The Complications of Vascular Access in Hemodialysis Avais Masud, MD1

Eric J. Costanzo, DO1

Roman Zuckerman, DO1

1 Department of Medicine, Seton Hall-Hackensack Meridian School of

Medicine, Jersey Shore University Medical Center, Neptune, New Jersey

Arif Asif, MD1

Address for correspondence Arif Asif, MD, MHCM, FASN, FACP, Department of Medicine, Seton Hall-Hackensack Meridian School of Medicine, Jersey Shore University Medical Center, 1945 Route 33, Neptune, NJ 07753 (e-mail: [email protected]).

Abstract

Keywords

► arteriovenous access ► dialysis catheter ► hemodialysis

Complications related to hemodialysis vascular access continue to have a major impact on morbidity and mortality. Vascular access dysfunction is the single most important factor that determines the quality of dialysis treatment. Vascular access stenosis is a common complication that develops in a great majority of patients with an arteriovenous access and leads to access dysfunction. By restricting luminal diameter, this complication leads to a reduction in blood flow and places the access at risk for thrombosis. Similarly, the development of catheter-related fibroepithelial sheath also causes catheter dysfunction with its detrimental effects on blood flow. In this article, we discuss the most common complications associated with dialysis access and provide therapeutic options to manage these problems.

Vascular access is one of the most important elements that determine morbidity and mortality in hemodialysis patients.1 Consequently, complications related to vascular access and their management gain serious importance. In simple terms, there are three main types of vascular accesses that are used to provide renal replacement therapy to hemodialysis patients. These include arteriovenous fistula, arteriovenous graft, and tunneled hemodialysis catheters.2–5 An arteriovenous fistula is created by surgically creating an anastomosis between an artery and a vein. Following the creation of this anastomosis, the vein undergoes maturation and is subsequently used for dialysis therapy. In contrast, an arteriovenous graft is created by anastomosing a polytetrafluoroethylene (PTFE) tube to the side of an artery and the end of a vein. In patients with an arteriovenous graft, the PTFE material serves for needle insertion for dialysis. Finally, tunneled hemodialysis catheters are inserted in a central vein and can be successfully used to provide dialysis therapy. While these forms of dialysis accesses can effectively provide dialysis, they are associated with multiple complications that directly hinder the quality of dialysis therapy delivered (►Table 1). This is because blood flow is the single

Issue Theme Perturbation of Hemostatic Function by Nonbiologic Surfaces; Guest Editors: Hau C. Kwaan, MD, FRCP, and Jun Teruya, MD, DSc, FCAP.

most important element that determines the quality of dialysis. Dialysis access complications directly affect the blood flow and cause detrimental effects on dialysis therapy. In this article, we discuss the most common complications associated with dialysis access and provide therapeutic options to manage these complications.6–10 In recent years, major advances have been made in our understanding of dialysis access complications as well as the management of these complications.2–19 Three most common complications continue to surround hemodialysis access.16 These include vascular access stenosis, vascular access thrombosis, and catheter-related fibroepithelial sheath formation.

Stenosis of Vascular Access The development of vascular access stenosis is the single most important complication that develops in an arteriovenous access.16 This complication directly reduces blood flow in a dialysis access. In this way, it can directly lower the quality of dialysis therapy. Consequently, the treatment of stenosis is of paramount importance to provide vital dialysis therapy to an end-stage renal disease patient.

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DOI https://doi.org/ 10.1055/s-0037-1606180. ISSN 0094-6176.

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Table 1 Advantages and disadvantages of the three common types of dialysis accessa

a

Parameter

Mature fistulas

Arteriovenous grafts

Tunneled dialysis catheters

Infection

Lowest

Higher

Highest

Thrombosis

Lowest

Higher

Highest

Patency rates

Highest

Higher

Lowest

Number of interventions

Lowest

Higher

Highest

Associated costs

Lowest

Higher

Highest

Hospitalizations

Lowest

Higher

Highest

Mature arteriovenous fistulas offer the best profile.

