Percutaneous Endovascular Creation of a Neo-arteriovenous Fistula in Dysfunctional Hemodialysis Fistulas.

PURPOSE: Arteriovenous fistulas (AVF) is the preferred type of hemodialysis access, but when an arteriovenous anastomosis (AVA) calcifies, surgical revision of the AVF may be required. We report a technique to create percutaneous artery-to-vein intervascular neo-fistulas for re-anastomosis of AVA and evaluate its safety and efficacy. MATERIALS AND METHODS: 9 patients who failed either guidewire navigation or conventional balloon dilation for calcified AVA stenosis/occlusion underwent a salvage procedure of their dialysis shunt by the percutaneous creation of a new arteriovenous fistula. Needle puncture of the adjacent supplying artery and outflow vein under ultrasonographic and/or fluoroscopic guidance was performed and followed by balloon dilation, with or without stent graft placement. The detailed techniques, technical success, primary neo-fistula patency, primary and secondary access patency rates were reported herein. RESULTS: Technical success was achieved in 100% of the 9 patients treated (7 neo-fistulas with stents and 2 neo-fistulas without stent placement). The median primary neo-fistula and access patencies were 15 and 5 months, respectively. The primary neo-fistula patency rates at 6, 12, and 18 months were 72.9%, 54.7% and 27.9%, respectively, with secondary neo-fistula and access patency rates of 72.9%, 72.9% and 72.9%, respectively. One delayed complication of pseudoaneurysm formation occurred, which was managed by the successful endovascular deployment of a stent graft on an out-patient basis. CONCLUSION: Percutaneous artery-to-vein intervascular neo-fistula creation is feasible for re-anastomosing calcified AVA, with low adverse effects and acceptable primary neo-fistula and secondary access patency.

Compressão intermitente imediata sobre anastomose vascular: Uma nova técnica para prevenir trombose? / Immediate intermittent compression over vascular anastomosis: a new technique to prevent thrombosis

Introdução: Este estudo tem o objetivo de avaliar o efeito da compressão intermitente imediata sobre anastomoses arteriais microcirúrgicas em comparação com compressão fixa e com utilização isolada de irrigação com soro fisiológico e heparina em laboratório experimental. Método: 12 ratos Wistar foram aleatoriamente divididos em três grupos para terem suas artérias femorais seccionas e anastomosadas de forma término-terminal, para comparação de patência com 30 minutos e 7 dias. Grupo I: foi realizada compressão intermitente imediata sobre a anastomose por 60 segundos; grupo II: uma compressão fixa foi mantida imediatamente após a anastomose, também por 60 segundos; grupo III, após o término da anastomose, não foi feita nenhuma intervenção adicional. Além da avaliação da patência, os animais foram pesados e medidos os diâmetros arteriais operados. Resultados: 24 artérias femorais foram abordadas. As médias de peso inicial dos ratos dos grupos I, II e III foram, respectivamente, de 243,8g, 254,6g e 260,4g, enquanto as finais foram de 264,4g, 281g e 282,1g (p<0,001). O diâmetro médio das artérias abordadas foi, respectivamente, de 0,89mm, 0,88mm e 0,90mm, e os tempos de anastomoses em minutos, de 25,6, 24,5 e 24,5, respectivamente; As patências finais após 7 dias foram, respectivamente, de 62,5% (p=0,07), 25% (p=0,48) e 50% (p=0,13). Conclusão: A compressão intermitente imediata pode ser realizada ao término de anastomoses arteriais microcirúrgicos sem prejuízo na patência final do procedimento.

