Management of infected prosthetic dialysis arteriovenous grafts

Management of infected arteriovenous grafts for haemodialysis: Outcomes and strategies using a novel objective scoring system

BACKGROUND

In haemodialysis patients with exhausted autogenous options, prosthetic arteriovenous grafts (AVGs) are frequently utilised as tertiary vascular access. However, the prosthetic nature of AVGs precipitates an increased risk of infection which may translate to excess morbidity and life-threatening complications. The current evidence remains divided on the optimal treatment strategy for arteriovenous graft infections (AVGi) with arguments for conservative management by antibiotics, salvaging with graft revision or total/subtotal excision. To address this gap, we assessed the outcomes of AVGi patients treated in our institution, developing an AVGi severity classification model and a proposed treatment algorithm to guide AVGi management.

METHODS

We conducted a single centre retrospective review of outcomes of patients with AVGi managed either by sole antibiotics therapy, graft revision or surgical excision between June 2016 and May 2021. Outcomes of AVGi patients across differing treatment groups were compared, including 1-year mortality, 6-month and 1-year functional vascular access. We also analysed the outcomes of tunnelled haemodialysis lines (THL), which were used as a temporary vascular access in several AVGi patients in our study.

RESULTS

A total of 34 AVGi patients were managed within that time frame and included in the study (5 conservatively management by antibiotics, 5 graft revisions and 24 surgical excision) with a mean age of 60.4 ± 14.4 years (67.6% males). Overall 1-year mortality was 14.7%. A 6-month functional vascular access status across the three groups stood at 60%, 60% and 10% while 1-year functional vascular access status was 60%, 75% and 42% respectively.

CONCLUSIONS

When clinically appropriate, conservative management by antibiotics or salvage/graft revision can present as prudent AVGi treatment options. The adoption of our proposed severity classification system and treatment algorithm provides a more thorough objective assessment of the infection and helps guide the clinical decision-making process.

Surgical Referral for Hemodialysis Access Maintenance

Hemodialysis access is the lifeline for end-stage renal disease patients. However, dialysis access is associated with a host of complications, including thrombosis, recurrent stenosis, infection, aneurysmal changes and bleeding. Although endovascular therapy remains the first-line treatment owing to its less invasive nature, there are certain situations where surgical referral is recommended or even necessary. Regardless, management of dialysis access complications requires a multidisciplinary approach. Interventional radiologists should be familiar with the appropriate timing for surgical referral to better serve the complex patient population.

Pseudomonas aeruginosa Infections Are Associated with Infection Recurrence in Arteriovenous Grafts Treated with Revision

Background and Objectives: This study was conducted to investigate whether Pseudomonas aeruginosa (PA) infections of arteriovenous grafts (AVGs) recur more frequently than other bacterial infections following treatment with revision. Materials and Methods: Operative procedures, including total excision, subtotal excision, and revision, were performed on 60 patients to treat 65 AVG infections. Final outcomes were classified as no infection recurrence, infection recurrence, and death without prior recurrence. In the competing risk setting, the cumulative incidence was estimated using the cumulative incidence function and Gray's test, and the associations between outcomes and different variables were estimated using a subdistribution hazard (SDH) model. Results: Comparing AVG infections with and without recurrence, PA infection was not associated with a higher risk of infection recurrence (p = 0.13); however, the first operative procedure type was associated with infection recurrence (p = 0.04). AVGs with PA infection were associated with a higher total number of surgical interventions (p < 0.05) than AVGs without PA infection. Regarding the cumulative incidences of outcomes, for AVGs treated with subtotal excision or revision, the cumulative incidence of recurrent infection was 3.3-fold higher for those with PA infection than without one year after the first surgery. However, when AVGs were treated with revision alone, the cumulative incidence was 4.1-fold. After excluding AVGs treated with total excision, the SDH model was applied, obtaining a hazard ratio for infection recurrence of 16.05 (p = 0.02) for AVGs with PA infection compared with AVGs without PA infection. No other variables were significantly associated with infection recurrence. Conclusions: For subtotal resection and revision, AVGs infected with PA had a higher recurrence rate than those infected with other species. However, revision surgery may aggravate the recurrence rate.

Intimal growth on the luminal surface of arteriovenous grafts in rats

BACKGROUND

Endothelial cells are known to grow on the luminal surface of arteriovenous grafts (AVGs) used in hemodialysis. Although endothelial cells are important for preventing infection, a detailed growth of endothelial cells in AVGs is unknown. This study sought to create a simpler animal model of AVGs and to investigate how endothelial cells form on the luminal surface.

METHODS

Polyethylene grafts were placed between the cervical artery and vein of Wistar rats. The grafts were removed at 6 h, 24 h, 3 days, or 7 days after placement. The luminal surface was observed under optical and polarizing microscopy and stained with endothelial cell markers (LEL, CD31), the progenitor cell marker CD34, and the macrophage marker ED-1.

RESULTS

Microscopy demonstrated many diffuse vascular endothelial cells on the luminal surface of AVGs after placement. While there was no difference in the number of LEL-positive cells between the arterial side (AS) and venous side (VS) at 6 h or 7 days, there were significantly more of these cells on the VS at both 24 h and 3 days (p < 0.05). Analysis at 24 h showed some CD31-positive cells and few CD34-positive cells.

CONCLUSIONS

This was the first study to use a simple rat model of AVG placement. Endothelial cell formation was initially more active on the VS than on the AS, but these cells subsequently increased in number across the luminal surface. Future clinical studies might contribute clinically by confirming whether AS versus VS puncture results in different infection rates.

