Arteriovenous Fistula Surgery Research Articles

Abstract 4137902: Layer-specific Gene Expression Associated with Intima Hyperplasia in Arterio-venous Fistula

Background: The mechanism of hemodialysis arteriovenous fistula (AVF) vein intima hyperplasia (IH) may be specific to its layers (intima, media, and adventitia) but is poorly understood. To address this gap, we studied layer-specific transcriptomics related to IH in veins of two-stage AVF creation. Methods: Vein samples were collected during the initial creation of brachial artery-basilic vein AVF (1st stage) and vein transposition surgery 6 weeks later (2nd stage) and were sectioned in OCT. Tissues from each layer were separately collected by laser microdissection. Following Takara’s SMARTer Stranded Total RNA-Seq Pico Input protocol, libraries were constructed and sequenced in NovaSeq. The sequencing reads were processed by fastp, aligned to genome GENCODE 45 by STAR and gene-level counts were estimated by RSEM. Intima was assessed by histology. Layer-specific differentially expressed genes in pre-access or AVF veins associated with IH in AVF veins were detected by edgeR and further identified the enriched pathways and predicted functions using Qiagen IPA. Results: 44 veins were collected from 22 patients. 13,522 protein-coding genes that had a raw count of at least 10 in more than 70% of samples were included in analysis. 10 AVF veins had severe IH. Among the layers of pre-access vein, intima had the largest number of genes significantly associated with severe AVF IH and most or all these genes were upregulated (35/4, 26/2, 5/0 for the number of up/downregulated genes in intima, media, and adventitia of pre-access vein, respectively); cellular movement and immune cell trafficking were more strongly activated in intima of pre-access vein with severe AVF IH. No genes in any layer of AVF vein were significantly associated with severe AVF IH. From 1 st to 2 nd stage, more genes significantly changed expression in intima with severe AVF IH than intima without severe AVF IH (197/150 vs 144/93 for up/downregulated genes), while media (20/4 vs 149/31) and adventitia (99/27 vs 196/70) were the opposite; TGFB1, angiotensinogen, and TNF were more strongly activated in intima, while cell survival and migration were diminished in media and adventitia with severe AVF IH, respectively. Conclusion: Intima of pre-access vein has more genes associated with severe AVF IH. The layer-specific gene expression changes during AVF development and predicted functions are associated with AVF IH. These data can be used to develop layer-specific therapies to reduce AVF IH.

Ischemic monomelic neuropathy following arteriovenous fistula surgery: a case report

Ischemic monomelic neuropathy following arteriovenous fistula surgery: a case report

Efficacy of Using a Vessel Dilator during Surgery to Evaluate Vein Diameter and Predict Radiocephalic Arteriovenous Fistula Maturation and Patency

Background: We use vessel dilators to assess the diameter of the target vein during surgery for arteriovenous fistula (AVF) creation in hemodialysis patients. This study investigates the efficacy of using vein diameter as measured using dilators (surgical diameter; SD) versus that as measured by preoperative ultrasonography (ultrasonographic diameter; UD) to predict postoperative complications and patency. Methods: Sixty-three patients who underwent radiocephalic AVF creation and had measurements of UD and SD were retrospectively analyzed. Cutoff values for UD and SD regarding complications were used to dichotomize the patients into high and low groups for comparisons. Results: The 2-year primary and secondary patency rates overall were 66.5% and 88.9%, respectively. The optimal UD and SD cutoff values were 2.4 and 3.5 mm, respectively. The 2-year primary patency rate was higher in the high-SD group than the low-SD group (88.2% vs. 58.6%; p = 0.0426). The 2-year secondary patency rate was significantly higher in the high-UD/high-SD group than the low-UD/low-SD group (91.7% vs. 68.4%; p = 0.0067). Conclusions: Intraoperative measurement of vein diameter using dilators during AVF creation might be a useful method of predicting patency, particularly when SD is used in combination with UD.

Application of prophylactic flow restriction in brachiocephalic arteriovenous fistulas