Introduction: This study aims to evaluate the effect of immediate intermittent compression on microsurgical arterial anastomoses in comparison with fixed compression and only observation in an experimental laboratory. Methods: The two femoral arteries of twelve male Wistar rats were sectioned and reanastomosed to compare patency at 30 minutes and 7 days. Group I: immediate intermittent compression was performed over the anastomosis for 60 s; group II: a fixed compression was maintained immediately after the anastomosis for 60 s; group III: after completion of the anastomosis, no additional intervention was performed. In addition to the patency assessment, the animals were weighed and the operated arterial diameters were measured. Results: Twenty-four femoral arteries were examined. Initial average weights of the rats in groups I, II, and III were 243.8g, 254.6g, and 260.4g, respectively, while the final weights were 264.4g, 281g, and 282.1g (p<0.001), respectively; mean diameter of the approached arteries was 0.89, 0.88, and 0.90mm, respectively, and the anastomoses (time in minutes) were 25.6, 24.5, and 24.5, respectively; final patencies after 7 days were 62.5% (p=0.07), 25% (p=0.48), and 50% (p=0.13), respectively. Conclusion: Immediate intermittent compression can be performed at the end of microsurgical arterial anastomoses without affecting the final patency of the procedure.

Successful replantation of an avulsed frontal scalp through microvascular anastomoses of only one artery and one vein: a case report.

Scalp avulsion is a devastating injury. The best possible procedure is replantation. Several successful scalp replantations with anastomoses of several vessels in large defects have been reported. In this report, we present a case of replantation of a large scalp avulsion using revascularizing with only one artery and vein. Despite the initial signs of flap congestion, we could predict the survival of the replanted scalp and terminate the procedure after detecting good perfusion and washout with indocyanine green fluorescence imaging. The procedure was successful following the patient's recovery of sensory and sweating functions without complications such as flap necrosis or infection. Several important factors for successful scalp replantation with positive esthetic and functional outcomes were considered.

Photoplethysmography for Assessing Microcirculation in Hypertensive Patients After Taking Antihypertensive Drugs: A Review.

High blood pressure (BP) is a common disease and is associated with many chronic diseases. Measuring BP is essential for the treatment and management of many diseases, and therefore there is a growing need for a non-invasive, sleeveless and continuous BP monitoring device. With the development of technology, pulse waveform analysis using photoplethysmography (PPG) has become more feasible for evaluating BP. This study aimed to evaluate the changes of vascular elasticity and blood volume over time by using the characteristic parameters extracted by PPG. We reviewed the latest progress and literature on the observation of capillary network characteristics in hypertensive and non-hypertensive patients by PPG, the influence of different drugs on microcirculation characteristics in hypertensive patients with PPG, and further explored the key relationship between microcirculation and hypertension. We found that the PPG waveform produced by the fingertips of hypertensive patients is very different from that of healthy people, and the PPG waveform changes significantly during diastolic period after antihypertensive treatment. With the rapid development of medical technology, people can get more intuitive microcirculation image data, which provides beneficial help for the comprehensive understanding of hypertension.

Prospective multicenter study of a novel endovascular venous anastomotic procedure and device for implantation of an arteriovenous graft for hemodialysis.

INTRODUCTION: The traditional sutured venous anastomosis used during arteriovenous graft implantation is associated with a high incidence of subsequent stenosis that is attributed to neointimal hyperplasia. Hyperplasia results from multiple factors, including hemodynamic abnormalities and vessel trauma during implantation. A novel anastomotic connector device was designed to provide an alternative, less traumatic, endovascular venous anastomosis that may ameliorate the clinical challenges associated with a sutured anastomosis. A prospective single-arm multicenter study was performed to evaluate safety and effectiveness of graft implantation using the study device. METHODS: Patients requiring graft creation and who met the study criteria were enrolled between February 2018 and July 2021 and observed for 6 months. Collected data included baseline characteristics, graft patency and use for hemodialysis, graft interventions, and adverse events. The primary study endpoint was cumulative graft patency, compared to a pre-specified Performance Goal of 75%. Secondary endpoints included primary unassisted patency and serious adverse events, defined as the occurrence of death, graft infection, emergent surgery, significant bleeding, and pseudoaneurysm. RESULTS: A total of 158 patients were enrolled from 10 study sites, among which 144 subjects were evaluable at 6 months and 14 were censored with partial follow-up observation. Three patients died and the graft was abandoned in 12. The primary endpoint was met (p-value < 0.001). By Kaplan Meier survival analysis, cumulative patency was 92.08% with a lower 95% Confidence Bound of 86.98%. Primary unassisted patency was 60.21% with a lower 95% Confidence Bound of 50.84%. Graft infections occurred in six patients, all unrelated to the study device. There were no reports of emergent surgery, significant bleeding or pseudoaneurysm. CONCLUSION: These results demonstrate that the study device can be used for successful endovascular anastomosis of a vein to a graft for hemodialysis, with acceptable cumulative patency and safety profile at 6 months. CLINICAL TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT02532621.