Management of Arteriovenous Graft Infection

Objective: Arteriovenous graft (AVG) infection influences the survival and quality of life of patients, causing life-threatening sepsis reducing dialysis access. This study aimed to evaluate an appropriate treatment strategy for AVG infection. Methods: We analyzed 61 cases involving AVG infections identified at a single center. The cases were divided into two groups based on the type of AVG and surgical methods, namely, currently used AVG (cAVG) (n=29) or abandoned AVG (aAVG) (n=32) and total graft excision (TGE) (n=10) or partial graft excision (PGE) (n=46). Results: There was a significant difference in lower procedure frequency (p<0.001) and longer procedure time (p=0.014) in the cAVG group. A significant difference in lower reinfection rate (p=0.009) was found in the TGE group. Multivariable analysis confirmed that aAVG significantly independently affected the reinfection rate (hazard ratio, 2.208; 95% confidence interval, 1.069-4.561; p=0.032). Staphylococcus aureus was the most frequent cause of AVG infection (61.5%); 77.5% of Staphylococcus aureus were methicillin-resistant Staphylococcus aureus. Conclusion: We found a higher risk of reinfection after PGE than TGE, and aAVG infection was associated with approximately two times higher likelihood of reinfection. These findings suggest that TGE should be considered for patients with AVG infections, particularly aAVG infections.

The evolving panorama of vascular access in the 21st century

There are three major types of hemodialysis vascular access: hemodialysis catheters, arteriovenous grafts, and arteriovenous fistulas. Arteriovenous fistulas provide the best access due to their reliability and long-term patency. They are recommended by the current Kidney Disease Outcomes Quality Initiatives (K-DOQI) guidelines; however, not all patients benefit from arteriovenous fistulas due to poor maturation or a lack of adequate vasculature. Currently, hemodialysis is initiated via catheters in the majority of patients. Catheters are associated with high morbidity and mortality due to infection, lower quality of dialysis, and the development of central vein stenosis. The varied responses of patients to the different access types exemplify the need to choose the "right access for the right patient" based on scores that can predict death risk and progression of chronic kidney disease. Additionally, vascular access, often referred to as the "Achilles' heel" of hemodialysis patients, represents a significant percentage of the Medicare budget that continues to increase yearly. The purpose of this paper is to review the current literature on the management of vascular access complications and infection treatment and prevention. The paper also explores emerging research regarding the devices and methods to improve access outcomes such as early cannulation arteriovenous grafts, endovascular arteriovenous fistula creation, and regenerative grafts with resorbable scaffolds, among others. The data were collected through literature searches via PubMed, Athens and web search engines.

Meta-analysis of total versus partial graft excision: Which is the better choice to manage arteriovenous dialysis graft infection?

BACKGROUND

Arteriovenous graft infection (AVGI) is a major cause of hemodialysis access failure. Delayed diagnosis and inappropriate treatment may lead to increased morbidity (3-35%) and mortality up to 12%.

OBJECTIVES

Compare the postoperative outcomes of total graft excision (TGE) and partial graft excision (PGE) in the treatment of AVGI.

DESIGNS

Systematic review and meta-analysis METHODS: The dataset was defined by searching PubMed, EMBASE, Google Scholar, and the Cochrane database for articles outlining the terms arteriovenous graft infection, infected dialysis graft, TGE and PGE published between 1995-2020. The data analysis evaluated the outcomes of TGE and PGE in the management of AVGI. The meta-analysis was performed using Review Manager Software version 5.4.1.

MAIN OUTCOME MEASURES

30-day mortality, recurrent infection, and reoperation rate.

SAMPLE SIZE

Eight studies, including 555 AVGI, and 528 patients.

RESULTS

PGE showed a significant increase in recurrent graft infection rate (OR=0.23,95% CI=0.13-0.41, P<.00001) and re-operation rate for control of infection (OR=0.14,95% CI=0.03-0.58, P<.007). However, the 30-day mortality rate did not differ significantly between the groups (OR=0.92,95% CI=0.39-2.17, P=.85).

CONCLUSIONS

TGE remains a safe and effective surgical method for the management of AVGI. PGE is associated with a higher risk of graft infection and need for re-operation. As a result, PGE should only be considered in carefully selected patients.

LIMITATION

Risk of bias due to the differences in patient characteristics.

CONFLICT OF INTEREST

None.

Application and implications of a standardised reporting system for arteriovenous access graft infection

INTRODUCTION

The perception that arteriovenous graft infection (AVGi) is frequent and severe is not based on contemporary data from large units using modern AVG. Furthermore, older reports compounded misperceptions by using non-standardised reporting that prevents easy comparison against the alternative modalities. The aim of this article is to use a recently published reporting scheme to analyse the frequency, management and outcome of AVGi in a large series of sequential early-cannulation AVG with long-term follow-up.

METHODS

A single-center series analysis was performed of 277 early-cannulation AVG with minimum 1-year follow-up (total 120,082 days). Infections relating to the AVG were classified, root-cause analysed and the outcomes presented.

RESULTS

Sixteen percent of all AVG implanted (51 episodes) developed infection related to the AVG. Primary AVGi (related to the insertion procedure or within 28 days) occurred in 9 (3%); secondary AVGi (related to AVG in use) occurred 33 times (rate 0.27/1000 haemodialysis days), at a mean of 382 days, and tertiary AVGi (in AVG no longer in use) occurred nine times. Only 1/3 of all AVGi led to bacteraemia, and ½ did not lead to loss of functional access.

SUMMARY

AVG infection is not common, caused a systemic infection in only one-third, did not lead to metastatic infection, and importantly, was treatable without loss of access in one-half of all cases. Using an objective system that discriminates between aetiology and outcome allows a more complete objective understanding of relative infection risks and outcomes for AVG that can inform discussions with patients requiring vascular access for haemodialysis.

A systematic review of brachial artery ligation as a safe and feasible option in the management of arteriovenous dialysis access infection

OBJECTIVE

Creation of good long-term arteriovenous access is essential in patients requiring hemodialysis for end-stage renal failure. However, arteriovenous grafts or fistulae can be complicated by infection that may require emergency surgery. For infections that involve the brachial artery anastomosis, or if total graft explantation is indicated, brachial artery repair or reconstruction is often required. An alternative management strategy would be brachial artery ligation (BAL). We performed a systematic review to evaluate the outcomes of BAL that has been performed for infected arteriovenous grafts or fistulae.

