Demography and Outcomes of Arteriovenous Fistula: Challenges and Future Directions

The incidence and prevalence rates of treated end-stage kidney disease (ESKD) patients are on the rise worldwide. Hemodialysis remains the main modality of providing renal replacement therapy for the ESKD patients, and the preferred vascular access is an arteriovenous fistula (AVF). The objective is to assess the patency rates and primary failures of the AVF. All patients who attended the Royal Hospital in Muscat, Oman, from January 2010 to December 2014 for AVF creation were included in this study. Data were extracted from the hospital's electronic medical record system where data are entered prospectively. During the period of study from 2010 to 2014, 465 primary fistulae were created in 427 patients. The mean age of the patient was 58 years. Only 6% needed general anesthesia, while the rest were done under regional or local anesthesia. Fifty-one percent of the patients were diabetic. Preemptive AVF was constructed in only 12% of patients. Most cases (47%) had left brachiocephalic (BC) fistulae. The left radiocephalic (RC) fistulae constituted 25.7% and the left brachiobasilic fistulae 9.9%. The remaining were constructed in the right upper limb. The total patency was achieved in 80% of fistulae and the failure rate was 20% at 6 months. Whereas, at 12 months, the total patency rate was 71% and the failure rate was 29%. Thus, we can conclude that more than 50% of patients, half of them being females, were diabetics. This resulted in more fistulae being constructed in the arm, namely left BC fistulae and left RC fistulae. Furthermore, it is important to note that only a very small percentage of patients had an established preemptive AVF. These factors may be responsible for a failure rate of 20% and 29% of the AVFs at 6 months and 12 months, respectively.

Influence of intradialytic systolic blood pressure changes on arteriovenous access thrombosis in maintenance hemodialysis patients

BACKGROUND

Arteriovenous access (AV) thrombosis is an important and preventable problem amongst chronic hemodialysis (HD) patients. Systolic blood pressure (SBP) fluctuation relates to higher cardiovascular mortality amongst these patients. We proposed there is a close relation between SBP changes and arteriovenous (AV) access thrombosis. We also determined other risk factors and biochemical parameters related to AV access failure.

METHODS

50 HD patients with thrombosis and 50 HD patients without thrombosis were included in the study. Odds ratios and 95% confidence intervals were estimated with multivariate-adjusted logistic regression models to determine the association between potential thrombosis-related risk factors and thrombosis risk.

RESULTS

Elder adults, women, and patients with AV grafts, lower intradialytic SBP and higher SBP variations during HD sessions had higher incidence of AV access thrombosis. AV access infection and decreased blood flow (BF) velocity were associated with an increased incidence of thrombotic events, whereas the use of anti-thrombotic agents was associated with a decreased incidence of thrombotic events. Further, anaemia, hypoalbuminemia, hyperlipidemia, and impaired mineral metabolism parameters were also found to be associated with AV access thrombosis.

CONCLUSIONS

Close monitoring and management of intradialytic hypotension and SBP fluctuation in every HD session are important. Some important and novel modifiable risk factors related to AV access thrombosis were identified in this study (eg, AV access infection, decreased BF and abnormal biochemical parameters, etc). Earlier surveillance and modification of these risk factors is crucial to prevent AV access failure in HD patients.

Antiphospholipid antibodies in end-stage renal disease: A systematic review and meta-analysis

INTRODUCTION

The relationship between autoimmune hemolytic anemia and antiphospholipid antibodies (aPL) and/or antiphospholipid syndrome has never been systematically addressed.

METHODS

Systematic review of EMBASE and PubMed databases performed according to PRISMA guidelines from inception to March 2020; meta-analysis performed by Peto's odds ratio for rare events.

FINDINGS

Forty-five studies with different outcomes met the inclusion/exclusion criteria. The pooled prevalence (PP) of IgG anticardiolipin antibodies (aCL) positivity was greater in end-stage renal disease (ESRD) than controls (20.2% vs. 2.6%, P = 0.001, I²  >80%; I² = heterogeneity), particularly in hemodialysis patients (18.3% vs. 8%, I² = 0%). The PP of lupus anticoagulant was greater in ESRD than controls (8.7% vs. 0.2%, P < 0.0001, I² = 0%). The standardized mean difference of IgG aCL favored ESRD rather than controls (P < 0.0001, I² =97%). The PP of fistula occlusion was greater in IgG aCL-positive patients than negative patients (39% vs. 27%, I² =97%); the PP of IgG aCL positivity was greater in patients with fistula occlusion than without fistula occlusion (26.9% vs. 23.2%, P = 0.01, I² =72%); the same applied to the PP of lupus anticoagulant positivity (23% vs. 0.3%, P < 0.0001, I² = 0%). The standardized mean difference of IgG aCL favored fistula occlusion (P = 0.004, I² = 91%).

DISCUSSION

Lupus anticoagulant relates to ESRD regardless of management whereas IgG aCL relates specifically to ESRD on hemodialysis, but only lupus anticoagulant associates with fistula occlusion. The expression of aPL as patients positive for aPL rather than as titers precludes further assumptions on the relationship.

High low-density lipoprotein cholesterol level is the independent risk factor of primary patency rate of arteriovenous fistula

OBJECTIVES

An arteriovenous fistula is the first choice of vascular access in dialysis patients. However, the correlations between patient factors and the arteriovenous fistula patency rate remain unclear. Therefore, we examined the effect of dialysis patient factors on arteriovenous fistula patency rate.