Application of parachute suture technique in variant donor renal artery anastomosis of living-donor renal transplantation / 国际外科学杂志

Objective:To investigate the effects and advantages of parachute technique in arterial anastomosis of living-donor renal transplantation with anatomical variations of renal artery.Methods:A total of 79 pairs of donors and recipients who received living-donor renal transplantation at the Department of Urology, Beijing Friendship Hospital, Capital Medical University from January 2020 to November 2022 were retrospectively collected. 11 pairs with completeness data and multiple donor renal arteries were selected. According to the different techniques, the cases using parachute technique were classified as experimental group and other cases as control group using traditional two-three-point fixation technique. There were 5 pairs in the experimental group and 6 pairs in the control group. The medical records of the two groups were collected, containing general data, the state of donated kidney, the arterial reonstruction method, the condition of perioperation and recovery of recipients. Measurement data were expressed as mean ± standard deviation ( ± s). Student- t test was used for inter-group comparison. The Chi-square test or Fisher exact probability method were used to compare the count data of groups. Results:The donations of experimental group and control group were left-sided kidney. There were no statistical difference in age, gender, body mass index and estimated glomerular filtration rate of donors and recipients. The average number of renal arteries in the experimental group was 2.2, and that in the control group was 2.0. There were no statistical difference between the two groups in the mean time of transplantation surgery[(152.0±23.9) min vs (148.3±24.0) min], estimated blood loss [(90.0±41.8) mL vs (91.7±58.5) mL] and mean arterial anastomosis time [(21.0±5.4) min vs (20.8 ± 4.7) min]. At the end of arterial anastomosis, no case in the experimental group need acupuncture or secondary anastomosis, while the control group had 3 cases, the difference was statistically significant ( P=0.002). There was no statistical difference in the recovery of renal function and complications related to renal arteries between the two groups ( P>0.05). Conclusions:Parachute suture technique can more accurately achieve the purpose of layer-to-layer eversion suture of vascular wall under the condition of narrow arterial lumen, and will not significantly prolong the operation time. It may have a good application value in living kidney transplantation with renal artery variation.

Von Hippel-Lindau disease with intracranial hemorrhage due to arteriovenous anastomosis via multiple spinal hemangioblastomas: illustrative case.

BACKGROUND: Some spinal hemangioblastomas (HBLs) resemble spinal vascular malformations. Intracranial subarachnoid hemorrhage (SAH) secondary to spinal HBL has rarely been reported. OBSERVATIONS: A 67-year-old man with a prolonged von Hippel-Lindau disease (VHL) history presented with sudden headache and vomiting. Cranial and cervical computed tomography (CT) revealed severe infratentorial, supratentorial, and cervical SAH. Cranial CT angiography and magnetic resonance imaging revealed a mismatch in hemorrhage and intracranial tumor localization, with no vascular lesions that could lead to intracranial SAH. Cervical CT angiography revealed abnormal blood vessels originating from 5 spinal tumors suspected to be HBLs. We considered that the SAH was caused by venous reflex from vascular malformation-like spinal HBLs. Transarterial embolization (TAE) of the feeding artery of HBLs was performed to improve symptoms and reduce rebleeding risk. Nine months after TAE, angiography showed no venous reflux into the intracranial space. Ten months later, the authors excised the T1-2 tumor because the patient complained of progressive paralysis of the right upper extremity. LESSONS: In HBL with prolonged VHL, intracranial hemorrhage due to venous regurgitation via a mimicked vascular malformation may occur. Reducing venous reflux with TAE may improve symptoms and prevent rebleeding.

Extended lifetimes of bubbles at hyperbaric pressure may contribute to inner ear decompression sickness during saturation diving.

