A more accurate descriptive and clinically useful diagnosis based upon pathophysiology for what is commonly referred to as venous outflow stenosis is inflow-outflow imbalance. In these cases, the total outflow capacity of the AV access is inadequate to handle the inflow volume (Qa) without an increase in pressure. The relative inadequacy of the access outflow capacity in comparison to Qa results in increased outflow resistance and a proportional increase in intraluminal pressure. The clinical indicators associated with venous stenosis are the resulting manifestations of this imbalance. The point at which this occurs is dependent upon variations in these two parameters-Qa and outflow resistance. The variations in these two parameters are considerable and reciprocal. Excessive Qa results in or can lead to an entire list of serious problems that adversely affect patient morbidity and mortality. Most studies dealing with AV access Qa reduction have been for the treatment of an existing condition rather than its prevention; however, prevention of disease rather than waiting for its development is an important tenet of medical practice. The resulting clinical picture of inflow-outflow imbalance is taken as an indication for corrective treatment. In the past, in most cases this has meant angioplasty to open the outflow if it is reduced; however, this clinical picture may be associated with an excessive Qa and angioplasty in these cases creates the risk for a further increase in Qa. It is the authors' opinion that access flow measurements should be a part of the evaluation of these cases prior to planning treatment. Using this information, a bimodal approach to primary treatment should be adopted involving either angioplasty for cases with a low or normal Qa or flow reduction in cases with an elevated Qa.

• Keywords
• AV access flow reduction, Dialysis access, cardiac complications of AV access, excess AV access blood flow, interventional nephrology, techniques and procedures,
• MeSH
• Angioplasty * adverse effects   MeSH
• Arteriovenous Shunt, Surgical * adverse effects   MeSH
• Vascular Resistance MeSH
• Renal Dialysis * MeSH
• Hemodynamics * MeSH
• Humans MeSH
• Graft Occlusion, Vascular * physiopathology   therapy   etiology   diagnosis   MeSH
• Vascular Patency MeSH
• Regional Blood Flow MeSH
• Risk Factors MeSH
• Blood Flow Velocity MeSH
• Treatment Outcome MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Review MeSH

OBJECTIVES: Vascular access (VA) stenoses play a significant role in the morbidity of the haemodialysed population. Classifications for diagnosis, assessment and proposal of treatment strategies can be useful clinical and methodological tools. This review aims to present a comprehensive summary and propose further methodological approaches. DESIGN: A systematic review of the literature, evaluating classifications for dialysis-related VA stenosis. DATA SOURCES: Web of Science, Scopus, PubMed, Google Scholar and the ClinicalTrials.gov registry were searched from inception to 7 December 2024. ELIGIBILITY CRITERIA: All articles containing classifications regarding dialysis VA were eligible, with no restrictions on the study type or language of the full text. DATA EXTRACTION AND SYNTHESIS: Two independent researchers performed the search and initial screening. Four vascular surgeons assessed the included classifications using a modified Buchbinder's critical appraisal tool to evaluate quality. RESULTS: From 4771 screened papers, 59 full-text papers were retrieved and 24 articles contained classifications. Three classifications were dedicated to VA stenosis, all based on the anatomical location of lesions. According to the modified Buchbinder's appraisal, the classifications were assessed as moderate-to-good quality. The literature disposes of immense inconsistency in terms of the definition of significant stenosis indicated for treatment. CONCLUSIONS: VA significant stenosis and its classification is a non-uniformly understood issue with many different criteria and categorisations. This basic methodological problem leads to inconsistent results. We recommend the unification of the criteria and their validation in prospective studies.

• Keywords
• Cardiovascular Disease, Dialysis, End stage renal failure, Vascular medicine, Vascular surgery,
• MeSH
• Arteriovenous Shunt, Surgical * adverse effects   MeSH
• Vascular Access Devices * adverse effects   MeSH
• Renal Dialysis * adverse effects   MeSH
• Humans MeSH
• Constriction, Pathologic classification   etiology   MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Scoping Review MeSH