Intimal Hyperplasia, Stenosis, and Arteriovenous Fistula Maturation Failure in the Hemodialysis Fistula Maturation Study.
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SUBMITTER: Cheung AK
PROVIDER: S-EPMC5619966 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:The contribution of intimal hyperplasia (IH) to arteriovenous fistula (AVF) failure is uncertain. This observational study assessed the relationship between pre-existing, postoperative, and change in IH over time and AVF outcomes.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.96 patients from a single center who underwent AVF surgery initially planned as a 2-stage procedure. Veins and AVF samples were collected from 66 and 86 patients, respectively. Matched-pair tissues were available from 56 of these patients.Pre-existing, postoperative, and change in IH over time.Anatomic maturation failure was defined as an AVF that never reached a diameter > 6mm. Primary unassisted patency was defined as the time elapsed from the second-stage surgery to the first intervention.Maximal intimal thickness in veins and AVFs and change in intimal thickness over time.Pre-existing IH (>0.05mm) was present in 98% of patients. In this group, the median intimal thickness increased 4.40-fold (IQR, 2.17- to 4.94-fold) between AVF creation and transposition. However, this change was not associated with pre-existing thickness (r(2)=0.002; P=0.7). Ten of 96 (10%) AVFs never achieved maturation, whereas 70% of vascular accesses remained patent at the end of the observational period. Postoperative IH was not associated with anatomic maturation failure using univariate logistic regression. Pre-existing, postoperative, and change in IH over time had no effects on primary unassisted patency.The small number of patients from whom longitudinal tissue samples were available and low incidence of anatomic maturation failure, which decreased the statistical power to find associations between end points and IH.Pre-existing, postoperative, and change in IH over time were not associated with 2-stage AVF outcomes.
| S-EPMC5002252 | biostudies-literature
Project description:BACKGROUND AND OBJECTIVES:Preoperative arterial function is associated with arteriovenous fistula (AVF) development. Because arterial pathology may correlate with its function, preexisting arterial intimal hyperplasia may be associated with AVF development. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS:Vascular specimens obtained from 125 patients (with minimal 2 mm arterial diameter and 2.5 mm venous diameter) undergoing AVF creation were quantified for arterial intimal hyperplasia, arterial medial fibrosis, arterial microcalcification, and venous intimal hyperplasia. A 6-week postoperative ultrasound quantified AVF diameter, blood flow, and stenosis. Clinical AVF maturation was assessed using a predefined protocol. In a prospective cohort study design, we investigated the association of preexisting arterial intimal hyperplasia with the postoperative AVF diameter, blood flow, stenosis, and clinical maturation failure, after controlling for baseline demographics, comorbidities, and preoperative vein diameter. Additional analyses evaluated whether other vascular pathologies interacted with arterial intimal hyperplasia in affecting AVF outcomes. RESULTS:The median intimal thickness of the native artery was 22.0 μm (interquartile range, 14.8-37.1 μm). The median postoperative AVF diameter was 4.8 (interquartile range, 3.7-6.8) mm, blood flow was 796 (interquartile range, 413-1036) ml/min, and stenosis was present in 37 out of 98 patients with ultrasound data (38%). AVF nonmaturation occurred in 37 out of 125 patients (30%). Preexisting arterial intimal thickness was not significantly associated with AVF blood flow (-12 ml/min; 95% confidence interval [95% CI], -55 to 30 ml/min), diameter (-0.04 mm; 95% CI, -0.21 to 0.14 mm), stenosis (odds ratio, 0.93; 95% CI, 0.75 to 1.14), or clinical maturation failure (odds ratio, 1.07; 95% CI, 0.90 to 1.28), all per 10 μm increase. There was no significant interaction of preexisting arterial intimal thickness and postoperative AVF outcomes with arterial medial fibrosis, arterial microcalcification, or venous intimal hyperplasia. CONCLUSIONS:Preexisting arterial intimal hyperplasia is not associated with the 6-week AVF blood flow, diameter or stenosis, or clinical maturation when the preoperative arterial diameter is ≥2 mm.
