Vascular Access versus the Effect of Statins on Inflammation and Fibrinolysis in Renal Dialysis Patients

Distinct subsets of T cells and macrophages impact venous remodeling during arteriovenous fistula maturation

Patients with end-stage renal failure depend on hemodialysis indefinitely without renal transplantation, requiring a long-term patent vascular access. While the arteriovenous fistula (AVF) remains the preferred vascular access for hemodialysis because of its longer patency and fewer complications compared with other vascular accesses, the primary patency of AVF is only 50-60%, presenting a clinical need for improvement. AVF mature by developing a thickened vascular wall and increased diameter to adapt to arterial blood pressure and flow volume. Inflammation plays a critical role during vascular remodeling and fistula maturation; increased shear stress triggers infiltration of T-cells and macrophages that initiate inflammation, with involvement of several different subsets of T-cells and macrophages. We review the literature describing distinct roles of the various subsets of T-cells and macrophages during vascular remodeling. Immunosuppression with sirolimus or prednisolone reduces neointimal hyperplasia during AVF maturation, suggesting novel approaches to enhance vascular remodeling. However, M2 macrophages and CD4+ T-cells play essential roles during AVF maturation, suggesting that total immunosuppression may suppress adaptive vascular remodeling. Therefore it is likely that regulation of inflammation during fistula maturation will require a balanced approach to coordinate the various inflammatory cell subsets. Advances in immunosuppressive drug development and delivery systems may allow for more targeted regulation of inflammation to improve vascular remodeling and enhance AVF maturation.

Plasma D-Dimer Level and the Failure of Forearm Autologous Arteriovenous Fistula in Patients With End-Stage Renal Disease

Failed autologous arteriovenous fistula (AVF) is a major issue in the creation of functional hemodialysis vascular access. To date, the relationship between D-dimer and AVF failure is still uncertain. Hence, we conducted a retrospective cohort study to explore the patency rate of forearm AVFs and to clarify whether plasma D-dimer level can predict the failure of AVFs. In this study, 290 ESRD patients (the mean age 54.1 ± 14.6 years, 63.8% of them were males) receiving forearm AVFs surgery were consecutively enrolled with a median follow-up time of 34 months. Primary patency rates and risk factors associated with AVFs failure were explored by the Kaplan-Meier method or Cox proportional hazards model. Patients were divided into two groups based on the median level of D-dimer (group 1 <1.1 mg/L and group 2 ≥1.1 mg/L). The Kaplan-Meier survival analysis demonstrated that the patency of AVF in group 1 was similar in group 2, which were 92.4% versus 88.9%, 84.8% versus 84.0%, 80.0% versus 79.2%, 76.7% versus 78.5%, and 76.7% versus 78.5% at 12, 24, 36, 48, and 60 months (Log-rank test, P = 0.8), respectively. In the crude analysis, D-dimer (per 1 mg/L increase) was independently associated with AVFs failure, with OR of 1.08 (95% CI, 1.02-1.15). However, after adjusting for potential confounders, the D-dimer (per 1 mg/L increase) was not associated with the AVFs failure (OR = 1.06, 95% CI = 0.99-1.13). This study did not find that the plasma D-dimer level can predict the failure of forearm AVFs.

Iron therapy in chronic kidney disease: Recent changes, benefits and risks

Anemia is a common complication in patients with chronic kidney disease (CKD), mainly due to inadequate renal production of erythropoietin. In hemodialysis (HD) patients this condition may be aggravated by iron deficiency (absolute or functional). The correction of this anemia is usually achieved by treatment with erythropoiesis stimulating agents (ESAs) and iron (oral or intravenous). Studies questioning the safety of ESAs (especially at higher doses) changed the pattern of anemia treatment in CKD patients. According to the new guidelines, when transferrin saturation is lower than 30% and ferritin lower than 500 ng/mL, a trial with iron should be started, to avoid therapy with ESAs or at least to reduce the doses needed to treat the anemia. Recent reports showed increasing ferritin levels, towards values above 800 ng/mL, in CKD patients treated according to the guidelines. In this review we focus on the risks of the increased iron use to treat CKD anemia, namely, iron overload and toxicity, increased risk of infections, as well as mortality.