Computational Analysis of Turbulent Hemodynamics in Radiocephalic Arteriovenous Fistulas to Determine the Best Anastomotic Angles

Prouse, Giorgio; Stella, Simone; Vergara, Christian; Quarteroni, Alfio; Engelberger, Stephan; Canevascini, Reto; Giovannacci, Luca

doi:10.1016/j.avsg.2020.04.004

Cited by 7 publications

(6 citation statements)

References 31 publications

(7 reference statements)

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“…When the vein exits the anastomosis stoma at 90° anastomotic angle using functional ETS anastomosis, the vein will show obvious angulation deformity and possibly narrow the diameter of the vein, which is different from traditional ETS anastomosis. Several studies have shown that 30–45°, 60–70°, 135°in traditional ETS anastomosis might be good anastomotic angle analyzed by the flow pattern in models of AVF using three-dimensional grids and computational modeling [ 11 – 14 ]. Therefore, in our study of functional ETS anastomosis, if the artery and vein were far apart, we tried to form an acute angle of less than 70° or a smooth obtuse angle of 135° by fully separating the vein.…”

Section: Discussionmentioning

confidence: 99%

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Comparison of different anastomosis angles in radiocephalic fistula with modified functional end-to-side anastomosis

Wang¹,

Lu²,

Tang³

et al. 2023

Int Urol Nephrol

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Objective Functional vein end to arterial side (ETS) anastomosis uses vein side to arterial side anastomosis with distal vein ligation, which is different from traditional ETS anastomosis. To date, there are no studies concerning different anastomotic angles of fistula with functional ETS anastomosis. The purpose of the study was to analyze the clinical outcomes concerning different anastomotic angles of functional ETS anastomosis in radiocephalic fistula. Methods Between January 2018 and December 2020, we performed a prospective cohort study concerning functional ETS anastomosis in radiocephalic fistula. According to vascular anatomy of patients, the anastomosis angles of fistula were designed at 30 ≤ angle ≤ 50°, 50 < angle ≤ 70°, and 135° smooth obtuse angle. The end points were the primary patency rate (PPR), the secondary patency rate (SPR) and the cumulative rate of reintervention (CRR) near anastomotic venous segment. Results 124 patients with functional ETS anastomosiss were enrolled in this study. Pearson χ2 test showed that the group of 135°anastomosis angle had the maximum distance between arteries and veins, and the group of 30–50°anastomosis angle had the minimum distance between arteries and veins (P < 0.01). 30–50°anastomosis angle had the highest PPR at 12 months (P = 0.03) and the lowest CRR near anastomotic venous segment at 3 months (P = 0.04) and 12 months (P = 0.01). There were no significant differences among different anastomosis angles concerning the SPR within 12 months (P > 0.05). Kaplan–Meier and log-rank analysis showed that 30–50°anastomosis had the highest PPR (P = 0.03) and the lowest CRR near anastomotic venous segment (P = 0.01). A multivariable Cox model showed anastomotic angle was an independent factor predictive of the PPR (P = 0.04) and the CRR near anastomotic venous segment (P = 0.03). 50–70°anastomosis angle was a risk factor of decreasing PPR (P = 0.03). 50–70° (P = 0.01) and 135° (P = 0.03) anastomosis angle were both obvious risk factors of increasing CRR near anastomotic venous segment. Conclusion 30–50°were the best anastomotic angles for functional ETS anastomosis, which had the highest PPR and lowest CRR near anastomotic venous segment.

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Section: Discussionmentioning

confidence: 99%

“…The best anastomosis angles of traditional ETS anastomosis were different in the different studies. The study of Prouse showed the best anastomosis angles approached 60–70° [ 11 ]. The study of Lee showed the best anastomosis angle was 135° [ 12 ].…”

Section: Introductionmentioning

confidence: 99%

Comparison of different anastomosis angles in radiocephalic fistula with modified functional end-to-side anastomosis

Wang¹,

Lu²,

Tang³

et al. 2023

Int Urol Nephrol

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“…Diagrammatic of AVF failure is demonstrated in Fig 1 . Furthermore, disturbed flow, characterized by low and reciprocating flow, may develop in zones of the AVF, indicating the sites of future stenoses [6]. Vessel stenosis formation tends to occur in areas of disturbed flow [32,42,43]. To reduce the rate of AVF immaturity from stenosis formation, hemodynamics should be optimized by creating more laminar flow transition at the curved vessel region as much as possible [44].…”

Section: Formulation Of the Problemmentioning

confidence: 99%

“…This advanced modeling approach incorporates different thicknesses and elasticities between the vein and artery, closely mimicking actual vascular anatomy and properties compared to previous works. This advanced modeling approach has demonstrated success in predicting AVF behavior, preventing maturation failure [ 32 ], and contributing to a better understanding of vascular biology, ultimately leading to improved solutions for AVF creation [ 33 ].…”

Section: Introductionmentioning

confidence: 99%

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

Wongchadakul,

Lohasammakul,

Rattanadecho

2024

PLoS ONE

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Purpose 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. Methods 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. Results 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°. Conclusion 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.

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“…References [4][5][6] pointed out that the RCAVF maturity is closely related to D ra and D cv . References [7][8][9][10][11] are based on numerical simulations of different RCAVF shapes to enforce that θ has an impact on the hemodynamic distribution in a fistula by observing the wall shear stress. However, these previous works do not offer theoretical explanations, and literature about the hemodynamic conditions in a recent AVF remains poor.…”

Section: Introductionmentioning

confidence: 99%

Optimization of Maturation of Radio-Cephalic Arteriovenous Fistula Using a Model Relating Energy Loss Rate and Vascular Geometric Parameters

Yang¹,

Schiava²,

Kulisa³

et al. 2021

JBiSE

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The main reason for the early failure of radio-cephalic arteriovenous fistula (RCAVF) is non-maturity, which means that the blood flow rate in the fistula cannot increase to the expected value for dialysis. From a mechanical perspective, the vascular resistance at the artificially designed anastomosis causes an energy loss that affects blood flow rate growth and leads to early failure. This research studied how to maximize the RCAVF maturity and primary patency by controlling the energy loss rate. We theoretically analyzed and derived a model that evaluates the energy loss rate E avf in RCAVF as a function of its blood vessel geometric parameters (GPs) for given flow rates. There was an aggregate of five controllable GPs in RCAVF: radial artery diameter (D ra ), cephalic vein diameter (D cv ), blood vessel distance between artery and vein (h), anastomotic diameter (D a ), and anastomotic angle (θ).Through this analysis, it was found that E avf was inversely proportional to D ra , D cv , D a , and θ, whereas proportional to h. Therefore, we recommended surgeons choose the vessels with large diameters, close distance, and increase the diameter and angle of the anastomosis to decrease the early failure of RCAVF. Simultaneously, we could explain the results of many clinical empiricisms with our formula. We found that increasing D cv and θ was more significant in reducing E avf than increasing D ra and D a . Based on our model, we could define two critical energy loss rates (CEL a , CEL b ) to help surgeons evaluate the blood vessels and

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Computational Analysis of Turbulent Hemodynamics in Radiocephalic Arteriovenous Fistulas to Determine the Best Anastomotic Angles

Cited by 7 publications

References 31 publications

Comparison of different anastomosis angles in radiocephalic fistula with modified functional end-to-side anastomosis

Comparison of different anastomosis angles in radiocephalic fistula with modified functional end-to-side anastomosis

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

Optimization of Maturation of Radio-Cephalic Arteriovenous Fistula Using a Model Relating Energy Loss Rate and Vascular Geometric Parameters

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