The main objective of this study is to assess the 2-year survival with salvage of the lower limb of patients who have undergone subgonal bypass grafting by venous allograft in the treatment of Occlusive Peripheral Arterial Disease (OPAD) in critical ischemia, in the absence of usable great saphenous vein.

Inclusion Criteria:

• Man or woman over 18 (under effective contraception, hormonal contraceptive or intrauterine device, if premenopausal).
• Patient with critical ischemia of the lower limb (stage 4-5-6 according to the Rutherford classification) requiring revascularization by sub-gonal bypass
• Patient eligible and scheduled for bypass in venous allograft stored at + 4 ° C with distal anastomosis below the knee
• Patient without usable autologous great Saphenous vein
• Subject affiliated or beneficiary of a social security scheme
• Patient having received the appropriate information concerning the objectives and procedures of the study and having declared his non-objection.

Exclusion Criteria:

• Use of unscheduled allografts
• Patient requiring composite bypass in AGV + autologous venous material or prosthesis
• Patient requiring replacement of infected prostheses
• Patient with acute ischemia
• Patient with severe coagulation disorders
• Patient classified physical status score 4
• Patient participating in another clinical trial
• Potential allergy to the graft
• Protected patients: Adults under guardianship, curatorship or other legal protection, deprived of their liberty by judicial or administrative decision
• Pregnant or breastfeeding woman