Six-Month Angiographic and Clinical Outcomes of Therapeutic Ultrasound Pretreatment Associated With Plain Balloon Angioplasty for Below-the-Knee Lesions in Patients With Critical Limb Ischemia: A Prospective, Single-Center Pilot Study

Purpose: To evaluate the safety and efficacy of low-frequency, high-intensity ultrasound energy delivered via a new dedicated ultrasound catheter followed by conventional balloon angioplasty to treat calcified infrapopliteal lesions. Materials and Methods: A prospective, nonrandomized, single-center pilot study enrolled 12 patients (mean age 72.2 +/- 5.3 years; 8 men) with critical limb ischemia (9 Rutherford category 5 and 3 category 6) between January and November 2017. Of the 19 target lesions, 11 had severe calcification. Patients were treated with the Kapani ultrasound system before conventional balloon dilation. Primary safety endpoints included 30-day death, major target limb amputation, and target vessel acute occlusion. The main efficacy outcome was primary patency at 6 months, defined as freedom from both clinically-driven target lesion revascularization (TLR) and angiographically-defined restenosis (>50% lumen reduction). Results: Technical success (<30% residual stenosis) was achieved in all lesions without complications or stent implantation. Ultrasound energy was delivered over a mean 185.2 +/- 67.3 seconds followed by low-pressure dilation (mean 6.1 +/- 1.9 atm). Angiography confirmed primary patency at 6 months in 18 (95%) of 19 lesions. No death, TLR, or amputation was reported in follow-up. Complete ulcer healing was observed in all 12 patients at 6 months. Conclusion: This pilot trial with a small number of patients suggests that low-frequency, high-intensity ultrasound energy delivery followed by plain balloon angioplasty is a safe approach to treat infrapopliteal atherosclerotic lesions. Angiographically-documented results at 6 months indicate a potential for this combined therapy in the treatment of CLI patients with calcified BTK lesions. Further studies on a larger randomized cohort are needed to confirm these positive clinical outcomes.