To investigate the effects of prophylactic flow restriction for brachiocephalic arteriovenous fistula on postoperative high-flow-related complications and patency rate in patients undergoing hemodialysis. Clinical data of patients with end-stage renal disease who underwent brachiocephalic arteriovenous fistula surgery for hemodialysis from February 2017 to May 2022 in Department of Nephrology, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine were retrospectively analyzed. During surgery, a 4-5 mm vascular suture loop was placed around the vein near the anastomosis as a flow restriction device in 43 patients (flow restriction group), while 42 patients did not receive the prophylactic flow restriction ring (control group). All patients were followed up for 1 to 5 years. The incidence rates of complications related to the hemodialysis access pathway, including distal ischemia syndrome, the formation of arteriovenous fistula aneurysms, thrombus, high-flow congestive heart failure, anastomosis of the vein within 1 cm of the anastomosis and cephalic arch stenosis, were compared between the two groups. The natural blood flow rate of the arteriovenous fistula, anastomosis size, the internal diameter of the vein near the anastomosis, primary patency rate, assisted primary patency rate, and secondary patency rate of the arteriovenous fistula, were also evaluated and compared between the two groups. Logistic regression analysis was used to investigate the factors affecting arteriovenous fistula patency rates, as well as the impact of the flow-restricting ring on postoperative factors. Ultrasound measurements showed that the internal diameter of the vein at the site of the flow restriction ring in the flow restriction group was (3.7±0.6) mm at three months postoperatively, which was significantly smaller than the internal diameter of the narrowest part of the vein near the anastomosis in the control group [(4.1±1.0) mm, t=－2.416, P<0.01]. The postoperative anastomotic diameter and natural blood flow rate of the arteriovenous fistula in the flow restriction group were both significantly lower than those in the control group (both P<0.05). Furthermore, the incidence rates of various complications in the flow restriction group were significantly lower than those in the control group (all P<0.05). At 6, 12, and 24 months postoperatively, the primary patency rate and assisted primary patency rate in the flow restriction group were significantly higher than those in the control group (both P<0.05), while there was no significant difference in secondary patency rates between the two groups (P>0.05). Binary logistic regression analysis indicated that age, diabetes, and natural blood flow rate of the arteriovenous fistula at 3 months postoperatively were independent risk factors for primary patency rate, while the flow restriction for brachiocephalic arteriovenous fistula was an independent protective factor for primary patency rate (P<0.01 or P<0.05). The application of flow restriction was negatively correlated with anastomotic diameter at 6 and 12 months, natural arteriovenous fistula blood flow, and the incidence rates of cephalic arch stenosis and aneurysm formation (all P<0.05). The prophylactic constriction during brachiocephalic arteriovenous fistula surgery in patients undergoing hemodialysis can limit the size of the anastomosis and postoperative arteriovenous fistula blood flow, reducing complications such as cephalic arch stenosis and high-flow heart failure, and increasing primary patency rates of arteriovenous fistula and delay the reintervention of the fistula.

Clinical study on the establishment of radio-cephalic autogenous arteriovenous fistulas in small blood vessels by multi-segment balloon dilation technique.

To investigate the effect of dilating small blood vessels using a balloon dilation (BD) technique on the occurrence of radio-cephalic autogenous arteriovenous fistulas in terms of patency, blood flow, and vein diameter (VD). The subjects included in this study were all patients with chronic renal failure and required radio-cephalic arteriovenous fistula surgery for the first time and had not received dialysis before. Patients with VDs <2 mm were included as study subjects. They were either assigned treatment using a BD group or a control group that received hydrostatic dilation. The differences between the 2 groups were analyzed in terms of patency, blood flow, and VD. A total of 22 patients were enrolled in the balloon dilatation group and 20 patients in the control group. The diameters of cephalic veins (mm) of the experimental and control group were compared at various time points: immediately postoperation, 2.89 ± 0.42 versus 1.99 ± 0.28 (P < .001); 1 week later, 3.16 ± 0.59 versus 2.66 ± 0.60 (P = .022); 1 month later, 3.76 ± 0.91 versus 3.18 ± 0.83 (P = .087); and 2 months later, 4.08 ± 1.15 versus 3.38 ± 1.13 (P = .169). Brachial artery flows (mL/min) of the 2 groups at various time points were given as follows: immediately postoperation, 413.49 ± 145.09 versus 235.61 ± 87.77 (P < .001); 1 week later, 563.26 ± 206.83 versus 331.30 ± 126.78 (P < .001); 1 month later, 679.34 ± 218.56 versus 376.79 ± 156.25 (P < .001); and 2 months later, 736.31 ± 202.61 versus 394.60 ± 161.96 (P < .001). The primary patency at 1 year for the experimental group was 61.9% compared to 11.1% for the control group (P = .045). Similarly, the secondary patency rates at 1 year were 90.5% for the experimental group and 55.6% for the control group (P = .030). The results showed that the functional primary patency rate within 1 year was 57.1% versus 16.7% (P = .032), and the functional secondary patency rate within 1 year was 85.7% versus 50.0% (P = .038). BD has obvious advantages over hydrostatic dilation for chronic renal failure patients with small veins in establishing arteriovenous fistula in terms of patency and blood flow.

Comprehensive Clinical Profile and Hemodialysis Outcomes in Patients Attending a Tertiary Care Hospital.

