Arteriovenous Fistula Placement Research Articles

Internal Mammary Artery Graft Flow Steal by a Large Dialysis Arteriovenous Fistula Characterized by Electrical Storm

Background: Steal syndrome describes a condition in which a dilated vessel distal to a smaller artery attempts to compensate for decreased blood flow by “stealing” from the smaller artery. Steal syndrome is not uncommon and can be seen in certain physiologic and pathologic states. The classic example is an occluded atherosclerotic coronary artery resulting in a misdirection of blood flow into the open channels that have developed over time resulting in downstream ischemia. Case Report: A 66-year-old male fourteen years post 4-vessel coronary artery bypass grafting using his left internal mammary artery to bypass a stenotic segment of the left anterior descending artery, along with three saphenous venous conduits to the right coronary artery. He also had a stent placement by PCI. He was on dual antiplatelet therapy with aspirin and clopidogrel. An electrophysiology study revealed inducible VF and he underwent implantation of a dual chamber ICD 9 months prior to presentation. He experienced an unprovoked fall at home and a workup revealed the flow volume through the patient’s fistula increased to such a degree that the patient developed a steal syndrome from his left internal mammary artery graft. In addition, went into a state of electrical storm caused by ischemic damage to cardiac tissue distal to the graft. By ligating the fistula, the patient’s steal syndrome resolved and he did not suffer further ventricular arrhythmias. Conclusion: Both coronary bypass grafting and fistula formation are common and necessary interventions and providers should take care to monitor for interactions between these proposed interventions to best serve their patients without causing additional harm. Increased vascular flow through any portion of the body can induce a steal syndrome from an upstream region. Patients who undergo arteriovenous (AV) fistula placement may develop a steal syndrome from ipsilateral bypass grafts.

Accuracy of physical examination versus Doppler ultrasonography for determining maturity in postoperative arteriovenous fistula formation

Differentiating between arteriovenous fistula (AVF) maturation and failure can help determine which AVF will undergo successful canulation and which ones will require immediate rescue. A prospective observational study was conducted at Vajira Hospital in Bangkok, Thailand, between October 2020-November 2022. A single vascular surgeon performed a physical examination on patients with chronic kidney disease undergoing AVF placement, and a radiologist conducted Doppler ultrasonography during the second and sixth postoperative weeks. Dialysis nurses determined AVF maturity by performing cannulation. The study compared the accuracy of physical examination and Doppler ultrasonography. A model was developed to predict the success of AVF use. Out Of the 125 recruited patients, 81% demonstrate unassisted maturation of their AVF. The male sex and brachiocephalic type are associated with AVF maturation. The physical examination findings of palpable thrill and the absence of a strong pulse at the 6th week show an area under the receiver operating curve (AUC) value of 0.79. Similarly, arterial end-diastolic velocity on ultrasonography at the 6th week also demonstrates a comparable predictive value with an AUC of 0.82 (p=0.697). Meanwhile, the model that combined end-diastolic velocity and venous volume flow yields the best results for predicting AVF maturation, with an AUC of 0.92. These models provide more accurate predictions compared to physical examination alone (AUC: 0.92 vs. 0.79; p<0.01). Although a prudent physician predicts AVF maturation through a thorough physical examination, Doppler ultrasonography is preferred in anticipating the success of postoperative AVF placement.

