Neointimal Hyperplasia in Early Arteriovenous Fistula Failure

Background

Hemodialysis vascular access dysfunction currently is a huge clinical problem. Although arteriovenous fistulas (AVFs) are the preferred form of permanent dialysis access, they continue to have significant problems with early AVF failure. Although inadequate dilatation of the venous segment was believed to have a role in early AVF failure, the exact pathogenesis of early AVF failure is unknown despite the magnitude of the clinical problem.

Study Design

Case series.

Setting & Participants

Hemodialysis patients.

Outcomes & Measurements

Stenotic venous segments from 4 patients with early AVF failure were subjected to a detailed histological, morphometric, and immunohistochemical analysis.

Results

All 4 patients had significant luminal stenosis, primarily as a result of eccentric neointimal hyperplasia. This was confirmed through morphometric analysis, which documented intima-media area and thickness ratios that were greater than unity. Cellular phenotyping studies showed that the majority of cells within the region of neointimal hyperplasia were myofibroblasts, with smaller numbers of contractile smooth muscle cells.

Limitations

We described only a limited number of specimens.

Conclusions

We show for the first time that aggressive neointimal hyperplasia is present in venous segment specimens from patients with early AVF failure. Future therapies to address this problem will need to target this pathogenetic pathway.

Index Words: Arteriovenous fistula, early failure, vascular stenosis, neointimal hyperplasia