Assessment of Foot Perfusion Before and After Revascularization of Critically Ischemic Foot Using Indocyanine Green Fluorescence Imaging

Abstract

Introduction: Critical limb ischemia (CLI) is a clinical diagnosis, confirmed by objective tests, usually ABI, toe pressure (TP) and TcPO2. Indocyanine green fluorescence imaging (ICG-FI) is a diagnostic modality for assessing the perfusion of tissues. Although some application has been described of ICG-FI in the assessment of ischemic foot, the technique is uncommon in vascular surgery. Our aim was to study the usefulness of ICG-FI in the quality control of revascularization. Methods: One hundred and one patients with 104 CLI limbs were studied with ICG-FI using SPY Elite. ABI and TP were measured in all patients. After ICG-FI, assessment of circulation was done using time–intensity curve derived from two regions of interest. Three parameters were derived from the curves: Maximum ingress, meaning the absolute value of the maximum intensity; ingress rate, meaning the value from the time intensity curve describing the increase in maximum ingress per seconds and SPY10, which is the intensity achieved during the first 10 seconds after the foot starts to gain intensity. Results: Ninety-five technically successful procedures was achieved, 63 (66.3%) endovascular and 32 (33.7%) surgical revascularizations. In 9 (9.5%) patients, an open line from the aorta to the foot was not achieved due to a failure to recanalize the occlusion (n = 7) or due to distal embolization (n = 2). The mean ingress values before and after the procedure in patients who underwent successful revascularization were 81 ± 47 units and 120 ± 5 units of ingress (p < .001) and ingress rates 4.2 ± 4 units/second and 8.0 ± 6.2 units/second (p = .001), respectively. In the PTA patients in whom the revascularization was unsuccessful, no changes were seen in the hemodynamic parameters. In 6 (8.8%) patients who underwent technically successful revascularization, the SPY values were worse after the revascularization than at the baseline. In all cases an explanation was found in closer evaluation. Conclusion: ICG-FI with SPY Elite provides reliable information on the success of revascularization, in addition to implicating possible failure if there is no improvement in the ICG-FI variables. It gives valuable information to complement traditional assessment methods. Disclosure of Interest: None Declared.