Early quantitative evaluation of indocyanine green angiography in patients with critical limb ischemia

Abstract

Objective: Patients requiring lower extremity revascularization are increasingly complex. Traditional means of evaluating perfusion before and after revascularization are often limited by the presence of medial calcinosis, open wounds, prior toe or forefoot amputations, and infection. We evaluated the initial application of indocyanine green angiography (ICGA) to patients with severe lower extremity ischemia to develop quantitative, reproducible parameters to assess perfusion.

Methods: ICGA uses a charge-coupled device camera, a laser, and intravenous contrast to visually assess skin surface perfusion. From January 2011 to April 2012, we performed ICGA within 5 days of 31 revascularization procedures in patients with Rutherford class 5 and 6 ischemia. We also compared ICGA before and after revascularization in a subset of 13 patients. We evaluated multiple, quantitative parameters to assess perfusion.

Results: Twenty-four patients underwent ICGA associated with 31 revascularization procedures (26 endovascular, four open, one hybrid) for 26 lower limb wounds; 92% were diabetic and 20% were dialysis-dependent. In 50% of these patients, it was not possible to measure ankle-brachial indexes due to medial calcinosis. Paired analysis of ingress (increase in pixel strength [PxS]), ingress rate (slope of increase in PxS), curve integral (area under the curve in PxS over time), end intensity (PxS at end of study), egress (decrease in PxS from maximum), and egress rate (slope of decrease in PxS) increased significantly (P < .05) after revascularization.

Conclusions: ICGA provides rapid visual and quantitative information about regional foot perfusion. We believe this is the first report describing quantification of foot perfusion before and after lower extremity revascularization for severe limb ischemia. Further study is warranted to help define the utility of this intriguing new technology to assess perfusion, response to revascularization, and potentially, to predict likelihood of wound healing.