Prospective, observational study evaluating the clinical use and outcomes of the FLEX Vessel Prep (VP) system in arteriovenous fistulae or grafts presenting with clinical or hemodynamic abnormalities following 12 months post treatment.

Prospective, observational study evaluating the clinical use and outcomes of the FLEX Vessel Prep (VP) system in arteriovenous fistulae or grafts presenting with clinical or hemodynamic abnormalities in real-world subjects per the Institution's standard practice and at 1-, 6-, and 12-months following treatment.

Inclusion Criteria:

1. Subject is ≥18 years of age.

2. Subject is currently scheduled to undergo an endovascular intervention of arteriovenous fistula or graft due to clinical and hemodynamic abnormalities meeting the KDOQI Guidelines for AV access dysfunction:

   • Elevated venous pressure during hemodialysis,
   • Abnormal physical findings, and
   • Unexplained decrease in delivered dialysis dose.

3. Subject has a reasonable expectation of remaining on hemodialysis for ≥12 months.

4. Subject is legally competent, informed of the study, voluntarily agrees to participate, and signs the informed consent form.

5. Subject understands the study and is willing and able to comply with the follow-up requirements.

Exclusion Criteria:

1. Subject has a known or suspected systemic infection.
2. Subject has a known or suspected infection of the hemodialysis graft.
3. Subject has an untreatable allergy to radiographic contrast material.
4. In the opinion of the operating physician, the subject's hemodialysis access is unsuitable for endovascular treatment.

Subjects with AVF/AVG stenosis who are eligible for FLEX/Angioplasty treatment