Complications of a High-flow Access and Its Management

Right ventricular-pulmonary arterial coupling and pulmonary hypertension in hemodialysis: insights into structural cardiac changes and clinical implications

OBJECTIVES

This cross-sectional analysis from the CZecking Heart Failure in patients with advanced Chronic Kidney Disease trial (ISRCTN18275480) examined pulmonary hypertension and right ventricular-pulmonary arterial coupling in patients on chronic hemodialysis. The aims of this analysis were: 1. To analyze relations between pulmonary hypertension and right ventricular-pulmonary arterial coupling with dialysis access flow and current hydration; 2. To analyze structural heart changes associated with right ventricular-pulmonary arterial uncoupling; 3. To reveal the prevalence, etiology and severity of pulmonary hypertension in the Czech hemodialysis population.

METHODS

We performed expert echocardiography, vascular access flow measurements, bioimpedance analysis, and laboratory testing in 336 hemodialysis patients.

RESULTS

Pulmonary hypertension was present in 34% (114/336) patients and right ventricular-pulmonary arterial uncoupling was present in 25% of patients with pulmonary hypertension. Only weak associations between the flow of the dialysis arteriovenous access and estimated pulmonary arterial systolic pressure and right ventricular-pulmonary arterial coupling was proved. There was a strong association between hydration status assessed by estimated central venous pressure with pulmonary arterial systolic pressure (Rho 0.6, p < 0.0001) and right ventricular-pulmonary arterial coupling (Rho -0.52, p < 0.0001) and association between overhydration to extracellular water ratio with pulmonary arterial systolic pressure (Rho 0.31, p = 0.0001) and right ventricular-pulmonary arterial coupling (Rho -0.29, p = 0.002). The prevalence of heart failure was significantly higher in patients with right ventricular-pulmonary arterial uncoupling (88% vs. 52%, p = 0.0003).

CONCLUSION

These findings suggest that optimizing volume status and treating heart failure should be prioritized in hemodialysis patients to prevent pulmonary hypertension progression and right ventricular-pulmonary arterial uncoupling.

Effect of flow reduction surgery in a patient with high flow arteriovenous fistula with aortic dissection using 4D flow magnetic resonance imaging: A case report

This study aimed to investigate cardiovascular function in a patient with high-flow arteriovenous fistula (AVF) who underwent aortic dissection (AD) using four-dimensional (4D) flow magnetic resonance imaging (MRI) as well as analyze the effect of flow reduction surgery on AD. On March 12, 2017, a 60-year-old woman underwent emergency surgery for AD. After that, she experienced acute kidney injury, and hemodialysis was initiated. On April 24, 2017, a left brachiocephalic arteriovenous fistula (AVF) was created to facilitate her dialysis. However, after 5 years, the patient presented with a high-flow AVF, and a flow reduction surgery was performed on March 11, 2022. To evaluate the procedure's effectiveness, we measured the changes in left ventricular (LV) function and blood flow in the aorta and vascular access before and after surgery using 4D flow MRI. Notable changes were observed in LV function, blood flow in the aorta before and after the surgery, and maximum velocity and flow volume after surgery. During the 6-month follow-up after the surgery, the maximum velocity and flow volume in the aorta and vascular access were reduced; also, indicators such as LV volume, cardiac output, cardiac index, and LV mass were improved. In patients with high-flow AVF, flow reduction surgery should be considered as it may improve LV function and reduce the risk of AD recurrence by lowering the flow volume of the aorta.

Safety of bilateral arm pressure measurements in the diagnostic workup of dialysis-associated steal syndrome

OBJECTIVE

Although bilateral brachial pressure measurement is routinely included in the diagnostic work-up of upper extremity ischemia, it is generally avoided in the presence of hemodialysis access due to fears of inducing access thrombosis. This study evaluated the safety of bilateral brachial pressure measurement in patients with clinical suspicion of dialysis-associated steal syndrome (DASS).

METHODS

Patients undergoing non-invasive testing for steal syndrome between September 2015 and December 2021 were included in this study. The diagnostic workup was performed by certified vascular sonographers in an outpatient vascular lab and consisted of bilateral brachial pressures, photoplethysmography, and duplex ultrasonography of the access. Interarm differential (IAD) was defined as systolic blood pressure (SBP) in the contralateral arm minus SBP in the access arm. The primary endpoint was immediate access thrombosis.

RESULTS

The study sample consisted of 331 subjects with a mean age of 61 ± 13 and a median access age of 9 months (3-31 months) with radiocephalic fistulas present in 29%. Many patients (68%) presented with paresthesia and 4% presented with tissue loss. The mean brachial systolic pressure was 152 ± 37 mmHg on the ipsilateral arm versus 143 ± 34 mmHg on the contralateral (p-value <0.001), with an inter-arm differential (IAD) of -8.4 ± 19 mmHg. A total of 16 subjects (5%) presented a differential ⩾20 mmHg. A positive thrill was noted in all the accesses immediately following blood pressure measurement and no occurrence of access thrombosis was noted at 30 days. Proximal arterial revascularization interventions were performed in 11 cases (3%). Subjects who presented an IAD ⩾20 mmHg had lower ipsilateral digital-brachial index (0.39 ± 0.18 vs 0.68 ± 0.26; p = 0.037), a higher tendency of being referred for angiograms (37.5% vs 10.5%, p = 0.006), and more proximal arterial revascularization procedures (25.0% vs 2.2%, p = 0.001).

