Early results of a prospective trial of spliced vein vs PTFE graft with a distal vein cuff for limb-threatening ischaemi

1. Early results of a prospective trial of spliced vein vs PTFE graft with a distal vein cuff for limb-threatening ischaemia 16th June 2003 PRINCE OF WALES HOSPITAL JOURNAL CLUB

2. The Question • Case Study • Limb-threatening ischaemia • Distal (below knee) arterial bypass needed • LSV unavailable for use • Options: • Synthetic graft +/- vein cuff +/- distal AVF • Spliced vein graft • Composite graft • Distal graft origin • What is the best reconstruction option?

3. The Answers • Medline search • MESH: Arterial Occlusive Diseases (18731) Femoral Artery (17096) ‘and’ (2811) • Keywords: & ‘bypass’ (791) ‘distal or crural’ (224) • Limit: Human/Abstracts (41) English/ >1995 • Paper Chosen • Compares Goretex with spliced vein grafting

4. Introduction • Single piece of autologous vein is best • Unavailable in 50% patients • Spliced vein bypass grafting • Constructed joining segments of vein • 2 year patency rates reported 23-73% • Prosthetic conduit bypass grafting • Patency • 30-40% at 3 years • 60% at 3 years with distal AVF • 60-79% at 4 years with vein cuff & Warfarin • Hypothesis • PTFE/Cuff/Warfarin as good as spliced vein

5. Patients & Methods • Single centre, prospective, randomised trial • Inclusion criteria • Presence of limb threatening ischaemia • No one piece vein bypass graft option • Available vein segments for splicing • No composite sequential bypass option • Randomisation into 2 groups • PTFE Group • Spliced Vein Group

6. Patients & Methods • Spliced vein group • Vein selection on basis of preop Duplex • Proximal anastomosis prior to further harvest • 2-3 end-end anastomoses 8/0 prolene • PTFE graft group • Venous boot constructed at distal end • All patients Warfarinised long term

7. The Venous Boot (Tyrell & Wolfe 1991)

8. Monitoring • Intra/Perioperative • Physical examination & Doppler • Completion angiography • Ward protocols • Medium/Long term • Physical examination & Duplex scanning • At 1/3/6/9/12 months then 6-monthly

9. Results • Between 1996-2000 • 39 bypass grafts in 36 patients recruited • 20: PTFE • 19: Spliced vein • Randomisation process • Equivalent: • Age/sex/ABPI/DM/Smoking/Previous grafts • Non-equivalent: • Significantly higher cardiac risk status in spliced vein group (P<.0001)

10. 39 Grafts 20 PTFE/Cuff Group 19 Spliced Vein Group Inflow Artery Graft/Iliac: 5 (25%) CFA: 15 (75%) Inflow Artery Graft/Iliac: 2(10%) CFA: 10 (53%) SFA: 4 (21%) PFA: 3 (16%) Outflow Artery Pop: 4 (20%) AT: 6 (30%) Per: 6 (30%) PT: 4 (20%) DP: 0 (0%) Outflow Artery Pop: 4 (21%) AT: 1 (5%) Per: 8 (42%) PT: 3 (16%) DP: 3 (16%)

11. Perioperative Statistics • Cardiac & bleeding complications were ‘more frequent & severe’ in the spliced group

12. Long term Statistics • Note: 1 patient in the PTFE/Cuff group lost to follow up • 4/10 PTFE/Cuff failures were associated with cessation of Warfarin therapy

13. Study Conclusions • Spliced vein reconstruction • Increased morbidity/mortality • Increased need for revision • Trend for superior patency rates • PTFE/Cuff reconstruction • Aggressive anticoagulation therapy needed • 4/10 PTFE failures because Warfarin ceased • Primary patency @ 2years with Warfarin: 71% • Less time, less blood loss & shorter stay • ??Less risk in morbidity/mortality

14. Study Strengths • Prospective, randomised trial • Well defined entry criteria • Good patient follow up • Objective measurement of outcome • Applicable to clinical practice

15. Study Weaknesses • Small sample size • Unequal randomisation • Cardiac risks (higher in spliced group) • Increased morbidity/mortality • Most distal bypasses (DP) all in spliced group • All inframalleolar bypasses • Statistically, • Increased probability of a type II error • Low Power study

16. Study Weaknesses • No controls • Particularly relevant wrt to limb salvage • Unclear information • Process of randomisation • Monitoring of Warfarin therapy in PTFE group