Background Chronic kidney disease (CKD) can lead to serious conditions such as anemia and cardiovascular disease, posing a growing global health challenge. End-stage renal disease (ESRD) requires treatments such as dialysis or kidney transplantation. Despite the widespread impact and rising prevalence of CKD and ESRD, comprehensive data remains limited in India. This study seeks to investigate the clinical, socio-demographic, and etiological profiles of CKD patients undergoing hemodialysis at a tertiary care hospital, with the goal of enhancing understanding and improving patient care. Methodology This retrospective cohort study, conducted at a tertiary care center, included 500 CKD patients undergoing hemodialysis, with comprehensive medical records. Data collected covered demographics (age, sex, education, and occupation), CKD etiology, disease duration, hemodialysis duration, viral marker status, blood transfusions, and vascular access details. With continuous variables reported as mean ± standard deviation (SD) and categorical variables as counts (percentages), statistical analysis was carried out using SPSS version 21 (IBM Corp., Armonk, New York, USA). The connections were examined using the Pearson Chi-square test, with P≤0.05 being deemed significant. Results The study revealed that hypertension was the primary cause of CKD in 58% of patients, followed by diabetes mellitus in 13%. A significant 93% of patients tested negative for viral markers such as human immunodeficiency virus (HIV), hepatitis C virus (HCV), and hepatitis B surface antigen (HBsAg). Hemodialysis duration varied, with 68% of patients undergoing dialysis for one to five years. Most patients had two (40%) or three (58%) dialysis sessions per week, and 84% had only one arteriovenous (AV) fistula surgery. Blood transfusions were common, with 62% of patients receiving between one and five transfusions. The gender distribution showed more males (372) than females (201), and the majority of patients were aged between 41 and 60 years. Conclusion This study highlights the importance of early detection and management of CKD, emphasizing preventive health measures, enhanced diagnostic capabilities, and sufficient resource allocation to reduce the disease burden. It also calls for further research into unknown CKD causes and strategies to improve patient care and outcomes.

Reliable Stenosis Detection Based on Thrill Waveform Analysis Using Non-Contact Arteriovenous Fistula Imaging.

Hemodialysis therapy is an extracorporeal circulation treatment that serves as a substitute for renal function. In Japan, patients receive this efficient four-hour treatment, three times per week, allowing them to maintain a social life nearly equivalent to that of healthy individuals. Before the treatment, two punctures are performed to establish extracorporeal circulation, and a high blood flow rate is essential to ensure efficient therapy. Specialized blood vessels created through arteriovenous fistula (AVF) surgery are utilized to achieve high blood flow rates. Although the AVF allows safe and efficient dialysis treatment, AVF stenosis leads to a serious problem in dialysis. To early detect this abnormal blood flow, auscultation and palpation methods are widely used in hospitals. However, these methods can only provide qualitative judgment of the AVF condition, so the results cannot be shared among other doctors and staff. Additionally, since the conventional methods require contact with the skin, some issues require consideration regarding infection and low reproducibility. In our previous study, we proposed an alternative method for auscultation using non-contact optical imaging technology. This study aims to construct a reliable AVF stenosis detection method using Thrill waveform analysis based on the developed non-contact device to solve the problem with the contact palpation method. This paper demonstrates the performance validation of the non-contact imaging in the normal AVF group (206 total data, 75 patients, mean age: 69.1 years) and in the treatable stenosis group (107 total data, 17 patients, mean age: 70.1 years). The experimental results of the Mann-Whitney U test showed a significant difference (p=0.0002) between the normal and abnormal groups, which indicated the effectiveness of the proposed method as a new possible alternative to palpation.

Vein distensibility is superior to vein diameter for predicting unassisted maturation of arteriovenous fistulae