Management of depth to achieve timely arteriovenous fistula utilization

ObjectiveFailure to achieve timely arteriovenous fistulae (AVFs) utilization due to excessive depth (>6 mm) remains an ongoing concern for dialysis access. This study evaluates the outcomes of radiocephalic (RCF) and brachiocephalic (BCF) fistula elevation required for access utilization. MethodsA retrospective review of all patients undergoing first-time autologous access over 10 years was undertaken. RCF and BCF were analyzed, and cases of initial access failure due to depth alone were selected for study. Primary and staged brachio-basilic AVF were excluded. Outcomes of early thrombosis, line placement, maturation (successful progression to hemodialysis [HD), reintervention, and functional dialysis (continuous HD for 3 consecutive months) were examined. ResultsFrom January 2012 to December 2022, 1733 patients (67% female; mean age, 61 ± 14 years) underwent autologous AVF placement. Of these, 298 patients (17%) had depth-related AVF access issues (BCF, 71% and RCF, 29%). Nineteen percent of these AVFs underwent a primary balloon-assisted maturation (BAM), and 2% had side branch coil embolization before consideration for elevation. The average time to intervention for depth was 11 ± 4 weeks after primary creation. During elevation, side branch ligation occurred in 38% of cases, and 15% underwent intraoperative BAM, The pre-elevation depth was 8.2 ± 3.1 mm, and the mean post-elevation depth was 4.7 ± 2.9 mm (P = .002). Early thrombosis (<18 days) occurred in 4% of cases. There was no mortality, and the 30-day major adverse cardiac event rate was 2%, with a 30-day morbidity of 5%, which was driven by wound issues. Six percent of the AVFs underwent follow-up BAM within 3 months. Mean maturation of the AVFs was 74% ± 3% vs 72% ± 3% (P = .58) for the elevation vs no-elevation groups at 24 weeks, respectively. However, there was an increase in tunneled central line placement in pre-emptive fistula patients due to the delay in maturation (elevation, 17% vs no-elevation, 8%; P = .008). There was a mean successful access time of 6 ± 3 weeks after elevation (16 ± 4 weeks after access creation). There was a median of 2.4 secondary interventions per year after elevation compared with a median of 2.7 secondary interventions per year without elevation. Mean access functionality was 68% ± 8% vs 75% ± 8% at 3 years for the elevation vs no-elevation groups, respectively (P = .25). ConclusionsElevation of deep BCF and RCF occurs late after placement but can be successfully achieved with low morbidity and satisfactory long-term functionality. It results in an increase in tunneled central line placement in pre-emptive fistula patients. Elevation is a valuable adjunct to AVF maturation and enhances an autologous access policy.

Follow-up evaluation of snuffbox arteriovenous fistula as an alternative site for hemodialysis - a case series in a lower-middle country

Link of Video Abstract: https://youtu.be/MSeO8kuKhGc   Introduction: The preferred vascular access for hemodialysis in chronic kidney disease patients is the arteriovenous fistula (AVF). It is recommended to create AVFs as distally as possible. The snuffbox, situated at the far end of the wrist, is infrequently utilized for AVF insertion due to the prevalent smaller vessel calibers.  Case: This case series involves seven patients with chronic kidney disease scheduled for first AVF placement in the snuffbox region, with an average age of 56.71 years.  All patients showed an average radial artery caliber of 20.3mm, a mean peak systolic velocity of 67.14 cm/s, and a cephalic vein caliber of 22.7mm, according to preoperative vascular ultrasound. The AVF placement involved an end-to-side anastomosis. All patient demonstrated anastomosis clinical maturation, the primary patency rate was 86%. Follow-up Doppler examinations revealed that patients achieving functional patency had an average caliber of 5.22mm and an average flow rate of 810.65 ml/s.  Conclusion: SAVF are created less frequently due to predominantly smaller vessel caliber. However, it can be a viable alternative site for fistula implantation. Vascular mapping is required to ensure that both vessels have minimum 2 mm caliber. Maturation in SAVF have comparable results with the other sites.

Temporal trends in hemodialysis access creation during the fistula first era

ObjectiveAlthough forearm arteriovenous fistulas (AVFs) are the preferred initial vascular access for hemodialysis based on national guidelines, there are no population-level studies evaluating trends in creation of forearm vs upper arm AVFs and arteriovenous grafts (AVGs). The purpose of this study was to report temporal trends in first-time permanent hemodialysis access type, and to assess the effect of national initiatives on rates of AVF placement. MethodsRetrospective cross-sectional study (2012-2022) utilizing the Vascular Quality Initiative database. All patients older than 18 years with creation of first-time upper extremity surgical hemodialysis access were included. Anatomic location of the AVF or AVG (forearm vs upper arm) was defined based on inflow artery, outflow vein, and presumed cannulation zone. Primary analysis examined temporal trends in rates of forearm vs upper arm AVFs and AVGs using time series analyses (modified Mann-Kendall test). Subgroup analyses examined rates of access configuration stratified by age, sex, race, dialysis, and socioeconomic status. Interrupted time series analysis was performed to assess the effect of the 2015 Fistula First Catheter Last initiative on rates of AVFs. ResultsOf the 52,170 accesses, 57.9% were upper arm AVFs, 25.2% were forearm AVFs, 15.4% were upper arm AVGs, and 1.5% were forearm AVGs. From 2012 to 2022, there was no significant change in overall rates of forearm or upper arm AVFs. There was a numerical increase in upper arm AVGs (13.9 to 18.2 per 100; P = .09), whereas forearm AVGs significantly declined (1.8 to 0.7 per 100; P = .02). In subgroup analyses, we observed a decrease in forearm AVFs among men (33.1 to 28.7 per 100; P = .04) and disadvantaged (Area Deprivation Index percentile ≥50) patients (29.0 to 20.7 per 100; P = .04), whereas female (17.2 to 23.1 per 100; P = .03), Black (15.6 to 24.5 per 100; P < .01), elderly (age ≥80 years) (18.7 to 32.5 per 100; P < .01), and disadvantaged (13.6 to 20.5 per 100; P < .01) patients had a significant increase in upper arm AVGs. The Fistula First Catheter Last initiative had no effect on the rate of AVF placement (83.2 to 83.7 per 100; P=.37). ConclusionsDespite national initiatives to promote autogenous vascular access, the rates of first-time AVFs have remained relatively constant, with forearm AVFs only representing one-quarter of all permanent surgical accesses. Furthermore, elderly, Black, female, and disadvantaged patients saw an increase in upper arm AVGs. Further efforts to elucidate factors associated with forearm AVF placement, as well as potential physician, center, and regional variation is warranted.

