Classifications of haemodialysis vascular access stenosis: a scoping review

OBJECTIVES

Vascular access (VA) stenoses play a significant role in the morbidity of the haemodialysed population. Classifications for diagnosis, assessment and proposal of treatment strategies can be useful clinical and methodological tools. This review aims to present a comprehensive summary and propose further methodological approaches.

DESIGN

A systematic review of the literature, evaluating classifications for dialysis-related VA stenosis.

DATA SOURCES

Web of Science, Scopus, PubMed, Google Scholar and the ClinicalTrials.gov registry were searched from inception to 7 December 2024.

ELIGIBILITY CRITERIA

All articles containing classifications regarding dialysis VA were eligible, with no restrictions on the study type or language of the full text.

DATA EXTRACTION AND SYNTHESIS

Two independent researchers performed the search and initial screening. Four vascular surgeons assessed the included classifications using a modified Buchbinder's critical appraisal tool to evaluate quality.

RESULTS

From 4771 screened papers, 59 full-text papers were retrieved and 24 articles contained classifications. Three classifications were dedicated to VA stenosis, all based on the anatomical location of lesions. According to the modified Buchbinder's appraisal, the classifications were assessed as moderate-to-good quality. The literature disposes of immense inconsistency in terms of the definition of significant stenosis indicated for treatment.

CONCLUSIONS

VA significant stenosis and its classification is a non-uniformly understood issue with many different criteria and categorisations. This basic methodological problem leads to inconsistent results. We recommend the unification of the criteria and their validation in prospective studies.

Using ultrasound in preoperative mapping and surveillance of arteriovenous grafts for haemodialysis improves patency rates: Single-centre experience

BACKGROUND

This study aimed to evaluate patency outcomes of arteriovenous grafts (AVGs) before and after using Duplex doppler ultrasonography (DUS) in preoperative mapping and surveillance of AVG.

METHODS

In this single-centre, retrospective cohort study 212 patients receiving AVGs from January 2009 to December 2022 were included. In group 1, the creation of AVG as well as screening was based on physical examination alone. In contrast, DUS was used in the preoperative mapping and surveillance of AVG in group 2. The patients also received sulodexide as supplemental medication. Outcomes included primary and secondary patency. The Mann-Whitney U-test was used to compare the differences between groups in number of thrombectomies and preemptive percutaneous transluminal angioplasties (PTAs).

RESULTS

Group 1 included 90 AVGs. The mean follow-up time was 333 days (range: 1-1230 days, standard deviation: 318 days). The primary and secondary graft patency rates were 13.3%, 62.2% at 6 months; 2.2%, 52.1% at 12 months; 0%, 44.3% at 24 months and 0%, 44.3% at 36 months respectively. During the 7-year surveillance of AVG, significantly more thrombectomies were performed than preemptive PTA (p < 0.0001). Group 2 included 122 AVGs. The mean follow-up time was 584 days (range: 1-2040 days, standard deviation: 463 days). The primary and secondary graft patency rates were 54.9%, 95.9% at 6 months; 29.5%, 77.8% at 12 months; and 9.8%, 56.5% at 24 months; 2.5%, 47.1% at 36 months respectively. The primary and secondary graft patency was significantly longer (p < 0.0001, p = 0.002). During the 7-year surveillance of AVG there were significantly more preemptive PTAs performed (p = 0.0004).

CONCLUSIONS

The primary and secondary patency of AVG were significantly improved after using DUS in preoperative mapping and surveillance. DUS surveillance led to a decrease in AVG occlusion. A potential positive effect of sulodexide on patency rate of AVG needs more research.

Color Doppler ultrasound evaluation of arteriovenous grafts for hemodialysis

Although arteriovenous fistula (AVF) continues to be the vascular access of choice for the hemodialysis, arteriovenous graft (AVG) can be the best choice in certain categories of patients and could have several advantages over AVF in a "patient centered approach" to vascular access. In the clinical management of prosthetic fistulas, color Doppler ultrasound (CDU) is the imaging method of choice for identifying stenosis and other AVG complications. In this review, besides highlighting the pivotal role of CDU in the diagnosis of AVG complications, we will underline the key role that ultrasound can play in identifying those stenosis most likely to cause AVG thrombosis. Furthermore, we will emphasize the support that CDU can play in distinguishing the different types of grafts and prosthetic devices such as stent-grafts, in identifying AVG with lower survival, CDU utilities and limitations in the evaluation of freshly-implanted grafts, the different sites available for AVG volume flow measurement and their use based on the configuration of the prosthesis, the time interval elapsed from the surgical intervention and the integrity of the prosthetic walls.