METHODS

A thorough literature search was conducted using various electronic databases. We included articles that reported outcomes of BAL performed for infected arteriovenous grafts or fistulae. The primary outcome was the incidence of upper limb ischemia after BAL. Secondary outcomes were the need for urgent revascularization, need for upper limb amputation, and incidence of postoperative neurological deficit after BAL.

RESULTS

A total of five studies with a total of 125 patients were included in our systematic review. BAL was performed for infected arteriovenous grafts or fistulae for all studies. Follow-up period ranged from 1 to 27 months. The incidence of upper limb ischemia after BAL was low. Only a single study reported three patients who developed upper limb ischemia. Two patients required urgent revascularization, and one patient required forearm amputation after proximal ligation. All studies reported clearance of infection with no recurrence.

CONCLUSIONS

Distal BAL may be performed safely for patients with infected arteriovenous fistulae or grafts with low risk of upper limb ischemia, postoperative neurological deficit, and recurrent infection.

[Complications of permanent vascular access for haemodialysis]

Permanent vascular access is the basis of renal replacement therapy by the method of programmed haemodialysis, on whose stable functioning depends the life of patients with end-stage renal disease. At the present time, there is significant deficit of scientific and methodological Russian-language literature on this problem, with no Russian consensus documents concerned. This article is a review of the contemporary world literature dedicated to the problem of permanent vascular access, including currently in force European (2018) and North American (2019) guidelines for good clinical practice, also discussing the problems of strategy and tactics of creating a permanent vascular access, monitoring its dysfunction, pathophysiology of functioning of arteriovenous fistulas. Presented herein are unified approaches to diagnosis and treatment of thrombolytic and haemorrhagic complications associated with the access, as well as local infectious and non-infectious complications. Special attention is paid to indications for the operation and rational therapeutic decision-making.

The safety of bovine tissue arterial repair in removal of infected prosthetic hemodialysis grafts

BACKGROUND

More than 400,000 Americans require dialysis, and many receive it via a prosthetic arteriovenous graft. Infection of these grafts is rare, but associated with significant morbidity and mortality. The gold standard is total graft excision with arteriotomy closure. This was previously done with autologous vein, but bovine tissue offers a reasonable alternative. The objective of this article is to evaluate a community hospital experience with bovine tissue arterial repair after total graft excision of infected prosthetic arteriovenous graft.

METHODS

A retrospective review was performed of all cases of infected prosthetic arteriovenous graft removal with bovine tissue arterial repair was performed. Thirteen cases were identified. Presentation, location of graft, and causative organism were reviewed; outcomes including reoperation and mortality were recorded.

RESULTS

Of the 13 patients, 12 (92%) had positive cultures of the graft, bloodstream, or wound. Methicillin-resistant Staphylococcus aureus was the most commonly isolated organism (54%). There were two unplanned reoperations including hematoma drainage and wound debridement within the first year. Over the 1-year follow-up period, 1 patient died for a mortality of 8%. There were no re-infections during follow-up.

DISCUSSION

Prosthetic arteriovenous graft infection remains a difficult challenge and is associated with significant morbidity and mortality. It presents in a variety of ways, including within an old thrombosed graft. Over the last several years, the causative organism has increasingly become drug resistant. Treatment with total graft excision requires arteriotomy closure, and for this bovine tissue has been demonstrated to be a viable option.

Total Resection of Infected Peripheral Hemodialysis Grafts Has a Favorable Impact on Outcomes

BACKGROUND

Surgical resection could be an eradication treatment for patients with infected hemodialysis arteriovenous grafts (AVGs). This study aimed to investigate the outcomes of 3 surgical methods, including total resection, subtotal resection, and revision.

METHODS

The patients who underwent surgical excision of infected AVGs performed at a single center from August 2012 to March 2019 were retrospectively analyzed. The following 3 surgical methods were used in our study: revision, subtotal resection, and total resection. Patients' demographics, medical history, perioperative details, reconstruction time, and follow-up data were collected. The outcomes including perioperative complications (within 30 days), mortality, reinfection rate of AVGs, with new access reconstruction or not, and the outcomes between reconstruction and nonreconstruction in the follow-up period were evaluated.

RESULTS

Forty-one patients had infected AVGs in our study. Patients' mean age was 62 years, and 65.9% of the patients were female. The mean duration from the time of diagnosis to the operation was 14.4 days. Signs and symptoms at presentation included fever (51.2 %), swelling (43.9%), pain (58.5%), erythematous change (92.7%), and more severe features, such as altered consciousness (14.6%) and hypotension (12.2%). The pathological changes in the infected grafts included bleeding (29.3%), pus formation (73.2%), pseudoaneurysm (26.8%), and graft exposure (17.1%). Wound and graft cultures revealed an infectious etiology with fungi (7.3%), Pseudomonas aeruginosa (12.2%), Enterococcus spp. (2.4%), and Staphylococcus spp. (58.5%), with methicillin-resistant Staphylococcus aureus accounting for only 7.3%. Total resection, subtotal resection, and revision surgery were performed in 17.1%, 63.4%, and 19.5% of patients, respectively. Seven patients with complications required reoperation (17.1%), and adhesion ileus and hospital-acquired pneumonia occurred in only 2.4% and 7.3% of patients, respectively. During follow-up, most patients (82.9%) had reconstruction of the peripheral hemodialysis access with mean time of 64.3 (range: 21-92) days; mean time of use of new access was 90.5 days; and mean time of removal of catheter was about 106.3 days. Mortality rates in patients without and with reconstructed AV access during follow-up were 50% and 18%, respectively (P < 0.004). Eight cases (19.5%) had recurrence of AV access infections during follow-up; of these, 2 had revision surgery and 6 had subtotal resection. However, no patient with total resection had recurrent infections.