The rodent models of arteriovenous fistula.

Arteriovenous fistulas (AVFs) have long been used as dialysis access in patients with end-stage renal disease; however, their maturation and long-term patency still fall short of clinical needs. Rodent models are irreplaceable to facilitate the study of mechanisms and provide reliable insights into clinical problems. The ideal rodent AVF model recapitulates the major features and pathology of human disease as closely as possible, and pre-induction of the uremic milieu is an important addition to AVF failure studies. Herein, we review different surgical methods used so far to create AVF in rodents, including surgical suturing, needle puncture, and the cuff technique. We also summarize commonly used evaluations after AVF placement. The aim was to provide recent advances and ideas for better selection and induction of rodent AVF models. At the same time, further improvements in the models and a deeper understanding of AVF failure mechanisms are expected.

Factors Associated with Dialysis Initiation in Patients with Predialysis Arteriovenous Fistula

Introduction: A large proportion of patients initiated hemodialysis with a central vein catheter rather than a permanent vascular access which was recommended by guidelines. One major barrier was the paucity of evidence regarding the optimal timing of vascular access creation in predialysis patients. Methods: Our study prospectively enrolled 300 patients undergoing predialysis arteriovenous fistula (AVF) creation in our center from 2015 to 2018. Cox proportional hazard regression was performed to identify which demographic and clinical factors were associated with the initiation of hemodialysis after AVF surgery. A receiver operating characteristic area under the curve (AUC) was used to assess the predictive power of preoperative factors for the likelihood of hemodialysis initiation. Results: Overall, 163 (54.3%), 214 (71.3%), and 275 (91.7%) patients initiated hemodialysis within 3 months, 6 months, and 1 year, respectively, after AVF creation. The median time between AVF creation and hemodialysis start was 71.5 days. Using multivariate Cox regression analysis, three factors were associated with hemodialysis initiation within 1 year: serum phosphorus (HR = 1.407, p = 0.021), diabetic kidney disease (DKD) (HR = 1.429, p = 0.039), and cystatin C (HR = 1.179, p = 0.009). Cystatin C alone had a moderate predictive value for dialysis initiation (AUC = 0.746; p < 0.001), whereas the full model had a higher predictive value (AUC = 0.800; p < 0.001). Conclusion: DKD, serum cystatin C, and phosphorus at access surgery were associated with hemodialysis initiation within 1 year of the predialysis AVF creation. Our findings provide a basis for a more customized approach to planning AVF placement in patients with chronic kidney disease.

Temporal serum metabolomic and lipidomic analyses distinguish patients with access-related hand disability following arteriovenous fistula creation

For end-stage kidney disease (ESKD) patients, hemodialysis requires durable vascular access which is often surgically created using an arteriovenous fistula (AVF). However, some ESKD patients that undergo AVF placement develop access-related hand dysfunction (ARHD) through unknown mechanisms. In this study, we sought to determine if changes in the serum metabolome could distinguish ESKD patients that develop ARHD from those that have normal hand function following AVF creation. Forty-five ESKD patients that underwent first-time AVF creation were included in this study. Blood samples were obtained pre-operatively and 6-weeks post-operatively and metabolites were extracted and analyzed using nuclear magnetic resonance spectroscopy. Patients underwent thorough examination of hand function at both timepoints using the following assessments: grip strength manometry, dexterity, sensation, motor and sensory nerve conduction testing, hemodynamics, and the Disabilities of the Arm, Shoulder, and Hand (DASH) questionnaire. Nineteen of the forty-five patients displayed overt weakness using grip strength manometry (P < 0.0001). Unfortunately, the serum metabolome was indistinguishable between patients with and without weakness following AVF surgery. However, a significant correlation was found between the change in tryptophan levels and the change in grip strength suggesting a possible role of tryptophan-derived uremic metabolites in post-AVF hand-associated weakness. Compared to grip strength, changes in dexterity and sensation were smaller than those observed in grip strength, however, post-operative decreases in phenylalanine, glycine, and alanine were unique to patients that developed signs of motor or sensory disability following AVF creation.