Inner ear decompression sickness (IEDCS) may occur after upward or downward excursions in saturation diving. Previous studies in nonsaturation diving strongly suggest that IEDCS is caused by arterialization of small venous bubbles across intracardiac or intrapulmonary right-to-left shunts and bubble growth through inward diffusion of supersaturated gas when they arrive in the inner ear. The present study used published saturation diving data and models of inner ear inert gas kinetics and bubble dynamics in arterial conditions to assess whether IEDCS after saturation excursions could also be explained by arterialization of venous bubbles and whether such bubbles might survive longer and be more likely to reach the inner ear under deep saturation diving conditions. Previous data show that saturation excursions produce venous bubbles. Modeling shows that gas supersaturation in the inner ear persists longer than in the brain after such excursions, explaining why the inner ear would be more vulnerable to injury by arriving bubbles. Estimated survival of arterialized bubbles is significantly prolonged at high ambient pressure such that bubbles large enough to be filtered by pulmonary capillaries but able to cross right-to-left shunts are more likely to survive transit to the inner ear than at the surface. IEDCS after saturation excursions is plausibly caused by arterialization of venous bubbles whose prolonged arterial survival at deep depths suggests that larger bubbles in greater numbers reach the inner ear.NEW & NOTEWORTHY Inner ear decompression sickness that occurs during deep saturation diving is explained by arterialization of venous bubbles across intracardiac or intrapulmonary right-to-left shunts and growth of these bubbles if they arrive in the inner ear. Bubbles in arterial blood have prolonged lifetimes at hyperbaric pressures compared with at sea level. This can explain why inner ear decompression sickness is more characteristic of rapid decompressions at great depths than of decompression at sea level.

Association between arteriovenous access flow and ventricular function: A cross-sectional study.

Background: Permanent hemodialysis access comes with a myriad of problems on top of the well-known benefits; flow disturbances, risk of infection and revision being among them. All of these could eventually lead to impaired cardiac function. Even so, the relationship between impaired cardiac function due to arteriovenous access in patients undergoing hemodialysis has not been clearly described. This study aimed to analyze the relationship of flow in an artificial arteriovenous access with left and right ventricular function in patients with chronic kidney disease (CKD) undergoing hemodialysis at a referral hospital in Indonesia. Material and methods: This was a cross sectional study with consecutive sampling technique. Samples were patients with CKD undergoing hemodialysis at Dr. Soetomo General Hospital from December 2021to January 2022. A total of 47 patients who met the inclusion criteria underwent Doppler ultrasound to assess arteriovenous access flow and transthoracic echocardiography to assess left and right ventricle function. Results: From 47 patients, 26 (55.3%) had high arteriovenous access flow. The clinical characteristics of the patients between the high and low arteriovenous access flow groups were not significantly different. We found that the value of left ventricular ejection fraction in the non-high-flow access group was significantly higher than the high-flow access group (p < 0.05). Other than that, the median right ventricle fractional area changes in the non-high-flow access group was also higher than the high-flow access group (p < 0.05). Conclusion: Arteriovenous access flow as measured by Doppler ultrasonography has a significant relationship with impaired left and right ventricular functions based on systolic function parameters from echocardiography.

Neurodevelopmental outcomes in twin-to-twin transfusion syndrome survivors at 12 months old after fetoscopic laser occlusion of chorioangiopagous vessels / 中华围产医学杂志