CONCLUSIONS

The total resection group had no recurrent infection compared to the subtotal and revision groups. In addition, patients with reconstruction of peripheral hemodialysis access had a low mortality rate during the follow-up period.

Management of Vascular Infections in Low- and Middle-Income Countries

Background: Vascular infections are rare and challenging conditions with significant deaths and morbidity. Their management necessitates a multi-disciplinary approach and substantial human and financial resources. The management selected may be influenced by the available resources in low- and middle-income countries (LMICs), where such resources may be variable. Methods: We reviewed the published literature and reviewed the management options for various vascular infections with a focus on carotid, aortic, infrainguinal, and dialysis access infections. Results: Recommendations related to prevention and treatment will be offered from the perspective of LMICs. The general principles for prevention are in compliance with established surgical site infection guidelines and minimize the use of prosthetic material. Early detection and intervention by removing all infected prosthetic material, debridement, drainage, and coverage of the infected field with vascularized tissue are essential steps in the management of the infection. Revascularization using an extra-anatomic or in situ approach is individualized based on the resources and expertise available. Conclusions: The prevention and management of vascular infections in LMICs are effective by adhering to time-proven principles even with limited resources.

Arteriovenous Grafts' Types of Indications and Their Infection Rate

BACKGROUND

Arteriovenous graft infection is a well-known and frequent complication. The objective of this study was to compare infection rates of primary and secondary indicated arteriovenous grafts (AVGs).

SUBJECTS AND METHODS

Retrospectively, we evaluated the indications for AVGs created at our institution which became infected. One hundred forty AVGs were evaluated. Of these AVGs, 33 (23.6%) were primary and 107 (76.4%) secondary indicated.

RESULTS

Infection of a primary AVG was detected in 5 patients (15.2 %). Infection of a secondary AVG was detected in 30 patients (28.0%). Primary and secondary patency were significantly lower in patients with infected AVG (P = 0.006; P = 0.0001). The effect of diabetes mellitus and age on development of infection was not confirmed.

CONCLUSIONS

Indications for AVG creation clearly influence the future risk of infection. If the indication to use the AVG is to correct a complicated arteriovenous fistula, the risk of infection is 2 times higher.

The utility of portable negative pressure wound therapy in the management of prosthetic dialysis arteriovenous graft infection

The management of prosthetic dialysis arteriovenous graft infection comprises antibiotic treatment and total or partial excision of infected grafts for infectious source control. Partial excision with graft bypass is an important graft preservation strategy for localized infection but carries a higher reinfection risk. Here, we report a case of prosthetic graft infection that was successfully treated with partial excision, a graft bypass procedure, and a portable negative pressure wound therapy system, PICO, applied to the open wound postoperatively. The combined approach may be a useful strategy that decreases reinfection risk, shortens the length of hospital stay, and preserves graft 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.

Risk assessment of significant upper extremity arteriovenous graft infection in the Vascular Quality Initiative

OBJECTIVE

Infectious complications of arteriovenous grafts (AVGs) are a major source of morbidity. Our aim was to characterize contemporary risk factors for upper extremity AVG infection.

METHODS

The Vascular Quality Initiative (2011-2018) was queried for all patients undergoing upper extremity AVG creation. AVG infection was classified as an infection treated with antibiotics, incision and drainage, or graft removal. Multivariable analyses were used to evaluate risk factors for short- and long-term AVG infection.

RESULTS

Of 1758 upper extremity AVGs, 49 (2.8%) developed significant infection within 3 months, resulting in incision and drainage in 24% and graft removal in 76% of cases. None were managed with antibiotics alone in the study sample. Patients with significant AVG infection were more likely to be white, to be insured, to have a history of coronary artery bypass graft and intravenous (IV) drug use, to be undergoing a concomitant vascular procedure, and to be discharged on an anticoagulant. In multivariable analysis, significant AVG infection within 3 months was associated with IV drug use history (odds ratio [OR], 5; 95% confidence interval [CI], 1.75-14.3; P = .003), discharge to a health care facility (OR, 2.66; 95% CI, 1.07-6.63; P = .035), discharge on an anticoagulant (OR, 2.31; 95% CI, 1.13-4.72; P = .021), white race (OR, 2.3; 95% CI, 1.21-4.34; P = .011), and female sex (OR, 2.02; 95% CI, 1.06-3.85; P = .033). Kaplan-Meier analysis showed that freedom from graft site infection at 1 year was 96.4%. Longer term graft infection at 1 year was independently associated with IV drug use history (hazard ratio [HR], 1.98; 95% CI, 1.06-3.68; P = .032), initial discharge to a health care facility (HR, 1.88; 95% CI, 1.19-2.97; P = .007), and white race (HR, 1.64; 95% CI, 1.23-2.19; P = .001).

CONCLUSIONS

Although significant AVG infection was uncommon in the Vascular Quality Initiative, the majority were treated with graft removal. In select high-risk patients, extra care should be taken and alternative forms of arteriovenous access may be considered.

Current Concepts in Hemodialysis Vascular Access Infections

Infection-related causes are second only to cardiovascular events for mortality among end-stage renal disease patients. This review will provide an overview of hemodialysis catheter-, graft-, and fistula-related infections with emphasis on diagnosis and management in specific settings. Use of catheters at the initiation of dialysis has remained unchanged at 80%. Of all access-related bloodstream infections (BSIs), 70% occur in patients with catheters. The risk factors for BSIs in tunneled, cuffed catheters include the duration of the catheter, past catheter-related bacteremia, left-sided internal jugular vein catheters, hypoalbuminemia, and immunosuppression. Surprisingly, human immunodeficiency virus infection has not been associated with a higher risk of catheter-related bacteremia. Catheter-related bloodstream infection is a clinical definition that requires specific laboratory testing to identify the catheter as the source of the BSI. A central line-associated bloodstream infection is a primary BSI in a patient who had a catheter within the 48-h period before the development of the BSI with no other identifiable source. Guidewire exchange of catheter is a viable alternative in select patients to aid in preserving venous access sites. Catheter lock therapy can decrease infectious complications and mortality. Arteriovenous graft infections are prevalent with significant morbidity. Studies evaluating the impact of stent use in infection risks of the arteriovenous graft are sorely needed.