CONCLUSION

Bilateral arm pressure measurement in the context of dialysis access-associated steal syndrome (DASS) appears safe and useful for identifying subjects whose symptoms are due to proximal arterial inflow disease. We therefore recommend this test be considered in the diagnostic algorithms of DASS.

Covered stent combined with embolization treatment for complex congenital lower limb arteriovenous malformations: case report and literature review

BACKGROUND

Currently, the treatment outcomes for complex congenital arteriovenous malformations (AVMs) remain unsatisfactory. This article reports on the utilization of an abdominal aortic stent graft, in conjunction with embolization techniques, for managing acute heart failure triggered by complex congenital arteriovenous malformations in the lower limb.

CASE PRESENTATION

We present a case involving a patient with congenital AVMs in the lower limb, who had suffered from prolonged swelling in the left lower limb and recently developed symptoms of heart failure. At the age of 67, the patient was definitively diagnosed with a complex congenital AVMs in the lower limb. This article delves into the practical experiences and limitations encountered in employing an abdominal aortic stent graft, coupled with embolization, to address acute heart failure caused by complex congenital AVMs in the lower limb.

CONCLUSIONS

Our article presents the initial report on the challenges and limitations encountered in treating acute heart failure triggered by complex congenital AVMs in the lower limb, utilizing a combination of abdominal aortic stent graft placement and embolization techniques.

A rare hemodialysis vascular access complication-Internal jugular vein reflux

Hemodialysis (HD) arteriovenous fistulas commonly present with late vascular access complications, but are rarely in association with internal jugular vein (IJV) reflux. We reported two patients who had severe and mild IJV reflux, respectively. Case 1 was a 48-year-old male with end-stage renal disease (ESRD) who had been treated with HD for 5 years. He presented with persistent headaches, nausea, and vomiting. Combined with all the examinations, it was revealed severe IJV reflux, brachiocephalic vein stenosis, high-flow vascular access, and IJV valve dysfunction. Case 2 was a 59-year-old female with ESRD who had constructed an AVF for 4 months and had been on HD for only 1 day. She presented with dizziness and nausea after the first hemodialysis and duplex ultrasonography showed slightly continuous IJV reflux, high-flow vascular access, and IJV valve dysfunction. Furthermore, we reviewed 16 case reports to identify the characteristics of IJV reflux in HD patients. IJV reflux in HD patients may be caused by high-flow access, central venous stenosis or occlusion, and valve dysfunction. Severe IJV reflux can develop neurological symptoms secondary to intracranial venous reflux in this article. Etiological treatment is helpful for these patients, but there is a risk of recurrence.

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

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.

Effect of proximal artery restriction on flow reduction and cardiac function in hemodialysis patients with high-flow arteriovenous fistulas

OBJECTIVE

Arteriovenous fistula is the preferred vascular access for hemodialysis patients. High-flow arteriovenous fistula may cause high-output heart failure. Various procedures are used to reduce high-flow arteriovenous fistula. This study aimed to assess the efficacy of proximal artery restriction combined with distal artery ligation on flow reduction for high-flow arteriovenous fistula and on cardiac function and echocardiographic changes in patients undergoing hemodialysis.

METHODS

A retrospective analysis was performed on data collected from the medical records of patients undergoing hemodialysis with heart failure and high-flow arteriovenous fistula between May 2018 and May 2021. Thirty-one patients were treated with proximal artery restriction (banding juxta-anastomosis of the proximal artery) combined with distal artery ligation (anastomosis distal artery ligation). Changes in the Acute Dialysis Quality Initiative Workgroup cardiac function class, blood pressure, and echocardiography before and 6 months after flow restriction were compared, and post-intervention primary patency was followed-up.

RESULTS

The technical success rate of the surgery was 100%, and no surgery-related adverse events occurred. Blood flow and blood flow/cardiac output decreased significantly after flow restriction. Blood flow decreased from 2047.21 ± 398.08 mL/min to 1001.36 ± 240.42 mL/min, and blood flow/cardiac output decreased from 40.18% ± 6.76% to 22.34% ± 7.21% (P < .001). Post-intervention primary patency of arteriovenous fistula at 6, 12, and 24 months was 96.8%, 93.5%, and 75.2%, respectively. The Acute Dialysis Quality Initiative Workgroup cardiac function class improved significantly after 6 months of flow restriction (P < .001). The systolic and diastolic left heart function improved, as evidenced by a significant decrease in left atrial volume index, left ventricular end-diastolic/end-systolic diameters, left ventricular end-diastolic volume, left ventricular mass index, cardiac output, and cardiac index and an increase in lateral peak velocity of longitudinal contraction, average septal-lateral s', and lateral early diastolic peak velocity after flow restriction (P < .05). Systolic pulmonary artery pressure decreased from 32.36 ± 8.56 mmHg to 27.57 ± 8.98 mmHg (P < .05), indicating an improvement in right heart function.

