Vaso-Lock for sutureless anastomosis in a pig arteriovenous loop model.

A vascular anastomosis is a critical surgical skill that involves connecting blood vessels. Traditional handsewn techniques can be challenging and resource intensive. To address these issues, we have developed a unique sutureless anastomotic device called Vaso-Lock. This intraluminal device connects free vascular ends using anchors to maintain traction and enable a rapid anastomosis. We tested the anastomotic capability of Vaso-Locks in a pig common carotid-internal jugular arteriovenous model. The use of Vaso-Lock allowed us to accomplish this procedure in less than 10 min, in contrast to the approximately 40 min required for a handsewn anastomosis. The Vaso-Lock effectively maintained patency for at least 6 weeks without causing significant tissue damage. Histological analysis revealed that the device was successfully incorporated into the arterial wall, promoting a natural healing process. Additionally, organ evaluations indicated no adverse effects from using the Vaso-Lock. Our findings support the safety and effectiveness of the Vaso-Lock for arteriovenous anastomosis in pigs, with potential applicability for translation to humans. Our novel sutureless device has the potential to advance surgical practice and improve patient outcomes.

Arterio-venous Anastomoses of the Sucquet-Hoyer Type: Complexity and Distribution in the Human Dermis.

Our study aims at providing detailed information on numbers, form, and spatial distribution of arterio-venous anastomoses of the Sucquet-Hoyer type in the dermis of the nail bed, nail fold corner, thumb pad, arm, nose, glabella, lip, and ear. It further aims at providing a system, which relies on objective morphologic criteria for classifying Sucquet-Hoyer canals (SHCs). Using high-resolution episcopic microscopy (HREM), digital volume data of eight samples of each skin region were produced. Virtual three-dimensional (3D) models of the dermally located SHCs were created, and their 3D tortuosity (τ) values were determined. Dermal SHCs were identified in all 24 finger samples and in 1 lip sample. Beneath a field of 2 × 2 mm2, an average of four were located in the nail bed, three in the dermis of the thumb pad, and one in the dermis of the nail fold corner. Only a single dermal SHC was found in one lip sample. No SHCs were observed in the dermis of the other samples. The τ values of the SHCs ranged from 1.11 to 10. Building on these values, a classification system was designed, which distinguishes four SHC classes. The dermal distribution of the SHCs of different classes was similar in all specimens.

Small Arteriovenous Anastomosis in Fistula Creation: Establishing a Functional Vascular Access while Minimizing Steal Syndrome.

BACKGROUND: The size selection of the arteriovenous (AV) anastomosis in dialysis access creation requires a careful balance: the diameter must be large enough to accommodate sufficient flow for hemodialysis but small enough to minimize the complication of steal syndrome. Steal syndrome affects up to 10% of patients after creation of dialysis access with sometimes devastating consequences. Conventional teaching recommends a 7-10 mm anastomosis. We sought to assess the efficacy of using a smaller (5-6 mm) anastomosis in new arteriovenous fistula (AVF) creation. METHODS: We conducted a comparative retrospective analysis of patients who underwent fistula creation with a small versus regular size anastomosis at any upper extremity anatomic site between March 2019 and October 2020 at our institution. Anatomic sites included radiocephalic, brachiocephalic, and brachiobasilic. All AV anastomoses were measured intraoperatively to be 5-6 mm in diameter for the small size groups and 8-10 mm for the regular size group. Endpoints included steal syndrome, functional patency, primary patency, and secondary patency. RESULTS: Out of 110 patients who underwent an AVF creation, 59.1% received a 5-6 mm anastomosis with a median follow-up time of 10 ± 6 months. Patients' demographics and comorbidities were relatively similar between the 2 groups except for a higher rate of hyperlipidemia (55.4% vs. 28.9%, P = 0.008) in the small size group. Patients in the small size group were more likely to undergo a radiocephalic fistula (40% vs. 4.5%, P < 0.001) and to have a smaller mean vein diameter on preoperative duplex ultrasound (3.2±1 mm vs. 3.9±1 mm, P = 0.0016) when compared to their regular size counterparts. During follow-up, none of the patients in the small group developed steal syndrome (0% vs. 9%, P = 0.015). At 1 year, patients in the regular size group achieved higher rates of primary patency (67.9% vs. 46.9%, P = 0.02); however, no difference was seen in 1-year primary-assisted patency (84.9% vs. 73.6%, P = 0.3), secondary patency (89.6% vs. 79.5%, P = 0.3), or functional patency (87.7% vs. 82.2%, P = 0.64) between the small and regular size groups, respectively. CONCLUSIONS: The use of a 5-6 mm anastomosis in the creation of new AVFs of the upper extremities appears to be a technically safe option for dialysis access. Our experience suggests that smaller anastomosis still creates enough flow to maintain a functional AV access while minimizing the incidence of steal syndrome. Additionally, even with smaller vein sizes preoperative, adequate dialysis access can be created via a small sized anastomosis, including distal arm access. Larger studies with longer follow-up are needed to evaluate long-term outcomes of small anastomosis fistulas.

