Fistula Stenosis Research Articles

Mineralocorticoid receptor antagonism attenuates arteriovenous fistula stenosis by modulating the phenotype of vascular smooth muscle cells

Mineralocorticoid receptor antagonism attenuates arteriovenous fistula stenosis by modulating the phenotype of vascular smooth muscle cells

Midterm results of endovascular treatment of ateriovenous fistula stenosis at Dong Nai General Hospital

Introduction: AVF stenosis is a common complication, leading to impaired dialysis function, increased risk of occlusion and increased mortality. Endovascular intervention treatment of AVF stenosis is an important technique in the management of dialysis patients, particularly at local hospitals. Methods: This is a retrospective study performed at Dong Nai general hospital from 2022-2024. Results: The success rate of endovascular intervention to treat AVF stenosis at Dong Nai General Hospital is 91%, 3-month primary patency was 93.1% and 6-month primary patency was 86.2%. Drug-coated balloons (DCB) shows superior effectiveness compared to conventional balloons (PBA) with a lower restenosis rate. Conclusion: Endovascular intervention to treat AVF stenosis at Dong Nai General Hospital has good short term and midterm results. Drug-eluting balloons have a statistically significantly lower mid-term restenosis rate than conventional balloons. Implementing this technique at provincial hospitals helps reduce the burden on central hospitals and reduce medical costs for chronic kidney failure patients requiring hemodialysis.

Feasibility of an antegrade-retrograde single-sheath inverse technique via vertical puncture in dysfunctional hemodialysis arteriovenous fistula angioplasty

BackgroundStenosis resulting in dysfunctional dialysis access may occur simultaneously on the anastomotic and central venous side. The purpose of this study was to retrospectively evaluate the feasibility of a single sheath inverse technique using the vertical puncture approach to perform bidirectional transvenous percutaneous transluminal angioplasty (PTA) from a single sheath for such dialysis access stenoses.Materials and MethodsTwenty patients (26 cases; 13 males; median age, 74 [range: 50–89] years) who underwent PTA using the sheath inverse technique for dysfunctional arteriovenous fistula stenoses between April 2019 and June 2023 were included. All procedures were performed in an outpatient setting. A 4-cm sheath (4Fr, four cases; 5Fr, 19 cases; 6Fr, three cases) was inserted by vertical puncture through a cutaneous vein in the forearm (20 cases) or upper arm (six cases). After treating one side of the lesion, the sheath was reversed to treat the lesion on the opposite side. The vessel diameter at the sheath insertion site, the success rate of sheath inversion, the number of PTA balloon catheters used, the PTA success rate, adverse events, and primary and secondary patency rates up to one year after PTA were evaluated.ResultsThe median diameter at the sheath indwelling site was 5.2 (range: 3.6–9.5) mm, and sheath inversion was successful in all cases, eliminating the need to place an additional sheath at another site for contralateral stricture treatment. The number of balloon catheters used was one and two in 17 (65%) and eight cases (31%), respectively, and three in one case wherein a drug-coated balloon was used. PTA was successful in all cases and major complications were not observed. However, in one case wherein a sheath had to be placed at the arterial needle puncture site, the skin was hard, leading to difficulty in inversion, and transient venous spasm occurred post-inversion. The primary patency rates at 3, 6 and 12 months after the PTA were 87.5%, 41.7%, and 20.8%, respectively. The secondary patency rates at 6 and 12 months were 100% and 75%, respectively.ConclusionThe single-sheath inverse technique for arteriovenous fistulas was feasible without sheath withdrawal.Graphical

Assessment of Sonographic Parameters for Predicting Primary Patency Rate in Hemodialysis Patients With Venous Valve-Related Stenosis.