CONCLUSIONS

Proximal artery restriction combined with distal artery ligation effectively reduced the blood flow of high-flow arteriovenous fistula and improved cardiac function.

Novel external stenting for reconstruction of high flow arteriovenous fistula

BACKGROUND

High-flow arteriovenous fistulae (HF-AVF) may lead to adverse cardiac remodeling in hemodialysis patients. We have investigated whether a novel external stent is safe and effective in reducing and stabilizing flow rates during a 1-year follow-up after HF-AVF reconstruction.

METHODS

All patients with HF-AVF (access flow rate ⩾ 1500 ml/min), who underwent HF-AVF reconstruction with external stenting in two centers between June 2018 and May 2020, were included in this retrospective analysis. During HF-AVF reconstruction, the dilated vein segment was resected, underwent volume reduction, and was externally stabilized using a braided cobalt-chromium external stent. AVF flow rates were assessed preoperatively, intraoperatively, and at follow up visits using duplex ultrasound.

RESULTS

Forty-three HF-AVFs in 42 patients were reconstructed and supported with an external stent (mean age 49 years, range 20-86 years; 74% men). Fifty-one percent were forearm AVFs, 49% were upper arm. The mean preoperative flow rate was 2622 ± 893 ml/min (range: 1500-6000 ml/min) and was decreased to 710 ± 221 ml/min (range: 300-1300 ml/min) intra-operatively after HF-AVF reconstruction. At 6 and 12-months follow-up, the mean flow rates were 1132 ± 320 ml/min (range: 470-1700 ml/min) and 1453 ± 888 ml/min (range: 300-3800 ml/min), respectively. Recurrence of high flow (>1500 ml/min) occurred in 16% and 25% of the patients at 6 and 12 months and primary patency rates were 86% and 70%, respectively.

CONCLUSIONS

This early experience with novel external stenting for HF-AVF reconstruction demonstrates that it is a safe and effective method for reducing and stabilizing flow rates up to 1-year post procedure. Additional studies are required to evaluate the durability of this procedure over the longer term and assess its effect on cardiac remodeling.

Arteriovenous Fistulae in Chronic Kidney Disease and the Heart: Physiological, Histological, and Transcriptomic Characterization of a Novel Rat Model

Background Arteriovenous fistulae (AVFs) are the gold standard for vascular access in those requiring hemodialysis but may put an extra hemodynamic stress on the cardiovascular system. The complex interactions between the heart, kidney, and AVFs remain incompletely understood. Methods and Results We characterized a novel rat model of five-sixths partial nephrectomy (NX) and AVFs. NX induced increases in urea, creatinine, and hippuric acid. The addition of an AVF (AVF+NX) further increased urea and a number of uremic toxins such as trimethylamine N-oxide and led to increases in cardiac index, left and right ventricular volumes, and right ventricular mass. Plasma levels of uremic toxins correlated well with ventricular morphology and function. Heart transcriptomes identified altered expression of 8 genes following NX and 894 genes following AVF+NX, whereas 290 and 1431 genes were altered in the kidney transcriptomes, respectively. Gene ontology and Kyoto Encyclopedia of Genes and Genomes analysis revealed gene expression changes related to cell division and immune activation in both organs, suppression of ribosomes and transcriptional activity in the heart, and altered renin-angiotensin signaling as well as chronodisruption in the kidney. All except the latter were worsened in AVF+NX compared with NX. Conclusions Inflammation and organ dysfunction in chronic kidney disease are exacerbated following AVF creation. Furthermore, our study provides important information for the discovery of novel biomarkers and therapeutic targets in the management of cardiorenal syndrome.

Customizable modification of banding with external stenting for arteriovenous fistula flow reduction

We performed a single-center retrospective study of prospectively collected data for all patients who had flow reduction surgery with FRAME FR between November 2020 and January 2021. Ten patients had arteriovenous fistula flow reduction surgery with this technique. One patient had a distal fistula, whereas nine were within the cubital fossa. In nine patients the device was applied over the postanastomotic arteriovenous fistula outflow vein and in one in the preanastomotic radial artery. Technical success was achieved in all patients with a median flow reduction from 2150 to 825 mL/min. There were no wound or device-specific complications.

High-flow arteriovenous fistula and hemodynamic consequences at 1 year after kidney transplantation

INTRODUCTION

There are only scarce data regarding the cardiovascular impact of arteriovenous fistula after kidney transplantation depending on fistula flow.

METHODS

We performed a single-center, prospective, cohort study including 49 patients with a functional fistula at 1 year from kidney transplantation. Patients were convened for a clinical work-up, a biological analysis, a fistula's Doppler ultrasonography and an echocardiography. Main judgment criterion was comparison of echocardiography parameters between patients with relative (fistula flow >1 L/min and a fistula flow/cardiac output ratio >20%), absolute high-flow fistula (fistula flow >2 L/min) and normal-flow fistula.

