Importance of Pedal Microcirculation to Wounds for Wound Healing After Bypass Surgery in Chronic Limbthreatening Ischemia

In the treatment of chronic limb-threatening ischemia (CLTI), complete wound healing is an important goal. Although foot perfusion status seems to be important for wound healing, the global limb anatomic staging system (GLASS) of the Global Vascular Guidelines (GVG) does not include pedal artery status for the staging process due to the lack of sufficient evidence of its importance. This study aimed to clarify the importance of pedal perfusion status for wound healing after bypass surgery. Among the 153 CLTI cases that underwent bypass distal to popliteal arteries from 2014 to 2018, 117 CLTI limbs with wounds and with sufficient pedal angiographic data were enrolled. They were classified into two groups, based on the wound status 6 months postoperatively; early wound healing group (n = 78), which achieved complete wound healing within 6 months postoperatively, and prolonged healing or unhealed wounds group (n = 39), which failed to achieve wound healing within 6 months. Various factors associated with wound healing, including the wound, ischemia, and foot infection (WIfI) classification, graft flow, and pedal angiographic data, were analyzed. Regarding pedal angiographic data, in addition to the GLASS inframalleolar/pedal disease descriptor (GLASS-IPD), newly formed classification system of the pedal microcirculatory status in association with the location of wounds was included: pedal microcirculatory status was classified into two groups as visualized micro-arteries towards wounds (visualized perfusion) and barely visualized micro-arteries towards wounds (barely visualized perfusion) (Fig 1). Univariate analysis showed preoperative albumin (odds ratio [OR], 0.47; 95% confidence interval [CI], 0.24-0.94; P = .027), higher WIfI clinical stage (OR, 3.88; 95% CI, 1.74-10.1; P = .0005), higher GLASS-IPD (OR, 2.16; 95% CI, 1.16-4.02; P = .012), and barely visualized perfusion to wounds (OR, 5.74: 95% CI, 2.45-14.0; P < .0001) as significant for prolonged wound healing. Multivariate analysis showed higher WIfI stage (OR, 5.04; 95% CI, 1.74-14.6; P = .0029) and barely visualized perfusion to wounds (OR, 4.34; 95% CI, 1.71-11.0; P = .0021) as significant, whereas GLASS-IPD was not detected as significant. Although graft flow was not significantly associated with wound healing, it was significantly lower in GLASS-IPD P2 than P0/P1, whereas graft flow was similar between visualized perfusion and barely visualized perfusion to wounds, suggesting that the distribution of blood supply towards wounds would be more important than the total amount of blood supply to the foot for wound healing. WIfI clinical stage and pedal micro-circulatory environment were important factors for wound healing. Pedal anatomical classification system including perfusion status would be important for decision making in CLTI treatment.