Obesity drives secondary procedures to achieve access maturation in end-stage renal disease

BackgroundEstablishing long-term arteriovenous access is an important component in the long-term care of a patient with end-stage renal disease. The increasing frequency of obesity is reported to impact the access management of end-stage renal disease patients. This study aims to evaluate the outcomes of arteriovenous fistulae (AVF) in obese and nonobese patients. MethodsA retrospective review of all patients over ten years with primary autogenous AVF (radiocephalic, brachiocephalic, and brachial-basilic) was undertaken at a single center. Patients were subcategorized by body mass index into nonobese, class I, II, and III obesity. Outcomes of maturation (successful progression to hemodialysis), reintervention, functional dialysis (continuous hemodialysis for 3 consecutive months), and patency were examined. ResultsFrom January 1999 to December 2019, 2311 patients (67% female; mean age, 61 ± 15 years) underwent primary AVF placement (12% radiocephalic, 53% brachiocephalic, and 35% brachial basilic). Forty-one percent were nonobese, 29% had class I obesity, 19% had class II obesity, and 11% had class III obesity. The majority of patients were diabetic and Hispanic. The 30-day major adverse cardiovascular event rate was elevated in class II (0.20%) and class III (0.50%) obesity compared with class I obesity (0.15%) and nonobese (0.05%). The 30-day morbidity rate was higher in all classes of obesity (0.5% vs0.3% vs 0.2% vs 0.05% for class III vs class II vs class I obesity and nonobese, respectively). Early thrombosis was significantly increased in class II (9%) and class III obesity (12%) compared with class I obesity (5%) and nonobese (3%). There was a two-fold increase in procedures to effect maturation in class II (51%) and class III (74%) obesity compared with class I obesity (22%) and nonobese (34%). Secondary patency at 3 years was significantly lower in class III (62 ± 4%) and class II (79 ± 3%) compared with class I obesity (87 ± 2%) and nonobese (93 ± 4%). All classes of obesity required significantly more secondary Interventions per year compared with nonobese (3.9 vs 3.1 vs 2.5 vs 1.4 secondary interventions per year for class III vs class II vs class I obesity and nonobese, respectively). ConclusionsAdvancing obesity class is associated with an increased number of procedures to achieve AVF maturation and is associated with poorer patency and functionality as the category of obesity advances.

Association between preoperative C-reactive protein to albumin ratio and late arteriovenous fistula dysfunction in hemodialysis patients: a cohort study

Arteriovenous fistula (AVF) dysfunction is a critical complication in hemodialysis (HD) patients, with inflammation potentially contributing to its development. This retrospective cohort study aimed to investigate the association between preoperative C-reactive protein to albumin ratio (CAR) and AVF dysfunction in Chinese HD patients. A total of 726 adults with end-stage renal disease who underwent new AVF placement between 2011 and 2019 were included. Multivariable Cox regression and Fine and Gray competing risk models were employed to assess the relationship between CAR and AVF dysfunction, considering death and renal transplantation as competing risks. Among 726 HD patients, 29.2% experienced AVF dysfunction during a median follow-up of 36 months. Adjusted analyses revealed that higher CAR levels were associated with an increased risk of AVF dysfunction, with a 27% higher risk per one-unit increase in CAR. Furthermore, patients with CAR values ≥ 0.153 exhibited a 75% elevated risk compared to those with CAR values < 0.035 (P = 0.004). The relationship between CAR and AVF dysfunction varied by the site of internal jugular vein catheter placement (P for trend = 0.011). Notably, the Fine and Gray analysis confirmed the association between CAR and AVF dysfunction, with a 31% increased risk per one-unit increase in CAR. The highest CAR tertile remained an independent predictor of AVF dysfunction (HR = 1.77, 95% CI 1.21–2.58, P = 0.003). These findings highlight the potential of CAR as a prognostic marker for AVF dysfunction in Chinese HD patients. Clinicians should consider CAR levels and catheter placement site when assessing the risk of AVF dysfunction in this population.

