The goal of this clinical trial is to test the Thor system in adult (≥ 18 year old) patients with de novo (new, never treated) calcified lesions in infrainguinal (leg) arteries (peripheral artery disease or PAD).

The main question[s] it aims to answer are:

• Is the Thor system safe in treating these lesions
• Does the Thor system work to treat these lesions

Participants will:

• Receive treatment with the Thor system
• Have follow-up visits at Discharge, 30 days, 6 months, and 12 months

Up to 30 sites in the U.S. will be selected to do this study.

Patients with pain in their legs when walking and/or resting that is due to lack of blood flow to their legs may be able to join the study. To join the study patients must also have blockages in their leg arteries that meet the study criteria.

Before the Thor procedure, patients will have a screening visit that includes a review of their medical records, questions about their medical history and medications taken for blood thinning or circulation, a physical examination of their legs, a test to check the blood flow in their legs (by checking arm and leg blood pressures), blood tests, and a pregnancy test if they are a female able to have children. Patients will also answer questions about any trouble they have had with walking in the last week and their overall quality of life.

All patients in the study will have treatment with the Thor system. There is no "control group" (a group of patients that receives only standard treatment or receives no treatment at all) in this study. During the procedure, the doctor will take x-ray pictures of the leg arteries. They may also use other treatments such as angioplasty balloons, drug-coated balloons, stents, and filters that collect blood clots, if needed.

Patients treated with the Thor system will be watched until they are ready to go home or up to 24 hours after the procedure if they do not go home right away. Before they go home they will have a test to check the blood flow to their legs (by checking arm and leg blood pressures) and be checked for any adverse events.

Patients will return for visits at 30 days, 6 months, and 12 months after the Thor procedure. At these visits patients will be asked questions about their medical history and medications taken for blood thinning or circulation, have a physical examination of their legs, have a test to check the blood flow in their treated leg (by checking arm and leg blood pressures), have an ultrasound of their treated leg, and be checked for any adverse events. Patients will also answer questions about any trouble they have had with walking in the last week and their overall quality of life.

It will take up to 24 months (2 years) to enroll all of the patients in the study. Patients who join the study will be in the study for about 12 months (1 year) and will have all of the visits with their doctor that they would normally have for their PAD.

Inclusion Criteria:

• Patient age is ≥18 years
• Patient agrees to participate and to comply with the protocol by signing an IRB approved patient consent form
• Patient is able to walk unassisted or with non-motorized assistive devices
• Patient has PAD with documented Rutherford Class 2-4 of the target limb
• Anticipated life expectancy >12 months, in the opinion of the investigator at the time of enrollment.

Angiographic Inclusion Criteria:

• Patient has de novo atherosclerotic disease of the native SFA and/or the popliteal arteries
• Target lesion has ≥70% diameter stenosis by investigator via visual assessment
• Target lesion length ≤150mm. Total treatment zone may not exceed 150mm, and may include one or more lesions.
• Chronic total occlusion lesion length is <100mm of the total ≤150mm target lesion
• Minimum reference vessel diameter (RVD) 4.0mm by visual estimate
• Target lesion crossed and intraluminal guidewire placement confirmed; successful crossing defined as tip of the guidewire distal to the target lesion in the absence of flow limiting dissections or perforations
• At least one patent tibial vessel (defined as <50% stenosis) with runoff to the foot
• Target lesion has moderate to severe calcification graded using the Peripheral Academic Research Consortium (PARC) criteria

Exclusion Criteria:

• Patient has active infection requiring antibiotic therapy
• Stenting planned within the target lesion
• Known positive for COVID-19 within the last 2 weeks and actively symptomatic
• Pregnant (positive pregnancy test) or currently breast feeding
• Evidence of Acute Limb Ischemia in the target limb within 7 days prior to procedure
• Cerebrovascular accident (CVA) <60 days prior to procedure
• Myocardial infarction <60 days prior to procedure
• History of unstable coronary artery disease or other uncontrollable comorbidity resulting in hospitalization within the last 60 days prior to baseline screening
• Known contraindication to aspirin, or antiplatelet/anti-coagulant therapies required for procedure/follow-up
• Known allergy to contrast media that cannot adequately be premedicated prior to study procedure
• History of Thrombophilia, Heparin-induced Thrombocytopenia (HIT), or Heparin-induced Thrombotic Thrombocytopenia Syndrome (HITTS)
• Serum creatinine ≥2.5mg/dL (unless dialysis-dependent) tested within 30 days prior to procedure
• Planned lower limb major amputation (above the ankle)
• Other surgical or endovascular procedure in the target limb that occurred within 14 days prior to index procedure or is planned on target limb for within 30 days following index procedure, with the exception of diagnostic angiography
• Currently participating in any investigational device or drug clinical trial that, in the opinion of the investigator, will interfere with the conduct of the current study
• The use of specialty balloons, re-entry or additional atherectomy devices is required for treatment of the target lesion.

Angiographic Exclusion Criteria:

• Subject has significant stenosis (>50% stenosis) or occlusion of inflow tract before target treatment zone (e.g. iliac or common femoral) not successfully treated.
• Subject requires treatment of a peripheral lesion on the ipsilateral limb distal to the target site at the time of the index procedure.