BackgroundA mature arteriovenous fistula (AVF) is the preferred hemodialysis access owing to its durability and lower risk of complications. Various factors have been implicated as predictors for maturation, including vein diameter and access type. Vein distensibility, which refers to the ability of the vein to dilate in response to changes in blood flow and pressure, has been proposed as a potential predictor for maturation, but its utility remains poorly studied. MethodsThis is a single-institution retrospective study of AVFs performed under regional anesthesia. Vein distensibility was defined as the absolute and relative difference in target vein diameter (TVD) between the preoperative ultrasound vein mapping performed with tourniquet and a repeat ultrasound examination after a regional block before AVF creation and without a tourniquet. ResultsForty-six patients underwent first-time AVF surgery with distensibility recorded in a prospectively maintained database. The mean initial preoperative TVD was 2.7 mm, and after the block 3.4 mm. The unassisted maturation rate for the entire cohort was 76%. In patients with an absolute change of TVD of <0.5 mm (Δ<0.5), the unassisted maturation rate was 63% (12/19), even though 95% of the group had a preoperative TVD of >3 mm. In those with ≥0.5 mm, the unassisted maturation rate was 85% (23/27; P = .08), even though the preoperative vein map TVD was 2.3 mm and 75% had a vein map TVD of <3 mm. For radiocephalic AVFs (n = 26), the unassisted maturation rate was 75% for Δ<0.5 vs 94% for Δ≥0.5 (P = .16), despite a preoperative vein map TVD of >3 mm in 92% vs 75%, respectively. The receiver operatring characteristic area under the curve for unassisted maturation with a Δ≥0.5 mm was 0.68 (P = .26). ConclusionsQuality in dialysis access surgery requires optimizing the unassisted maturation rate. A physiological measure that accounts for the dynamic process of maturation may be more informative than anatomic measurements alone. The results shown here demonstrate that vein distensibility may be a better predictor than absolute vein diameter on standard vein mapping ultrasound examinations.

Comparative study on efficacy of ultrasound-guided supraclavicular versus costoclavicular brachial plexus block in patients for arteriovenous fistula surgery

Background: Patients with end-stage renal failure (ESRF) who require arteriovenous fistula (AVF) creation often have multiple comorbidities, making the brachial plexus block a suitable choice for anaesthesia. The objective of this study is to compare the efficacy of ultrasound-guided supraclavicular and costoclavicular brachial plexus blocks for AVF creation. Methods: A total of 70 patients scheduled for the creation of AVF in the distal upper extremity were randomly assigned to 2 groups: supraclavicular block (SCB), Group A: n = 35, and costoclavicular block (CCB), Group B: n = 35. Both groups received 20 ml of 0.5% ropivacaine and 10 ml of 1% lidocaine. The measured parameters included the speed of onset of motor and sensory blockade, the quality of blockade, procedural-related pain score, patient satisfaction, and regional perfusion. Results: The costoclavicular block demonstrated a significantly faster onset to achieve complete paralysis (p = 0.01) in all sensory and motor nerves compared to the supraclavicular block. Additionally, there was a significant difference in regional perfusion, with higher perfusion observed in the supraclavicular block (p = 0.013). However, there were no significant differences in the quality of block (p = 0.573), and procedural-related pain score (p = 0.117) between the 2 groups. Conclusion: The costoclavicular block offers a faster onset of sensory and motor blockade compared to the supraclavicular block. However, they are comparable in terms of the quality of the block and procedural-related pain. This new technique can be considered as an alternative for providing anaesthesia in patients with ESRFundergoing AVF creation.

#3008 Very low protein diet with ketoanalogues supplementation could start haemodialysis with AVF without additional CVCs insertion

Abstract Background and Aims Nutritional interventions and a low-protein diet (LPD) are a critical point in the management of chronic kidney disease (CKD). Several protein-restricted dietary regimens have been proposed in patients with end stage kidney disease: a typical LPD provides around 0.6–0.7 g·kg meanwhile a very low-protein diet (VLPD) provides around 0.3–0.4 g·kg and it is basically a vegetarian diet which has to be supplemented with essential amino acids (EAA) to satisfy the body nitrogen need and with nitrogen-free ketoanalogues (KA) to recirculate the endogenous urea, whose serum levels are elevated in patients with CKD. KA and EAA reduce the rate of progression of chronic kidney disease and improve the inflammatory state; they reduce the absorption of phosphates and can maintain a good state of nutrition even if associated with diets with very low protein content. On the contrary, an excessively restrictive and inadequate diet in terms of EAA or calorie intake induces a negative nitrogen balance, therefore cachexia. The recommended vascular access to start dialysis treatment is represented by the arteriovenous fistula (AVF). An early referral to the vascular surgeon for vascular access creation is pivotal for deciding on a patient-specific strategy for planning access. Guidelines advise referral at least 3–6 months before the expected start of HD, because time is needed for AVF maturation and possible repeat interventions when it is impaired. An early referral results in more autologous AVFs, which have a better long-term patency, whereas late referral, results in a greater risk of AVF non-maturation and failure and therefore the need for additional central venous catheters (CVCs) to initiate dialysis. Recent studies have shown that pre-dialysis patients who undergo a VLDP + KA require less emergency dialysis access and have better elasticity of the arterial wall, better maturation rates and duration of the AVF and sometimes a reduction in the uremic toxins responsible of endothelial dysfunction. The aim of the study was to evaluate if patients could start haemodialysis with fistula cannulation, without central venous catheter insertion. Method 10 patients, late referral end stage renal disease were enrolled in a prospective, single arm study starting very low protein diet supplemented with ketoanalogues after arteriovenous fistula creation; they were followed with periodically assessment of renal function, uremic toxin, and acid-base balance until they need to start haemodialysis. It was evaluated AVF maturation and needs to additional CVC insertion. Results Patients (3 females, 7 males) mean age was 71.2 years; before AVF creation, baseline mean value was: sCr: 6.46 mg/dl, sUrea: 150 mg/dl, phosphorus: 4.45 mg/dl, bicarbonates: 19.8 mmol/l, eGFR: 8,37 ml/min. After 3 months of VLPD supplemented with KA, eGFR and sCr was stable to 8.25 ml/min and 6.69 respectively, sUrea and phosphorus reduced to 115 mg/dl and 3.8 mg/dl, and bicarbonate increased to 22.4 mmol/l. All 10 patients achieved AVF maturation within 3 months, no one needed CVC insertion. Conclusion In this small group we see how late referral ESRD patients, undergone AVF surgery, after 3 months of VLPD supplemented with KA, had stability of renal function, with reduction of urea and phosphorus, improvement of acid-base balance and achievement of AVF maturation, without needing of CVC insertion. For these reasons VLPD + KA could be useful in delaying haemodialysis start in late referral ESRD patients who have created AVF, without emergency placement of a central venous catheter.