Objective:To investigate the risk factors for cerebral injury in survivors of twin-to-twin transfusion syndrome (TTTS) after fetoscopic laser occlusion of chorioangiopagous vessels(FLOC) and to analyze the neurodevelopmental outcomes at 12 months of corrected age.Methods:A total of 136 cases of TTTS receiving FLOC in the Third Affiliated Hospital of Zhengzhou University from May 2018 to August 2021 were retrospectively selected as the FLOC group, and the survivors were followed up. Neurological development at 12 months of corrected age was assessed using the Griffiths mental development scales-Chinese (GDS-C) from five dimensions with locomotor, personal-social, hearing and language, hand-eye coordination and performance subscales. Eighty-eight fetuses of TTTS pregnancies receiving expectant treatment or amniotic fluid reduction were selected as the non-FLOC group. The perinatal mortality and the incidence of cerebral injury in the two groups were compared, as well as the incidence of cerebral injury between patients undergoing Solomon surgery and selective laser surgery in the FLOC group. Generalized estimating equations were used to analyze the risk factors for neonatal cerebral injury after FLOC and the factors influencing general developmental quotient score at the corrected age of 12 months. Chi-square test, t-test, and Mann-Whitney U test were used for statistical analysis. Results:(1) The perinatal mortality rate in the FLOC group was lower than that in the non-FLOC group [14.7% (20/136) vs 26.1% (23/88), χ 2=4.50, P=0.034]. There was no statistical significance in the incidence of neonatal cerebral injury between the two groups [18.7% (23/123) vs 21.8% (17/78), χ 2=0.29, P=0.592], but the incidence of severe cerebral injury in the FLOC group was lower than that in the non-FLOC group [6.5% (8/123) vs 15.4% (12/78), χ 2=4.20, P=0.040]. (2) In the FLOC group, there was no significant difference in the incidence of cerebral injury between donors and recipients, or between Solomon surgery and selective laser surgery [16.4% (10/61) vs 21.0% (13/62), χ 2=0.42; 20.0% (9/45) vs 17.9% (14/78), χ 2=0.08; both P>0.05]. (3) Multivariate analysis showed that neonatal asphyxia ( OR=7.04, 95% CI: 1.45-34.20, P=0.016) and higher preoperative TTTS stage ( OR=2.05, 95% CI: 1.10-3.82, P=0.023) were risk factors for neonatal cerebral injury. (4) Fifty-two cases were successfully followed up at the corrected age of 12 months, and the incidence of developmental delay in at least one dimension was 34.6% (18/52). Developmental delay was mainly manifested in locomotor skills and language, accounting for 26.9% (14/52) and 11.5% (6/52). No significant difference in Z value was found between recipients and donors in each dimension (all P>0.05). Solomon surgery, larger gestational age at operation and low birth weight were related to low general developmental quotient score (95% CI:－11.71 to－0.23，－1.99 to－0.47，0.00-0.01，respectively，all P<0.05). Conclusions:The occurrence of cerebral injury in TTTS survivors after FLOC is related to preoperative TTTS staging and intrapartum neonatal asphyxia. Neurodevelopment of survivors is related to birth weight and gestational age at surgery, and there is a higher incidence of mild developmental delay at corrected age of 12 months.

Arteriovenous Anastomosis in Human Hand Digital Skin.

While a digital arteriovenous anastomosis (Hoyer-Grosser's organ, Masson's glomus) is a well-known structure, photographic evidence of communication between arterial and venous lumens might not be demonstrated in routine histological or immunohistochemical analysis. Abundant clusters of so-called glomera were found in semi-serial sections of the distal aspect of 14 fingers obtained from 7 donated elderly cadavers. Two to six round or oval clusters were observed in each longitudinal section (over 0.3-0.6 mm in maximum diameter) in subcutaneous tissue 0.5-1.5 mm below the basal layer of the skin, whereas none were often observed in transverse sections. Lumen-to-lumen communication between arteriole and venule at 8 sites in 2 cadavers was identified in these clusters of glomera. The opening in the arteriole was large (50 µm in diameter) at 3 sites in specimens from an 80-year-old man, whereas it was small (10-30 µm) at 5 sites in those from a 91-year-old man. The arterial aspect was tightly surrounded by abundant nerve fibers expressing tyrosine hydroxylase immunoreactivity, whereas the venous part was not. No or little expression of S100 protein immunoreactivity suggested that these nerve fibers were unmyelinated. The morphology at the lumen-to-lumen communication was simple - possibly an end-to-end anastomosis - rather than a sinuous curve of arteriole opening on to a short funnel-shaped venule as seen in the standard textbooks.

Device Therapy of Hypertension.