[Application of supraclavicular fasciocutaneous island flap for reconstruction after removal of tumors in parotid and auricle area].

Objective: To evaluate the efficacy of supraclavicular fasciocutaneous island flap (SIF) for repairing the defect of parotid or auricle regions after tumor resection. Methods: From February 2019 to June 2021, 12 patients (11 males and 1 female, aged 54-77 years old), of whom 4 with parotid adenoid cystic carcinoma and 8 with auricular basal cell carcinoma underwent reconstruction surgery for postoperative defects in the parotid gland area and auricular area with SIF in the Department of Otorhinolaryngology Head and Neck Surgery, the Second Xiangya Hospital of Central South University and their clinical data were retrospectively analyzed. Size of the SIF, time for harvesting SIF, neck lymph node dissection and postoperative complications were recorded. Results: The flap areas were (6-9) cm × (8-13) cm, and the harvesting time for SIF ranged from 40 to 80 min, averaging 51.7 min. The donor sites were directly closed. All patients underwent ipsilateral levels Ⅰ-Ⅲ neck dissection, with 4 cases undergoing additional level Ⅳ neck dissection and 2 cases undergoing level Ⅳ-Ⅴ neck dissection. Of the 12 SIF, 10 were completely survival and 2 had flap arterial crisis with partial flap necrosis, in addition, 1 had donor site wound dehiscence. With follow-up of 10-42 months, there were no tumor recurrences in 10 patients, 1 patient was lost to follow-up at 10 months postoperatively, and 1 patient experienced local tumor recurrence at 11 months after surgery and died 15 months later. Conclusion: SIF is an easily harvested flap with good skin features matching the skin in parotid and auricle regions and less damage to donor site, and this flap has no need for microvascular anastomosis technique. SIF is feasible and effective for repairing defects in parotid and auricle area.

Relationship between macular intervortex vein anastomosis and optical coherence tomography biomarkers in chronic central serous chorioretinopathy.

BACKGROUNDS: To evaluate the optical coherence tomography (OCT) biomarkers of patients with central serous chorioretinopathy (CSC) according to the presence or absence of direct anatomical relation to intervortex vein anastomosis (IVA) on indocyanine green angiography. METHODS: We reviewed the records of 39 patients with chronic CSC. Patients were categorized in 2 groups: presence of IVA(Group A) or absence of IVA(Group B) in the macular region. Localization of IVA was categorized in 3 areas according to ETDRS grid:inner 1 mm circle (area-1), 1-3 mm middle circle (area-2) and 3-6 mm outer circle (area-3). RESULTS: There were 31 eyes in Group A,21 eyes in Group B. Mean age of the patients was 52.5 ± 11.3years in Group A,47.2 ± 11years in Group B(p<0.001).Mean initial visual acuity (VA) was 0.38±0.38LogMAR in Group A, 0.19±0.21LogMAR in Group B(p<0.001).Mean subfoveal choroidal thickness(SFCT) was 436.3 ± 134.3µ in Group A,480.2 ± 136.6µ in Group B(p<0.001).Localization of IVA in area-1 was correlated with inner choroidal attenuation (ICA) and leakage on IVA(p = 0.011,p = 0.02). Localization of IVA in area-3 was correlated with irregular lesions on RPE(p = 0.042).Smokestack configuration,intraretinal cysts and ICA were correlated with worse initial VA(p<0.001,p = 0.001 and p = 0.04).Shaggy subtype of photoreceptor disruption was associated with better initial VA(p = 0.003). CONCLUSIONS: We detected older age, worse initial VA and thinner SFCT in patients with chronic CSC and macular region IVA(m-IVA). Long term follow-up of patients with and without m-IVA may exhibit the difference in treatment outcomes and development of neovasculopathy.