Heat therapy preconditioning improves the skeletal muscle contractile and mitochondrial function in a mouse model of access-related hand dysfunction

Introduction: Hemodialysis via arteriovenous fistula (AVF) is a life-line treatment for patients with end-stage kidney disease. However, hemodialysis access-related hand dysfunction (ARHD) including ischemia, muscle weakness and alterations in mitochondrial function is prevalent following AVF placement. We tested the hypothesis that two-weeks of daily heat therapy prior to AVF surgery would improve hindlimb function in a mouse model of ARHD. Methods: Adult male C57BL/6J mice (N=9-11/group) were fed a 0.2% adenine diet to induce chronic kidney disease. Following two weeks of the initial adenine diet, animals were randomly allocated to heat therapy (HT) or control (CON) groups. Animals assigned to HT were exposed to environmental heat at 40°C in a climate chamber for 30 min/day, six days/week, for two weeks while the control mice were exposed to room temperature (~22°C). The AVF was created using the left common iliac artery and vein 24-48 hours after the last treatment session. Laser Doppler perfusion to the ventral paw was assessed post-operatively (POD) and AVF patency was verified using a high-frequency duplex ultrasound system three days prior to euthanasia. Following 14 days of recovery, in situ tibialis anterior (TA) muscle contractility and gastrocnemius muscle mitochondrial function were assessed. RNA sequencing analysis of the hindlimb skeletal muscle (N=4/group) was performed. Results: Compared to baseline, the level of blood urea nitrogen was similarly elevated ( P&lt;0.05) in both groups following four weeks of adenine diet. In both groups, blood perfusion to the paw was decreased by ~50% immediately after AVF creation and progressively recovered to ~80% at POD13 without a treatment effect ( P=0.4467). No differences in body weight and muscle mass in the TA, extensor digitorum longus, and soleus muscles were observed (all P&gt;0.05). Notably, however, the absolute ( P=0.0250) and specific force ( P=0.0101) frequency relationship of the TA muscle were significantly improved in the animals exposed to HT. In addition, compared with control animals, HT mice had significant improvement in oxidative phosphorylation (OXPHOS) in both pyruvate ( P=0.0145) and octanoylcarnitine ( P=0.0196) fueled conditions. RNA sequencing results revealed that genes involved in nervous system development and metabolism were significantly different between HT and CON groups. Conclusion: Daily application of heat therapy for two weeks prior to the AVF surgery has beneficial effects on both skeletal muscle contractile and mitochondrial function suggesting this pre-habilitation strategy may mitigate the risk of ARHD in patients undergoing AVF surgery. 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 2024 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.

Digital exoscope versus surgical microscope in spinal dural arteriovenous fistula surgery: a comparative series.

