Microcirculation Evaluated by Intraoperative Fluorescence Angiography after Tibial Bypass Surgery

Intact microperfusion of the foot in the critical ischemic limb remains a crucial condition for ulcer healing. Aim of this clinical study was to evaluate the immediate effect of tibial bypass surgery on the microcirculation by usage of fluorescence angiography.

Prospective analysis of 33 patients presenting with critical limb ischemia (Rutherford IV-VI) undergoing tibial bypass surgery was performed. Macroperfusion was investigated by measurement of ankle-brachial index. For assessment of microperfusion, intraoperative fluorescence angiography (SPY Elite, NOVADAQ) was undertaken during general anesthesia immediately before and after operation. For each investigation, a fluorescence dye (Indocyanine green) with an amount of 0.1 mg/kg was administered intravenously. Follow-up investigations were performed to assess the clinical outcome.

The mean follow-up time was 8.28 (±4.46) months. The parameters Ingress (IN) and Ingress rate (InR) of the fluorescence dye representing the microcirculation showed a significant improvement to preoperative values and correlated with the ankle-brachial index significantly. Furthermore, a significant difference between the individual improvement of the microcirculation parameters (preoperative-postoperative) between patients with postoperative clinical improvement (wound healing, absence of rest pain) and those without could be demonstrated (InR: P = 0.039, IN: P = 0.036).

The parameters IN and InR significantly reproduced the postoperative improvement of the microcirculation. An increased ankle-brachial index significantly correlated with increased microcirculation parameters. A better clinical outcome was found in those patients who had a higher relative improvement of microcirculation postoperatively.