Revascularization of Cruro-Pedal Arteries
The complication rate after surgical interventions on the infrapopliteal arteries is significantly higher despite sufficient expertise than after reconstructions of proximally located vessel segments (pelvic and thigh level), which is why they are performed almost exclusively in the stage of chronic critical limb ischemia (CLI, critical limb ischemia). The CLI represents the endpoint of PAD and is characterized by an impending amputation of the affected extremity. The bypass material of first choice is the great saphenous vein (GSV).
Autologous Bypass Procedures
After femorocrural bypasses using autologous veins, patency rates of up to 82% and limb salvage rates of 80% are achieved after 5 years [1-4]. The preferred autologous bypass material is the GSV. If the GSV is unavailable, arm veins or the femoral vein are alternatives. Autologous bypasses composed of multiple segments have poorer long-term results than single-segment GSV bypasses. However, they are better suited for infrapopliteal CLI than alloplastic prosthetic bypasses [5, 6].
Long-segment combined occlusions of upper and lower leg arteries should be reconstructed with a knee-joint-crossing bypass (femorocrural). Conte et al. reported in a randomized multicenter study in CLI patients with predominantly crural anastomosis of primary/secondary patency rates of 61% and 80% respectively after one year, with a limb salvage rate of 88% and survival of 84% [7]. Weis-Müller et al. followed 624 patients after infrainguinal crural (57%) and pedal (43%) bypass for CLI retrospectively over 10 years [8]. The limb salvage rate, which was not influenced by age, gender, or comorbidities (diabetes, CHD, or renal insufficiency), was 66.4%. However, the mortality after 30 days was 5%, after 5 years 52.7%.
Alternative or Alloplastic Bypass Procedures
Alternative allogeneic bypass procedures are performed using cryopreserved arterial or venous allografts, which however show poor long-term results. Chang et al. report a primary patency rate of 27% after one year and 17% after three years. The limb salvage rate after one and three years was 43% and 23% respectively [9].
If no vein is available as bypass material, synthetic prostheses come into consideration. Through reconstruction using composite grafts, a secondary patency rate of up to 61% after four years could be achieved. The primary/secondary patency rate of PTFE bypasses is 31% and 40% respectively after five years, with a limb salvage rate of 56%. Individual studies report, in contrast to the sole use of PTFE infragenual, patency rates of up to 55% after 48 months and a limb salvage rate of 67.5% [10-12].
In femorocrural bypass using heparin-coated PTFE prostheses, primary/secondary patency rates of 49.7% and 71.5% respectively could be achieved after five years [13]. The limb salvage rate in the same period was 84%. Other authors report similar results [14, 15].
Comparison of Alloplastic and Autologous Reconstruction Procedures
Uhl et al. reported retrospectively on 198 lower leg bypasses. Whenever possible, autologous veins were used for reconstruction (109 patients), otherwise heparin-coated PTFE prostheses (89 patients). The 3-year results show that veins are the bypass material of first choice: primary patency vein 68.2%/PTFE 34.1%, secondary patency vein 69.8%/PTFE 35.5%. The limb salvage rates were 81.8% and 56.5% respectively, the survival rates 62.8% and 46.7% [16]. Similar results were found in further studies [11, 17].
Significant advantages for the vein also resulted from a study by Arvela et al. from 2010, in which 290 infrainguinal reconstructions for CLI were compared retrospectively [18]. In 130 cases, reconstruction was performed with arm veins, in 160 with alloplastic material (91.2% PTFE). The primary patency rate showed no significant difference after three years (31.4% vein and 30.3% synthetic prosthesis). In cruro-pedal revascularization (95% arm vein, 57% synthetic), however, a clear superiority of the arm veins was shown: primary patency vein/synthetic 28.3% and 9.6%, secondary patency vein/synthetic 57.4% and 11.2%, limb salvage vein/synthetic 75% and 57.1%, and survival vein/synthetic 58.8% and 39.5%.