Definitions and End Points for Interventional Studies for Arteriovenous Dialysis Access

This paper is part of the Clinical Trial Endpoints for Dialysis Vascular Access Project of the American Society of Nephrology Kidney Health Initiative. The purpose of this project is to promote research in vascular access by clarifying trial end points which would be best suited to inform decisions in those situations in which supportive clinical data are required. The focus of a portion of the project is directed toward arteriovenous access. There is a potential for interventional studies to be directed toward any of the events that may be associated with an arteriovenous access' evolution throughout its life cycle, which has been divided into five distinct phases. Each one of these has the potential for relatively unique problems. The first three of these correspond to three distinct stages of arteriovenous access development, each one of which has been characterized by objective direct and/or indirect criteria. These are characterized as: stage 1-patent arteriovenous access, stage 2-physiologically mature arteriovenous access, and stage 3-clinically functional arteriovenous access. Once the requirements of a stage 3-clinically functional arteriovenous access have been met, the fourth phase of its life cycle begins. This is the phase of sustained clinical use from which the arteriovenous access may move back and forth between it and the fifth phase, dysfunction. From this phase of its life cycle, the arteriovenous access requires a maintenance procedure to preserve or restore sustained clinical use. Using these definitions, clinical trial end points appropriate to the various phases that characterize the evolution of the arteriovenous access life cycle have been identified. It is anticipated that by using these definitions and potential end points, clinical trials can be designed that more closely correlate with the goals of the intervention and provide appropriate supportive data for clinical, regulatory, and coverage decisions.

How to treat arteriovenous graft infection: total versus partial graft excision

Introduction:

Arteriovenous graft (AVG) infection can result in life-threatening sepsis and loss of vascular access. A retrospective study was performed to establish an appropriate treatment strategy for AVG infection.

Methods:

A total of 50 cases of AVG infection were treated between January 2005 and June 2016. The surgical methods used were total graft excision (TGE) (n = 34), or partial graft excision (PGE) with interposition graft (n = 16).

Results:

Infection was noted at a puncture site (n = 22), a prior incision for surgery or endovascular therapy (n = 20), and abandoned (currently unused) grafts (n = 5). Infection occurred within 1 month after AVG creation (n = 1), or any intervention (n = 14), and more than 1 month after creation or intervention (n = 35). Simultaneous remote infection was identified in 7 patients, 2 of whom underwent an operation for infective endocarditis and spondylitis. After PGE, 5 patients (5/16, 31.2%) having recurrent infection were treated with further graft excision; however, no patient showed life-threatening complications. After TGE, a central venous catheter (CVC) was inserted and used for a median period of 90 days. Among 34 patients who underwent TGE, new vascular access was created in 18 patients at a median period of 2 months later, and 12 patients continued to use a CVC until last follow-up or death.

Conclusions:

PGE could be a treatment option for AVG infection to achieve both infection eradication and vascular access preservation in selected patients. Because of a higher risk of recurrent infection, sufficient surgical removal and careful postoperative management are warranted.

Surgical Excision of Infected Arteriovenous Grafts: Technique and Review

Infected prosthetic arteriovenous grafts for hemodialysis present a profound risk to patient well being. Here we present five recent cases and describe our technique for total graft excision. We also review the literature and discuss the much debated role of partial, subtotal, and total graft excision.

Prosthetic Arteriovenous Grafts for Hemodialysis

Introduction

Prosthetic arteriovenous (AV) grafts are indicated in patients with failed AV fistula (AVF), exhausted superficial veins or unsuitable vessels. Increasing the proportion of prevalent hemodialysis (HD) patients using autogenous AVF should reduce the need for AV grafts and associated morbidity. This paper reviews the current role of prosthetic AV grafts in vascular access for HD.

Technical considerations

Prior to the insertion of a prosthetic AV graft, a comprehensive review of previous access procedures and full physical examination in addition to vessel mapping is required. Anastomotic technique should take into account the flow diffuser concept, graft geometry and an anastomotic angle of 15° in order to reduce the incidence of intimal hyperplasia.

Results

Many authors report 1 and 2-yr cumulative graft patency rates of 59–90% and 50–82%, respectively. The major drawbacks with synthetic grafts include: thrombosis, a five-fold increase in infection risk and steal syndrome. The choice between surgical and percutaneous methods of dealing with blocked AV grafts remains controversial, though percutaneous techniques are assuming an increasingly important role. Percutaneous strategies are successful in declotting access in 67–95% of cases. Stenting of stenotic lesions following thrombectomy improves secondary patency rates. Strategies for dealing with AV graft infection include antibiotic prophylaxis, partial, subtotal or total graft excision and the use of biological prosthesis.

Conclusions

Though more prone to complications than autogenous AVFs, AV grafts offer a short maturation period and are more amenable to thrombectomy by radiological or surgical means. Complex AV grafts may be appropriate in patients with exhausted access sites.

Hemodialysis access thrombosis

For the over 400,000 patients in the United States dependent on hemodialysis, arteriovenous (AV) access thrombosis may lead to missed dialysis sessions, inpatient admissions and the need for placement of temporary dialysis catheters. It is also the leading cause of permanent access loss. Percutaneous declotting is generally preferred over surgical thrombectomy. Various percutaneous approaches can be employed including the lyse-and-wait technique, thromboaspiration, pulse spray aided pharmacomechanical thrombolysis, and use of mechanical thrombectomy device.

