Tack Optimized Balloon Angioplasty Below the Knee (TOBA - BTK) Study

Inclusion Criteria: * Age of subject is \>18 * Subject or subject's legal representative has been informed of the nature of the study, agrees to participate and has signed the consent form * Subject has critical limb ischemia (CLI) * Subject has Rutherford Clinical Category 4-5. (hemodynamic reference) * Reference vessel diameter below the knee (BTK) is between 1.5mm and 4.5mm (inclusive). * De-novo target lesion(s) has stenosis \>70%. * Must be able to perform PTA. The PTA must result in a dissection Type A - F at some location along the treatment site. * Any vessel intervened on must have distal reconstitution above the ankle. * Inflow Iliac, SFA and Popliteal lesions can be treated during the same procedure using standard angioplasty and/or an approved device. These inflow lesions must be treated first, prior to consideration of treatment of BTK lesions. The patient can be enrolled if the inflow lesions are treated with good angiographic results (must have \<30% residual stenosis and no evidence of embolization). Key Exclusion Criteria: * The subject has a lesion on the plantar surface of the heel or over the Achilles tendon or has exposed calcaneus. * The subject has extensive forefoot gangrene / ischemic ulcer that cannot be resolved with standard metatarsal amputation. * Previous treatment failure of inflow arteries (Iliac, SFA and Popliteal) * Subject with below knee bypass. * Subject has significant stenosis or occlusion of inflow vessels tract (proximal disease) not successfully treated (\>30% residual stenosis and/or complication of the procedure) prior to BTK angioplasty and patient enrollment. * Subject is permanently wheel-chair bound or bedridden. * Subject has an allergy to contrast medium that cannot be pretreated. * Episode of acute limb ischemia within the previous 30 days. * Subject is undergoing atherectomy in the target limb or cryoplasty or stenting of BTK treatment site. * Subject has a systemic infection with positive blood cultures/bacteremia within one week. * Subject has undrained pus or spreading wet gangrene in the foot that is not controlled at the time of revascularization procedure. * Subject in whom antiplatelet, anticoagulant, or thrombolytic therapy is contraindicated. * Myocardial infarction within 30 days prior to enrollment. * History of stroke within 180 days prior to enrollment. * Subject has acute or chronic renal disease (e.g., as measured by a serum creatinine of \>2.5 mg/dL or \>220 umol/L). * Subject has a known hypersensitivity or contraindication to nitinol.