Perfusão arterial reversa gemelar: revisão da literatura / Twin reverse arterial perfusion: literature review

A perfusão arterial reversa gemelar é uma anormalidade rara que pode ocorrer em gestações gemelares monocoriônicas. Consiste em uma alteração na circulação fetoplacentária, com desvio de sangue de um dos gemelares para o outro, por meio de anastomoses arterioarteriais e venovenosas na superfície placentária e anastomoses arteriovenosas em áreas de circulação placentária compartilhada. O feto bombeador pode desenvolver insuficiência cardíaca devido ao aumento do débito cardíaco, e o feto receptor, perfundido por sangue pobre em oxigênio por meio do fluxo reverso, é severamente malformado, incompatível com a vida extrauterina. Este artigo apresenta o caso de uma gestação gemelar monocoriônica diamniótica, com manejo clínico conservador. O objetivo é relatar um caso de complicação rara de gestações monozigóticas e revisar condutas para diagnóstico e manejo adequado.(AU)

Twin reverse arterial perfusion is a rare abnormality that can occur in monochorionic twin pregnancies. It consists of an alteration in the fetal-placental circulation, with blood diversion from one of the twins to the other, through arterio-arterial and veno- venous anastomosis on the placental surface and arterio-venous anastomosis in areas of shared placental circulation. The pumping fetus may develop heart failure due to increased cardiac output, and the recipient fetus, perfused by oxygen-poor blood through reverse flow, is severely malformed, incompatible with extrauterine life. This article presents the case of a monochorionic diamniotic twin pregnancy, with conservative clinical management. The objective is to report a case of rare complication of monozygotic pregnancies and review procedures for diagnosis and adequate management.(AU)

Resultados del tratamiento endovascular de la estenosis de la anastomosis venosa en las fístulas arteriovenosas protésicas para hemodiálisis de PTFE. Análisis comparativo entre fístulas permeables y trombosadas / Results of endovascular treatment of venous anastomotic stenosis in prosthetic arteriovenous for hemodialysis PTFE grafts. Comparative analysis between patent and occluded grafts

Objetivo: Analizar los resultados del tratamiento endovascular (TEV) de las estenosis en las anastomosis venosas (EAV) de las fístulas arteriovenosas protésicas (FAVp), comparando su utilidad al realizarse sobre FAVp permeables frente a trombosadas.Material y métodosEstudio retrospectivo de pacientes intervenidos mediante TEV por EAV de fístulas humeroaxilares realizadas entre enero de 2009 y diciembre de 2019 en nuestro centro. Grupo A: FAVp trombosada secundaria a EAV; Grupo B: FAVp permeable con EAV detectada en seguimiento. Se definió éxito técnico como estenosis residual ≤ 30% y éxito clínico como diálisis efectiva inmediata. Tras el TEV se realizó un seguimiento clínico y con eco-Doppler semestral. Estudio estadístico: se realizó un análisis de supervivencia mediante el método Kaplan Meier para el estudio de permeabilidades.ResultadosGrupo A: 55 pacientes. Grupo B: 22 pacientes. No existieron diferencias significativas en las características demográficas ni anatómicas entre grupos.El éxito técnico y clínico fueron del 100% en el grupo B frente a un 94,5% y 91%, respectivamente, en el grupo A.La permeabilidad primaria a 1, 6 y 12 meses en el Grupo A fue: 81,8%, 22,4% y 15,7%, respectivamente, frente al Grupo B: 100%, 85,9%, 76,4% (p<0,001). Permeabilidad secundaria a 1, 6 y 12 meses en el Grupo A fue 85,2%, 45,8% y 31,3%, respectivamente, frente al Grupo B 100%, 95,3%, 95,2% (p<0,001). El uso de stents no cubierto se asoció a un mayor riesgo de oclusión (HR 2,669 IC 95% 1,146-6,216, p=0,010).ConclusiónEs esperable una mayor permeabilidad del TEV realizado sobre una FAVp permeable, por lo que es recomendable elaborar programas de seguimiento que sean capaces de detectar la EAV previo a su trombosis. (AU)