| S-EPMC6140554 | biostudies-other
Project description:BACKGROUND:The utility of early postoperative ultrasound measurements in predicting arteriovenous fistula (AVF) clinical maturation is uncertain. METHODS:We investigated the relationships of ultrasound parameters with AVF clinical maturation in newly created AVF, measured at 1 day and 2 and 6 weeks, in 602 participants of a multicenter, observational cohort study. A backward elimination algorithm identified ultrasound measurements that independently predicted unassisted and overall AVF maturation. Candidate variables included AVF blood flow, diameter, and depth, upper arm arterial diameter, presence of stenosis, presence of accessory veins, seven case-mix factors (age, sex, black race, AVF location, diabetes, dialysis status, and body mass index), and clinical center. We evaluated the accuracy of the resulting models for clinical prediction. RESULTS:At each ultrasound measurement time, AVF blood flow, diameter, and depth each predicted in a statistically significant manner both unassisted and overall clinical maturation. Moreover, neither the remaining ultrasound parameters nor case-mix factors were associated with clinical AVF maturation after accounting for blood flow, diameter, and depth, although maturation probabilities differed among clinical centers before and after accounting for these parameters. The crossvalidated area under the receiver operating characteristic curve for models constructed using these three ultrasound parameters was 0.69, 0.74, and 0.79 at 1 day and 2 and 6 weeks, respectively, for unassisted AVF clinical maturation and 0.69, 0.71, and 0.76, respectively, for overall AVF maturation. CONCLUSIONS:AVF blood flow, diameter, and depth moderately predicted unassisted and overall AVF clinical maturation. The other factors considered did not further improve AVF maturation prediction.
| S-EPMC6218859 | biostudies-literature
Project description:ObjectivesRadiocephalic arteriovenous fistulas (RCAVF) are the preferred vascular access (VA) for hemodialysis (HD). Cohort studies from North America revealed that nonmaturation is a significant disadvantage of RCAVFs compared to other VAs.DesignThis present retrospective study describes the incidence of nonmaturation of AVFs and functional failure of arteriovenous grafts (AVG) in a multicentre cohort in the Netherlands and attempts to create a prediction model for nonmaturation of RCAVFs. Furthermore, the efficacy of interventions to promote maturation as well as the variability between hemodialysis centers was evaluated.MaterialsMedical records from 8 hospitals from 1997 to 2016 were retrospectively evaluated for VA type, maturation/primary success and demographics and comorbidities.MethodsA prediction model was created for RCAVF nonmaturation using multivariate logistic regression analysis, selecting significant predictors using backward selection. Discrimination and calibration of the model were assessed.Results1383 AVFs and 273 AVGs were included in 1221 patients. Overall nonmaturation was 24% for RCAVFs, and 11% for upper arm AVFs. The functional failure rate for AVGs was 6%. The nonmaturation rate of contralateral RCAVFs after failure of an RCAVF was 22%. Procedures to improve RCAVF maturation were successful in 98/142 cases (69%). Predictors for nonmaturation were female gender, peripheral vascular disease, cerebrovascular disease and a cephalic vein diameter <2.5 mm, but the prediction model lacked sensitivity and specificity predicting individual RCAVF nonmaturation (C-statistic 0.629).ConclusionNonmaturation rates are highest for RCAVFs, but nonmaturation could not be predicted with demographic parameters.
| S-EPMC5934452 | biostudies-literature
Project description:BACKGROUND:Arteriovenous fistulas (AVFs) are the preferred form of hemodialysis vascular access, but maturation failures occur frequently, often resulting in prolonged catheter use. We sought to characterize AVF maturation in a national sample of prevalent hemodialysis patients in the United States. STUDY DESIGN:Nonconcurrent observational cohort study. SETTING & PARTICIPANTS:Prevalent hemodialysis patients having had at least 1 new AVF placed during 2013, as identified using Medicare claims data in the US Renal Data System. PREDICTORS:Demographics, geographic location, dialysis vintage, comorbid conditions. OUTCOMES:Successful maturation following placement defined by subsequent use identified using monthly CROWNWeb data. MEASUREMENTS:AVF maturation rates were compared across strata of predictors. Patients were followed up until the earliest evidence of death, AVF maturation, or the end of 2014. RESULTS:In the study period, 45,087 new AVFs were placed in 39,820 prevalent hemodialysis patients. No evidence of use was identified for 36.2% of AVFs. Only 54.7% of AVFs were used within 4 months of placement, with maturation rates varying considerably across end-stage renal disease (ESRD) networks. Older age was associated with lower AVF maturation rates. Female sex, black race, some comorbid conditions (cardiovascular disease, peripheral artery disease, diabetes, needing assistance, or institutionalized status), dialysis vintage longer than 1 year, and catheter or arteriovenous graft use at ESRD incidence were also associated with lower rates of successful AVF maturation. In contrast, hypertension and prior AVF placement at ESRD incidence were associated with higher rates of successful AVF maturation. LIMITATIONS:This study relies on administrative data, with monthly recording of access use. CONCLUSIONS:We identified numerous associations between AVF maturation and patient-level factors in a recent national sample of US hemodialysis patients. After accounting for these patient factors, we observed substantial differences in AVF maturation across some ESRD networks, indicating a need for additional study of the provider, practice, and regional factors that explain AVF maturation.