Ultrasonography is more frequently used in patients with arteriovenous fistula (AVF) stenosis. The aim of this study is to use sonographic parameters for predicting primary patency in hemodialysis patients with venous valve-related stenosis (VVRS) who are treated by ultrasound-guided percutaneous transluminal angioplasty (PTA). A total of 229 VVRS patients who underwent PTA between January 2017 and December 2021 were enrolled. Clinical characteristics were retrospectively collected. Sonographic parameters were measured both before and after PTA. Univariate and multivariate Cox analyses were performed to identify independent factors associated with primary patency rate. All measured sonographic parameters improved after PTA compared to before PTA. Before PTA, the diameter of VVRS > 1.0 mm, age ≤ 57 years, and body mass index (BMI) > 21.57 kg/m2 were associated with better outcomes. While the diameter of radial artery, proximal radial artery close to the anastomosis, brachial artery, the flow volume of brachial artery, the length and peak velocity (PV) of the VVRS, and the diameter and PV after the VVRS had no association with the primary patency rate. After PTA, only patients with a diameter of VVRS > 4.0 mm had favorable outcome. In addition, patients with a gain of diameter of VVRS > 2.4 mm after PTA had a trend of better outcomes. The diameter of VVRS before and after PTA could be served as markers to predict primary patency rate and second patency rate in AVF patients with VVRS. The gain of diameter of VVRS could also be a potential marker. Using simple markers of sonographic parameters, we could quickly identify patients with a higher risk of restenosis. These patients should be followed more closely in case of restenosis at early. It is also beneficial to the prevention of thrombosis. These measures help to preserve more valuable vascular for a long-term dialysis. Additionally, the physician should pay more attention on the dialysis-related complications in these risky patients, such as hemodialysis-related hypotension.

The role of physical examinations in detecting arteriovenous fistula stenosis among chronic hemodialysis patients: a cross-sectional study

The role of physical examinations in detecting arteriovenous fistula stenosis among chronic hemodialysis patients: a cross-sectional study

The Effectiveness of Electronic Cannulation Atlas in Patients with Arteriovenous Fistula.

This study aimed to assess the effectiveness of an electronic cannulation atlas in preventing and treating complications of arteriovenous fistula. The observation group, consisting of 92 dialysis patients from July to December 2021, was managed with an electronic cannulation atlas. After 6 months, the incidence of complications such as stenosis, hematoma, thrombus, aneurysm, and cannulation failure was compared between the groups. Nurse satisfaction with the electronic cannulation atlas system was also assessed through a questionnaire. The observation group had lower incidence rates of arteriovenous fistula stenosis, thrombus, aneurysm, and failure rate of cannulation compared to the control group, with statistically significant differences (p<0.05). The incidence rates of hematoa were similar in both groups, showing no significant difference (p>0.05). After 3 months of management, the incidence of arteriovenous fistula complications in the observation group was significantly lower than in the control group (p<0.05). Additionally, utilizing the electronic cannulation atlas system was found to increase nurses' job satisfaction. The use of electronic cannulation atlas for the treatment of patients' arteriovenous fistula could effectively reduce the incidence of complications of patients' arteriovenous fistula, reduce the failure rate of cannulation, reduce the workload of nurses, and improve the job satisfaction of nurses.

Calcium-Free Dialysate Hemodialysis: A Simplified Approach.

Intermittent hemodialysis (HD) in high-bleeding-risk patients presents a challenge as circuit anticoagulation using heparin is contraindicated in such cases. Recently, the use of calcium-free citrate-containing dialysate with calcium supplementation emerged as a viable alternative to heparin-circuit anticoagulation. This is a retrospective, monocentric study to evaluate dialysis efficacy using calcium-free citrate-containing dialysate with calcium reinjection into the venous line in hemodialysis patients at risk of bleeding. A total of 53 patients were analyzed: 52 had a temporary contraindication to systemic anticoagulation (active bleeding or surgical intervention), and 1 chronic HD patient had prolonged bleeding time due to inoperable arteriovenous fistula stenosis. Only 7 out of 79 dialysis sessions performed were prematurely terminated (vascular access dysfunction). The median dialysis time was 240 min (range: 150-300). The chronic dialysis patient had 108 sessions with no premature termination. Frequent monitoring of ionized calcium was performed throughout the dialysis sessions: levels remained stable at T0 and T + 60 min (1.08 ± 0.08 mmol/L) and slightly increased at the end of the dialysis session (1.19 ± 0.13 mmol/L), remaining within normal limits. Target postfilter ionized calcium <0.4 mmol/L was achieved in all sessions (0.31 ± 0.07 mmol/L). There were no cases of symptomatic hypo-/hypercalcemia and no need for calcium infusion rate adjustment throughout the sessions. Hemodialysis with calcium-free citrate-containing dialysate and calcium reinjection into the venous line is efficient and safe in HD patients with contraindications to systemic anticoagulation.