RESULTS

High-flow fistula frequency was 69%. Significantly higher left ventricular end-diastolic and systolic diameters were observed in this group compared with the normal-flow fistula group (53 ± 6 vs. 48 ± 7 mm; p = 0.04 and 33 ± 6 vs. 28 ± 8 mm; p = 0.02) and between the absolute and relative high-flow fistula subgroups (56 ± 6 vs. 51 ± 6 mm; p = 0.009 and 35 ± 6 vs. 31 ± 5 mm; p = 0.01). The study showed no other significant differences.

CONCLUSIONS

This study showed a significantly higher but not pathological left ventricular end-diastolic and systolic diameters values in patients with high-flow fistula compared with patients with normal-flow fistula and between patients with respectively absolute and relative high-flow fistula.

ASDIN white paper: Management of cephalic arch stenosis endorsed by the American Society of Diagnostic and Interventional Nephrology

Brachiocephalic arteriovenous fistulas (AVF) makeup approximately one third of prevalent dialysis vascular accesses. The most common cause of malfunction with this access is cephalic arch stenosis (CAS). The accepted requirement for treatment of a venous stenosis lesion is ⩾50% stenosis associated with hemodynamically abnormalities. However, the correlation between percentage stenosis and a clinically significant decrease in access blood flow (Qa) is low. The critical parameter is the absolute minimal luminal diameter (MLD) of the lesion. This is the parameter that exerts the key restrictive effect on Qa and results in hemodynamic and functional implications for the access. CAS is the result of low wall shear stress (WSS) resulting from the effects of increased blood flow and the unique anatomical configuration of the CAS. Decrease in WSS has a linear relationship to increased blood flow velocity and neointimal hyperplasia exhibits an inverse relationship with WSS. The result is a stenotic lesion. The presence of downstream venous stenosis causes an inflow-outflow mismatch resulting in increased pressure within the access. Qa in this situation may be decreased, increased, or within a normal range. Over time, the increased intraluminal pressure can result in marked aneurysmal changes within the AVF, difficulties with cannulation and the dialysis treatment, and ultimately, increasing risk of access thrombosis. Complete characterization of the lesion both hemodynamically and anatomically should be the first step in developing a strategy for management. This requires both access flow measurement and angiographic imaging. Patients with CAS present a relatively broad spectrum as relates to both of these parameters. These data should be used to determine whether primary treatment of CAS should be directed toward the anatomical lesion (small MLD and low Qa) or the pathophysiology (large MLD and high Qa).

Access flow volume (Qa) and survival in a hemodialysis population: An analysis of 5208 Qa measurements over a 9-year period

BACKGROUND

Aim of the study was to determine associations between characteristics of arteriovenous access (AVA) access flow volume (Qa, mL/min) and four year freedom from cardiovascular mortality (4yr-CVM) in hemodialysis (HD) patients.

METHODS

HD patients who received a primary AVA between January 2010 and December 2017 in one center were analyzed. Initial Qa was defined as the first Qa value obtained in a well-functioning AVA by a two-needle dilution technique. Actual Qa was defined as access flow at a random point of time. Changes in actual Qa were expressed per 3-month periods. CVM was assessed according to the ERA-EDTA classification. The optimal cut-off point for initial Qa was identified by a receiver operating characteristic curve. A joint modelling statistical technique determined longitudinal associations between Qa characteristics and 4yr-CVM.

RESULTS

A total of 5208 Qa measurements (165 patients, male n = 103; age 70±12 years, autologous AVA n = 146, graft n = 19) were analyzed. During follow-up (Dec 2010-Jan 2018, median 36 months), 79 patients (48%) died. An initial Qa < 900 mL/min was associated with an increased 4y-CVM risk (HR: 4.05; 95% CI [1.94-8.43], P<0.001). After 4 years, freedom from CVM was 34% lower in patients with a Qa < 900 mL/min (53 ±7% vs. Qa ≥ 900 mL/min: 87 ±4%, P <0.001). An association between increases in actual Qa over 3-month periods and mortality was found (HR: 4.48 per 100mL/min, 95% CI [1.44-13.97], P =0.010) indicating that patients demonstrating increasing Qa were more likely to die. By contrast, actual Qa per se was not related to survival.

CONCLUSIONS

Studying novel arteriovenous access Qa characteristics may contribute to understanding excess CVM in HD patients.

Skin perfusion pressure for predicting access-related hand ischemia following arteriovenous fistula surgery based on the brachial artery

BACKGROUND

Access-related hand ischemia (ARHI) is a major complication of arteriovenous fistula (AVF). This study aimed to assess the predictive efficacy of skin perfusion pressure (SPP) measurement for ARHI by examining the relationship between SPP and ARHI development and progression after AVF surgery.

METHODS

Twenty-five patients (16 men and 9 women) who underwent AVF surgery based on the brachial artery between January 2018 and December 2018 were included. The pre- and postoperative SPP values were measured on the day of surgery. ARHI occurrence and severity were measured within 3 days and at 6 months after surgery. Receiver operating characteristic curve analysis was used to evaluate the prediction model of ARHI, and the cutoff points for the calculated coefficients were determined.