Multiple reports have emphasized that percutaneous transluminal balloon angioplasty has assumed a central role in the management of arteriovenous dialysis access (graft and fistula) stenosis.5–17 Over the years, this treatment has proven to be safe as well as effective.4–11 This procedure is usually performed on an outpatient basis and the dialysis access can be used immediately following the angioplasty. The procedure allows one to get to all of the stenotic lesions within the access system. Stenotic lesions within the venous as well as the arterial tree can be successfully treated. Lesions in the central veins and arteries can also be accessed and treated. While both grafts and fistulas may develop vascular stenosis, it is the grafts that are more prone to stenosis. Neointimal hyperplasia plays a major role in the development of stenosis both in grafts and fistulas.18 The venous anastomosis is the most frequent site for the development of stenosis; however, the arterial anastomosis, peripheral, and central veins can also be involved. It is important to mention that stenotic lesions can exist as single or multiple, and in that, the patient could have multiple venous or coexisting venous and arterial lesions within the same access. The mere presence of stenosis alone in an access system does not justify its treatment.1 Angioplasty should be performed if the stenosis hinders flow that is associated with clinical abnormalities. These include elevated venous pressure, abnormal recirculation test or physical examination, unexplained decrease in the measured dialysis dose, and, most of all, decreased access flow.1 Angioplasty of stenosis improves survival of the dialysis access as well as blood flow and decreases access thrombosis. Consequently, establishing a surveillance program to monitor vascular access function to identify the failing access is of vital importance. In this way, stenosis can be managed before it leads to thrombosis. Indeed, the most common cause of vascular access thrombosis happens to be stenosis.10 In addition to thrombosis, the development of stenosis creates a major hurdle in the development of newly created fistulas. This condition is termed as early fistula failure or immature fistula.16 Early failure refers to the fistula that fails within 3 months of successful use after its creation or never develops to support dialysis therapy.4,7,8 Seminars in Thrombosis & Hemostasis

Beathard et al8 provided an approach to augment the maturation of a failing fistula. In their prospective observational study, percutaneous balloon angioplasty was successfully employed to salvage failing arteriovenous fistulas. One hundred patients with early failure underwent angioplasty and accessory vein ligation on an outpatient basis. The study found that stenosis and the presence of accessory veins (side branches stealing flow away from the main body of the fistula) alone or in combination were found to be the main culprits. In their analysis, venous stenosis was present in 78% of the patients. A majority of stenoses (48%) were juxtaanastomotic lesion (i.e., close to the anastomosis). Accessory veins were present in a significant number of patients (46%). Two relatively simple procedures (angioplasty and accessory vein obliteration) were used to salvage these nonmaturing fistulas. Balloon angioplasty resulted in 98% success rate and vein obliteration had a 100% success rate. It was possible to initiate dialysis using the fistula in 92% of the patients; 84% of these fistulas were functional at 3 months, 72% at 6 months, and 68% at 12 months of follow-up. While angioplasty can successfully salvage failing to mature fistulas, their diagnosis is of critical value. Physical examination has emerged as an important tool in the evaluation of the dialysis access. Physical examination should be performed at 4 to 6 weeks of fistula creation to ascertain its maturation.1 Once diagnosed, these patients should be referred for prompt evaluation and appropriate management.

Thrombosis of Hemodialysis Access Stenosis is the single most important cause of thrombosis in both fistulas and grafts, and in that, stenosis and thrombosis are intricately related. More than 90% of the patients with thrombosis have been known to have an underlying stenosis.10 Interventionalists routinely perform procedures for thrombosed fistulas and grafts.5,6,10,16 A variety of thrombectomy procedures have been performed to achieve declotting of a thrombosed access. Mechanical as well as pharmacomechanical thrombolysis procedures can be successfully performed.6,9,10,16 It is worth mentioning that the primary patency rates after declotting of a clotted vascular access are markedly reduced when compared with the primary patency following angioplasty of access stenosis.10,16 Declotting of a thrombosed access should be performed quickly for multiple reasons. First, a delay in the procedure can lead to solidification of the thrombus. This may result in lack of success in achieving successful declotting. Second, failure to successfully declot an access leads to the loss of arteriovenous access. Finally, the inability to achieve declotting frequently results in the insertion of a dialysis catheter that has its own adverse events.

Fibroepithelial Sheath and Tunneled Dialysis Catheters Tunneled hemodialysis catheters are an important form of dialysis access. These devices are often inserted to initiate dialysis therapy when an arteriovenous access has not been

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Dialysis Access Complications

Dialysis Access Complications

access programs should focus on incorporating strategies that focus on the complications presented in this article and their management. Acknowledgments This project was not funded by any grants or funding agencies. The authors declare no conflict of interest.

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vascular access. Am J Kidney Dis 2006;48(Suppl 1):S176–S247 2 Vesely TM. Complications related to percutaneous thrombectomy

of hemodialysis grafts. J Vasc Access 2002;3(02):49–57 3 Beathard GA. Percutaneous transvenous angioplasty in the

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Conclusion Vascular access continues to be the Achilles’ heel of dialysis therapy. While we have made significant advances in our understanding of vascular access, the development of neointimal hyperplasia continues to create a major problem in the delivery of dialysis therapy by restricting flow within the access system.18,19 Left untreated, the stenotic lesions go on to completely obliterate the lumen and occlude the blood flow and result in thrombosis of vascular access. Indeed, thrombosis of an arteriovenous access is a major cause of ultimate loss of vascular access. As the venous capital is not unlimited, implementation of treatment strategies to preserve vascular access is important. By treating the stenotic lesion, percutaneous balloon angioplasty has shown to restore and augment flow. The same procedure can be successfully employed to treat the tunneled dialysis catheter-related fibroepithelial sheath with a high success rate. Hemodialysis