Objective: To analyze the results of endovascular treatment of venous anastomotic stenosis (VAS) in humero-axillary arteriovenous grafts (HAG), comparing outcomes between patent and thrombosed HAG.Material and methodsA retrospective cohort study was made of endovascular treated patients because of a VAS in a HAG between January 2009 and December 2019. Group A: Thrombosed HAG secondary to a VAS. Group B: Patent HAG with a VAS detected during follow-up. Technical success was defined as residual stenosis after treatment <30%, and clinical success as satisfactory immediate dialysis after surgery. After ET a biannual clinical and ultrasound follow-up was performed. Statistical analysis: Survival analysis was performed for time-to-event data to assess patency.ResultsGroup A: 55 patients. Group B: 22. There were no significative differences in demographic and anatomical factors between groups.Technical and clinical success were 100% in Group B and 94.5% and 91% respectively in Group A.Primary patency at 1, 6 and 12 months was: Group A: 81.8%, 22.4% and 15.7% respectively. Group B: 100%, 85.9%, 76.4% (p<0.001). Secondary patency at 1, 6 and 12 months was: Group A: 85.2%, 45.8% and 31.3% respectively. Group B 100%, 95.3%, 95.2% (p<0.001). Use of non-covered stents was associated with an increased risk of occlusion (HR 2.669 95% CI 1.146–6.216, p=0.010).ConclusionA higher patency of EV performed on a patent HAG is expected. It is therefore advisable to develop surveillance programs that are capable to detect VAS before its occlusion. (AU)

A study on the correlation of placental characteristics and the onset of selective intrauterine growth restriction.

OBJECTIVE: To investigate the correlation between placental characteristics and the onset of selective intrauterine growth restriction (sIUGR) and to explore the influence of placental characteristics on sIUGR onset. METHODS: A retrospective cohort study was conducted at our hospital from April 2013 to April 2019. The pregnancy data and placental perfusion of 114 sIUGR patients who had received conservative treatment and delivered in our hospital were included. Correlation analysis was conducted between the total diameter of placental anastomoses, placental territory discordance, umbilical cord insertion point distance ratio, and the onset time of sIUGR. RESULTS: The prevalence of AA anastomoses was 88.6% (101/114), with an average total diameter of 2.8 ± 1.5 mm, the prevalence of AV anastomoses was 93.9% (107/114), with an average diameter of 5.4 ± 3.6 mm, and the prevalence of VV anastomoses was 18.4% (21/114), with an average diameter of 4.0 ± 1.9 mm. There was a significant negative correlation between the time of sIUGR onset and the placental territory discordance ratio with a Spearman correlation coefficient of -0.306 (P = 0.001). CONCLUSIONS: The larger the placental territory discordance, the earlier onset time of sIUGR.

Choroidal arteriovenous anastomoses: a hypothesis for the pathogenesis of central serous chorioretinopathy and other pachychoroid disease spectrum abnormalities.

The pachychoroid disease spectrum (PDS) includes several chorioretinal diseases that share specific choroidal abnormalities. Although their pathophysiological basis is poorly understood, diseases that are part of the PDS have been hypothesized to be the result of venous congestion. Within the PDS, central serous chorioretinopathy is the most common condition associated with vision loss, due to an accumulation of subretinal fluid in the macula. Central serous chorioretinopathy is characterized by distinct risk factors, most notably a high prevalence in males and exposure to corticosteroids. Interestingly, sex differences and corticosteroids are also strongly associated with specific types of arteriovenous anastomoses in the human body, including dural arteriovenous fistula and surgically created arteriovenous shunts. In this manuscript, we assess the potential of such arteriovenous anastomoses in the choroid as a causal mechanism of the PDS. We propose how this may provide a novel unifying concept on the pathophysiological basis of the PDS, and present cases in which this mechanism may play a role.

Anastomosis between the posterior superior alveolar artery and the infra-orbital artery: a review of current terminology / Anastomosis entre la arteria alveolar superior posterior y la arteria infra-orbital: una revisión de la terminología actual

SUMMARY: The posterior superior alveolar artery (PSAA) and the infra-orbital artery (IOA) present intraosseous and extraosseous rami which form an anastomosis in the lateral wall of the maxillary sinus. This anastomosis is always present, however it has not yet been included in anatomical terminology (AT), and different terms are used in scientific communication to refer to it. The aim of this study was to carry out a review of the different terms used to name this vascular structure. A literature review was carried out on the terms used to name the anastomosis between the PSAA and IOA in imaging studies and human cadavers that assessed the presence/frequency of this anatomical structure. The search was carried out in the Medline, EMBASE and LILACS databases, in Portuguese, Spanish and English, with no date restrictions. Qualitative analysis was applied to the studies selected, analysing the terminology used to refer to the anastomosis between the PSAA and IOA. Of the 2108 original articles found, 60 were selected as potentially relevant and 54 studies were finally included for qualitative analysis. Sixteen terms were found to refer to the anastomosis between the PSAA and IOA, the most frequent being Posterior Superior Alveolar Artery (PSAA), followed by Alveolar Antral Artery (AAA). Many terms are used in the medical literature to designate the anastomosis between the PSAA and IOA, the most frequent being PSAA and AAA. There is a need to unify the terms used to designate this vascular structure, and to incorporate the selected term into anatomical terminology, in order to avoid confusion in scientific communication.

