Safety and Performance Study of the Shockwave Lithoplasty System

Inclusion Criteria: 1. Subject is able and willing to comply with all assessments in the study. 2. Subject or subject's legal representative have been informed of the nature of the study, agrees to participate and has signed the approved consent form. 3. Age of subject is \>18. 4. Rutherford Clinical Category 2, 3, or 4. 5. Resting ankle-brachial index (ABI) of ≤0.90, or ≤0.75 after exercise, of the target leg. 6. Moderate to severe calcification of target lesion(s) per pre-procedure CT scan. (Calcification must be: 1) ≥180 degrees circumferential at some point in the lesion and 2) extend ≥50 percent length of lesion or absolute length ≥20mm.) 7. Estimated life expectancy \>1 year. Exclusion Criteria: 1. Rutherford Clinical Category 5 and 6. 2. Subject has active infection in the target leg. 3. Planned major amputation of the target leg (transmetatarsal or higher). 4. In-stent restenosis within the target lesion(s). 5. Highly tortuous arteries (bends greater than 30 degrees over the arc length of the balloon). 6. Chronic total occlusion of the target lesion(s). 7. Target lesion(s) within native or synthetic vessel grafts. 8. Chronic total occlusion of inflow vessel. 9. Lesion in contralateral limb requiring intervention within the next 30 days. 10. History of prior endovascular or surgical procedure on the index limb within the past 30 days. 11. Subject has significant stenosis (\>50% stenosis) or occlusion of inflow tract (upstream disease) not successfully treated with plain old balloon angioplasty or stent and without complications before target lesion(s) treatment. 12. Subject requires treatment of a peripheral lesion on the ipsilateral limb distal to the target lesion(s) at the time of the enrollment / index procedure. 13. Subject has a known coagulopathy or has a bleeding diatheses, thrombocytopenia with platelet count less than 100,000/microliter, or international normalized ratio \>1.5. 14. Subject in whom antiplatelet, anticoagulant, or thrombolytic therapy is contraindicated. 15. Subject has known allergy to contrast agents or medications used to perform endovascular intervention that cannot be adequately pre-treated. 16. Subject has known allergy to urethane, nylon, or silicone. 17. Myocardial infarction within 60 days prior to enrollment. 18. History of stroke within 60 days prior to enrollment. 19. History of unstable coronary artery disease or other uncontrollable comorbidity resulting in hospitalization within the last 60 days prior to enrollment. 20. History of thrombolytic therapy within two weeks of enrollment. 21. Subject has acute or chronic renal disease (e.g., as measured by a serum creatinine of \>2.5 mg/dL or \>220 umol/L), or on dialysis. 22. Subject is pregnant or nursing. 23. Subject is participating in another research study involving an investigational agent (pharmaceutical, biologic, or medical device) that has not reached the primary endpoint. 24. Subject has other medical, social or psychological problems that, in the opinion of the investigator, preclude them from receiving this treatment, and the procedures and evaluations pre- and post-treatment.