Predictors of Arteriovenous Fistula Maturation among Patients with Severe Obesity

There is an increasing prevalence of obesity among patients who develop end-stage renal disease and require dialysis. While referrals for arteriovenous fistulas (AVFs) among patients with class 2-3 obesity (i.e., body mass index [BMI] ≥ 35) are increasing, it is unclear what type of autogenous access is most likely to mature in this patient population. This study was designed to evaluate factors that impact maturation of AVF among patients with class ≥2 obesity. We retrospectively reviewed AVFs created at a single center from 2016 to 2019 for patients who had undergone dialysis within the same healthcare system. Ultrasound studies were used to evaluate factors that defined functional maturation, including diameter, depth, and volume flow rates through the fistula. Logistic regression models were used to evaluate the risk-adjusted association between class ≥2 obesity and functional maturation. A total of 202 AVFs [radiocephalic (24%), brachiocephalic (43%), and transposed brachiobasilic (33%)] were created during the study period, of which 53 (26%) patients had a BMI >35. Functional maturation was significantly lower among patients with class ≥2 obesity undergoing brachiocephalic (58% obese versus 82% normal-overweight; P=0.017), but not radiocephalic or brachiobasilic AVFs. This was primarily a result of excessive AVF depth in severely obese patients (9.6±4.0mm obese versus 6.0±2.7mm normal-overweight; P<0.001), whereas there was no significant difference found in average volume flow or AVF diameter between groups. In risk-adjusted models, a BMI ≥35 was associated with a significantly lower likelihood of achieving AVF functional maturation (odds ratio: 0.38; 95% confidence interval: 0.18-0.78; P=0.009) after controlling for age, sex, socioeconomic status, and fistula type. Patients with a BMI >35 are less likely to mature AVFs after creation. This principally affects brachiocephalic AVFs and occurs because of increased fistula depth as opposed to diameter or volume flow parameters. These data can help guide decision-making when planning AVF placement in severely obese patients.

#6448 IMPACT OF PRE-DIALYSIS FOLLOW-UP ON OUTCOMES IN DIALYSIS PATIENTS

Abstract Background and Aims Pre-dialysis care aims to slow down the decline in kidney function and to prepare patients for their potential start of renal replacement therapy. Patients who received attention earlier showed reduced mortality and hospitalization, better uptake of peritoneal dialysis, and earlier placement of arteriovenous fistula for hemodialysis. The objective of this study is to analyze the impact of pre-dialysis care in dialysis patients from Fresenius Medical Care Latin America (FME LatAm). Method Patients incident to dialysis that started treatment at FME LatAm between January 2019 and December 2022 were included in this retrospective observational study. They were classified according to whether they received pre-dialysis care or not as CKD (more than 10 days of follow up;) or No CKD (less than 10 days). CKD group was subclassified regarding the length of stay in pre-dialysis care in 10 to 45 days (10-45), 45 to 90 days (45–90), and more than 90 days (&amp;gt;90). Demographic variables, vascular access, and lab variables were compared between CKD and No CKD, and within subgroups during the observation period. Values are expressed in mean ± SD. Values compared using Student t-test or ANOVA accordingly. Results CKD patients were older than No CKD (CKD: 61.5 ± 16.6 vs NoCKD: 60.6 ± 17.2; p = 0.02), with lower male prevalence (CKD: 57.5% vs NoCKD: 60.2%; p=0.001). No significative differences in prevalence of diabetes were found. Patients under pre-dialysis treatment showed a higher rate of PD referrals (CKD: 44.6% vs NoCKD: 7.3%; p &amp;lt;0.0001). Regarding vascular access, a higher percentage of CKD patients started dialysis with definitive access (AVF or AVG) (CKD: 47.9% vs NoCKD: 31.5%; p &amp;lt;0.0001). In the same way, prevalence of definitive accesses was higher in patients with longer CKD stay (10-45: 38.4%, 45-90: 57.3%, &amp;gt;90: 50.2%; p&amp;lt;0.0001). Within patients who started treatment with a catheter, a higher percentage of CKD patients already had a fistula or graft performed at treatment start (CKD: 7.3% vs NoCKD: 2.7%; p &amp;lt;0.0001). EPO prescription was higher as the time of follow-up was longer (10-45: 3.3%, 45-90: 7%, &amp;gt;90: 14.9%; p&amp;lt;0.0001). As expected for CKD patients haemoglobin was higher and ferritin was lower (Table 1). Though TSAT, Calcium, and Albumin were significative different between CKD and No CKD, the difference was not clinically relevant. Phosphorus and iPTH was higher in CKD patients and creatitine clearence calculated by MDRD was lower in those patients, opposite of expected (Table 1). Conclusion Older and male patients are more likely to have CKD follow-up. Pre-dialysis treatment has a deep impact on PD referral, EPO prescription, type of vascular access at admission, and ready-made vascular access at treatment start. Some laboratory results were not as expected, maybe due to non proper medication accessibility or inadequate financial support at predialysis stages. Even though, CKD follow-up is crucial to prepare patients for a better start of renal replacement therapy.