Central vein stenosis in hemodialysis vascular access: clinical manifestations and contemporary management strategies

Central venous stenosis is a significant and frequently encountered problem in managing hemodialysis (HD) patients. Venous hypertension, often accompanied by severe symptoms, undermines the integrity of the hemodialysis access circuit. In central venous stenosis, dialysis through an arteriovenous fistula is usually inefficient, with high recirculation rates and prolonged bleeding after dialysis. Central vein stenosis is a known complication of indwelling intravascular and cardiac devices, such as peripherally inserted central catheters, long-term cuffed hemodialysis catheters, and pacemaker wires. Hence, preventing this challenging condition requires minimization of central venous catheter use. Endovascular interventions are the primary approach for treating central vein stenosis. Percutaneous angioplasty and stent placement may reestablish vascular function in cases of elastic and recurrent lesions. Currently, there is no consensus on the optimal treatment, as existing management approaches have a wide range of patency rates.

Multiparametric ultrasound for upper extremity dialysis access evaluation

The evolution of ultrasound (US) techniques has greatly improved the evaluation of many parameters in dialysis vascular access, which is typically achieved through an arteriovenous fistula (AVF) or graft (AVG). These techniques include grayscale B-mode, color Doppler, power Doppler, spectral Doppler, non-Doppler US flow imaging techniques, contrast-enhanced US, and elastography. In conjunction with a patient's medical history and physical examination, US provides crucial information about the native vascular bed prior to the surgical creation of an arteriovenous anastomosis. It also tracks the maturation progress of the newly created AVF or AVG and aids in diagnosing potential complications of the vascular access. These complications include thrombosis, steal syndrome, aneurysms, pseudoaneurysms, hematomas, infection, ischemic neuropathy, exacerbation of preexisting congestive heart failure, and stenosis.

Standardized Methodology for Duplex Ultrasound Examination of Arteriovenous Access for Hemodialysis: A Proposal of the French Society of Vascular Medicine and the French-Speaking Society of Vascular Access

Duplex ultrasound (DUS) is an essential tool for characterizing and monitoring arteriovenous (AV) access for hemodialysis. The aim of the work described here, requested by the French Society of Vascular Medicine in collaboration with the French-Speaking Vascular Access Society, is to propose a standardized methodology for performing and documenting DUS, taking into account the variety of AV access techniques and the problems routinely encountered. A steering committee reviewed the literature and selected the relevant references. A draft was prepared, and all items with missing or conflicting data were submitted to a Delphi consensus. The final document was discussed and approved by all participants. The principles of DUS evaluation of AV access consist of examination of the afferent artery, the anastomosis and the entire venous drainage system. DUS uses B-mode ultrasound, color flow, pulsed wave and power Doppler analysis. DUS can be used in a variety of clinical situations, which can directly influence the methodology of the examination and the interpretation of the results. Blood flow should be assessed as it correlates with the risk of thrombosis. The measurement should be adapted to the different anatomical and hemodynamic conditions encountered. Characterization of stenosis should take into account the residual diameter of the drainage vein and its hemodynamic consequences. Other complications can be assessed with a standardized DUS examination. When performed according to a rigorous methodology, DUS of the AV access allows a comprehensive assessment of its functionality and eliminates the need for further invasive diagnostic procedures.

Arteriovenous Hemodialysis Access Stenosis Diagnosed by Duplex Doppler Ultrasonography: A Review

Arteriovenous fistula (AVF) is currently the hemodialysis access with the longest life expectations for the patients. However, even the AVF is at risk for many complications, especially the development of stenosis. The latter can not only lead to inadequate hemodialysis but also lead to AVF thrombosis. Duplex Doppler ultrasonography is a very precise method, in the hands of experienced professionals, for the diagnosis of AVF complications. In this review, we summarize the ultrasound diagnostic criteria of significant stenoses and their indication for procedural therapy.

The role of Doppler ultrasonography in vascular access surveillance-controversies continue

Chronic hemodialysis therapy required regular entry into the patient’s blood stream with adequate flow. The use of arteriovenous fistulas and grafts is linked with lower morbidity and mortality than the use of catheters. However, these types of accesses are frequently affected by stenoses, which decrease the flow and lead to both inadequate dialysis and access thrombosis. The idea of duplex Doppler ultrasound surveillance is based on the presumption that in-time diagnosis of an asymptomatic significant stenosis and its treatment prolongs access patency. Details of performed trials are conflicting, and current guidelines do not support ultrasound surveillance. This review article summarizes the trials performed and focuses on the reasons of conflicting results. We stress the need of precise standardized criteria of significant access stenosis and the weakness of the metaanalyses performed.

