Pre-existing and Postoperative Intimal Hyperplasia and Arteriovenous Fistula Outcomes

Abstract

Background The contribution of intimal hyperplasia (IH) to arteriovenous fistula (AVF) failure is uncertain. This observational study assessed the relationship between preexisting, postoperative, and change in IH over time and AVF outcomes. Study Design Prospective cohort study with longitudinal assessment of IH at the time of AVF creation (pre-existing) and transposition (postoperative). Patients were followed-up for up to 3.3 years. Setting & Participants 96 patients from a single center who underwent AVF surgery initially planned as a two-stage procedure. Veins and AVF samples were collected from 66 and 86 patients, respectively. Matched-pair tissues were available from 56 of these patients. Predictors Pre-existing, postoperative and change in IH over time. Outcomes Anatomic maturation failure was defined as an AVF that never reached a diameter greater than 6 mm. Primary unassisted patency was defined as the time elapsed from the second-stage surgery until first intervention. Measurements Maximal intimal thickness in veins and AVF and change in intimal thickness over time. Results Pre-existing IH (> 0.05 mm) was present in 98% of the patients. In this group, the median intimal thickness increased 4.40-fold (IQR, 2.17- to 4.94-fold) between the AVF creation and transposition. However, this change was not associated with the preexisting thickness (r2=0.002; p=0.7). Ten of 96 AVFs (10%) never achieved maturation, while 70% of the vascular accesses remained patent at the end of the observational period. Postoperative IH was not associated with anatomic maturation failure using a univariate logistic regression. Pre-existing, postoperative, and change in IH over time had no effects on primary unassisted patency. Limitations The low number of patients from whom longitudinal tissue samples were available and the low incidence of anatomic maturation failure, which decreased the statistical power to find associations between end points and IH. Conclusions Pre-existing, postoperative, and change in IH over time were not associated with two-stage AVF outcomes.

New Insights into Dialysis Vascular Access: Impact of Preexisting Arterial and Venous Pathology on AVF and AVG Outcomes

“…These studies emphasized the profound histologic differences between preexisting and postoperative IH ( Figure 1). Postoperative lesions are recognized as eccentric concentrations of myofibroblasts in the intima of AVFs and AVGs (9,10,15), whereas the preexisting venous pathology consists of concentric accumulations of both myofibroblasts and contractile VSMCs underneath the endothelial line (10,13). The National Institute of Diabetes and Digestive and Kidney Diseases-funded multicenter, observational Hemodialysis Fistula Maturation (HFM) Study confirmed the high prevalence of preexisting IH in veins used to create an AVF in 370 patients with CKD.…”

“…Although it is unlikely that postoperative IH alone leads to critical AVF occlusion (10), it may be a contributing factor to AVF nonmaturation in the setting of inadequate outward remodeling. More recently, IH has been also identified as a common preexisting (13,14).…”

“…Nonetheless, similar pathologies have been observed in the cephalic and saphenous veins of elderly patients with normal renal function undergoing arterial grafting (18), suggesting that uremia is not the only biologic insult causing vascular intimal thickening in patients with CKD. Tabbara et al (10) obtained two consecutive basilic vein samples from patients undergoing a planned two-stage AVF: the first sample from the native vein used to create the AVF and the second one several weeks later from the draining vein of the AVF (Figure 1). Patient age, sex, and diabetes were not associated with the maximal intimal thickness of the native basilic vein, IH of the draining vein of the AVF, or the change in venous IH between paired vein samples from the same individual (10).…”

“…Tabbara et al (10) obtained two consecutive basilic vein samples from patients undergoing a planned two-stage AVF: the first sample from the native vein used to create the AVF and the second one several weeks later from the draining vein of the AVF (Figure 1). Patient age, sex, and diabetes were not associated with the maximal intimal thickness of the native basilic vein, IH of the draining vein of the AVF, or the change in venous IH between paired vein samples from the same individual (10). Although vascular trauma from venipuncture and intravenous peripheral lines may contribute to preexisting vascular pathologies, it does not explain the extensive IH frequently found in distal saphenous veins that have never been punctured or traumatized (18).…”

Dialysis Arteriovenous Fistula Failure and Angioplasty: Intimal Hyperplasia and Other Causes of Access Failure

“…Of note, the contribution of each of these factors to AVF failure is not certain and further research is warranted to determine the role of upstream and downstream events on stenosis. While IH is historically associated with stenosis and early failure of vascular accesses based on histologic observations, a recent study showed that it is improbable that this lesion alone causes critical AVF stenosis (12). This may explain why drug eluting stents or local delivery of anti-proliferative agents have shown promising results in animal models (13), but have failed to improve human AVF maturation outcome (14, 15)…”