RESULTS

There was a significant correlation between the occurrence of immediate ARHI and the SPP gradient (p = 0.024). An SPP gradient value >50 mmHg had sensitivity and specificity values of 53.85% and 91.67%, respectively, in predicting the occurrence of immediate ARHI. A postoperative SPP <48 mmHg was significantly correlated with the occurrence of 6-month ARHI (p = 0.005), with sensitivity and specificity values of 71.43% and 83.33%, respectively.

CONCLUSION

The SPP gradient and postoperative SPP values may be effective clinical predictors of ARHI occurring immediately and 6 months after surgery, respectively, with high specificity. These findings could allow clinicians to diagnose and begin early interventions to help prevent ischemic tissue damage in hemodialysis patients following AVF surgery.

A modified banding technique: experience of a center

BACKGROUND

A well-functioning vascular access is vital to patients on regular hemodialysis. Banding the access is indicated in high-flow-associated steal syndrome. It allows for the reduction of access flow while maintaining distal limb perfusion. Nonetheless, this procedure has some limitations as it can cause hemorrhage, infection, aneurysm formation, thrombosis of access in cases of overbanding, or otherwise insufficient reduction of vascular flow. Other surgical techniques to achieve the same benefit would be useful.

METHODS

We performed a modified banding technique without endovascular placement of the angioplasty balloon, which is a viable alternative to other techniques. This surgery was performed in patients on chronic dialysis with steal syndrome. Pre- and post-operative access flows were measured and resolution of symptoms was recorded. Primary patency rate was defined as the intervention-free access survival from the operative time.

RESULTS

We verified that this technique allowed for access flow reduction in all our six patients, with total resolution of symptoms in all patients. Primary patency rate at 12 months was 100%. No major complications were noted during our follow-up.

CONCLUSIONS

This technique allows for correction of high-flow arteriovenous fistulas in an efficient and safe way, and can be a viable alternative to other banding procedures.

To ligate or not to ligate hemodialysis arteriovenous fistulas in kidney transplant patients

There is significant disagreement about maintenance or ligation of arteriovenous fistulas (AVFs) in kidney transplant patients (KTPs). Potential harms from maintaining AVFs are their impact on cardiac function, cosmetic concerns and complications such as bleeding and rupture. High flow AVFs can place a strain on the heart and cause or exacerbate pre-existing cardiac dysfunction. There is an improvement in cardiac function after kidney transplantation independent of vascular access status. Studies comparing cardiac parameters in patients with and without AVFs after renal transplantation have shown conflicting results. Ligation of high flow AVFs in KTPs resulted in improvement in cardiac function and prevention of heart failure. In KTPs with deteriorating renal function and high flow AVFs, banding of the AVFs to reduce flow is an option. Patients who retain AVFs after renal transplant have the advantage of immediate, optimal access should the transplant fail and may have preserved kidney function. The patient's post-transplant kidney function, risk factors for transplant loss, AVF blood flow, and cardiac function play an important role when making the decision to ligate or preserve AVFs.

Challenges and novel therapies for vascular access in haemodialysis

Advances in standards of care have extended the life expectancy of patients with kidney failure. However, options for chronic vascular access for haemodialysis - an essential part of kidney replacement therapy - have remained unchanged for decades. The high morbidity and mortality associated with current vascular access complications highlights an unmet clinical need for novel techniques in vascular access and is driving innovation in vascular access care. The development of devices, biological approaches and novel access techniques has led to new approaches to controlling fistula geometry and manipulating the underlying cellular and molecular pathways of the vascular endothelium, and influencing fistula maturation and formation through the use of external mechanical methods. Innovations in arteriovenous graft materials range from small modifications to the graft lumen to the creation of completely novel bioengineered grafts. Steps have even been taken to create new devices for the treatment of patients with central vein stenosis. However, these emerging therapies face difficult hurdles, and truly creative approaches to vascular access need resources that include well-designed clinical trials, frequent interaction with regulators, interventionalist education and sufficient funding. In addition, the heterogeneity of patients with kidney failure suggests it is unlikely that a 'one-size-fits-all' approach for effective vascular access will be feasible in the current environment.

Angiectasia of the parietal pleura in a hemodialysis patient with central venous stenosis and bloody pleural effusion: a case report

Pleural effusion in hospitalized patients with long-term hemodialysis (HD) has been frequently reported. The most common causes of unilateral pleural effusions include hypervolemia, parapneumonic, uremic effusion, and malignancy. In contrast, central venous stenosis (CVS) has rarely been shown to result in pleural effusion. CVS is often diagnosed by percutaneous angiography, yet there are no reports of cases where percutaneous angiography missed CVS and instead intrathoracic endoscopy was performed. Herein, we report a case of CVS with angiectasia of the parietal pleura detected on intrathoracic endoscopy. A 62-year-old man with HD presented with massive unilateral pleural effusion. Although the cause of pleural effusion was suspected to be CVS, percutaneous angiography did not show apparent stenosis, and as a result, other potential causes of bloody effusion were investigated. The intrapleural cavity was assessed using intrathoracic endoscopy, which revealed angiectasia and no malignancy. As these findings might be suggestive of congestive and dilated vessels with venous stenosis or occlusion, 3D-computed tomography (CT) scans were performed instead of percutaneous angiography to determine whether a stenosis or occlusion was present. Brachiocephalic vein stenosis was found near the aortic arch. CVS was treated through ligation of the arteriovenous fistula (AVF), resulting in a dramatic decrease in the left pleural effusion. This case would suggest that CVS should be suspected when angiectasia of the parietal pleura is observed in HD patients. In addition, the benefit of utilizing 3D-CT should be considered when HD patients present with a unilateral hemothorax on the same side as that of the AVF, particularly when on the left side.