RESUMEN: La arteria alveolar superior posterior (AASP) y la arteria infra-orbital (AIO) tienen ramas intra y extra óseas que forman una anastomosis en la pared lateral del seno maxilar. Esta anastomosis está siempre presente, sin embargo, aún no ha sido incluida en la terminología anatómica (TA), por lo que en la comunicación científica se utilizan diferentes términos para referirse a ella. El objetivo de este estudio fue realizar una revisión sobre los diferentes términos utilizados para nombrar esta estructura vascular. Se realizó una revisión de la literatura sobre los términos utilizados para nombrar la anastomosis entre AASP y AIO en estudios imagenológicos y en cadáveres humanos que evaluaron la presencia/frecuencia de esta estructura anatómica. La búsqueda fue realizada en las bases de datosMedline, EMBASE y LILACS, en los idiomas portugués, español e inglés, sin restricción de fecha. Los estudios seleccionados fueron evaluados de forma cualitativa, analizando la terminología empleada para referirse a la anastomosis entre AASP y AIO. Fueron encontrados 2108 artículos originales, siendo seleccionados 60 artículos potencialmente relevantes y finalmente fueron incluidos 54 estudios para análisis cualitativo. Fueron encontrados 16 términos para referirse a la anastomosis entre AASP y AIO, siendo AASP el más frecuente seguido de arteria alveolo-antral (AAA). Son muchos los términos utilizados en la literatura médica para designar la anastomosis entre AASP y AIO, siendo AASP y AAA los más usados. La unificación de los términos utilizados para designar esta estructura vascular y su incorporación en la Terminología Anatómica contribuiría a evitar equívocos en la comunicación científica.

Comparison of pregnancy outcomes and placental characteristics between selective fetal growth restriction with and without thick arterio-arterial anastomosis in monochorionic diamniotic twins.

BACKGROUND: Unequal placental territory in monochorionic diamniotic twins is a primary cause of selective fetal growth restriction (sFGR), and vascular anastomoses play important role in determining sFGR prognosis. This study investigated differences in placental characteristics and pregnancy outcomes in cases of sFGR with and without thick arterio-arterial anastomosis (AAA). METHODS: A total of 253 patients diagnosed with sFGR between April 2013 and April 2020 were retrospectively analyzed. An AAA greater than 2 mm in diameter was defined as a thick AAA. We compared placental characteristics and pregnancy outcomes between cases of sFGR with and without thick AAA. RESULTS: Prevalence of AAA, thick arterio-venous anastomosis (AVA), veno-venous anastomosis (VVA), and thick VVA were significantly higher in the thick AAA group relative to the non-thick AAA group (100.0 vs. 78.5%, P < 0.001; 44.3 vs. 15.4%, P < 0.001; 27.1 vs. 10.8%, P = 0.017, and 24.3 vs. 6.2%, P = 0.004, respectively). The total numbers of AVA and total anastomoses were significantly higher in thick AAA group relative to the non-thick AAA group (5 [1, 14] vs. 3 [1, 15, P = 0.016; and 6 [1, 15] vs. 5 [1, 16], P = 0.022, respectively). The total diameter of AAA, AVA, VVA, and all anastomoses in the thick AAA group was larger than in the non-thick AAA group (3.4 [2.0,7.1] vs. 1.4 [0.0, 3.3], P < 0.001; 6.3 [0.3, 12.0] vs. 2.5 [0.3, 17.8], P < 0.001; 4.2±1.8 vs. 1.9±1.2, P =0.004; and 10.7 [3.2,22.4] vs. 4.4 [0.5, 19.3], P < 0.001, respectively). Growth-restricted fetuses in the thick AAA group exhibited significantly increased birthweight relative to those in thenon-thick AAA group (1570 (530, 2460)g vs. 1230 (610, 2480)g, p = 0.002). CONCLUSIONS: In the placentas associated with sFGR, thick AAA can co-occur with thick AVA and VVA, and placental angiogenesis may differ significantly based upon whether or not thick AAA is present. The birth weights of growth-restricted fetuses in cases of sFGR with thick AAA are larger than in cases without thick AAA.