#5737 THE ASSOCIATION OF SERUM IRISIN WITH EARLY PATENCY LOSS OF ARTERIOVENOUS FISTULA

Abstract Background and Aims In patients receiving hemodialysis (HD), arteriovenous fistula (AVF) is the preferred form of vascular access owing to its long-term patency and low risk of infection. Early patency loss of AVF (≤1 year) is associated with higher risk of mortality and morbidity. Irisin is thought to play a protective role in the regulation of endothelial function and vascular calcification. However, the relationship between serum irisin level and early patency loss of AVF is unclear. Method In 73 end-stage kidney disease (ESKD) patients, including pre-dialysis patients who receive AVF placement for the first time (n = 10), HD patients with early patency loss of AVF (n = 24), HD patients that lose AVF function more than 1 year (n = 39), fasting (&amp;gt;8 hours) serum irisin levels and other biochemical parameters (hemoglobin, serum albumin, calcium, phosphate, intact parathyroid hormone, triglyceride, total cholesterol, D-Dimer, fibrinogen, FGF23, C-reactive protein) were measured before receiving access placement or after AVF thrombosis. All patients had radial-cephalic fistula. Results Among 73 patients (median age 58 years, 60.3% male, 31.5% diabetes mellitus (DM)), patients with early patency loss of AVF had significantly higher serum irisin levels, and lower fibrinogen, compared with other two groups. Other characteristics had no significant difference among these three groups (shown in Table 1). Conclusion HD patients with early patency loss of AVF had higher serum irisin levels compared with pre-dialysis patients and HD patients whose AVF patency maintained more than 1 year. The increase of irisin may be related to its putative role in compensatory mechanisms against vascular injury, which is then lost with longer dialysis duration and aggravated vascular damage.

Impact of N-acetylcysteine supplementation on skeletal muscle myopathy in a mouse model of access-related hand dysfunction

Introduction: Hemodialysis is a life-line therapy for end-stage kidney disease patients that requires long-term arteriovenous access. Arteriovenous fistula (AVF) is the most durable and commonly employed access strategy. However, access-related hand dysfunction (ARHD) including ischemia, weakness, and neuromotor discoordination is prevalent (~50%) following AVF placement. Unfortunately, there are no pre-emptive non-surgical therapeutic studies available. We hypothesized that N-acetylcysteine (NAC) supplementation would attenuate hindlimb disability in a mouse model of ARHD. Methods: Adult male and female C57BL/6J mice (N=9/group) were fed adenine diet to induce kidney disease. Thereafter, animals were randomly allocated to receive NAC (150 mg/kg in 0.2 ml of 0.9% saline) or placebo (0.2 ml of saline) via oral gavage beginning 3 days prior to the AVF surgery and until euthanasia. Limb perfusion to the ischemic hindlimb and hindlimb grip strength were assessed post-operatively (POD) in vivo. Muscle contractile and mitochondrial function, and histological assessments of muscle and the neuromuscular junction were also performed. Results: Laser Doppler perfusion to the ventral paw was decreased immediately after AVF creation on the left common iliac artery (~25% of the contralateral limb) and recovered (~40-60%) at POD13 without a treatment effect. NAC treatment improved muscle mass in the tibialis anterior (TA) (+13~21%, P&lt;0.05) and soleus (+17~21%, P&lt;0.05) muscles in both male and female mice compared with placebo-treated animals. NAC female, not male, mice had significant improvement in grip strength (~20% greater at POD4 and POD12, P&lt;0.05) and maximal mitochondrial respiration (~30% higher at POD14, P&lt;0.05) compared with control animals. Muscle contractile function and myofiber area and capillarization in TA and soleus muscles were similar between NAC and placebo groups (P&gt;0.05). Interestingly, the area of the post-synaptic acetylcholine receptor clusters was significantly greater in the animals that received NAC treatment (+10~22%, P&lt;0.05) in both male and female mice. Conclusion: Daily treatment with a thiol reducing antioxidant, NAC, has beneficial effects on the recovery of muscle mass and neuromuscular junction morphology in both male and female mice with additional improvement in grip strength and mitochondrial function in female mice suggesting a potential therapeutic strategy targeting antioxidant defense to ameliorate ARHD. Funding Support: National Institutes of Health grant R01HL148597 and American Heart Association grant POST903198. This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Comparing post-maturation outcomes of arteriovenous grafts and fistulae.