#2464 Association of vascular access flow and volume status on fistula arm by bio-impedance analysis

Abstract Background and Aims Multi-frequency bio-impedance is a tool of body composition measure and can monitor changes in extracellular volume during dialysis. Arterio-venous fistulae (AVF) could potentially affect fluid retention in the arm. We investigated whether multi-frequency bio-impedance could defect AVF stenosis or association of AVF with fluid retention in the AVF arm. Method We measured the extracellular water (ECF) and total body water (TBW) in AVF arm following hemodialysis by multi-frequency bio-impedance (Inbody S10®) using an eight-electrode contact technique. We measured AVF or AVG flow by transonic ultrasonography using an ultrasound dilution technology (HD 03®) in hemodialysis. Results Total 82 patients (male 38 patients : female 44 patients) were enrolled. The causes of ESRD were DM : non-DM = 38 : 44. The mean age of patients was 54.89 ± 13.21 years. The ECW/TBW ration of fistula arm was a significantly higher than the ECW/TBW ration of non-fistula arm (0.389 ± 0.010 vs. 0.382 ± 0.001; p&amp;lt;0.05). The ECW/TBW ration of fistula arm was a significantly negative correlation with access flow level (mL/min) on fistula (p&amp;lt;0.05). The 5kHz reactance of fistula arm was a significantly positive correlation with access flow level (mL/min) on fistula (p&amp;lt;0.05). The 5kHz Phase Angle of fistula arm was a significantly positive correlation with access flow level (mL/min) on fistula (p&amp;lt;0.05). Conclusion Absolute and also relative extracellular fluid volumes are increased in the fistula arm of hemodialysis. We thought that extracellular fluid volumes in the fistula arm were associated with access flow level (mL/min) and/or relative fistula stenosis. We suggest that multi-frequency bio-impedance can be a useful assistant tool of vascular access flow measure.

Imaging diagnosis and treatment results of arteriovenous fistulas stenosis complication among hemodialysis patients

ABSTRACT Introduction: Percutaneous transluminal angioplasty (PTA) presents several advantages in addressing arteriovenous fistula (AVF) stenosis compared to surgical approaches. In addition, Doppler ultrasonography (DUS) serves as a noninvasive technique for stenosis measurement and access flow volume calculation. This study aimed to evaluate the agreement in stenosis diagnosis using PTA and DUS before intervention and to assess the effectiveness of the PTA method after intervention. Method: A non - controlled intervention study involved 15 chronic HD patients with a mature AVF in place for over three months, presenting AVF stenosis ≥ 50%, who underwent PTA intervention. Correlation analysis was employed to assess the similarity of AVF stenosis evaluations using DUS and PTA. The study also compared pre - and post - intervention indicators to evaluate the effectiveness of PTA intervention. Results: The results indicated a strong positive correlation between the two techniques (r = 0.997, r2 = 0.994, p &lt; 0.001). Following intervention, all patients were considered successful, with significant reductions observed in various indicators, including alterations in murmurs along AVF, VAPR, the number of patients with AVF stenosis ≥ 50% on DUS, and none with Qmin &lt; 500 mL/min. Conclusion: This study recommends utilizing DUS to evaluate stenosis before contemplating PTA intervention, owing to the correlation and similarity observed in the results of AVF stenosis examination between these two techniques. Ultimately, our research endorses PTA intervention as the preferred method for HD patients with AVF stenosis, considering the observed enhancements in clinical, hemodialysis, and DUS parameters

