Background: Evaluation of skin microcirculation in patients with critical limb ischemia (CLI) may be achieved by the measurement of transcutaneous oxygen pressure or skin perfusion pressure, but there is no practical method available for the evaluation of muscle microcirculation. Contrast enhanced ultrasonography (CEUS) has been used to assess muscle perfusion in patients with peripheral arterial disease. We conducted a monocentric pilot study evaluating the ability of CEUS to assess the impact of arterial revascularization on the perfusion of the calf muscle in patients with CLI.
Patients and methods: Patients with CLI (TASC II criteria) and a possibility of proximal or medial revascularization were included. In addition to TcPO2 and toe systolic blood pressure measurements, CEUS of the calf muscle was performed just before and one month after the therapeutic procedure. Parameters derived from muscular perfusion curves were evaluated in a blinded fashion and compared with the clinical outcome.
Results: Thirty eight patients were included (74 % men, median age 71 years, 53 % diabetics). Thirty benefited from revascularization with a clinical success rate of 70 %. Twenty three patients could benefit from analysis before and after revascularization. No significant difference was shown in time to peak (22.3 s vs 24.0 s, P = 0.61) nor in peak intensity (2.30 dB vs 1.27 db, P = 0,26), contrasting with significant improvements of TcPO2 (43 mm Hg vs 20 mm Hg, P = 0.007) and toe systolic blood pressure (54 mm Hg vs 32 mm Hg, P = 0.002).
Conclusions: The evaluation of muscular microvascular perfusion by CEUS as performed in this study is not enough sensitive to change to allow a clinically relevant evaluation of the improvement in muscle microvascular perfusion in patients with CLI benefiting from revascularization procedures.
Keywords: Microcirculation; contrast enhanced; critical limb ischemia; revascularization; toe systolic blood pressure; transcutaneous oxygen pressure; ultrasonography.