Surgical treatment of spinal dural arteriovenous fistulas (DAVFs) has been reported to be superior to endovascular treatment in terms of occlusion of the fistula. Despite the increased availability of digital 3D exoscopes, the potential benefits of using an exoscope in spinal DAVF surgery have not been studied. The purpose of this study was to report and compare the results of exoscope- and microscope-assisted surgery for spinal DAVFs. All consecutive adult patients (≥ 18 years of age) treated surgically for spinal DAVFs from January 2016 to January 2023 in a tertiary neurosurgical referral center were included. All patients were operated on by one neurosurgeon. Their pre- and postoperative clinical findings, imaging studies, and intra- and postoperative events were evaluated and surgical videos from the operations were analyzed. Altogether, 14 patients received an operation for spinal DAVF during the study period, 10 (71%) with an exoscope and 4 (29%) with a microscope. The DAVFs were most commonly located in the lower parts of the thoracic spine in both groups. The duration of exoscopic surgeries was shorter (141 vs 151 minutes) and there was less blood loss (60 vs 100 ml) than with microscopic surgeries. No major surgical complications were observed in either group. Of the 14 patients, 10 had gait improvement postoperatively: 7 (78%) patients in the exoscope group and 3 (75%) in the microscope group. None of the patients experienced deterioration following surgery. Exoscope-assisted surgery for spinal DAVFs is comparable in safety and effectiveness to traditional microscopic surgery. With practice, experienced neurosurgeons can adapt to using the exoscope without major additional risks to the patient.

Comparative analysis of RADAR vs. conventional techniques for AVF maturation in patients with blood viscosity and vessel elasticity-related diseases through fluid-structure interaction modeling: Anemia, hypertension, and diabetes.

This study aims to compare two surgical techniques, the standard Vein-to-Artery and the newer Artery-to-Vein (Radial Artery Deviation And Reimplantation; RADAR), for enhancing the success of Arterio-Venous Fistula maturation in end-stage renal disease patients. The impact of diseases like anemia, diabetes, hypertension, and chronic kidney disease were considered. The goals are to advance Arterio-Venous Fistula (AVF) surgery, improve patient outcomes, and contribute to evidence-based surgical guidelines. Fluid-structure interaction modeling was employed to investigate how hemodynamic and mechanical stresses impact arteriovenous fistula maturation, with a particular focus on the role of wall shear stress in determining maturation outcomes. The critical threshold for vessel injury was identified as wall shear stress values exceeding 35 N/m2, while stenosis formation was projected to occur at levels below 1 N/m2. This work introduced a novel approach by considering disease-related factors, including blood viscosity (anemia), and vessel elasticity (diabetes, hypertension, and chronic kidney diseases), which directly influence hemodynamics and the generation of wall shear stress. Furthermore, the model was designed to incorporate varying thicknesses and elasticities for both the vein and artery, accurately representing authentic vascular anatomy. The RADAR technique has demonstrated superior performance compared to the standard technique by providing appropriate wall shear stress in critical regions and minimizing the risk of wall damage. Its use of a thicker vessel also reduces the risk of vessel injury, making it particularly effective for patients with Chronic Kidney Disease (CKD), hypertension, anemia, and diabetes, ensuring optimal blood flow and fewer complications. However, there are minor concerns about stenosis formation in hypertension and anemia cases, which could be mitigated by adjusting the anastomosis angle to be lower than 30°. Diabetes and hypertension have significant physiological effects that increase the risks associated with arteriovenous fistula maturation. The anemic condition resulting from CKD may help reduce vessel injury but raises concerns about potential stenosis formation. Despite these co-morbidities, the RADAR technique has demonstrated its ability to induce more favorable hemodynamic changes, promoting arteriovenous fistula maturation.

Predicting factors for early failure of vascular access in hemodialysis patients.

This study aimed to investigate the incidence of early failure of vascular access for hemodialysis, and determine which factors measured in duplex ultrasound study could predict early failure. We performed a retrospective review of patients who underwent arteriovenous fistula (AVF) or arteriovenous graft (AVG) creation for hemodialysis between September 2019 and January 2023. Early failure was defined as any event that required surgical or endovascular intervention within 6 months following AVF or AVG creation. A total of 189 patients were included. Early failure occurred in 36 patients (19.0%), which included 22 AVFs and 14 AVGs. In the patients who underwent AVF, the preoperative venous diameter, postoperative venous and arterial diameters, and flow volume of AVF all were significantly smaller in the early failure group compared to the patent group. In AVG, the preoperative venous diameter was the only parameter that differed between the 2 groups. A sonographic score was defined based on these factors. In a multivariable analysis, male sex, a previous history of AVF or AVG creation, and sonographic score were found to be significantly associated with early failure. The postoperative venous diameter in AVF and the preoperative venous diameter in AVG were highly predictive of early failure (areas under the curves 0.92 and 0.82, respectively). Venous diameter measured 6 weeks following AVF operation and preoperative venous diameter in AVG were highly predictive of early failure among the duplex ultrasound parameters. Surveillance strategies in the early phase following vascular access creation can be based on these factors.