New therapeutic options provided by off-label deployment of stent graft for tailored arteriovenous access salvage: Two cases

A tailored therapy to patient requirements by combining endovascular and surgical steps can be necessary to prolong the life of a vascular access. Stent grafts play a growing role for the therapy of dialytic access complications. Randomized multi-center trials, however, support the on-label use of stent grafts in the treatment of graft venous outflow and in-stent restenosis. The main contraindication to their use is an ongoing infection. We report two cases of new off-label application of Viabahn (Gore, flagstaff, USA) stent graft. In the first case, the failure of a radiocephalic early cannulation graft was treated by stent graft placement on the arterial inflow anastomosis, when emergent angiographic examination revealed the previously unknown high takeoff of the radial artery from the axillary artery. At 13-month follow-up, the target lesion remained untreated. In the second case, elbow stent graft occlusion with extended thrombosis occurred in a right radiocephalic fistula after 3 years of unassisted patency. Being the last option for vascular access, successful endovascular recanalization was carried out. After 3 months, however, the clinical setting relapsed. A two-stage hybrid strategy with vascular surgeon was arranged due to ongoing signs of local infection. Flow was restored by emergent thromboaspiration associated with a new stent graft placement as a endovascular bridge to subsequent surgical treatment. After 2 days, the overlapped stent grafts were excised as planned. Surgical rerouting was completed by polytetrafluoroethylene prosthetic bridge implantation across the elbow. At 4 months, the follow-up remained uneventful. In selected instances, the off-label use of stent grafts may expand the therapeutic options of the vascular access team.

The Usefulness of Duplex Ultrasound for Hemodialysis Access Selection

Purpose

A native vessel is preferable to an artificial graft for dialysis access. Duplex ultrasound (DUS) is noninvasive, cost-effective modality to evaluate the vessels for dialysis. The purpose of this study was to compare the rates of utilization of native vessels after preoperative imaging with DUS and contrast venography (CV).

Materials and Methods

A retrospective review was performed on patients who received an arteriovenous fistula (AVF) or arteriovenous graft (AVG) between June 2006 and July 2010. Patients were classified into 3 groups. In group 1, CV was used to evaluate the vessel. Both DUS and CV were used in group 2. In group 3, only DUS was used. The frequency of utilization of a native vessel was analyzed in each group. The chi-square test was used for statistical analysis.

Results

During the study period, 173 patients received an AVF or AVG. Eighty-nine patients were male. The mean age was 60.6±14.6 years. A native vessel was used in 56/81 patients (69.1%) and 74/81 patients (91.4%) in groups 1 and 3, respectively (P<0.001). In group 2, all patients underwent access procedures using native vessels. AVG was initially planned for 2 patients in group 2 after vessel evaluation using CV, but a native vessel was successfully used because DUS identified optimal vessels for AVF. The 1-year primary patency rate was similar in 3 groups.

Conclusion

Preoperative DUS is safe and easy to use for vessel evaluation, and can be used as a primary imaging modality for creation of access.

Bovine carotid artery xenografts for hemodialysis access

OBJECTIVE

Bovine carotid artery (BCA) grafts have been described as a possibly superior alternative to expanded polytetrafluoroethylene hemoaccess grafts. However, published experience remains limited, and patency rates for nonautogenous arteriovenous grafts remain unsatisfactory. We report herein the largest published experience with the current generation of BCA grafts for dialysis access and analyze subgroups to determine whether obesity, gender, or prior access surgery influences patency.

METHODS

We retrospectively reviewed 134 BCA grafts (Artegraft, North Brunswick, NJ) implanted for hemodialysis access in the upper extremities of 126 patients between January 2012 and May 2015. Patients had a mean of 1.8 prior access operations. Primary, primary assisted, and secondary patency rates were calculated using the Kaplan-Meier method, and longitudinal infection risk was tabulated. Patency differences were calculated using the log-rank method.

RESULTS

For the entire group, 1-year primary patency was 32%, primary assisted patency was 49%, and secondary patency was 78%. Ten of 133 grafts (7%) developed infection requiring graft excision between 1 and 9 months after implantation. There was no statistical difference between men and women in primary or secondary patency (P = .88, P = .69). There was no difference in primary patency or secondary patency for patients with body mass index >30 or <30 (P = .85, P = .54). Patients who had a BCA graft as their first access attempt had a higher primary and primary assisted patency than that of patients who had the graft placed after prior access failure (P = .039, P = .024).

CONCLUSIONS

This represents the largest published series of BCA grafts for arteriovenous grafts in the modern era. The primary patency of BCA grafts in this series was lower than that reported in a smaller randomized study. However, primary assisted and secondary patency were similar. Infection rates in this series appear to be somewhat lower than polytetrafluoroethylene infection rates reported in the literature. BCA grafts are a satisfactory alternative to expanded polytetrafluoroethylene for hemodialysis access, but larger controlled studies are needed to determine whether superior primary patency previously reported is a reproducible finding.

Dialysis Access Hemorrhage: Access Rescue from a Surgical Emergency

BACKGROUND

Hemorrhage from a dialysis access can be a life-threatening condition. This study details our experience using access rescue strategies, including in situ graft replacement, primary repair, or conversion to an autogenous fistula, coupled with treatment of central vein occlusion to maintain access usage in patients presenting with conduit hemorrhage.

METHODS

During a 3-year period (2012-2014), 26 patients (14 women, 12 men) on chronic hemodialysis were treated for access conduit bleeding (n = 18) or life-threatening hemorrhage (n = 8), located in the upper extremity (n = 23) or thigh (n = 3). All patients had developed bleeding from a skin eschar/ulcer over a bovine (n = 9) or polytetrafluoroethylene (n = 9) bridge graft, or aneurysmal autogenous fistula (n = 8). A retrospective review of outcome relative to clinical signs, etiology of conduit bleeding (infection, wall erosion), and the type of rescue procedure(s) was performed. Duplex ultrasound testing was used to guide therapy based on the presence of aneurysmal degeneration, perigraft fluid, or access flow pattern indicative of venous outflow obstruction.