| S-EPMC6551206 | biostudies-literature
Project description:BACKGROUND AND OBJECTIVES: Arteriovenous fistula (AVF) failure remains an important cause of morbidity in hemodialysis patients. The exact underlying mechanisms responsible for AVF failure are unknown but processes like proliferation, inflammation, vascular remodeling, and thrombosis are thought to be involved. The current objective was to investigate the association between AVF failure and single nucleotide polymorphisms (SNPs) in genes related to these pathophysiologic processes in a large population of incident hemodialysis patients. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: A total of 479 incident hemodialysis patients were included between January 1997 and April 2004. Follow-up lasted 2 years or until AVF failure, defined as surgery, percutaneous endovascular intervention, or abandonment of the vascular access. Forty-three SNPs in 26 genes, related to proliferation, inflammation, endothelial function, vascular remodeling, coagulation, and calcium/phosphate metabolism, were genotyped. Relations were analyzed using Cox regression analysis. RESULTS: In total, 207 (43.2%) patients developed AVF failure. After adjustment, two SNPs were significantly associated with an increased risk of AVF failure. The hazard ratio (95% confidence interval) of LRP1 rs1466535 was 1.75 (1.15 to 2.66) and patients with factor V Leiden had a hazard ratio of 2.54 (1.41 to 4.56) to develop AVF failure. The other SNPs were not associated with AVF failure. CONCLUSIONS: In this large cohort of hemodialysis patients, only 2 of the 43 candidate SNPs were associated with an increased risk of AVF failure. Whether other factors, like local hemodynamic circumstances, are more important or other SNPs play a role in AVF failure remains to be elucidated.
| S-EPMC3731912 | biostudies-literature
Project description:Rationale & objectiveThe current clinical guidelines for vascular access do not have specific recommendations for older hemodialysis patients. Our study aimed to determine the association of age with arteriovenous fistula (AVF) placement, maturation, and primary and secondary patency loss among older hemodialysis recipients.Study designRetrospective cohort study.Setting & participantsA US national cohort of incident hemodialysis patients 67 years or older (N = 43,851) assembled from the US Renal Data System.ExposureAge at dialysis initiation.OutcomesAVF placement, maturation, primary patency loss, and abandonment.Analytical approachCause-specific and subdistribution proportional hazards models were used to examine the association of age and AVF outcomes, with kidney transplantation, peritoneal dialysis, and death treated as competing events. Age cutoff was identified by restricted cubic splines. We compared crude and inverse probability-weighted cumulative incidence functions using Gray's test.ResultsAs compared with those aged 67-<77 years, patients 77 years or older had significantly lower probabilities of AVF placement (adjusted cause-specific HR [cHR], 0.96 [95% CI, 0.92-0.99]; adjusted subdistribution HR [sHR], 0.92 [95% CI, 0.89-0.95]; Gray's test P < 0.001) and maturation (adjusted cHR, 0.95 [95% CI, 0.91-0.99]; adjusted sHR, 0.93 [95% CI, 0.90-0.97]; P < 0.001). However, age was not associated with AVF primary (adjusted cHR, 1.05 [95% CI, 1.00-1.11]; adjusted sHR, 1.04 [95% CI, 0.99-1.09]; P = 0.09) or secondary (adjusted cHR, 1.06 [95% CI, 0.94-1.20]; adjusted sHR, 1.05 [95% CI, 0.93-1.18]; P = 0.4) patency loss.LimitationsReliance on administrative claims to ascertain AVF outcomes.ConclusionsThe likelihood of AVF maturation is an important consideration for vascular access planning. Age alone should not be the basis for excluding older dialysis patients from AVF creation because maintenance of fistula patency was not reduced with older age despite a modest reduction in fistula maturation.