Though arteriovenous grafts (AVG) mature more reliably than arteriovenous fistulae (AVF) and require fewer maturation procedures (MP) to obtain functional patency, AVG are thought to have worse function after maturation. We explored differences in post-maturation outcomes between the following groups: AVF patients who did (AS-AVF) and did not (unAS-AVF) require assisted maturation and AVG patients who did (AS-AVG) and did not (unAS-AVG) require assisted maturation. Using the US Renal Data System (2012-2017), we retrospectively identified patients who initiated dialysis with a central venous catheter, underwent AVF or AVG placement and achieved successful two-needle cannulation. Primary patency and access abandonment after maturation were compared across groups using competing risks regression methods, generating sub-hazards ratios (sHR). We identified 42,664 AVF and 12,335 AVG that met inclusion criteria. A larger proportion of AVFs required interventions: 18,408 AVF (43.2%) versus 2594 AVG (21.0%; p < 0.01). Both AS-AVG and AS-AVF patients experienced patency loss at 1 year more frequently compared with unAS-AVG (67.5% & 57.5% vs 55.2% respectively). Patency loss was lowest in unAS-AVF (38.9%). These trends were robust on adjusted analysis (unAS-AVG reference, AS-AVG sHR = 1.44, p < 0.01; AS-AVF sHR = 1.08, p < 0.01, unAS-AVF sHR = 0.67, p < 0.01). AS-AVGs were more likely to be abandoned than unAS-AVGs (11.7% unAS-AVG vs 17.2% AS-AVG). Fistulae, assisted or not, had lower unadjusted rates of 1-year abandonment than grafts (8.9% AS-AVF vs 7.3% unAS-AVF). On adjusted analysis, AVF usage was protective against abandonment (unAS-AVG, reference; AS-AVF sHR = 0.67, p < 0.01; unAS-AVF sHR = 0.59, p < 0.01) while AS-AVG was not (AS-AVG sHR = 1.32, p < 0.01). unAS-AVF have the best long-term outcomes. AS-AVF lose primary patency at a higher rate than unAS-AVG. AVGs may be a better choice than AVFs if veins are marginal and likely to require assisted maturation. Further research is needed to identify anatomic and physiologic factors that affect long-term performance and influence conduit choice.

3D printed hemodialysis access and subcutaneous volume model as a guide for cannulation: A proof of concept training tool.

A 54-year-old underwent brachiocephalic arteriovenous fistula placement. Following maturation of the access, consistent cannulation for routine hemodialysis was challenging for clinical specialists. A three-dimensional intraluminal access model was generated, but clinical specialists adept at cannulation had difficulty orienting the model to the patient's anatomy without repeat supervision. When provided the model prima facie, 50% (4/8) clinical specialists were not able to spatially orient the model appropriately in the x-axis with respect to the coronal plane (2/8) or in the z-axis with respect to the transverse plane (2/8). Spatial renderings of the subcutaneous volume available for cannulation were then printed and physically applied to the vascular access model resulting in appropriate spatial orientation among all clinical specialists (n = 12) that were presented the models for the first time. Mean Kt/V increased during the 3-month period directly following model introduction. This case demonstrates the potential utility of 3D-modeling to readily visualize the subcutaneous volume of a hemodialysis vascular access and reduce cannulation error.

Doppler ultrasound assessment of calcified radial arteries prior to radio-cephalic arterio-venous fistula placement: an observational study.

In elderly and diabetic patients, arterial calcifications are prevalent and result in worse outcomes of arterio-venous fistulas (AVFs). Optimal ultrasound criteria for assessment of calcified arteries are unknown. We report our experience with ultrasound assessment of calcified arteries prior to placement of radio-cephalic (RC) AVFs. We included 85 patients in whom a RC-AVF placement was planned. Patients were divided according to the presence of radial artery calcifications into a calcified group (moderate/severe calcifications, N = 18) and control group (no changes/mild atherosclerosis, N = 67). Doppler ultrasound parameters were analyzed in the calcified group with focus on assessment of the artery, including grading of calcifications and Doppler measurements at rest and during reactive hyperemia (RH). In the calcified group mean patients' age was 72 ± 11 years, 72% were diabetics, mean resistance index (RI) during RH was 0.78 ± 0.09 (range 0.63-0.90). In 14 (78%) patients an AVF was successfully placed and in 12 it matured (67% maturation rate). A lower RI at rest was observed in the primary failure sub-group with high area under the ROC curve (0.89) and a cut-off value of 0.90 for RI. There was no difference in RI at RH between failed and matured AVFs. 1-year secondary patency was 66% and in eight patients with follow-up ultrasound available, blood flow was 350-1300 ml/min. For comparison, in the control group a radio-cephalic AVF was placed in all patients, primary failure rate was 6%, maturation rate 85% and 1-year secondary patency was 77%. Our very limited experience suggests that successful RC-AVF placement and maturation with good 1-year patency rates is possible in patients with moderately/severely calcified arteries and RI during RH of up to 0.90.