RESULTS

One-half of the patients were taken emergently to the operating room for hemorrhage control or impending rupture of an infected false aneurysm, the remaining repaired on an urgent basis. In 18 patients, emergency room personnel attempted control of access site bleeding by suturing (n = 14) or tourniquet (n = 4). Dialysis access salvage was achieved in 22 (85%) of 26 patients by in situ conduit replacement using a rifampin-soaked polytetrafluoroethylene conduit (n = 19) or primary repair (n = 3). Two patients with sepsis and ruptured, infected false aneurysm were treated by ligation, and 2 patients with nonsalvable access had conversion to an autogenous fistula. One-third of rescued accesses (n = 7) had staged endovascular treatment of central vein stenosis. One patient died within 30 days. All dialysis access revisions remained patent and used for immediate dialysis (n = 5), within 4-5 weeks (n = 19), or after vein maturation (n = 2). One replaced graft was revised for infection. Positive blood or bleeding site cultures were obtained from 9 (45%) of 20 patients tested.

CONCLUSIONS

Salvage of a functional dialysis access is possible in the majority of patients presenting with conduit hemorrhage. Loss of wall integrity, infection, and venous hypertension were etiologic factors. Application of in situ graft replacement strategies known to be effective in the treatment of graft infection should be considered in the management of this surgical emergency.

Arteriovenous Access: Infection, Neuropathy, and Other Complications

Complications of vascular access lead to morbidity and may reduce quality of life. In this module, we review both infectious and noninfectious arteriovenous access complications including neuropathy, aneurysm, and high-output access. For the challenging patients who have developed many complications and are now nearing their last vascular access, we highlight some potentially novel approaches.

Prosthetic Arteriovenous Graft Contact Dermatitis Masquerading as an Arteriovenous Graft Infection in a Hemodialysis Patient

Prosthetic arteriovenous (AV) graft is the second most common vascular access of choice in hemodialysis patients. Rare complications of such grafts are increasingly seen due to rising population of patients on hemodialysis. Infections and thrombosis are the most common complications. Though metallic implants are known to cause hypersensitivity skin reactions, prosthetic AV grafts are rarely known to cause such kind of reactions due to inert nature of materials used in their preparation. We present a case of 54-year-old male who developed contact dermatitis after AV graft creation which was mistreated initially as infection.

Operative and perioperative management of infected arteriovenous grafts

Vascular graft infections are a particularly troublesome complication for dialysis patients, many of whom are in an already immunocompromised state. The objective of this review is to detail the risk factors, etiology, diagnosis, perioperative and operative management of vascular graft infections.

Management of infected vascular grafts

Infections of vascular grafts are associated with significant mortality and morbidity risk and cost an estimated $640 million annually in the United States. Clinical presentation varies by time elapsed from implantation and by surgical site. A thorough history and physical examination in conjunction with a variety of imaging modalities is often essential to diagnosis. For infected aortic grafts, there are several options for treatment, including graft excision with extra-anatomic bypass, in situ reconstruction, or reconstruction with the neo-aortoiliac system. The management of infected endovascular aortic grafts is similar. For infected peripheral bypasses, graft preservation techniques can be utilized, but in cases where it is not possible, graft removal and revascularization through uninfected tissue planes is necessary. Infected dialysis access can be surgically treated by complete or subtotal graft excision. Diagnosis, general management, and surgical approaches to infected vascular grafts are discussed in this review.

Medical treatment of prosthetic vascular graft infections: Review of the literature and proposals of a Working Group

More than 400000 vascular grafts are inserted annually in the USA. Graft insertion is complicated by infection in 0.5-4% of cases. Vascular graft infections (VGIs) are becoming one of the most frequent prosthesis-related infections and are associated with considerable mortality, ranging from 10 to 25% within 30 days following the diagnosis. Treatment of VGI is based on urgent surgical removal of the infected graft followed by prolonged antibiotherapy. Data regarding the best antibiotherapy to use are lacking since no well designed trial to study antimicrobial treatment of VGI exists. Moreover, since VGIs demonstrate very specific pathophysiology, guidelines on other material-related infections or infective endocarditis treatment cannot be entirely applied to VGI. A French multidisciplinary group gathering infectious diseases specialists, anaesthesiologists, intensivists, microbiologists, radiologists and vascular surgeons was created to review the literature dealing with VGI and to make some proposals regarding empirical and documented antibiotic therapy for these infections. This article reveals these proposals.

Less Than Total Excision of Infected Prosthetic PTFE Graft Does Not Increase the Risk of Reinfection

Background:

Traditional treatment of infected polytetrafluoroethylene (PTFE) grafts consist of removal of the entire prosthesis. Closure of the native vessels may compromise vascular patency. We examined the outcomes for patients in whom a PTFE remnant of an infected graft was retained on the vessel.

Methods:

We reviewed the operating room log from 2000 to 2011 and identified all patients who had partial removal of an infected PTFE graft used for hemodialysis or peripheral bypass. These patients were examined for subsequent complications.

Results:

Twenty-seven patients underwent 30 partial graft excisions with mean follow-up of 27 months. A total of 17% (5 of 30) of the partial graft resection procedures resulted in complications. Of 48 total remnants left behind at the arterial or venous anastomoses, reinfection occurred in 15%.

Conclusions:

Leaving a well-incorporated small 1-to 5-mm PTFE remnant at the arterial or venous anastomoses can be performed safely with a low risk of complications.

Sustained release of vancomycin from novel biodegradable nanofiber-loaded vascular prosthetic grafts: in vitro and in vivo study

This study describes novel biodegradable, drug-eluting nanofiber-loaded vascular prosthetic grafts that provide local and sustained delivery of vancomycin to surrounding tissues. Biodegradable nanofibers were prepared by first dissolving poly(D,L)-lactide-co-glycolide and vancomycin in 1,1,1,3,3,3-hexafluoro-2-propanol. The solution was then electrospun into nanofibers onto the surface of vascular prostheses. The in vitro release rates of the pharmaceutical from the nanofiber-loaded prostheses was characterized using an elution method and a high-performance liquid chromatography assay. Experimental results indicated that the drug-eluting prosthetic grafts released high concentrations of vancomycin in vitro (well above the minimum inhibitory concentration) for more than 30 days. In addition, the in vivo release behavior of the drug-eluting grafts implanted in the subcutaneous pocket of rabbits was also documented. The drug-eluting grafts developed in this work have potential applications in assisting the treatment of vascular prosthesis infection and resisting reinfection when an infected graft is to be exchanged.