In the past decade, efforts to improve blood pressure control have looked beyond conventional approaches of lifestyle modification and drug therapy to embrace interventional therapies. Based upon animal and human studies clearly demonstrating a key role for the sympathetic nervous system in the etiology of hypertension, the newer technologies that have emerged are predominantly aimed at neuromodulation of peripheral nervous system targets. These include renal denervation, baroreflex activation therapy, endovascular baroreflex amplification therapy, carotid body ablation, and pacemaker-mediated programmable hypertension control. Of these, renal denervation is the most mature, and with a recent series of proof-of-concept trials demonstrating the safety and efficacy of radiofrequency and more recently ultrasound-based renal denervation, this technology is poised to become available as a viable treatment option for hypertension in the foreseeable future. With regard to baroreflex activation therapy, endovascular baroreflex amplification, carotid body ablation, and programmable hypertension control, these are developing technologies for which more human data are required. Importantly, central nervous system control of the circulation remains a poorly understood yet vital component of the hypertension pathway and mandates further investigation. Technology to improve blood pressure control through deep brain stimulation of key cardiovascular control territories is, therefore, of interest. Furthermore, alternative nonsympathomodulatory intervention targeting the hemodynamics of the circulation may also be worth exploring for patients in whom sympathetic drive is less relevant to hypertension perpetuation. Herein, we review the aforementioned technologies with an emphasis on the preclinical data that underpin their rationale and the human evidence that supports their use.

Introducing a "no-touch" maneuver to manage challenging anastomoses in arteriovenous fistulae.

Native arteriovenous fistula or interposition of a synthetic graft for vascular access is crucial for dialysis patients. Optimal surgical technique, microsurgery instrumentation and preventive hemostasis are considered beneficial for a successful surgical outcome. We describe a simple and novel maneuver using soft-feeding tubes to facilitate the manipulation of veins and perform successful anastomoses without using microsurgery instrumentation or vascular clamps during operations for vascular access.

Avoiding Venous Anastomotic Dehiscence of an Arteriovenous Graft in a Super-Obese Patient.

Surgeons avoid creating arteriovenous fistulae in obese patients owing to deep vessels, cannulation complications, and inconsistent outcomes. We describe placing an arteriovenous polytetrafluoroethylene (PTFE) graft between the brachial artery and axillary vein to avoid these complications. A 39-year-old super-obese woman with end-stage renal disease had undergone several hemodialysis access procedures on both arms. We traced the course of the arteriovenous graft course with the patient sitting and lying down. The ideal course was more accurate with the patient sitting; thus, the patient sat when the course was drawn, before lying on the operating bed. The PTFE graft was placed between the right brachial artery and axillary vein, according to the course in the opposite arm. No anastomotic dehiscence or pseudoaneurysm has taken place during 2 years of follow-up. In super-obese patients, the ideal course for arteriovenous grafts should be drawn while they are sitting, avoiding skin folds. This tip could avoid anastomotic dehiscence and pseudoaneurysm between the axillary vein and a PTFE graft.

A case of anti-VEGF therapy application in Takayasu arteries with retinopathy.

PURPOSE: Takayasu arteritis (TA) is a systemic granulomatous large vessel vasculitis that involves mainly the aorta and its primary branches, and occurs most commonly in young females. Ocular manifestations of TA include small vessels dilation, microaneurysm, arteriovenous anastomosis, retinal ischemia and retinopathy. However, no specific and effective treatments for Takayasu retinopathy is applied. This case aimed to demonstrate the role of anti-VEGF (vascular endothelial growth factor) therapy in treating Takayasu retinopathy. OBSERVATIONS: We herein reported an 18-year-old Asian woman who presented with typical wreath-like arteriovenous anastomosis around the disc in the right eye and vitreous hemorrhage in the left eye. The stenosis and occlusion of bilateral subclavian arteries, carotid arteries and other proximal arteries on angiography confirmed the diagnosis of TA. Meanwhile, elevated ESR and CRP revealed that TA was in the active stage. We applied anti-VEGF therapy in treating Takayasu retinopathy specially to inhibit neovascularization. Additionally, vitreous extraction was conducted in the left eye after the treatment of anti-VEGF therapy. CONCLUSIONS AND IMPORTANCE: This is the first report of effective application of anti-VEGF therapy in inhibiting wreath-like arteriovenous anastomosis and improving vitrectomy in TA.

THE DESIGN OF THE ARTERIOVENOUS VASCULAR LOOP DOES NOT AFFECT ITS PATENCY: EXPERIMENTAL STUDY.