Role of Doppler ultrasonography in the evaluation of hemodialysis arteriovenous access maturation and influencing factors

The goal of vascular access creation is to achieve a functioning arteriovenous fistula (AVF) or arteriovenous graft (AVG). An autologous fistula has been shown to be superior to AVG or to central venous catheters (CVCs) with lowest rate of re-intervention, but vessel obstruction or immaturity accounts for 20 % to 54% of cases with primary failure of AVF. This review is focused on the factors influencing maturation; indication and timing of preoperative mapping/creation of vascular access; ultrasound parameters for creation AVF/AVG; early postoperative complications following creation of a vascular access; ultrasound determinants of fistula maturation and endovascular intervention in vascular access with maturation failure. However, vascular accesses that fail to develop, have a high incidence of correctable abnormalities, and these need to be promptly recognized by ultrasonography and managed effectively if a high success rate is to be expected. We review approaches to promoting fistula maturation and duplex ultrasonography (DUS) of evaluating vascular access maturation.

Consensus document for ultrasound training in the specialty of Nephrology

Ultrasound is an essential tool in the management of the nephrological patient allowing the diagnosis, monitoring and performance of kidney intervention. However, the usefulness of ultrasound in the hands of the nephrologist is not limited exclusively to the ultrasound study of the kidney. By ultrasound, the nephrologist can also optimize the management of arteriovenous fistula for hemodialysis, measure cardiovascular risk (mean intimate thickness), implant central catheters for ultrasound-guided HD, as well as the patient's volemia using basic cardiac ultrasound, ultrasound of the cava inferior vein and lungs. From the Working Group on Interventional Nephrology (GNDI) of the Spanish Society of Nephrology (SEN) we have prepared this consensus document that summarizes the main applications of ultrasound to Nephrology, including the necessary basic technical requirements, the framework normative and the level of training of nephrologists in this area. The objective of this work is to promote the inclusion of ultrasound, both diagnostic and interventional, in the usual clinical practice of the nephrologist and in the Nephrology Services portfolio with the final objective of offering diligent, efficient and comprehensive management to the nephrological patient.

Quantification of the severity of outflow stenosis of hemodialysis fistulas with a pulse- and thrill-based scoring system

BACKGROUND

Hyper-pulsatility of hemodialysis arteriovenous fistula (AVF) is the basic physical examination finding when there is outflow stenosis. The arm elevation test can also be utilized to detect outflow stenosis. If there is no significant outflow stenosis, the AVF should collapse, at least partially, because of the effect of gravity when the AVF-bearing arm is elevated to a level above that of the heart. However, if there is significant outflow stenosis, the portion of the AVF downstream of the stenosis will collapse, while the portion upstream of the stenosis will remain distended (Clin J Am Soc Nephro 8:1220-7, 2013). In our daily practice, when performing the arm elevation test, we not only observe the collapsibility of the access outflow but also palpate the outflow to identify a background thrill that sometimes disappears with the arm at rest, only to reappear when the arm is elevated. If there is no thrill upon arm elevation, we assume that the outflow stenosis is severe and refer to this condition as "physical examination significant outflow stenosis" (PESOS). The aim of this study is to characterize PESOS using percentage stenosis and Doppler flow parameters.

METHODS

We performed a case-control study using data collected prospectively between June 2019 and December 2019. A pulse- and thrill-based score system was developed to assess the severity of AVF outflow stenosis. We recorded the outflow scores and Doppler measurements performed in 84 patients with mature fistulas over a 6-month period. Angiograms were reviewed to determine the severity of outflow stenosis, which was assessed by calculation of percentage stenosis.

RESULTS

Receiver operating characteristic analysis showed that a cutoff value of ≥74.44% stenosis discriminated PESOS from other AVF outflow scores, with an area under the curve of 0.9011. PESOS diagnosed cases with ≥75% outflow stenosis in an AVF, with a sensitivity of 80.39%, a specificity of 78.79%, a positive predictive value of 85.42%, and a negative predictive value of 72.22%.