Application of Freehand 3D Ultrasound Guidance in Percutaneous Transluminal Angioplasty for Autogenous Arteriovenous Fistula Stenosis

Objective: Using freehand three dimensional (3D) ultrasound imaging to evaluate arteriovenous fistula stenosis. Comparing the value of freehand 3D ultrasound and Doppler ultrasound in the application of percutaneous transluminal angioplasty (PTA) treatment for stenosis of an arteriovenous fistula. Methods: A retrospective analysis was conducted on 34 patients with arteriovenous fistula (AVF) stenosis who were treated at the 903RD Hospital of PLA and the Kidney Center of Zhejiang Provincial People's Hospital from August 2021 to August 2022. Based on the different types of surgical assistance, the patients were divided into two groups: the Doppler ultrasound group (Group A, n = 17) and the freehand 3D ultrasound imaging group (Group B, n = 17). Freehand 3D ultrasound and Doppler ultrasound were used to assess the narrowing of arteriovenous fistulas, and images and relevant data were collected before and after the PTA procedure. The differences in the time of puncture and sheath placement, guidewire insertion time, the duration of the procedure, complications, and methods to measure stenosis were compared between the two groups of patients, as well as the technical success rate, the initial patency rate, and the primary patency rates at 1, 3, 6 and 9 months post-surgery. This study discusses the clinical efficacy of using these two types of ultrasound to assist in the PTA treatment of arteriovenous fistula stenosis. Results: The differences in baseline demographics between the conventional ultrasound group (Group A) and the 3D ultrasound group (Group B) were not statistically significant (p &gt; 0.05). The intraoperative guidewire insertion time (4.647 ± 1.347 min vs. 2.824 ± 0.326 min) and the operating times (75.941 ± 7.557 min vs. 59.824 ± 8.175 min) between the two groups were statistically significant (t = 2.788, 3.069, p &lt; 0.01). The technical success rates for the two groups were 94.1% vs. 100%, not statistically significant (t = 1.03, p = 0.31). The first-time patency rates were 88.2% vs. 94.1%, with no statistically significant difference (t = 0.366, p = 0.545). No complications occurred in Group A, while one case of hematoma occurred postoperatively in Group B, with an incidence of 5.9% (1/17), which was not statistically significant (t = 1.03, p &gt; 0.05). Comparing the primary patency rates at 1, 3, 6 and 9 months post-surgery between Groups A and B, there were no statistically significant differences (p &gt; 0.05). However, the patency rates at different time points for Group B were consistently higher than Group A (94.1%, 82.4%, 82.4%, 82.4% vs. 88.2%, 82.4%, 76.5%, 76.5%). Conclusion: Freehand 3D ultrasound imaging can provide more intuitive, high-resolution, and high-definition three-dimensional images, clearly defining the lesion site and vascular structures. Its accuracy in assessing complications of arteriovenous fistulas is similar to that with conventional ultrasound. When used as an adjunct to PTA treatment, its efficacy is equivalent. It can significantly reduce guidewire insertion time and operation time, decrease postoperative recovery time, and alleviate the patients' concerns regarding surgical risks. It can be considered a new method for diagnosing, treating, and patients with AVF stenosis.

A Cost-Effective Approach to Resistant AV Fistula Stenosis: Successful Treatment Using Coronary OPN NC® Balloon in a Low-Income Setting.