[Features of balloon angioplasty in the treatment of central vein stenosis in patients with arteriovenous fistula on programmed hemodialysis]

OBJECTIVE

To analyze AVF patency rates after balloon angioplasty and palliative open surgery in patients with native AVF and central vein stenosis.

MATERIAL AND METHODS

The study included 39 patients who underwent percutaneous balloon angioplasty (main group) and 41 patients who underwent palliative interventions (comparison group): thrombectomy, proximalization of arteriovenous anastomosis, AVF blood flow reduction. All patients were diagnosed with stenosis of subclavian vein, innominate vein, inferior vena cava or multiple lesions.

RESULTS

Primary annual patency rate in the main group was 15.4% [95% CI 6.2; 28.3], in the comparison group - 0% (p=0.0011). Secondary annual patency rate was 66.7% [95% CI 49.6; 79.1] and 19.5% [95% CI 9.2; 32.7], respectively (p<0.0001). In the main group, a strong negative correlation between primary patency rate and stenosis-free period was revealed (r= -0.627 [95%CI -0.787; -0.388], p<0.0001). We did not find such correlation in the comparison group (r=0,049 [95% CI -0.262; 0.351], p=0.7599). Thus, balloon angioplasty is less effective for delayed stenosis. This feature should be considered in planning vascular approach. Different primary and secondary patency rates in the comparison group indicate that AVF blood flow reduction is an effective palliative treatment.

CONCLUSION

Balloon angioplasty can significantly increase duration of AVF patency. Effectiveness of this procedure significantly depends on the period of manifestation of central vein stenosis. Balloon angioplasty cannot be considered a radical method in case of significant stenosis. This method only prolongs period for creation of new permanent contralateral vascular approach. Reduction of AVF blood flow can significantly reduce clinical severity of central vein stenosis and slightly extends the period of AVF patency.

KDOQI Clinical Practice Guideline for Vascular Access: 2019 Update

The National Kidney Foundation's Kidney Disease Outcomes Quality Initiative (KDOQI) has provided evidence-based guidelines for hemodialysis vascular access since 1996. Since the last update in 2006, there has been a great accumulation of new evidence and sophistication in the guidelines process. The 2019 update to the KDOQI Clinical Practice Guideline for Vascular Access is a comprehensive document intended to assist multidisciplinary practitioners care for chronic kidney disease patients and their vascular access. New topics include the end-stage kidney disease "Life-Plan" and related concepts, guidance on vascular access choice, new targets for arteriovenous access (fistulas and grafts) and central venous catheters, management of specific complications, and renewed approaches to some older topics. Appraisal of the quality of the evidence was independently conducted by using a Grading of Recommendations Assessment, Development, and Evaluation (GRADE) approach, and interpretation and application followed the GRADE Evidence to Decision frameworks. As applicable, each guideline statement is accompanied by rationale/background information, a detailed justification, monitoring and evaluation guidance, implementation considerations, special discussions, and recommendations for future research.

The effect of angioplasty of single arteriovenous fistula-associated stenosis on arteriovenous fistula blood flow rate

INTRODUCTION

Percutaneous balloon angioplasty of arteriovenous fistula-associated stenosis is performed for a variety of indications. Successful percutaneous transluminal angioplasty (PTA) is expected to increase in arteriovenous fistula blood flow rate (Qa). A validated approach to predicting changes in Qa based upon stenosis characteristics is not available.

METHODS

Three baseline parameters were determined in a group of patients with a single arteriovenous fistula-associated stenosis undergoing PTA. These were percent estimated stenosis, stenosis minimum luminal diameter, and baseline Qa. The relationship between these parameters and changes in Qa following PTA was analyzed using Spearman's rank correlation and linear regression.

RESULTS

113 patients (total group) were studied. Of these,106 had peripheral stenosis (total peripheral subgroup) and 7 had central stenosis. For the total group and total peripheral subgroup, a highly significant inverse correlation was seen between changes in Qa and baseline Qa. A weaker correlation was seen between changes in Qa and minimum luminal diameter, but no correlation was seen with percent estimated stenosis. A minimum luminal diameter ⩽2.0 mm was predictive of ⩾300-mL/min increases in Qa, whereas a minimum luminal diameter >4.5 mm was associated with <300-mL/min increases in Qa. PTA of Central vein stenosis was not associated with significant changes in Qa.

CONCLUSION

Baseline Qa is the best predictor for change in Qa following PTA. Stenosis minimum luminal diameter cutoffs of ⩽2.0 and >4.5 mm are useful in predicting the magnitude of changes in Qa. Percent estimated stenosis is not predictive of change in Qa. PTA of central veins does not seem to change Qa.