OBJECTIVE: To evaluate the effect of the design of a femoral vascular loop with anastomosis in the femoral artery of rabbits on the presence of flow (patency) after seven days. METHODS: A total of 39 rabbits underwent arteriovenous microanastomosis using the microsurgical technique. Two loop designs were used: one circular and the other angled. The parameters evaluated were presence or absence of flow, signs of hemolysis and hemodynamic changes. RESULTS: After seven days, flow was present in 68% of the angled loops and 75% of the circular loops (p > 0.05). There was a significant intragroup decrease in pCO2 and a significant increase in pH. For the other parameters evaluated, no significant differences between the two loop models were found. CONCLUSIONS: A reproducible vascular loop model was shown. There was no significant difference between the two vascular loop models about the presence of flow after seven days. Level of Evidence V, Animal experimental study.

OBJETIVO: Avaliar, em coelhos, qual é a influência do desenho da alça de veia femoral com anastomose na artéria femoral, na presença de fluxo (patência) após sete dias. MÉTODO: 39 coelhos foram submetidos à microanastomose arteriovenosa com técnica microcirúrgica. As alças foram acomodadas em dois desenhos, um circular e outro, o mais alongado possível sem dobras na alça. Os parâmetros avaliados foram: presença ou não de fluxo, sinais de hemólise, alterações hemodinâmicas. RESULTADOS: após sete dias, o fluxo estava presente em 68% das alças anguladas e em 75% das alças circulares (p > 0,05). Houve, intragrupo, diminuição estatisticamente significante da pCO 2 e aumento estatisticamente significante do pH. Não houve diferença estatística no restante dos parâmetros avaliados entre os dois modelos de alça. CONCLUSÕES: apresentamos um modelo reprodutível de alça vascular. Não houve diferença estatística quanto à presença de fluxo após sete dias nos dois modelos de alça vascular. Nível de Evidência V, Estudo experimental em animais.

The design of the arteriovenous vascular loop does not affect its patency: experimental study / O formato da alça vascular não afeta a patência arteriovenosa: estudo experimental

ABSTRACT Objective: To evaluate the effect of the design of a femoral vascular loop with anastomosis in the femoral artery of rabbits on the presence of flow (patency) after seven days. Methods: A total of 39 rabbits underwent arteriovenous microanastomosis using the microsurgical technique. Two loop designs were used: one circular and the other angled. The parameters evaluated were presence or absence of flow, signs of hemolysis and hemodynamic changes. Results: After seven days, flow was present in 68% of the angled loops and 75% of the circular loops (p > 0.05). There was a significant intragroup decrease in pCO2 and a significant increase in pH. For the other parameters evaluated, no significant differences between the two loop models were found. Conclusions: A reproducible vascular loop model was shown. There was no significant difference between the two vascular loop models about the presence of flow after seven days. Level of Evidence V, Animal experimental study.

RESUMO Objetivo: Avaliar, em coelhos, qual é a influência do desenho da alça de veia femoral com anastomose na artéria femoral, na presença de fluxo (patência) após sete dias. Método: 39 coelhos foram submetidos à microanastomose arteriovenosa com técnica microcirúrgica. As alças foram acomodadas em dois desenhos, um circular e outro, o mais alongado possível sem dobras na alça. Os parâmetros avaliados foram: presença ou não de fluxo, sinais de hemólise, alterações hemodinâmicas. Resultados: após sete dias, o fluxo estava presente em 68% das alças anguladas e em 75% das alças circulares (p > 0,05). Houve, intragrupo, diminuição estatisticamente significante da pCO 2 e aumento estatisticamente significante do pH. Não houve diferença estatística no restante dos parâmetros avaliados entre os dois modelos de alça. Conclusões: apresentamos um modelo reprodutível de alça vascular. Não houve diferença estatística quanto à presença de fluxo após sete dias nos dois modelos de alça vascular. Nível de Evidência V, Estudo experimental em animais.

Arteriovenous anastomosis learning curve using low cost simulator.