Stenosis in the anastomotic site or venous limb of an arteriovenous fistula (AVF) is the most frequent cause of AVF failure. Percutaneous angioplasty with a standard or high-pressure balloon is the first-line treatment for AVF stenosis due to its higher technical success rate (90%) and lower complication rate (4%). Almost 20% of stenosis cases are resistant or undilatable by regular-pressure balloon angioplasty due to fibrosis, leading to technical failure or restenosis. Alternative therapies, such as atherectomy devices or cutting balloons, are expensive and difficult to obtain in low-income developing countries. We successfully treated resistant AVF stenosis with a coronary OPN-NC® ultra-high-pressure balloon and produced a good angiographic result with technical success. Coronary hardware is easily available and relatively cheaper compared to dedicated peripheral balloons or devices in our country due to reuse, which can be a boon in such type of cases. According to the standard hospital protocol, Cathlab hardware was reused.

Ankle-brachial index associates with arteriovenous fistula stenosis.

Arteriovenous fistula (AVF) stenosis is associated with pre-existing arterial atherosclerosis of AVF and results in significant morbidity and hospitalization for hemodialysis patients. The ankle brachial index (ABI) is a noninvasive method of assessing atherosclerosis. This study was to examine whether ABI is a significant predictor for AVF stenosis. This was a retrospective, longitudinal cohort study. Patients with hemodialysis between 1 January 2016 and 31 December 2022 were reviewed. ABI was assessed in January 2016. AVF stenosis was diagnosed by fistulography. A total of 82 patients were included. Forty-two patients experienced AVF stenosis. The univariate logistic regression analysis showed that AVF stenosis was associated with age (OR: 1.045, p = 0.033), DM status (OR: 5.529, p = 0.013), 7-year averaged cholesterol level (OR: 1.018, p = 0.034), 7-year averaged triglyceride level (OR: 1.007, p = 0.017), and ABI (OR: 0.011, p < 0.001). In multivariate logistic regression analysis, ABI was a strong predictor for AVF stenosis (OR: 0.036, p = 0.023). Then, a cut-off point of ABI with optimal sensitivity and specificity for AVF stenosis was 1.01. An analysis of time to events with adjustment for other variables showed that patients with ABI < 1.01 were significantly associated with AVF stenosis (HR: 3.859, p < 0.001). ABI below 1.01 was associated with AVF stenosis. This finding may be useful in tailoring surveillance programs for monitoring AVF function.

Efficacy of cutting balloon angioplasty versus high-pressure balloon angioplasty for the treatment of arteriovenous fistula stenoses in patients undergoing hemodialysis: Systematic review and meta-analysis.

This systematic review and meta-analysis aimed to assess and compare the therapeutic outcomes of cutting balloon angioplasty and high-pressure balloon angioplasty for arteriovenous fistula stenosis in hemodialysis patients. All studies indexed in PubMed, Embase, and Cochrane Library Web of Science were retrieved. The retrieval deadline was July 15, 2023. Risk of bias 2.0 was used to evaluate the quality of the included studies. Revman 5.4 software was used for data analysis. This review included three studies and 180 patients, with 90 patients in the cutting balloon angioplasty group and 90 patients in the high-pressure balloon angioplasty group. The results of the meta-analysis suggested that compared with high-pressure balloon angioplasty, cutting balloon angioplasty can improve primary lesion patency rates of internal arteriovenous fistulas at 6 months (relative risk, 1.45; 95% confidence interval, 1.08-1.96; P = 0.01). However, there were no significant differences between the technical success rate (relative risk, 0.99; 95% confidence interval, 0.93-1.05; P = 0.72) and clinical success rate (relative risk, 1.01; 95% confidence interval, 0.95-1.07; P = 0.73). Therefore, cutting balloon angioplasty is likely to increase primary lesion patency rates at 6 months. However, more high-quality, large-sample, multicenter, randomized controlled trials are needed for further validation due to the limited number of included studies.