Comparison of Flixene™ and Standard PTFE Arteriovenous Graft for Early Haemodialysis

Purpose

The purpose is to compare the outcomes of FLIXENE™ arteriovenous graft (AVG) to standard polytetrafluoroethylene (PTFE) AVG for early haemodialysis.

Methods

This is a prospective observational study of all AVGs placed over a 40-month period between 2008 and 2011 at our vascular unit. Primary outcome was to examine early cannulation rates for FLIXENE™. Secondary outcomes included patency rates, usability of grafts, complications in particular infections, interventions and death in comparison to standard PTFE grafts.

Results

Forty-five FLIXENE™ and 19 standard PTFE AVGs were placed in the study period; 89% of FLIXENE™ grafts were used for dialysis, with 78% cannulated within 3 days. At 18 months, primary patency (FLIXENE™ 34% vs standard PTFE 24%), primary assisted patency (35% vs 36%) and secondary patency rate (51% vs 48%) were not statistically different; 20.2% of FLIXENE™ grafts were infected at 18 months requiring explantation compared with 40.3% of standard PTFE grafts (p=0.14).

Conclusions

FLIXENE™ can be cannulated for dialysis within 3 days. It has similar patency and complication rates as other prosthetic grafts in the market. In patients who have no access and require urgent dialysis, FLIXENE™ is a viable option.

Vascular access for hemodialysis: current perspectives

A well-functioning vascular access (VA) is a mainstay to perform an efficient hemodialysis (HD) procedure. There are three main types of access: native arteriovenous fistula (AVF), arteriovenous graft, and central venous catheter (CVC). AVF, described by Brescia and Cimino, remains the first choice for chronic HD. It is the best access for longevity and has the lowest association with morbidity and mortality, and for this reason AVF use is strongly recommended by guidelines from different countries. Once autogenous options have been exhausted, prosthetic fistulae become the second option of maintenance HD access alternatives. CVCs have become an important adjunct in maintaining patients on HD. The preferable locations for insertion are the internal jugular and femoral veins. The subclavian vein is considered the third choice because of the high risk of thrombosis. Complications associated with CVC insertion range from 5% to 19%. Since an increasing number of patients have implanted pacemakers and defibrillators, usually inserted via the subclavian vein and superior vena cava into the right heart, a careful assessment of risk and benefits should be taken. Infection is responsible for the removal of about 30%-60% of HD CVCs, and hospitalization rates are higher among patients with CVCs than among AVF ones. Proper VA maintenance requires integration of different professionals to create a VA team. This team should include a nephrologist, radiologist, vascular surgeon, infectious disease consultant, and members of the dialysis staff. They should provide their experience in order to give the best options to uremic patients and the best care for their VA.

Infected prosthetic dialysis arteriovenous grafts: a single dialysis center study

BACKGROUND

The prosthetic arteriovenous grafts (AVG) being used increasingly to create hemodialysis access are prone to infections that pose potentially life-threatening infectious and bleeding complications, as well as loss of dialysis access. In this study, we identified the bacteriologic agents of infected AVGs by site swab, blood culture, and prosthesis cultures, and to evaluate the role of microbiological findings in the management of the infection.

METHODS

We focused on 51 patients with 53 AVGs operated on in our clinic from January 2006 to December 2009. An infected AVG was identified by clinical, ultrasound, and microbiological findings. Sensitivity to antibiotics was determined for all bacterial strains. Isolates were identified by pulsed-field gel electrophoresis (PFGE) of bacterial DNA. In a few cases, positron emission tomography-computed tomography (PET-CT) examination was performed.

RESULTS

Strains of Staphylococcus spp., especially S. aureus, were the most frequent cause of infected AVG. All S. aureus strains were sensitive to methicillin. With the exception of a single case, isolates obtained simultaneously from the skin site and the vascular prosthesis were identical genetically.

CONCLUSIONS

Our results suggest that bacterial infectious agents detected in site swab, blood, or graft culture confirm a suspicion of AVG infection. A PET-CT examination can provide confirmation. The combination of microbiologic and radionuclide findings can improve the management of the AVG infection, but surgery remains essential.

Unused Arteriovenous Grafts as a Source of Chronic Infection in Haemodialysed Patients with Relevance to Diagnosis of Fluorodeoxyglucose PET/CT Examination

Introduction: Clotted arteriovenous grafts (AVG) for haemodialysis which are not used (silent grafts) can serve as a potential source of chronic bacterial infection in patients on dialysis programs. In some cases, the local finding is unclear. The patient only suffers from repeated metastatic infection and the detection of AVG infection is difficult. Nuclear medicine methods have the potential to uncover AVG infection. In this study, we correlated the positron emission tomography (PET)/ computed tomography (CT) findings of the AVG examination with the microbiological findings from removed grafts. The aim was to evaluate the relevance of the Fluorodeoxyglucose (FDG) PET/CT method in detecting clotted graft infection. Material and Methods: A cohort of 13 patients with clotted grafts were followed-up. Four patients had overall symptoms of infection and 9 patients were asymptomatic. In all cases, the PET CT examination and microbiological examination of the removed graft were provided. Results: Only one mismatch—negative PET CT finding and positive microbiological culture was recorded in the 13 followed-up patients. Conclusion: In patients with silent grafts and recurrent infection of equivocal aetiology, PET CT examination can contribute to the diagnosis of AVG infection and, subsequently, to prevent further infectious complications, if the AVG infection is treated appropriately and the graft is removed. Key words: ePTFE prosthesis, Nuclear medicine imaging, Staphylococcus aureus, Vascular access infection