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treatment of vascular access stenosis. Kidney Int 1992;42(06): 1390–1397 Schon D, Mishler R. Pharmacomechanical thrombolysis of natural vein fistulas: reduced dose of TPA and long-term follow-up. Semin Dial 2003;16(03):272–275 Faiyaz R, Abreo K, Zaman F, Pervez A, Zibari G, Work J. Salvage of poorly developed arteriovenous fistulae with percutaneous ligation of accessory veins. Am J Kidney Dis 2002;39(04):824–827 Nassar GM, Rhee E, Khan AJ, Nguyen B, Achkar K, Beathard G. Percutaneous thrombectomy of AVF: immediate success and long-term patency rates. Semin Dial 2015;28(02):E15–E22 Vesely TM. Role of stents and stent grafts in management of hemodialysis access complications. Semin Vasc Surg 2007;20(03): 175–183 Beathard GA, Arnold P, Jackson J, Litchfield T; Physician Operators Forum of RMS Lifeline. Aggressive treatment of early fistula failure. Kidney Int 2003;64(04):1487–1494 Beathard GA. We refuse to give up on nonmaturing fistulas. Semin Dial 2016;29(04):284–286 Beathard GA, Welch BR, Maidment HJ. Mechanical thrombolysis for the treatment of thrombosed hemodialysis access grafts. Radiology 1996;200(03):711–716 Asif A, Byers P, Vieira CF, Roth D. Developing a comprehensive diagnostic and interventional nephrology program at an academic center. Am J Kidney Dis 2003;42(02):229–233 Ash SR. The evolution and function of central venous catheters for dialysis. Semin Dial 2001;14(06):416–424 Schon D, Whittman D. Managing the complications of long-term tunneled dialysis catheters. Semin Dial 2003;16(04):314–322 Beathard GA. Management of bacteremia associated with tunneledcuffed hemodialysis catheters. J Am Soc Nephrol 1999;10(05): 1045–1049 Saad TF. Bacteremia associated with tunneled, cuffed hemodialysis catheters. Am J Kidney Dis 1999;34(06):1114–1124 Beathard GA, Litchfield T; Physician Operators Forum of RMS Lifeline, Inc. Effectiveness and safety of dialysis vascular access procedures performed by interventional nephrologists. Kidney Int 2004;66(04):1622–1632 Beathard GA, Urbanes A, Litchfield T. Changes in the profile of endovascular procedures performed in freestanding dialysis access centers over 15 years. Clin J Am Soc Nephrol 2017;12(05): 779–786 Roy-Chaudhury P, Kruska L. Future directions for vascular access for hemodialysis. Semin Dial 2015;28(02):107–113 Beathard GA. Role of interventional nephrology in the multidisciplinary approach to hemodialysis vascular access care. Kidney Res Clin Pract 2015;34(03):125–131

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created. They are often used when an arteriovenous access is awaiting maturation. These devices are also needed for patients who have exhausted their venous capital for the creation of a fistula. Finally, patient’s choice is an important determination and in such patients, catheters are placed based on patient’s choice. While tunneled catheters can successfully provide hemodialysis therapy, their use is associated with many complications.12–15 Catheter malfunction occurs frequently and leads to a reduction in blood flow. A reduction in blood flow due to catheter dysfunction ultimately results in a reduction of dialysis dose delivered to a hemodialysis patient. The development of catheter-related fibroepithelial sheath leads to catheter malfunction and catheter occlusion.12,13 Radiocontrast studies have demonstrated that this complication is found in more than half of the patients with catheter dysfunction.12,13 Catheter exchange alone does not help the condition. The treatment of fibroepithelial sheath is required to fix catheter dysfunction. Percutaneous balloon angioplasty has emerged as a major tool in successfully treating the fibroepithelial sheath. During angioplasty, balloon inflation can disrupt the fibroepithelial sheath and restore flow. In one study, an 8-mm diameter balloon was used to treat tunneled dialysis catheter dysfunction patients with a 100% success rate.16 After balloon angioplasty, radiocontrast administration confirmed that the sheath had been treated successfully. Following the disruption of the fibroepithelial sheath, catheter blood flow augmentation was observed in 99% of patients.16,17 A significant number of hemodialysis patients receive dialysis therapy with a catheter. It is important to understand that catheter dysfunction due to the presence of fibroepithelial sheath is a relatively common cause of catheter dysfunction.12–15 This complication can be successfully treated by the percutaneous balloon angioplasty procedure and dialysis therapy provided to our patients.

Masud et al.