CONCLUSIONS

PESOS can be used to diagnose ≥75% outflow stenosis in an AVF, with or without a significant collateral vein, and its diagnostic accuracy is high. The use of PESOS as an indicator for treatment implies that physical examination may represent a useful surveillance tool.

Spanish Clinical Guidelines on Vascular Access for Haemodialysis

Vascular access for haemodialysis is key in renal patients both due to its associated morbidity and mortality and due to its impact on quality of life. The process, from the creation and maintenance of vascular access to the treatment of its complications, represents a challenge when it comes to decision-making, due to the complexity of the existing disease and the diversity of the specialities involved. With a view to finding a common approach, the Spanish Multidisciplinary Group on Vascular Access (GEMAV), which includes experts from the five scientific societies involved (nephrology [S.E.N.], vascular surgery [SEACV], vascular and interventional radiology [SERAM-SERVEI], infectious diseases [SEIMC] and nephrology nursing [SEDEN]), along with the methodological support of the Cochrane Center, has updated the Guidelines on Vascular Access for Haemodialysis, published in 2005. These guidelines maintain a similar structure, in that they review the evidence without compromising the educational aspects. However, on one hand, they provide an update to methodology development following the guidelines of the GRADE system in order to translate this systematic review of evidence into recommendations that facilitate decision-making in routine clinical practice, and, on the other hand, the guidelines establish quality indicators which make it possible to monitor the quality of healthcare.

The Role of Doppler Ultrassonography in Significant and Borderline Stenosis Definition

Background: The definition of significant stenosis (SS) remains controversial. Methods: We retrospectively reviewed 1,040 consultations. SS was defined in the presence of clinical and echo-Doppler (DDU) criteria: Qa <500 mL/min or Qa decrease >25%; RI >0.7 in the feeding artery or absolute minimal luminal stenosis diameter <2.0 mm. Stenosis without any additional criteria were considered borderline stenosis (BS). Results: Two hundred twenty-one arteriovenous fistulas (AVFs) were included: 58.8% had SS, 18.6% had BS, and 22.6% had no dysfunctional access (ND). SS had a significantly higher thrombotic events than BS and ND (13.1 vs. 4.4%, p = 0.018). The annual thrombosis rate was 0.007, 0.037, and 0.004 in the ND, SS, and BS, respectively. AVF cumulative survival at 5 years was significantly lower in SS (89.5%) compared to BS (100%) and ND (97.4%; p = 0.03). BS had an HR for AVF failure of 1.1, p = 0.955, while the SS presented an HR of 5.9, p = 0.09. Conclusion: AVF clinical monitoring with additional DDU criteria appear to be appropriate for therapeutic referral.

Dialysis arteriovenous access monitoring and surveillance according to the 2017 Spanish Guidelines

The Spanish Multidisciplinary Group on Vascular Access (GEMAV), which includes experts from the five scientific societies involved (nephrology (S.E.N.), vascular surgery (SEACV), interventional radiology (SERAM-SERVEI), infectious diseases (SEIMC), and nephrology nursing (SEDEN)), along with the methodological support of the Iberoamerican Cochrane Centre, has developed the Spanish Clinical Guidelines on Vascular Access for Hemodialysis. This article summarizes the main issues from the guideline's chapter entitled "Monitoring and surveillance of arteriovenous access." We will analyze the current evidence on conflicting topics such as the value of the flow-based screening methods for the arteriovenous access surveillance or the role of Doppler ultrasound as the imaging exploration to confirm suspected stenosis. In addition, the concept of significant stenosis and the criteria to perform the elective intervention for stenosis were reviewed. The adoption of these guidelines will hopefully translate into a reduced risk of thrombosis and increased patency rates for both arteriovenous fistulas and grafts.

Hemodialysis Vascular Access Ultrasonography: Tips, Tricks, Pitfalls and a Quiz

Duplex ultrasonography (DU) is a useful tool to optimize vascular access care in hemodialysis patients. However, the professional training of most healthcare workers caring for dialysis patients does not routinely include the teaching of DU (in this setting), thus limiting its use. The aim of this article is to provide some practical tips, tricks and potential pitfalls of this technique, both to the trainee ultrasonographer and to the healthcare worker already applying this technique in practice. The topics covered are 1) basic ultrasound principles (physics, machines and transducers), 2) the modes needed in vascular access DU in combination with the respective ways to optimize image quality, and 3) the assessment of access flow, stenosis and access induced ischemia by ultrasonography. This is done in the format of a quiz with 12 questions and answers.