Can the fistula arm be used to lift heavy items? Six-pound dumbbells versus handgrip exercise in a 6-month follow-up secondary analysis of a randomized controlled trial

INTRODUCTION

Patients with arteriovenous fistulas are advised to avoid carrying heavy objects draped over the fistula arm. Awareness gradually leads to overprotection and a reduction in the use of the fistula arm. However, restricting motion in the fistula arm leads to decreased quality of life and diminished muscle strength. The current safety recommendations regarding lifting heavy items with the fistula arm are primarily based on experience. Few studies have provided evidence clarifying the scope of safe activity and the influence of load bearing on the continued patency of arteriovenous fistulas.

METHODS

This prospective observation was based on a long-term follow-up study in which 86 hemodialysis recipients with arteriovenous fistulas were randomized into either a dumbbell group or a handgrip group. The dumbbell group exercised with 6-lb dumbbells, while the handgrip group squeezed rubber balls. Postintervention primary patency and adverse events at the 6-month follow-up were analyzed.

RESULTS

No significant difference in postintervention primary patency was observed between the dumbbell group and the handgrip group at 6 months (97.4% vs 95.0%). There were two participants with high-flow fistulas in the dumbbell group and three in the handgrip group, with no significant difference between the two groups (5.3% vs 7.5%). In both groups, there were no other adverse events reported regarding cardiac failure, aneurysm, puncture site hematoma, or hemorrhage.

CONCLUSION

Hemodialysis patients can safely use their fistula arm to lift objects weighing less than 6 lb, which encourages increased motion and helps preserve the functionality of the fistula arm.

Effect of high flow arteriovenous fistula on cardiac function in hemodialysis patients

BACKGROUND

Vascular access for hemodialysis (HD) with an inappropriately high flow may underlie the onset of high output heart failure (HOHF).The aim of this study was to determine the prevalence of high flow access (HFA) in chronic HD patients, and to determine its effects on cardiac functions.

METHODS

This cross sectional study was conducted on 100 chronic hemodialysis patients through arteriovenous fistula (AVF). The study cohort was subdivided into 2 groups based on AVF flow: Group A (Non-HFA group with Qa < 2000 ml/min), and Group B (HFA group with Qa ≥ 2000 ml/min). AVF flow (Qa) was assessed using Color Doppler ultrasonography. Transthoracic echocardiography was performed for all patients to assess cardiac dimensions and functions.

RESULTS

Prevalence of HFA among study population was 24%. Mean AVF Qa was 958.63 ± 487.35 and 3430.13 ± 1256.28 ml/min, for group A and B respectively. The HFA group demonstrated a significant dilatation in LV dimensions and volumes and significantly larger LA volume as compared to non-HFA group. A significantly lower LV ejection fraction [EF] was also observed in group B with a mean value of 57.32 ± 6.19% versus 62.90 ± 5.76%. A significant association between HFA group and high Qa/cardiac output (CO) ratio (≥20%) was also observed.

CONCLUSION

HFA is a prevalent hemodialysis vascular access problem. HFA was associated with dilated LV dimensions, impaired LV systolic function. High Qa/CO ratio (≥20%) was an independent predictor of high output heart failure (HOHF) in our study population.

Subclavian steal syndrome without subclavian stenosis

Subclavian steal syndrome (SSS) has been well described in the setting of subclavian stenosis. We describe an unusual case of SSS caused by a high-flow arteriovenous dialysis fistula in the absence of subclavian stenosis, provide a review of the literature, and propose that arteriovenous fistula-induced SSS is an underdiagnosed cause of syncope in this population of patients.

Controversies in the management of the haemodialysis-related arteriovenous fistula following kidney transplantation

Arteriovenous fistula (AVF) is regarded as the best vascular access for chronic haemodialysis (HD). Still, AVF inherently causes significant haemodynamic changes. Although the necessity for vascular access despite its putative cardiovascular complications favours AVF creation in patients under chronic HD, one may question whether sustaining a functional AVF after successful kidney transplantation extends the haemodynamic threat. Small prospective series suggest that AVF ligation causes rapid and sustained reduction in left ventricular hypertrophy. Still, the benefits of such a cardiac remodelling in long-terms of cardiovascular morbi-mortality still need to be proven. Furthermore, the elevation of diastolic blood pressure and arterial stiffness caused by AVF ligation may blunt the expected cardio-protection. Finally, the closure of a functioning AVF may accelerate the decline of kidney graft function. As a whole, the current management of a functioning AVF in kidney transplant recipients remains controversial and does not rely on strong evidence-based data. The individual risk of graft dysfunction and a return to chronic HD also needs to be balanced. Careful pre-operative functional assessments, including cardio-pulmonary testing and estimated glomerular filtration rate slope estimation, may help better selection of who might benefit the most from AVF closure. Large-scale prospective, ideally multi-centric, trials are essentially needed.

The closure of arteriovenous fistula in kidney transplant recipients is associated with an acceleration of kidney function decline

Background

The creation of arteriovenous fistula (AVF) may retard chronic kidney disease progression in the general population. Conversely, the impact of AVF closure on renal function in kidney transplant recipients (KTRs) remains unknown.