Comparison of ultrasound features and lesion sites in dysfunctional arteriovenous fistula

This study aimed to investigate ultrasound features of arteriovenous fistula stenosis and their relationship with primary patency after percutaneous transluminal angioplasty (post-intervention primary patency) and compare this classification with that using lesion location. Hemodialysis patients who underwent ultrasound-guided percutaneous transluminal angioplasty for arteriovenous fistula stenosis from July 2020 to December 2021 were retrospectively evaluated. Lesions (excluding inflow arteries) were categorized into five groups based on ultrasound features, and the clinical characteristics and risk factors affecting the post-intervention primary patency of the arteriovenous fistula were analyzed. Among 185 patients, 100 (54.05%), 36 (19.46%), 22 (11.89%), 11 (5.95%), and 16 (8.65%) were classified into the intima-dominant, non-intima-dominant, valve obstruction, vascular calcification, and mixed groups, respectively. The dialysis duration and arteriovenous fistula use time were the highest in the vascular calcification group at 86 (interquartile range: 49–140) and 77 (interquartile range: 49–110) months, respectively. Diabetes mellitus was most common in the intima-dominant group (42.0%). In Kaplan–Meier and univariate Cox analysis, type III lesion location (stenosis in the venous confluence site) was associated with the lower post-intervention primary patency. In the multivariate Cox analysis, percutaneous transluminal angioplasty times (the number of times patients were treated with percutaneous transluminal angioplasty for arteriovenous fistula stenosis dysfunction), vascular calcification, calcification at the lesion site requiring percutaneous transluminal angioplasty, and serum parathyroid hormone levels were independent risk factors for post-intervention primary patency. Ultrasound features showed that calcification of the arteriovenous fistula was detrimental to the post-intervention primary patency of arteriovenous fistula.

Rate of Arteriovenous Fistula Stenosis and Access Recirculation among Individuals Receiving Maintenance Hemodialysis

Background: Arteriovenous fistula stenosis and access recirculation in hemodialysis represent critical challenges, influencing the efficiency of vascular access and dialysis treatment outcomes. Objective: The objective is to assess the prevalence of arteriovenous fistula (the AVF) stenosis as well as access recirculation (AR) in patients of hemodialysis. Study Design: Cross sectional study. Settings: Department of Nephrology, Bolan Medical Complex Hospital, Quetta. Duration: From 1st April 2022 to 1st September, 2022. Methods: Adult patients having age 18 years to 80 years receiving maintenance hemodialysis 3 times in a week were included in this study. Patients who were willing to provide informed consent participated in the study. Patients with active infections or sepsis, with a history of vascular access interventions within the last three months, pregnant or lactating women as well as patients with cognitive impairment were excluded from study. Outcome variables will be incidence of AVF Stenosis which was determined by regular ultrasound assessments and monitoring of clinical symptoms. Statistical analyses were performed using SPS version 22. Results: The study comprised 150 maintenance hemodialysis patients with a mean age of 55±10. Age distribution showed that 20% were between 18-40 years, 53.3% between 41-60 years, 23.3% between 61-80 years, and 3.3% were older than 80 years. Sixty percent (60%) of the participants were male, while 40% were female. The mean duration of AV fistula use was 3.21± 2.65 years, with 14.66% having duration of 6-12 months, 41.33% between 1-3 years, and 44% using AV fistulas for more than 3 years. Seventy-five point three percent (75.3%) of patients had hypertension, 40.0% had diabetes mellitus, and 28.0% had cardiovascular disease. Additionally, 16.7% of patients presented with other comorbidities. Out of total 25 (16.7%) patients were affected by arteriovenous fistula (AVF) stenosis, while access recirculation was observed in 20 patients (13.3%). Conclusion: In conclusion, our study reveals a notable incidence of arteriovenous fistula (AVF) stenosis and access recirculation among maintenance hemodialysis patients. The observed associations with age and AVF duration underscore the complexity of vascular access complications.

