Low Enrollment rate: The study targeted a highly selected and complex patient population, making the identification and enrollment of eligible patients particularly challenging for all participating centers

The study will evaluate the safety and efficacy of Peripheral Intravascular Lithotripsy system with Shockwave S4 catheter® for the treatment of de novo, re-stenosis or re-occlusive,calcified chronic total occlusion (CTOs) lesions in patients with Critical Limb Threatening Ischemia (CLTI).

The present study is designed as a multicentre, prospective, single-arm, observational study.

All eligible subjects for undergoing intervention with Shockwave S4 catheter® Peripheral Intravascular Lithotripsy (IVL) at sites participating in the study will be considered for enrolment and will be asked to give consent prior to participating.

Subjects will be considered enrolled in the study at the time written informed consent is given to the use of their personal data. Once patients are enrolled, their demographics, medical history, disease-relevant conditions, treatment details and outcomes will be collected for up to 12 months from the procedure.

The study will collect information about the medical care patients receive during their planned procedure. No additional testing or procedures will be done.

The procedure with Shockwave S4 catheter® Peripheral Intravascular Lithotripsy (IVL) will be performed as per the current instructions for use.

After discharge all patients will attend clinic visits at 30 days (±14 days), 6 months (±30 days),12 months (±30 days).

Inclusion Criteria:

• Age ≥18 years
• Patient has signed an approved informed consent form
• Patient with Critical Limb Ischaemia, Rutherford category 4 (ischaemic rest pain), 5(minor tissue loss) or 6 (major tissue loss)
• Patient with Stenotic (>50% luminal loss) or occluded infrapopliteal artery, including the tibiofibular trunk, the anterior tibial artery, the posterior tibial artery and the peroneal artery
• The vascular lesion length will be no longer than 150 mm.
• Patient with no significant disease at the inflow: common iliac, external iliac, superficial femoral and popliteal artery on the ipsilateral side prior to enrollment, and patient with no significant disease at the outflow - runoff to ankle level: plantar for posterior tibial, pedal for anterior tibial, anterior and posterior perforant branches for peroneal vessels or previous successful revascularization of the disease segments (inflow-outflow)
• Live expectancy > 1 year.
• Presence at least ≥1 filling pedal vessel on the target limb.

Exclusion Criteria:

• Subject pregnant or planning to become pregnant during the study
• Subject no able to perform the follow up or other factors making clinical follow-up difficult
• Acute or Subacute limb ischaemia which requires thrombolysis as first treatment modality or previous thrombolytic therapy in the last 48-72 hours.
• Known allergy to concomitant medication, antiplatelet anti-coagulant or thrombolytic medication
• Poor inflow due to ipsilateral stenoses or occlusions of the iliac or femoropopliteal arteries
• Significant stenoses (> 50%) distal to the target lesion that might require revascularization or impede run-off
• Desert foot condition. No Patent foot main arteries
• Subject enrolled in another investigational study that has not reached its primary endpoint

Patients affected by lower extremities artery disease and referred for the endovascular treatment of infrapopliteal calcified stenoses and/or occlusions in patients with critical limb ischaemia