Vascular access type and mortality in elderly incident hemodialysis patients

IntroductionThe ideal vascular access type for elderly hemodialysis (HD) patients remains debatable. The aim of this study was to analyze the association between patterns of vascular access use within the first year of HD and mortality in elderly patients. MethodsSingle-center retrospective study of 99 incident HD patients aged≥80 years from January 2010 to May 2021. Patients were categorized according to their patterns of vascular access use within the first year of HD: central venous catheter (CVC) only, CVC to arteriovenous fistula (AVF), AVF to CVC, and AVF only. Baseline clinical data were compared among groups. Survival outcomes were analyzed using Kaplan–Meier survival curves and Cox's proportional hazards model. ResultsWhen compared with CVC to AVF, mortality risk was significantly higher among CVC only patients and similar to AVF only group [HR 0.93 (95% CI 0.32–2.51)]. Ischemic heart disease [HR 1.74 (95% CI 1.02–2.96)], lower levels of albumin [HR 2.16 (95% CI 1.28–3.64)] and hemoglobin [HR 4.10(95% CI 1.69–9.92)], and higher levels of c-reactive protein [HR 1.87(95% CI 1.11–3.14)] were also associated with increased mortality risk in our cohort, p<0.05. ConclusionOur findings suggested that placement of an AVF during the early stages of dialysis was associated with lower mortality compared to persistent CVC use among elderly patients. AVF placement appears to have a positive impact on survival outcomes, even in those who started dialysis with a CVC.

Metabolomic profiling reveals muscle metabolic changes following iliac arteriovenous fistula creation in mice.

End-stage kidney disease, the most advanced stage of chronic kidney disease (CKD), requires renal replacement therapy or kidney transplant to sustain life. To accomplish durable dialysis access, the creation of an arteriovenous fistula (AVF) has emerged as a preferred approach. Unfortunately, a significant proportion of patients that receive an AVF experience some form of hand dysfunction; however, the mechanisms underlying these side effects are not understood. In this study, we used nuclear magnetic resonance spectroscopy to investigate the muscle metabolome following iliac AVF placement in mice with CKD. To induce CKD, C57BL6J mice were fed an adenine-supplemented diet for 3 wk and then randomized to receive AVF or sham surgery. Two weeks following surgery, the quadriceps muscles were rapidly dissected and snap frozen for metabolite extraction and subsequent nuclear magnetic resonance analysis. Principal component analysis demonstrated clear separation between groups, confirming a unique metabolome in mice that received an AVF. AVF creation resulted in reduced levels of creatine, ATP, and AMP as well as increased levels of IMP and several tricarboxylic acid cycle metabolites suggesting profound energetic stress. Pearson correlation and multiple linear regression analyses identified several metabolites that were strongly linked to measures of limb function (grip strength, gait speed, and mitochondrial respiration). In summary, AVF creation generates a unique metabolome profile in the distal skeletal muscle indicative of an energetic crisis and myosteatosis.NEW & NOTEWORTHY Creation of an arteriovenous fistula (AVF) is the preferred approach for dialysis access, but some patients experience hand dysfunction after AVF creation. In this study, we provide a detailed metabolomic analysis of the limb muscle in a murine model of AVF. AVF creation resulted in metabolite changes associated with an energetic crisis and myosteatosis that associated with limb function.

A Murine Model of Hemodialysis Access-related Hand Dysfunction.

Chronic kidney disease is a major public health problem, and the prevalence of end-stage renal disease (ESRD) requiring chronic renal replacement therapies such as hemodialysis continues to increase. Autogenous arteriovenous fistula (AVF) placement remains a primary vascular access option for ESRD patients. Unfortunately, approximately half of the hemodialysis patients experience dialysis access-related hand dysfunction (ARHD), ranging from subtle paresthesia to digital gangrene. Notably, the underlying biologic drivers responsible for ARHD are poorly understood, and no adequate animal model exists to elucidate the mechanisms and/or develop novel therapeutics for the prevention/treatment of ARHD. Herein, we describe a new mouse model in which an AVF is created between the left common iliac artery and vein, thereby facilitating the assessment of limb pathophysiology. The microsurgery includes vessel isolation, longitudinal venotomy, creation of arteriovenous anastomosis, and venous reconstruction. Sham surgeries include all the critical steps except for AVF creation. Iliac AVF placement results in clinically relevant alterations in central hemodynamics, peripheral ischemia, and impairments in hindlimb neuromotor performance. This novel preclinical AVF model provides a useful platform that recapitulates common neuromotor perturbations reported by hemodialysis patients, allowing researchers to investigate the mechanisms of ARHD pathophysiology and test potential therapeutics.