Open repair could be recommended in a first line of treatment to revascularize critical limb ischemia patients or performed in a second line of treatment in case of failure of endovascular repair. A good quality vein is one of the main factors that influence the clinical success of open revascularization for below-knee popliteal. In the absence of an suitable autologous vein, prosthesis such as polytetrafluoroethylen (PTFE) graft could be an option but demonstrated worse clinical and morphological results compared to autologous greater saphenous vein. Consequently, there is still a room for improvement in CLI patients in the absence of an suitable autologous vein in whom endovascular repair failed.

Recently, PTFE with heparin-bound to the luminal surface (Hb-PTFE) significantly reduced the overall risk of primary graft failure by 37%, in particular, risk reduction was 50% in femoropopliteal bypass cases in cases with critical ischemia (58% Primary patency for crude ePTFE versus 80% primary patency for PROPATEN at 1 year follow-up) (Lindholt, et. al. 2011).

Additionally, a weighted average from the literature suggests a 76% primary patency for below knee bypasses performed with PROPATEN at one year follow-up, whereas a published meta-analysis suggests a 59% primary patency for below knee crude ePTFE at one year follow-up. At two year follow-up using the same approach, the average primary patency for PROPATEN was 67% versus 43% for standard ePTFE.

The aim of this study is to assess PTFE with heparin-bound to the luminal surface as an alternative to crude PTFE in absence of good venous conduit in patients with CLI.

Patient inclusion in this study will be proposed 60 to 1-days period preceding the surgical procedure. The patient will be randomized in the crude PTFE or in the Propaten groups. Regarding the intervention, the technique used during the therapeutic procedure shall be left to the operator's discretion, except the type of the graft. Demographic, intraoperative and postoperative data will be collected prospectively. Patient will be assessed and followed up according a current care. The cost difference between both groups will be identified.

Inclusion Criteria:

• Patient ≥18 years
• Patient presented critical limb ischemia (Rutherford classification: 4-6)
• Indication of below the knee bypass with an artificial graft
• Absence of an suitable autologous vein
• Patient is affiliated to the Social Security or equivalent system
• Patient has been informed of the nature of the study, agrees to its provisions and has signed the informed consent form prior to any study related procedure
• Patient agrees to undergo all protocol required follow-up examinations and requirements at the investigational site

Exclusion Criteria:

• No atheromatous disease
• Female of child bearing potential
• Patient has a history of coagulopathy or will refuse blood transfusions
• Patient is receiving or scheduled to receive anticancer therapy for malignancy within 1 year prior to or after the procedure
• Severe concomitant disease with life expectation < one year
• Known allergy to heparin
• Indication for ipsilateral major amputation
• Patient is not able to give informed consent
• Patient is currently participating in an investigational drug or device study that has not completed the primary endpoint or that clinically interferes with the current study endpoints Note: Trials requiring extended follow-up for products that were investigational, but have become commercially suitable since then, are not considered investigational trials
• In the Investigator's opinion patient has (a) co-morbid condition(s) that could limit the patient's ability to participate in the study, compliance with follow-up requirements or impact the scientific integrity of the study