Methods

From 2007 to 2013, we retrospectively categorized 285 KTRs into three groups: no AVF (Group 0, n = 90), closed AVF (Group 1, n = 114) and left-open AVF (Group 2, n = 81). AVF closure occurred at 653 ± 441 days after kidney transplantation (KTx), with a thrombosis:ligation ratio of 19:95. Estimated glomerular filtration rate (eGFR) was determined using the Modification of Diet in Renal Disease equation. Linear mixed models calculated the slope and intercept of eGFR decline versus time, starting at 3 months post-KTx, with a median follow-up of 1807 days (95% confidence interval 1665-2028).

Results

The eGFR slope was less in Group 1 (-0.081 mL/min/month) compared with Group 0 (-0.183 mL/min/month; P = 0.03) or Group 2 (-0.164 mL/min/month; P = 0.09). Still, the eGFR slope significantly deteriorated after (-0.159 mL/min/month) versus before (0.038 mL/min/month) AVF closure (P = 0.03). Study periods before versus after AVF closure were balanced to a mean of 13.5 and 12.5 months, respectively, with at least 10 observations per patient ( n = 99).

Conclusions

In conclusion, a significant acceleration of eGFR decline is observed over the 12 months following the closure of a functioning AVF in KTRs.

Arteriovenous access banding revisited

Purpose

The aim of this study is to validate the current applicability of arteriovenous access banding in high flow access (HFA) and/or haemodialysis access-induced distal ischaemia (HAIDI).

Methods

This retrospective study was conducted at the GEV (Grupo de Estudos Vasculares) vascular access centre. The clinical records of consecutive patients undergoing banding for HAIDI and HFA symptoms, between June 2011 and January 2015, were reviewed until April 2015. All vascular access patients’ consultation records and surgical notes were reviewed. We analysed and compared patients’ age, gender, comorbidities, symptoms and intraoperative ultrasound control. We defined technical failure as recurrence of symptoms, requiring new banding. Excessive banding, access thrombosis, rupture and false aneurysm development were registered as complications. Primary clinical success was defined as improvement of symptoms or effective flow reduction after banding, with no need for reintervention. If one reintervention was necessary, we have defined it as secondary clinical success.

Results

Overall, 119 patients underwent banding: 64 (54%) with HAIDI and 55 (46%) with HFA. The HAIDI group was significantly older (65 ± 13 years compared with 56 ± 22 years, p = 0.001) and had significantly greater number of patients with diabetes (56% vs 24%, p = 0.004). Primary success was achieved in 85 patients (71.4%) and the secondary success rate was 84.9%. Older age (p = 0.016) and intraoperative ultrasound control (p = 0.012) were significantly associated with primary success.

Conclusions

Our results do not corroborate the high incidence of thrombosis previously reported as associated with AV access banding and suggest that ultrasound control is crucial for preventing technical failure. The procedure was effective on both compared groups.

Permanent Arteriovenous Fistula or Catheter Dialysis for Heart Failure Patients

Heart failure (HF) is the most frequent cardiovascular disease associated with chronic kidney disease and represents a high risk for cardiovascular mortality in incident hemodialysis (HD) patients. This risk is especially high during the arteriovenous fistula (AVF) maturation period due to the marked hemodynamic changes related to the large increase in the blood flow and also within the first 120 days after HD inception because in this period the highest mortality rate occurs. When planning the vascular access for each incident HF patient, the risk of aggravating HF after AVF creation must be evaluated carefully alongside the risk of catheter-related complications, but avoiding a non-selective ‘catheter first’ approach for all these patients. HF patients classified within the New York Heart Association (NYHA) Class I-II and the American College of Cardiology/American Heart Association (ACC/AHA) Stage A-B could initiate HD through a distal arm AVF. High-flow brachial artery-based AVF creation must be avoided because it displays the highest risk of worsening the cardiac function. The decision for AVF creation or tunneled central catheter placement in HF patients classified within the NYHA Class III and the ACC/AHA Stage C must have been individualized according the degree of systolic and/or diastolic dysfunction. HF patients with significant reduction in systolic function (ejection fraction lower than 30%) or classified within the NYHA Class IV and the ACC/AHA Stage D, are candidates for tunneled catheter placement to start HD treatment.

External dilator-assisted banding for high-flow hemodialysis arteriovenous fistula

Creation of arteriovenous fistula (AVF) may lead to left ventricle hypertrophy and predispose for development or worsening of heart failure. It was postulated to reduce access blood flow if exceeded 2 L/min or cardiac index was higher than 3.0 L/min/m(2). Numbers of techniques decreasing flow were described. The major disadvantage was the complexity of procedure and necessity of intraoperative flow measurement needed to establish desired flow. The technique of dilator-assisted banding with no endovascular catheterization is presented. After blunt dissection non absorbable thread was placed around vessel and tied over the dilator. Then the dilator was gently removed and blood flow was confirmed by palpation. We performed 12 banding procedures. Mean brachial blood flows were 3733.2 ± 826.2 mL/min preoperatively and 1461.2 ± 337.7 mL/min after surgery. Mean flow reduction was 2272.2 ± 726.9 mL/min. The external dilator-assisted banding is a feasible method for vascular access flow reduction without necessity of endovascular catheterization.