
  bypasses
• Journal of Vascular Surgery Nov 2002

2
Long held view that results are equivalent

• Only a few randomized trials in the literature
• Amazing that at time of recruitment 1993, only 1
  other trial to compare to.

3
PTFE perceived advantages

• Faster
• Preserved the vein for other reconstructions -
  CABG, Femoral bypasses

4
Past assumptions

• Patency not an issue
• Infection while prosthetic infection is worse
  the low rates of graft infection meant that
  statistically it should not matter unless very
  large numbers were compared.

5
Things that change

• Movement away from LSV for CABG, now IMA and
  radial arteries are preferred.
• Sequential techniques that reduce the amount of
  conduit required
• Reduction in amount of CABG due to drug eluting
  stents.

6
Things that change

• Graft surveillance scanning.
• The improves the patency of vein bypasses but not
  of PTFE.
• Different methods
• Serial resting ABIs
• Exercise ABIs
• Full duplex study

7
Things that do not change

• It is the reverse that is more relevant to the
  bulk of patients
• As CABG occurs in a different set of patients and
  generally about 10 years earlier the question is
  can the vein be left for us.
• If the LSV is harvested, it is taken from the
  ankle up. This allows for sizing to the small
  coronary

8
The study

• Looks good
• Presumed single centre
• Randomized
• 75 and 76 in the groups

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Randomization

• Only if the AK popliteal was suitable and the
  vein was good did randomization occur. Begs the
  question how they did this without making long
  incisions.

10
Surgical technique

• All vein bypasses were reversed, no insitus.
• Uniform technique.

11
Surveillance

• Haemodynamic profile ABI and velocity profile
  of the vessels above and below the bypass.
• This is not our standard.

12
Cohorts

• More diabetics in the PTFE group
• However run off scores were similar.

13
The key endpoints
14
Patency

• Better for vein
• The differences only showing up after 2 years.
• Both primary
• Vein 75 vs PTFE 52
• And secondary patency
• Vein 80 and PTFE 58

15
Patency

• In comparison with other series the differences
  are more marked as the PVD worsens.
• 4 year patency was 61 vs. 38 and 75 vs. 50 in
  those series with higher proportions of critical
  ischaemic in the cohorts. Veith 1986, Johnson
  2000.

16
Patency

• In claudicants the patency is much closer.
• In the one trial with only claudicants in it
  patency at 6 years was not significantly
  different. Abdu Rhama 1999 Surgery

17
Patency vs. Mortality

• After 5 years 38 of the patients had died.
• Previously it has been established that patients
  with critical ischaemia are fragile.
• Claudicants have a much better outlook.

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Was the vein needed for CABG?

• No.
• Only 2 of the 76 PTFE underwent CABG and the vein
  was not used anyway.
• Only 1 of 75 in the vein group and the distal
  vein was available and taken.

19
If the vein was spared was it used later?

• Mystery here
• Of the 29 failed prosthetic bypasses 16 had redo
  ops
• 13 went below the knee, yet only 3 of these used
  vein !
• The authors do not specify why. This is a key
  question.

20
Why not use the vein at re-operation

• Either
• It had been damaged at the original operation.
• Was overlooked.

21
What are the consequences of graft occlusion

• Held that prosthetic occlusions are often more
  serious as they take out the run off
• Here if a graft occluded and it was more than 7
  days then a wait and see approach was used.
• Only 24 of the cohort had critical ischaemia to
  begin with.

22
Prosthetic

• If the 29 PTFE occlusions 16 went back i.e. more
  than half.
• This you would not expect if only ¼ were
  critically ischaemic pre op.
• The mandatory take back if with 7 days may have
  swelled this figure.

23
Vein

• Of the 14 vein occlusions only 5 went back.
• This is more expected.

24
What could explain these differences?

• The occlusion of the PTFE graft does sacrifice
  run off.
• The authors suggest that PTFE grafts may promote
  distal atheroma. I dont like this.
• They imply this as more patients went back and
  then the grafts were taken more distally.

25
Why the difference.

• The decision to go below knee is easier to make
  if you have unlimited conduit fresh tissue
  planes etc.
• May have been more likely to accept a diseased AK
  pop with a short vein.

26
Limb loss

• 2 amputations in the venous group
• Had redo venous bypasses block, then redo PTFE
  distal bypasses block then limb loss.

27
Limb Loss

• 2 amputations in prosthetic gp
• Both after failed PTFE distal bypasses
• Both groups similar

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Conclusions

• Use the vein first
• Better patency
• Lower risk of re-intervention
• Re-intervention tends to be more proximal
• The LSV is unlikely to be needed elsewhere
  especially CABG

29
Conclusions

• Vascular patients die
• In those with high operative risk and short life
  expectancy then a prosthetic graft works well for
  2 years.
• Reasonable second line conduit especially in
  claudicants.