Síndrome de transfusão feto-fetal: revisão de literatura / Twin-twin transfusion syndrome: a literature review

A síndrome de transfusão feto-fetal é uma complicação das gestações gemelares monocoriônicas. Além de ocorrer comumente no segundo trimestre, apresenta elevada morbimortalidade fetal e neonatal, e taxas de incidência que variam de 10 a 15% dentre todas as gravidezes monocoriônicas. O objetivo deste estudo é realizar uma revisão de literatura a partir de levantamento bibliográfico acerca dos principais aspectos epidemiológicos, clínicos e terapêuticos da STFF. A base de dados PubMed foi consultada, uma vez que os termos de pesquisa utilizados foram "síndrome de transfusão feto-fetal", "diagnóstico" e "tratamento". Obtiveram-se sessenta e oito artigos de revisão de literatura e/ou revisão sistemática, sendo que apenas vinte e nove foram selecionados após aplicação dos critérios de elegibilidade. Em relação à fisiopatologia, a síndrome é explicada pela transferência sanguínea direta entre os fetos gemelares através de anastomoses arteriovenosas placentárias, conceitualmente determinando a existência de um feto receptor e outro doador. Embora as gestantes comumente se apresentam assintomáticas, as repercussões clínicas fetais costumam ser graves. O diagnóstico é exclusivamente ultrassonográfico e deve ser feito o mais precocemente possível, ressaltando-se a importância da detecção da corionicidade da gestação gemelar, além de acompanhamento ultrassonográfico seriado para rastreio do desenvolvimento da síndrome. Apesar de ainda não haver protocolo de tratamento bem estabelecido, a ablação dos vasos placentários a laser é tida como o padrão-ouro dentre as opções terapêuticas disponíveis. Apresenta elevada taxa de sobrevida de pelo menos um dos fetos e baixos índices de sequelas neurológicas neonatais, podendo ser realizada somente até a 26ª semana de gestação.

Twin-twin transfusion syndrome is a complication of monochorionic twin pregnancies. In addition to commonly occurring in the second trimester, it has high fetal and neonatal morbidity and mortality and incidence rates ranging from 10 to 15% among all monochorionic pregnancies. This study aims to perform a literature review based on a bibliographic survey about the main epidemiological, clinical and therapeutic aspects of TTTS. The PubMed database was consulted, as the search terms used were "twin-twin transfusion syndrome", "diagnosis", and "treatment". Sixty-eight literature review and systematic review articles were obtained, and only twenty-nine were selected after applying the eligibility criteria. About the pathophysiology, the syndrome is explained by direct blood transfer between the twin fetuses through placental arteriovenous anastomoses, determining the existence of a recipient fetus and another donor. Although pregnant women are usually asymptomatic, the clinical fetal repercussions are often severe. Diagnosis is exclusively ultrasonographic and must be made as early as possible, emphasizing the importance of detecting chorionicity in twin pregnancy, in addition to serial ultrasonographic follow-up to track the development of the syndrome. Although there is still no well-established treatment protocol, endoscopic laser ablation of vascular anastomoses is considered the gold standard among the available therapeutic options. It has a high survival rate for at least one of the fetuses and low rates of neonatal neurological sequelae and can only be performed until the 26th week of pregnancy.

Tailoring of arteriovenous graft-to-vein anastomosis angle to attenuate pathological flow fields.

Arteriovenous grafts are routinely placed to facilitate hemodialysis in patients with end stage renal disease. These grafts are conduits between higher pressure arteries and lower pressure veins. The connection on the vein end of the graft, known as the graft-to-vein anastomosis, fails frequently and chronically due to high rates of stenosis and thrombosis. These failures are widely believed to be associated with pathologically high and low flow shear strain rates at the graft-to-vein anastomosis. We hypothesized that consistent with pipe flow dynamics and prior work exploring vein-to-artery anastomosis angles in arteriovenous fistulas, altering the graft-to-vein anastomosis angle can reduce the incidence of pathological shear rate fields. We tested this via computational fluid dynamic simulations of idealized arteriovenous grafts, using the Bird-Carreau constitutive law for blood. We observed that low graft-to-vein anastomosis angles ([Formula: see text]) led to increased incidence of pathologically low shear rates, and that high graft-to-vein anastomosis angles ([Formula: see text]) led to increased incidence of pathologically high shear rates. Optimizations predicted that an intermediate  ([Formula: see text]) graft-to-anastomosis angle was optimal. Our study demonstrates that graft-to-vein anastomosis angles can significantly impact pathological flow fields, and can be optimized to substantially improve arteriovenous graft patency rates.