Laser tool aims to save legs from amputation

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

Inclusion Criteria: * Age of subject is ≥ 18. * Estimated life expectancy ≥1 year. * Subject is able and willing to comply with all assessments in the study. * Subject has been informed of the nature of the study, agrees to participate, and has signed the approved consent form. * Rutherford Category classification of 4 or 5 of the target limb. * Subject is a suitable candidate for angiography and endovascular intervention in the opinion of the investigator or per hospital guidelines. Angiographic Inclusion Criteria * Target lesion that is located in a native, de novo infra-popliteal artery (extending from P3 of the popliteal artery to the margin of the ankle mortise). * Target lesions(s) must be viewed angiographically and have 50-100% stenosis. * Only a single lesion is included in the study per subject. * The vessel segment distal to the target lesion must be patent all the way to the ankle, with no significant lesion (≥ 50% stenosis). * Lesion length ≥50mm and ≤300mm. * Intraluminal crossing of the lesion. Successful crossing is defined as tip of the guidewire distal to the target lesion in the absence of flow limiting dissections or perforations. If this is not certain, IVUS or OCT may be used to verify this at the operator's discretion. * Target Lesion reference vessel diameter (RVD) between 1.5mm - 4.5mm by investigator estimate. Exclusion Criteria: * Target lesion is in a vessel graft or synthetic graft. * Treatment of target lesion with radial access. * Planned target limb major amputation (above-the-ankle). * Acute limb ischemia or required thrombolysis as a primary treatment modality of the target limb. * History of prior endovascular or surgical procedure on the index limb within 30 days prior to enrollment or planned within 30 days of the index procedure. * Subject is pregnant or breastfeeding. (Female subjects of childbearing potential must be non-breastfeeding and have a negative pregnancy test ≤ 7 days before the procedure.) * Subject has a known coagulopathy or has bleeding diatheses/disorder, thrombocytopenia with platelet count less than 100,000/microliter / less than 80,000K. * Subject in whom antiplatelet or anticoagulant therapy is contraindicated. * Subject has known allergy to contrast agents or medications used to perform endovascular intervention that cannot be adequately pre-treated. * Myocardial infarction within 60 days prior to enrollment. * History of stroke/CVA/TIA within 60 days prior to enrollment. * History of thrombolytic therapy within 14 days of enrollment. * Subject has acute or chronic renal disease defined as serum creatinine of \>2.5 mg/dL or \>220 umol/L, or is on dialysis. * Subject is participating in another research study involving an investigational agent (pharmaceutical, biologic, or medical device) that has not reached the primary endpoint. * Subject has other medical, social or psychological problems that, in the opinion of the investigator, preclude them from receiving this treatment, and the study requirements and evaluations pre- and post-treatment. * Subject experiencing ongoing cardiac problems that per the investigator judgment would not make the subject ideal per the procedure. * Subject has evidence of intracranial or gastrointestinal bleeding within the past 3 months. Angiographic Exclusion Criteria * Failure to treat clinically significant inflow lesions in the ipsilateral iliac, femoral, or P1-P2 segments of the popliteal arteries with \<50% residual stenosis with no serious angiographic complications (e.g., embolism or dissection) prior to treatment of the target lesion. * Residual stenosis, and/or serious angiographic complications (e.g., embolism) prior to the investigational device usage. * The use of adjunctive devices to treat the target lesion other than the investigative Auryon laser catheter and/or PTA devices, such as scoring balloons, drug-eluting balloons, re-entry devices, lithotripsy devices, or other atherectomy devices (with the exception of bailout stents for Class C/D dissections). Subjects that do not meet eligibility criteria for the randomized controlled trial are eligible to be enrolled in the observational study. Observational Study Inclusion Criteria: * Subjects intended to be treated with the Auryon Atherectomy System for de-novo, restenotic or ISR lesions of the infra-popliteal arteries. * Subjects presenting with symptomatic PAD with claudication or CLI by Rutherford Category 2 - 6 of the target limb. * Age of subject is ≥ 18. * Subject has been informed of the nature of the study, agrees to participate, and has signed the approved study consent form. Observational Study Exclusion Criteria: * Subjects with any medical condition that would make him/her an inappropriate candidate for treatment with Auryon Atherectomy System as per Instructions for Use (IFU) or investigator's opinion. * Subject is pregnant or breastfeeding. (Female subjects of childbearing potential must be non-breastfeeding and have a negative pregnancy test ≤ 7 days before the procedure.) * Subject is already enrolled in other investigational (interventional) studies that would interfere with study endpoints.