METHODS

This study included 101 patients who received maintenance dialysis and used arteriovenous fistula for vascular access at Atami Hospital, International University of Health and Welfare in July 2018. A retrospective review was performed from the time of arteriovenous fistula creation to July 2018, and the primary and secondary arteriovenous fistula patency rates were investigated. The patency rate was calculated using the Kaplan-Meier method, and risk factor analysis was performed using Cox proportional hazards regression analysis.

RESULTS

The primary patency rate of arteriovenous fistula was 71.2% at one year and 43.0% at five years, and the secondary patency rate was 92.7% at one year and 79.8% at five years. In the multivariate analysis, high low-density lipoprotein cholesterol (LDL-C) level and a history of diabetes were considered significant risk factors (HR 1.023, p value <0.01 and HR 2.550, p value <0.01, respectively). A log rank test was conducted on the groups of patients with LDL <90 mg/dl and LDL ≥90 mg/dl, and the <90 mg/dl group resulted in a good primary patency rate (p value 0.0327).

CONCLUSIONS

High LDL-C level was considered the independent risk factors of arteriovenous fistula primary patency rate.

Significant association of anti-platelet factor 4/heparin antibody with cardiovascular disease in hemodialysis patients: a longitudinal 7-year study

BACKGROUND

Hemodialysis patients have a high incidence of anti-platelet factor 4/heparin antibody (PF4-H Ab) and are at a high risk of cardiovascular disease. This study determines the association between PF4-H Ab and cardiovascular events including coronary artery disease (CAD), ischemic stroke (IS), and native arteriovenous fistula thrombosis (AVFT), in a longitudinal 7-year follow-up.

PATIENTS AND METHODS

84 hemodialysis patients were enrolled. Data collection included chart reviews and assessments of laboratory records. PF4-H Ab was evaluated by ELISA and a titer ≥ 0.4 was defined to have PF4-H Ab.

RESULTS

30 patients were PF4-H Ab positive, 30 patients had CAD, 29 patients had IS, and 43 patients had AVFT. In Cox proportional hazard regression analysis, PF4-H Ab (HR 2.72, p = 0.01) was a significant risk factor for CAD. Age (HR 1.06, p = 0.003), PF4-H Ab (HR 4.53, p < 0.001), 7-year averaged serum phosphate levels (HR 0.53, p = 0.012), and 7-year averaged blood platelet count (HR 1.01, p = 0.029) were risk factors for IS. Age (HR 1.03, p = 0.047), PF4-H Ab (HR 3.57, p < 0.001), and 7-year averaged serum triglyceride levels (HR 1.01, p = 0.005) were risk factors for AVFT. In PF4-H Ab-positive groups, thrombocytopenia was not associated with CAD, IS, and AVFT by Fisher's test analysis.

CONCLUSION

This study reveals that PF4-H Ab is a risk factor for developing CAD, IS, and AVFT among hemodialysis patients.

Clinical Course of Hemodialysis Access After Initial Endovascular Intervention for Stenosis in Asian Renal Failure Patients

BACKGROUND

Arteriovenous fistula (AVF) and arteriovenous fistula graft (AVG) access for hemodialysis can develop stenosis, eventually leading to thrombosis and access failure. Prompt endovascular intervention can salvage the access but restenosis does occur. Clinical course, restenosis pattern, and risk factors associated with initial stenosis of AVFs/AVGs in Asian hemodialysis patients were studied.

METHOD

A retrospective study was conducted (January 2009-June 2012) on consecutive patients with renal failure who developed the first-time stenosis in the vascular access and were managed with endovascular intervention. One hundred fourteen patients (54 AVFs and 60 AVGs) were studied, and all clinical outcomes were recorded until October 2013.

RESULTS

The mean time from access creation to endovascular intervention for the first-time stenosis for patients with AVF and AVG was 23.5 (32.7 standard deviation [SD]) months and 12.5 (11.0) months, respectively. An average of 1.7 (range, 1-5) interventions were performed for AVFs, whereas 2.4 (range, 1-11) for AVGs ( P = .008). Upon conclusion of the study, 23 patients with AVF survived with functional index access, whereas 10 passed away with a functional original access. The remaining 21 patients with AVFs failed, requiring new access, tunneled catheter, or peritoneal dialysis. Of the 60 patients with AVG, 6 survived and 8 died with functional index access; 46 required new access or other forms of dialysis ( P = .000). Kaplan-Meier estimated that access patency and survival with functional access were significantly lower for AVGs than for AVFs after the first salvage intervention. Female patients had an increased risk of restenosis with both univariate ( P = .016) and multivariate ( P = .013) analysis. With univariate analysis ( P = .039), patients with hyperlipidemia had a higher risk of developing restenosis in the vascular access.

CONCLUSION

The clinical course and prognosis of failing AVFs and AVGs are distinct. The information on access prognosis and stenosis recurrence patterns will be helpful for patient counseling and planning of follow-up intervals, after the first-time intervention for access stenosis.

The molecular mechanisms of hemodialysis vascular access failure

The arteriovenous fistula has been used for more than 50 years to provide vascular access for patients undergoing hemodialysis. More than 1.5 million patients worldwide have end stage renal disease and this population will continue to grow. The arteriovenous fistula is the preferred vascular access for patients, but its patency rate at 1 year is only 60%. The majority of arteriovenous fistulas fail because of intimal hyperplasia. In recent years, there have been many studies investigating the molecular mechanisms responsible for intimal hyperplasia and subsequent thrombosis. These studies have identified common pathways including inflammation, uremia, hypoxia, sheer stress, and increased thrombogenicity. These cellular mechanisms lead to increased proliferation, migration, and eventually stenosis. These pathways work synergistically through shared molecular messengers. In this review, we will examine the literature concerning the molecular basis of hemodialysis vascular access malfunction.