USE of IMplanting the Biotronik PassEo-18 Lux drug coated balloon to treat failing haemodialysis arteRiovenous FIstulas and grafts (SEMPER FI Study)

Background: Plain old balloon angioplasty has been the mainstay of treatment for arteriovenous fistula (AVF) stenoses. Recent studies suggest that drug coated balloons (DCB) may significantly reduce re-intervention rates on native and recurrent lesions. The Passeo-18 Lux DCB (Biotronik AG, Buelach, Switzerland) is packaged with a 3.0 µg/mm2 dose of paclitaxel. The hypothesis is that its use provides better target lesion primary patency (TLPP), primary assisted patency (PP), secondary patency (SP) rates and reduces the number of visits for re-intervention in a cohort of patients with stenotic AVF and arteriovenous grafts (AVGs). Methods: The USE of IMplanting the Biotronik PassEo-18 Lux DCB to treat failing haemodialysis arteRiovenous FIstulas and grafts trial (SEMPER FI) was a prospective double-centre, multi-investigator, non-consecutive, non-blinded single-arm study investigating the efficacy and safety of the Passeo-18 Lux DCB in patients with stenotic AVF/AVG lesions between January 2021 and January 2022. Patient demographics, clinical characteristics, vascular access history, operative indications, details and outcomes were collected prospectively. TLPP, circuit access primary patency (CAP), PP, SP and deaths 6- and 12-months post-intervention were studied. Results: Ninety-one patients with 110 lesions were recruited across the two centres. 62.6% ( n = 57) were male with a median age of 63.5 years (SD = 10.5). 62.6% ( n = 57) were taking anti-platelets. Eighty-five AVFs and six AVGs were treated. 60% ( n = 54) of AVFs intervened were radiocephalic. 52.7% ( n = 58) of targeted lesions were juxta-anastomotic stenosis (JAS) and one-third ( n = 33) at the AVF/AVG outflow. 70.9% ( n = 78) of lesions were recurrent. Median time from last intervention was 219 days. 78% of target lesions ( n = 85) and circuits ( n = 70) were patent at 6-months, of which 96.7% ( n = 87) of those requiring assisted intervention were patent. Conclusion: This study shows that the Passeo-18 Lux DCB can be an effective and safe tool in the treatment of failing haemodialysis AVFs/AVGs.

Arteriovenous Fistula Stenosis: Correlating Degree of Neointimal Hyperplasia With Reduction in Volume Flow Measured on Ultrasound and Ultrasound Characterization Based on Stenosis Morphology

Introduction: Duplex ultrasound (DUS) is commonly used to diagnose and grade arteriovenous fistula (AVF) stenosis. Duplex ultrasound may also be used to examine stenosis type based on measurement of intimal-medial thickness (IMT). There are, as yet, no criteria in use to define the different stenosis types based on measurement of percentage IMT (%IMT). In this study, we have examined stenosis morphology using ultrasound. We have examined consecutive DUS examinations to assess the incidence and degree of IMT and correlated %IMT with volume flow as an indicator of AVF dysfunction. Methods: Duplex ultrasound was performed as per standard of care. Volume flow was measured within the ipsilateral brachial artery. Measurements of luminal diameter and vessel wall diameter were used to calculate %IMT. Results: The study group included 156 consecutive DUS examinations demonstrating a greater than 50% AVF stenosis. Mean %IMT was 45%. There were 17 (11%) lesions where there was no measurable IMT; the remainder had measurable IMT. On receiver-operating characteristic (ROC) analysis, a %IMT of 54% predicted low flow with 62.5% sensitivity and 62.7% specificity. Conclusion: Intimal-medial thickness has a moderate predictive value in predicting volume flow. Based on our results, there are 4 lesion types: (1) lesions with no measurable intimal hyperplasia, (2) a predominantly intimal hyperplastic lesion, (3) those with nonpredominant intimal hyperplasia, and (4) those with a valve type stenosis. A value based on correlation with volume flow could be considered based on our results at 54%IMT or based on morphology at 45%IMT to distinguish between predominant and nonpredominant intimal hyperplasia groups. Including measurements of %IMT in clinical trials could further our knowledge of how lesions with no measurable IMT and those with different degrees of intimal hyperplasia respond to different percutaneous interventions. This could potentially improve outcomes for patients and target more costly treatment options where there is most benefit.

