Journal clubJournal club

Vein versus PTFE for above knee Vein versus PTFE for above knee femoropopliteal bypasses femoropopliteal bypasses

Journal of Vascular Surgery Nov Journal of Vascular Surgery Nov 20022002

Long held view that results are Long held view that results are equivalentequivalent

• Only a few randomized trials in the Only a few randomized trials in the literatureliterature

• Amazing that at time of recruitment Amazing that at time of recruitment 1993, only 1 other trial to compare 1993, only 1 other trial to compare to.to.

PTFE perceived advantagesPTFE perceived advantages

• FasterFaster

• Preserved the vein for other Preserved the vein for other reconstructions - CABG, Femoral reconstructions - CABG, Femoral bypassesbypasses

Past assumptionsPast assumptions

• Patency not an issuePatency not an issue

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

Things that changeThings that change

• Movement away from LSV for CABG, Movement away from LSV for CABG, now IMA and radial arteries are now IMA and radial arteries are preferred.preferred.

• Sequential techniques that reduce Sequential techniques that reduce the amount of conduit requiredthe amount of conduit required

• Reduction in amount of CABG due to Reduction in amount of CABG due to drug eluting stents.drug eluting stents.

Things that changeThings that change

• Graft surveillance scanning.Graft surveillance scanning.

• The improves the patency of vein The improves the patency of vein bypasses but not of PTFE.bypasses but not of PTFE.

• Different methodsDifferent methods

• Serial resting ABI’sSerial resting ABI’s

• Exercise ABI’sExercise ABI’s

• Full duplex studyFull duplex study

Things that do not changeThings that do not change

• It is the reverse that is more relevant to It is the reverse that is more relevant to the bulk of patientsthe bulk of patients

• As CABG occurs in a different set of As CABG occurs in a different set of patients and generally about 10 years patients and generally about 10 years earlier the question is can the vein be left earlier the question is can the vein be left for us.for us.

• If the LSV is harvested, it is taken from the If the LSV is harvested, it is taken from the ankle up. This allows for sizing to the small ankle up. This allows for sizing to the small coronarycoronary

The studyThe study

• Looks goodLooks good

• Presumed single centrePresumed single centre

• Randomized Randomized

• 75 and 76 in the groups75 and 76 in the groups

RandomizationRandomization

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

Surgical techniqueSurgical technique

• All vein bypasses were reversed, no All vein bypasses were reversed, no insitu’s.insitu’s.

• Uniform technique.Uniform technique.

SurveillanceSurveillance

• ‘‘Haemodynamic profile’ – ABI and Haemodynamic profile’ – ABI and velocity profile of the vessels above velocity profile of the vessels above and below the bypass.and below the bypass.

• This is not our standard.This is not our standard.

CohortsCohorts

• More diabetics in the PTFE groupMore diabetics in the PTFE group

• However run off scores were similar.However run off scores were similar.

The key endpointsThe key endpoints

PatencyPatency

• Better for veinBetter for vein

• The differences only showing up after The differences only showing up after 2 years. 2 years.

• Both primary Both primary

• Vein 75% vs PTFE 52%Vein 75% vs PTFE 52%

• And secondary patencyAnd secondary patency

• Vein 80% and PTFE 58%Vein 80% and PTFE 58%

PatencyPatency

• In comparison with other series the In comparison with other series the differences are more marked as the differences are more marked as the PVD worsens.PVD worsens.

• 4 year patency was 61 vs. 38% and 4 year patency was 61 vs. 38% and 75 vs. 50% in those series with 75 vs. 50% in those series with higher proportions of critical higher proportions of critical ischaemic in the cohorts. ischaemic in the cohorts. Veith 1986, Veith 1986, Johnson 2000.Johnson 2000.

PatencyPatency

• In claudicants the patency is much In claudicants the patency is much closer.closer.

• In the one trial with only claudicants In the one trial with only claudicants in it patency at 6 years was not in it patency at 6 years was not significantly different.significantly different. Abdu Rhama Abdu Rhama 1999 Surgery1999 Surgery

Patency vs. MortalityPatency vs. Mortality

• After 5 years 38% of the patients had After 5 years 38% of the patients had died.died.