BACKGROUND: In order to reduce difficulties with learning surgical techniques, supplementary tools for training were developed. This paper describes the learning curve followed by student volunteer research subjects who used an alternative model for practicing vascular anastomosis. OBJECTIVES: To evaluate the vascular anastomosis technique learning curve and development of manual skills using a low-cost experimental model. METHODS: Experimental and prospective study using end-to-side vascular anastomosis in latex balloons over five successive phases, initiated after theoretical and practical guidance given by experienced vascular surgeon. The study subjects were six undergraduate medical students from Universidade Federal da Paraíba (UFPB), João Pessoa, PB, Brazil, in their third to fifth years of the course. Cluster analysis was used to interpret the data collected on the quality of anastomoses and the time taken. RESULTS: The time taken to perform anastomosis reduced for all students, with statistical differences from phase 1 compared to phases 4 and 5. There was also a trend to increasing scores on the quality index as the phases progressed. However, no statistical differences were detected using the Friedman test, which is appropriate for data measured with ordinal levels (quality was assessed on a scale of 1 to 5). CONCLUSIONS: It was found that the training model used was effective for increasing learning of this technique. It is believed that future studies with larger samples or a higher number of phases could demonstrate both reduced time and improved quality of the anastomoses performed with statistical significance.

Curva de aprendizado de anastomose arteriovenosa com uso de simulador de baixo custo / Arteriovenous anastomosis learning curve using low cost simulator

Resumo Contexto A redução das dificuldades no aprendizado da técnica cirúrgica levou ao surgimento de ferramentas complementares. Este trabalho descreve a curva de aprendizado dos alunos sujeitos da pesquisa, utilizando um modelo alternativo para a prática de anastomose vascular. Objetivos Avaliar a curva de aprendizado da técnica de anastomose vascular e do desenvolvimento de habilidades manuais a partir da utilização de um modelo experimental de baixo custo. Métodos Este trabalho é um estudo experimental e prospectivo, com a realização de anastomoses vasculares do tipo terminolateral em balões de látex durante cinco fases sucessivas, iniciadas após orientação teórico-prática de uma cirurgiã vascular experiente. Os sujeitos foram seis graduandos do curso de Medicina, do terceiro ao quinto ano, da Universidade Federal da Paraíba (UFPB), João Pessoa, Paraíba, Brasil. A interpretação do material coletado acerca da qualidade das anastomoses e do tempo utilizado seguiu a análise de agrupamento. Resultados Houve redução do tempo de realização das anastomoses de todos os alunos, com diferença estatística da fase 1 quando comparada às fases 4 e 5, bem como tendência crescente no índice de qualidade ao longo das fases. Porém, não foi detectada diferença estatística a partir do teste de Friedman, apropriado para dados com nível de mensuração ordinal (escala de 1 a 5 na avaliação da qualidade). Conclusões O modelo de treinamento utilizado foi efetivo para incremento do aprendizado dessa técnica, acreditando-se que amostras de maior tamanho ou com maior número de fases em trabalhos futuros poderiam demonstrar redução do tempo associada a melhora da qualidade da anastomose realizada com significância estatística.

Abstract Background In order to reduce difficulties with learning surgical techniques, supplementary tools for training were developed. This paper describes the learning curve followed by student volunteer research subjects who used an alternative model for practicing vascular anastomosis. Objectives To evaluate the vascular anastomosis technique learning curve and development of manual skills using a low-cost experimental model. Methods Experimental and prospective study using end-to-side vascular anastomosis in latex balloons over five successive phases, initiated after theoretical and practical guidance given by experienced vascular surgeon. The study subjects were six undergraduate medical students from Universidade Federal da Paraíba (UFPB), João Pessoa, PB, Brazil, in their third to fifth years of the course. Cluster analysis was used to interpret the data collected on the quality of anastomoses and the time taken. Results The time taken to perform anastomosis reduced for all students, with statistical differences from phase 1 compared to phases 4 and 5. There was also a trend to increasing scores on the quality index as the phases progressed. However, no statistical differences were detected using the Friedman test, which is appropriate for data measured with ordinal levels (quality was assessed on a scale of 1 to 5). Conclusions It was found that the training model used was effective for increasing learning of this technique. It is believed that future studies with larger samples or a higher number of phases could demonstrate both reduced time and improved quality of the anastomoses performed with statistical significance.