Microcirculation should be assessed before and after tibial bypass surgery by intraoperative fluorescence angiography. According to this, the direct and the indirect angiosomes should be compared according to the individual microcirculatory improvement.

Only patients at CLI stage Rutherford IV to VI with the necessity of tibial Bypass surgery will be included. Macrocirculation is measured by the ankle-brachial index (ABI). In order to assess the skin microcirculation intraoperative fluorescence angiography is used (SPY Elite™, NOVADAQ, Canada). The alteration of microcirculation is compared in direct and indirect revascularized angiosomes by calculation of the fluorescence parameters Ingress (IN) and Ingress rate (InR). Clinical Follow-up investigations will be performed and the wound healing rate is compared between the different revascularization methods.

Inclusion Criteria:

• Patients at CLI Rutherford stages IV to VI
• Patients with necessity of tibial Bypass surgery

Exclusion Criteria:

• Allergy against indocyanine green
• Iodine allergy
• Contrast allergy
• Penicillin allergy
• Allergic diathesis
• Liver insufficiency
• Pregnancy
• Hyperthyreosis
• Pulmonary arterial hypertension