Arteriovenous Fistula Stenosis: Correlating Degree of Neointimal Hyperplasia With Reduction in Volume Flow Measured on Ultrasound and Ultrasound Characterization Based on Stenosis Morphology

Introduction: Duplex ultrasound (DUS) is commonly used to diagnose and grade arteriovenous fistula (AVF) stenosis. Duplex ultrasound may also be used to examine stenosis type based on measurement of intimal-medial thickness (IMT). There are, as yet, no criteria in use to define the different stenosis types based on measurement of percentage IMT (%IMT). In this study, we have examined stenosis morphology using ultrasound. We have examined consecutive DUS examinations to assess the incidence and degree of IMT and correlated %IMT with volume flow as an indicator of AVF dysfunction.Methods: Duplex ultrasound was performed as per standard of care. Volume flow was measured within the ipsilateral brachial artery. Measurements of luminal diameter and vessel wall diameter were used to calculate %IMT.Results: The study group included 156 consecutive DUS examinations demonstrating a greater than 50% AVF stenosis. Mean %IMT was 45%. There were 17 (11%) lesions where there was no measurable IMT; the remainder had measurable IMT. On receiver-operating characteristic (ROC) analysis, a %IMT of 54% predicted low flow with 62.5% sensitivity and 62.7% specificity.Conclusion: Intimal-medial thickness has a moderate predictive value in predicting volume flow. Based on our results, there are 4 lesion types: (1) lesions with no measurable intimal hyperplasia, (2) a predominantly intimal hyperplastic lesion, (3) those with nonpredominant intimal hyperplasia, and (4) those with a valve type stenosis. A value based on correlation with volume flow could be considered based on our results at 54%IMT or based on morphology at 45%IMT to distinguish between predominant and nonpredominant intimal hyperplasia groups. Including measurements of %IMT in clinical trials could further our knowledge of how lesions with no measurable IMT and those with different degrees of intimal hyperplasia respond to different percutaneous interventions. This could potentially improve outcomes for patients and target more costly treatment options where there is most benefit.