<qa>  What is the purpose of the Shockwave Coronary Rx Lithoplasty System?Prospective, multi-center, single arm study designed to evaluate the safety and performance of the Shockwave Coronary Rx Lithoplasty System to treat calcified lesions in the coronary arteries for the purpose of enhancing the placement of stents and reducing the ultimate residual stenosis. Patients will be enrolled and consented in the study based on history and in some instances an angiogram obtained prior to the study. The study is designed to demonstrate that the Shockwave device can safely and effectively deliver localized shockwave energy for balloon dilatation of calcified, stenotic, coronary arteries. Subjects will be prepared for PCI per the institutions standard protocol. Medications will be administered per the treatment protocol. Femoral access will be obtained using a 6F access sheath, and guiding catheter placed at the ostia of the right or left coronary artery. Baseline angiography of the culprit lesion will be performed prior to placement of a 0.014 guide wire. Baseline and either IVUS or OCT will be performed to determine the Maximum Lumen Area MLA, percent stenosis, and volumetric lesion assessment. Baseline angiography will be performed to determine lesion length, stenosis and reference vessel diameter. The investigational device will be prepped per the IFU and positioned at the target lesion. The distal end of the balloon catheter will be connected to the patient cable. The balloon catheter will be inflated to 4 atm and the investigator will deliver 10 pulses for 20 seconds. The balloon will then be inflated to reference vessel diameter and then deflated to reestablish flow and complete one treatment cycle. The treatment cycle will then be repeated. Angiography and either IVUS or OCT will be repeated for the treated lesion.. A coronary stent will be deployed at the site of treatment. Angiography and either IVUS or OCT will be performed following stent placement. Patients will be followed through discharge and at 30 and 180 days. A subset of up to five 5 subjects will receive an angiographic assessment at the 180 day follow up visit, per the Sponsors discretion. 