The Flow Volume and Resistance Index of Patent Arteriovenous Fistulas, With Proper Function, Compared to Unhealthy Arteriovenous Fistulas, Using Spectral Doppler

Objective: This study was designed to use sonography and evaluate arteriovenous fistulas (AVFs) in dialysis patients. The aim was to determine criteria for distinguishing between patent AVFs with proper function (healthy) and unhealthy AVFs. Materials and Methods: This study enrolled 106 dialysis patients with an AVF. All fistulas were evaluated using spectral Doppler and grayscale sonography, assessing parameters such as draining vein diameter, distance of the venous vein from the skin surface, feeding artery diameter, presence of thrombosis, and fistula stenosis. Subsequently, Doppler criteria such as flow volume (FV) and resistance index (RI) were measured and compared between healthy and unhealthy AVFs. Results: This cohort’s spectral Doppler findings demonstrated lower FV and higher RI, in unhealthy AVFs, compared to healthy ones (283.5 ± 101.26 mL/min vs 1383.43 ± 756.76 mL/min; P = .006) and (0.55 ± 0.33 vs 0.37 ± 0.14; P = .004) respectively. Conclusion: The spectral Doppler and grayscale sonographic imaging made it possible to evaluate AVF performance and determine its quality. In this cohort, a decreased FV, increased RI, and decreased draining vein diameter were observed in unhealthy AVFs. These results would suggest that sonographers and clinicians should pay close attention to these parameters when assessing the function of an AVF, for patients undergoing hemodialysis.

Deep learning analysis of blood flow sounds to detect arteriovenous fistula stenosis

For hemodialysis patients, arteriovenous fistula (AVF) patency determines whether adequate hemofiltration can be achieved, and directly influences clinical outcomes. Here, we report the development and performance of a deep learning model for automated AVF stenosis screening based on the sound of AVF blood flow using supervised learning with data validated by ultrasound. We demonstrate the importance of contextualizing the sound with location metadata as the characteristics of the blood flow sound varies significantly along the AVF. We found the best model to be a vision transformer trained on spectrogram images. Our model can screen for stenosis at a performance level comparable to that of a nephrologist performing a physical exam, but with the advantage of being automated and scalable. In a high-volume, resource-limited clinical setting, automated AVF stenosis screening can help ensure patient safety via early detection of at-risk vascular access, streamline the dialysis workflow, and serve as a patient-facing tool to allow for at-home, self-screening.

Effects of an arteriovenous fistula stenosis prevention program in patients receiving hemodialysis.

To increase the efficiency of hemodialysis, an appropriate vascular pathway must be created, and its function must be maintained. This study aimed to identify the effects of an arteriovenous fistula (AVF) stenosis prevention program on upper muscular strength, blood flow, physiological indexes, and self-efficacy among patients receiving hemodialysis. The participants were patients receiving hemodialysis at Keimyung University Dongsan Medical Center in Daegu, Republic of Korea. They were divided into experimental and control groups based on the day of the week they received hemodialysis at the outpatient department and included 25 participants each. The study was conducted for 8 weeks. The AVF stenosis prevention program was effective in improving upper extremity muscle strength (F=15.23, p<0.001) and blood flow rate (F=36.00, p<0.001). As a result of the program, the phosphorus index level, which is a physiological indicator in hemodialysis patients, decreased (F=8.64, p<0.001). Encouragement and support through text messages and practice lists also resulted in an increase in self-efficacy (F=18.62, p<0.001). The AVF stenosis prevention program in this study resulted in an increase in upper extremity muscle strength through grip strength exercises and was effective in preventing AVF stenosis by increasing the blood flow rate.