| S-EPMC7534584 | biostudies-literature
Project description:BackgroundAn arteriovenous fistula (AVF) is the preferred vascular access for hemodialysis treatment. After creation many of the AVFs will never mature or if functioning will need an intervention within 1 year due to an AVF stenosis. Studies investigating possible therapies that improves the AVF maturation and survival are scarce. Far infrared therapy (FIR) has shown promising results. In minor single centre and industry supported trials FIR has shown improved AVF maturation and survival. There is a need of a randomized multicentre controlled trial to examine the effect of FIR on the AVF maturation and survival and to explore the possible AVF protective mechanism induced by the FIR treatment.MethodsThis investigator initiated, randomized, controlled, open-labeled, multicenter clinical trial will examine the effect of FIR on AVF maturation in patients with a newly created AVF (incident) and AVF patency rate after 1 year of treatment in patients with an existing AVF (prevalent) compared to a control group. The intervention group will receive FIR to the skin above their AVF three times a week for 1 year. The control group will be observed without any treatment. The primary outcome for incident AVFs is the time from surgically creation of the AVF to successful cannulation. The primary outcome for the prevalent AVFs is the difference in number of AVFs without intervention and still functioning in the treatment and control group after 12 months. Furthermore, the acute changes in inflammatory and vasodilating factors during FIR will be explored. Arterial stiffness as a marker of long term AVF patency will also be examined.DiscussionFIR is a promising new treatment modality that may potentially lead to improved AVF maturation and survival. This randomized controlled open-labelled trial will investigate the effect of FIR and its possible mechanisms.Trial registrationClinicaltrialsgov NCT04011072 (7th of July 2019).
| S-EPMC8379732 | biostudies-literature
Project description:Vascular access is the lifeline for hemodialysis patients and the single most important component of the hemodialysis procedure. Arteriovenous fistula (AVF) is the preferred vascular access for hemodialysis patients, but nearly 60% of AVFs created fail to successfully mature due to early intimal hyperplasia development and poor outward remodeling. There are currently no therapies available to prevent AVF maturation failure. First, we showed the important regulatory role of nitric oxide (NO) on AVF development by demonstrating that intimal hyperplasia development was reduced in an overexpressed endothelial nitric oxide synthase (NOS3) mouse AVF model. This supported the rationale for the potential application of NO to the AVF. Thus, we developed a self-assembled NO releasing nanomatrix gel and applied it perivascularly at the arteriovenous anastomosis immediately following rat AVF creation to investigate its therapeutic effect on AVF development. We demonstrated that the NO releasing nanomatrix gel inhibited intimal hyperplasia formation (more than 70% reduction), as well as improved vascular outward remodeling (increased vein diameter) and hemodynamic adaptation (lower wall shear stress approaching the preoperative level and less vorticity). Therefore, direct application of the NO releasing nanomatrix gel to the AVF anastomosis immediately following AVF creation may enhance AVF development, thereby providing long-term and durable vascular access for hemodialysis.
| S-EPMC8724452 | biostudies-literature
Project description:An arteriovenous fistula (AVF) is the preferred vascular access for chronic hemodialysis, but high failure rates restrict its use. Optimizing patients' perioperative status and the surgical technique, among other methods for preventing primary AVF failure, continue to fall short in lowering failure rates in clinical practice. One of the predominant causes of AVF failure is neointimal hyperplasia (NIH), a process that results from the synergistic effects of inflammation, hypoxia, and hemodynamic shear stress on vascular tissue. Although several systemic therapies have aimed at suppressing NIH, none has shown a clear benefit towards this goal. Localized therapeutic approaches may improve rates of AVF maturation by providing direct structural and functional support to the maturating fistula, as well as by delivering higher doses of pharmacologic agents while avoiding the adverse effects associated with systemic administration of therapeutic agents. Novel materials-such as polymeric scaffolds and nanoparticles-have enabled the development of different perivascular therapies, such as supportive mechanical devices, targeted drug delivery, and cell-based therapeutics. In this review, we summarize various perivascular therapeutic approaches, available data on their effectiveness, and the outlook for localized therapies targeting NIH in the setting of AVF for hemodialysis use. Highlights: Most systemic therapies do not improve AVF patency outcomes; therefore, localized therapeutic approaches may be beneficial. Locally delivered drugs and medical devices may improve AVF patency outcomes by providing biological and mechanical support. Cell-based therapies have shown promise in suppressing NIH by delivering a more extensive array of bioactive substances in response to the biochemical changes in the AVF microenvironment.
| S-EPMC9599524 | biostudies-literature