• Previously it has been established Previously it has been established that patients with critical ischaemia that patients with critical ischaemia are fragile.are fragile.

• Claudicants have a much better Claudicants have a much better outlook.outlook.

Was the vein needed for Was the vein needed for CABG?CABG?

• No.No.

• Only 2 of the 76 PTFE underwent Only 2 of the 76 PTFE underwent CABG and the vein was not used CABG and the vein was not used anyway.anyway.

• Only 1 of 75 in the vein group and Only 1 of 75 in the vein group and the distal vein was available and the distal vein was available and taken.taken.

If the vein was spared was it If the vein was spared was it used later?used later?

• Mystery hereMystery here

• Of the 29 failed prosthetic bypasses Of the 29 failed prosthetic bypasses 16 had redo ops16 had redo ops

• 13 went below the knee, yet only 3 13 went below the knee, yet only 3 of these used vein ! of these used vein !

• The authors do not specify why. This The authors do not specify why. This is a key question. is a key question.

Why not use the vein at re-Why not use the vein at re-operationoperation

• Either Either

• It had been damaged at the original It had been damaged at the original operation.operation.

• Was overlooked.Was overlooked.

What are the consequences of What are the consequences of graft occlusiongraft occlusion

• Held that prosthetic occlusions are Held that prosthetic occlusions are often more serious as they ‘take out often more serious as they ‘take out the run off”the run off”

• Here if a graft occluded and it was Here if a graft occluded and it was more than 7 days then a wait and more than 7 days then a wait and see approach was used.see approach was used.

• Only 24 % of the cohort had critical Only 24 % of the cohort had critical ischaemia to begin with.ischaemia to begin with.

ProstheticProsthetic

• If the 29 PTFE occlusions 16 went If the 29 PTFE occlusions 16 went back i.e. more than half.back i.e. more than half.

• This you would not expect if only ¼ This you would not expect if only ¼ were critically ischaemic pre op.were critically ischaemic pre op.

• The mandatory take back if with 7 The mandatory take back if with 7 days may have swelled this figure.days may have swelled this figure.

VeinVein

• Of the 14 vein occlusions only 5 went Of the 14 vein occlusions only 5 went back. back.

• This is more expected.This is more expected.

What could explain these What could explain these differences?differences?

• The occlusion of the PTFE graft does The occlusion of the PTFE graft does sacrifice run off.sacrifice run off.

• The authors suggest that PTFE grafts The authors suggest that PTFE grafts may promote distal atheroma. I don’t may promote distal atheroma. I don’t like this.like this.

• They imply this as more patients They imply this as more patients went back and then the grafts were went back and then the grafts were taken more distally.taken more distally.

Why the difference.Why the difference.

• The decision to go below knee is The decision to go below knee is easier to make if you have unlimited easier to make if you have unlimited conduit – fresh tissue planes etc.conduit – fresh tissue planes etc.

• May have been more likely to accept May have been more likely to accept a diseased AK pop with a short vein. a diseased AK pop with a short vein.

Limb lossLimb loss

• 2 amputations in the venous group2 amputations in the venous group

• Had redo venous bypasses block, Had redo venous bypasses block, then redo PTFE distal bypasses block then redo PTFE distal bypasses block then limb loss.then limb loss.

Limb LossLimb Loss

• 2 amputations in prosthetic gp2 amputations in prosthetic gp

• Both after failed PTFE distal bypassesBoth after failed PTFE distal bypasses

• Both groups similarBoth groups similar

ConclusionsConclusions

• Use the vein firstUse the vein first

• Better patencyBetter patency

• Lower risk of re-interventionLower risk of re-intervention

• Re-intervention tends to be more Re-intervention tends to be more proximalproximal

• The LSV is unlikely to be needed The LSV is unlikely to be needed elsewhere especially CABGelsewhere especially CABG

ConclusionsConclusions

• Vascular patients dieVascular patients die

• In those with high operative risk and In those with high operative risk and short life expectancy then a short life expectancy then a prosthetic graft works well for 2 prosthetic graft works well for 2 years.years.

• Reasonable second line conduit Reasonable second line conduit especially in claudicants.especially in claudicants.