A rare case report: compartment syndrome after brachiocephalic arteriovenous fistula formation in a hemodialysis patient

Introduction: Acute compartment syndrome is a condition in which increased pressure in the tight fascia space reduces capillary perfusion below the level required for tissue viability. Very few cases of acute compartment syndrome associated with dialysis have been reported. It can lead to severe damage to the tissues of the arm. Case Illustration: A 47-year-old woman with end-stage renal failure presented to the emergency room with swelling and pain in the right upper extremity and has lasted for a day. Three days before admission, the patient underwent right brachiocephalic arteriovenous (AV) fistula surgery. Physical Examination showed a blackish bruise at the fossa cubiti, radial and ulnar artery were not palpable, but there is trill at AV fistula. Decreased motoric strength, reduced hand sensation and decreased capillary return in fingers. Oxygen blood saturation of the right fingers could not be read. Diagnosis of acute compartment syndrome was made. The patient was immediately taken to the operating room for decompression surgery. Emergency compartment fasciotomy was performed. After fasciotomy, necrotomy was performed. Furthermore, brachiocephalic AV fistula was ligated. Postoperative evaluation obtained good radial and ulnar artery. Six months after the surgery, the wound was fully healed and no sign of neuromuscular or vascular deficit. Conclusion: Compartment syndrome is a possible complication after AV fistula formation that can have disastrous consequences. However, it can be effectively treated if detected and treated early. Prognosis of compartment syndrome after fasciotomy depends on how quickly the condition is diagnosed and treated.

Early arteriovenous fistula failure associated with mortality and major adverse cardiovascular events in patients undergoing incident hemodialysis.

Arteriovenous fistula (AVF) patency is important for patients undergoing hemodialysis. The association between early AVF failure and the prognosis, including all-cause mortality and major adverse cardiovascular events (MACE), has not been fully investigated. The present study was performed to investigate the association between early AVF failure and 3-year mortality, cardiovascular disease (CVD) mortality, and MACE. We analyzed 358 patients who started hemodialysis in our institution from October 2008 to February 2020. We defined early AVF failure as cases requiring percutaneous transluminal angioplasty or reoperation within 1 year after AVF surgery. The patients were divided into two groups according to the presence or absence of early AVF failure, and the prognosis of each group was examined. The association between early AVF failure and outcomes (3-year all-cause mortality, CVD mortality, and MACE) was determined using Cox proportional hazards regression analysis. During the 3-year follow-up, 75 (20.9%) patients died (cardiovascular death: n = 39) and 145 patients developed MACE. According to the multivariable analysis, the early AVF failure group had a significantly higher risk of 3-year all-cause mortality (hazard ratio [HR], 1.42; 95% confidence interval [CI], 1.09-1.83; p = 0.009), CVD mortality (HR, 1.54; 95% CI, 1.29-2.08; p < 0.001), and MACE (HR, 1.68; 95% CI, 1.25-2.26; p < 0.001). When the patients were stratified by age, early AVF failure was associated with 3-year all-cause mortality in all groups except for the younger group (<65 years of age). Early AVF failure was associated with an increased risk of 3-year all-cause mortality, CVD mortality, and MACE.

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.

Slowly moving the needle away from Fistula First

ObjectiveIn 2019, the management of end-stage kidney disease (ESKD) shifted away from “Fistula First” (FF) to “ESKD Life-Plan: Patient Life-Plan First then Access Needs.” Indeed, some patients exhibit such excessive comorbidity that even relatively minor vascular surgery may be complicated. The purpose of this study was to retrospectively assess complications and mortality (and delineate operative futility) in patients undergoing arteriovenous fistula (AVF) creation in the FF era. MethodsConsecutive AVFs created in a single institution before 2021 were retrospectively reviewed. Operative futility was defined as never-accessed fistula, no initiation of dialysis, failure of access maturation (despite secondary intervention), hemodialysis access-induced distal ischemia requiring ligation, early loss of secondary patency, and/or patient mortality within the first 6 postoperative months. ResultsA total of 401 AVFs were created including radial-cephalic (44%), brachial-cephalic (41%), and brachial-basilic (15%) constructions. Patients exhibited a mean age of 69 ± 15 years; 63% were male, and most (74%) were already being hemodialyzed at the time of fistula creation. Forty-five patients (11%) suffered a cardiac event, and five patients died (1%) within 90 days of their access surgery. Perioperative cardiac events were significantly more common after age 80 (19% vs 8%; P = .004); age >80 years was an independent predictor of major 90-day complications (odds ratio [OR], 1.88; 95% confidence interval [CI], 1.04-3.39; P = .036) and the sole independent predictor of major morbidity defined as cardiopulmonary complications, stroke, or death within the first year (OR, 2.01; 95% CI, 1.24-3.25; P = .004). Operative futility was encountered in 52% of the cohort (n = 208 patients): 40% (n = 160) of primary AVFs failed to mature despite assistance, 19% (n = 77) had lost secondary patency by 6 months, 13% of patients (n = 53) were never started on dialysis after access creation, 4% (n = 16) were dead by 6 months, 2% of AVFs (n = 10) matured but were never accessed, and 2% (n = 9) required ligation for hemodialysis access-induced distal ischemia. Not surprisingly, the sole independent protector against operative futility was that catheter-based dialysis had been established prior to AVF creation (OR, 0.36; 95% CI, 0.22-0.59; P < .01). ConclusionsApproximately 50% of primary AVF operations performed in the aggressive FF era were deemed futile. Octogenarians were particularly prone to futility and complications during this era. A paradigm shift, from FF to an “ESKD Life-Plan” will, hopefully, more thoughtfully match vascular access strategies to individual patient needs.

