This study is a multicenter observational study designed to evaluate the the effectiveness and safety of drug-coated balloon (DCB) angioplasty for below the knee arterial lesions in patients critical with Limb Threatening Ischemia (CLTI).

Patients with critical limb ischemia (Rutherford category 4-6) and significant infrapopliteal lesions appropriate for angioplasty will be enrolled in this study. Subjects will be treated with the AcoArt drug coated balloon, then follow-up will be conducted at 1, 3, 6, 12 months after index procedure. Data on wound, ischemia, foot infection (WIfI) calcifications, clinical improvements, wound healing, freedom form target- lesion revascularization, patency of the target lesion and major adverse events will be collected.

Inclusion Criteria:

1. Rutherford grade 4-6.
2. Patients who understand the purpose of this study, volunteer to participate in the experiment, sign informed consent and are willing to follow up.
3. Single or sequential de novo or restenotic lesions (stenosis ≥ 70% diameter reduction or occlusion) in the infrapopliteal arteries >20 mm. Lesions should not extend beyond the ankle joint.
4. Successful wire crossing of the lesion. After the pre-dilation of the ordinary balloon, the angiography showed that there was continuous blood flow.
5. At least one of the infrapopliteal arteries received a drug-coated balloon.
6. For patients with aortoiliac artery disease and femoral-popliteal artery disease, after intravascular reconstruction, blood flow can be recanalized, and there is no residual stenosis of more than 50%.
7. In patients with lower extremity arterial thrombosis, after mechanical thrombectomy, percutaneous catheter thrombolysis, and thrombus removal, patients receiving blew the knee arterial drug balloon intervention.
8. Patients who have received DCB intervention for both lower limbs can be enrolled in the group according to the intracavitary treatment time.
9. Life expectancy> 24 months.

Exclusion Criteria:

1. Blood flow was not successfully reestablished.
2. Patients with stroke, cerebral hemorrhage, gastrointestinal hemorrhage or myocardial infarction within 3 months before enrollment.
3. Patients who are known to be allergic to heparin, aspirin, other antiplatelet drugs, contrast agents, etc.
4. Patients who have participated in clinical trials of drugs or other medical devices that interfere with this clinical trial within the past 3 months.
5. Pregnant and lactating women.
6. Patients with Berg's disease.
7. Patients requiring major amputation based on preoperative evaluation of limb infection or severe ischemia

Patients suffered with Chronic Limb Theratening Ischemia and with significant infrapopliteal artery lesions.