Arteriovenöz Fistül Cerrahisinde Rejyonal ve Lokal Anestezi Karşılaştırması: Tek Merkezli Bir Araştırma

Background: This retrospective study aimed to compare the outcomes of regional anesthesia and local anesthesia techniques in arteriovenous fistula operations, focusing on early patency rates, operation time, and postoperative pain. Methods: A total of 77 arteriovenous fistula and arteriovenous graft operations performed between April 2020 and April 2023 on adult patients with chronic renal failure were analyzed. The patients were divided into two groups based on the anesthesia technique: Group-1 (n=49) received local anesthesia, while Group-2 (n=28) received regional anesthesia. Results: The majority of operations in the local anesthesia group involved radio-cephalic arteriovenous fistula, while brachio-cephalic, brachio-basilic arteriovenous fistula, and arteriovenous grafts were predominantly performed in the regional anesthesia group. There was no significant difference in operation time between the two groups. However, the regional anesthesia group had a significantly lower need for pain relief within the first 24 hours postoperatively. There were no significant differences in early postoperative fistula failure or bleeding/hematoma between the groups. One case of local wound infection was observed in each group during post-discharge follow-up. Conclusion: This retrospective analysis suggests that regional anesthesia provides superior pain control in the first 24 hours following arteriovenous fistula surgery compared to local anesthesia. Regional anesthesia is a safe and effective technique and may be preferred for more sophisticated arteriovenous fistula procedures.

Developing the surgeon-machine interface: using a novel instance-segmentation framework for intraoperative landmark labelling.

The utilisation of artificial intelligence (AI) augments intraoperative safety, surgical training, and patient outcomes. We introduce the term Surgeon-Machine Interface (SMI) to describe this innovative intersection between surgeons and machine inference. A custom deep computer vision (CV) architecture within a sparse labelling paradigm was developed, specifically tailored to conceptualise the SMI. This platform demonstrates the ability to perform instance segmentation on anatomical landmarks and tools from a single open spinal dural arteriovenous fistula (dAVF) surgery video dataset. Our custom deep convolutional neural network was based on SOLOv2 architecture for precise, instance-level segmentation of surgical video data. Test video consisted of 8520 frames, with sparse labelling of only 133 frames annotated for training. Accuracy and inference time, assessed using F1-score and mean Average Precision (mAP), were compared against current state-of-the-art architectures on a separate test set of 85 additionally annotated frames. Our SMI demonstrated superior accuracy and computing speed compared to these frameworks. The F1-score and mAP achieved by our platform were 17% and 15.2% respectively, surpassing MaskRCNN (15.2%, 13.9%), YOLOv3 (5.4%, 11.9%), and SOLOv2 (3.1%, 10.4%). Considering detections that exceeded the Intersection over Union threshold of 50%, our platform achieved an impressive F1-score of 44.2% and mAP of 46.3%, outperforming MaskRCNN (41.3%, 43.5%), YOLOv3 (15%, 34.1%), and SOLOv2 (9%, 32.3%). Our platform demonstrated the fastest inference time (88ms), compared to MaskRCNN (90ms), SOLOV2 (100ms), and YOLOv3 (106ms). Finally, the minimal amount of training set demonstrated a good generalisation performance -our architecture successfully identified objects in a frame that were not included in the training or validation frames, indicating its ability to handle out-of-domain scenarios. We present our development of an innovative intraoperative SMI to demonstrate the future promise of advanced CV in the surgical domain. Through successful implementation in a microscopic dAVF surgery, our framework demonstrates superior performance over current state-of-the-art segmentation architectures in intraoperative landmark guidance with high sample efficiency, representing the most advanced AI-enabled surgical inference platform to date. Our future goals include transfer learning paradigms for scaling to additional surgery types, addressing clinical and technical limitations for performing real-time decoding, and ultimate enablement of a real-time neurosurgical guidance platform.