AV Fistulas and Grafts

Written by: Adesuwa Akhetuamhen, MD (PGY-3)  Edited by: Jordan Maivelett, MD (PGY-4)  Expert commentary by: Joel Topf, MD, FACP

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AV fistulas and AV grafts are permanent vascular access for patient’s who need hemodialysis. More than 1 million North American patients initiated dialysis of the past decade. As such EM doctors should be aware of common AV fistula/graft complications and how to manage them.

Bleeding

• Most commonly caused by uremic platelet dysfunction. If the patient is uremic and hemostasis is difficult to achieve, consider a dose of Vasopressin/Desmopressin (DDAVP).

• Minor oozing can be managed with application of topical hemostatic agents

• Larger bleeds can be sutured (e.g.,  purse string or figure-of-8). If unsuccessful, vascular surgery should be consulted for surgical repair.

Extremity swelling and thoracic central vein occlusion

• Mild to moderate swelling of the upper extremity and chest wall is common after AV access creation and usually subsides within 2 weeks

• If swelling is persistent beyond 2 weeks, an anatomic problem such as thoracic central vein occlusion (i.e., stenosis or thrombosis of a central vein) is present in 25% of cases

• Massive edema of the extremity with AV access is pathognomonic for thoracic central vein occlusion

• Vascular duplex ultrasound can evaluate for localized clotting but is unable to visualize the central thoracic veins

• The gold standard for diagnosing thoracic central vein occlusion is venography, with CT venography being a potential option as well

• Treatment involves endovascular or surgical intervention

AV fistula or graft thrombosis

• Presents as an AV fistula/graft with limited or nondetectable flow at the dialysis center, decreased or absent palpable thrill, and decreased or absent bruit

• Vascular duplex ultrasound can evaluate clot burden

• Thrombosis is more common in AV grafts than in AV fistulas (the thrombosis rate in fistulas is 1/6th the rate seen in grafts)

• Can lead to AV fistula/graft failure

• Treatment is endovascular or surgical

AV fistula/graft failure

• Most common complication of AV fistulas and grafts

• Definitions vary, with emphasis placed on time of creation and history of use

  • Primary failure (a.k.a., early failure or premature failure): failure before use or within 3 months of use

  • Mature failure: failure after 3 months of use

• Often due to an anatomic problem, including:

  • Pre-graft arterial stenosis

  • Post-graft venous stenosis

  • In-graft stenosis or thrombosis

• Presents as an AV fistula/graft with limited or nondetectable flow at the dialysis center, decreased or absent palpable thrill, and decreased or absent bruit

• Work-up includes vascular duplex ultrasound and angiography

• Treatment is endovascular or surgical with the goal of salvaging the graft if possible

Infection

• Bacteremia related to AV fistula cannulation is uncommon, with a rate of about 2% per 100 access days

• Most commonly due to Staph aureus and Staph epidermidis

• Bacteremia is thought to be related to concomitant seeding of heart valves and endocarditis. As such, the recommended treatment duration is 6 weeks of antibiotics.

• Surgical removal of the AV fistula is recommended if septic emboli are present

• Localized infection of an AV fistula itself is rare, involves pus/abscess formation, and requires surgical drainage

• AV grafts carry a higher infection risk than AV fistulas. In addition, secondary infection of a clot within the graft is more common than in AV fistulas.

Aneurysm

• Defined as a focal dilation >1.5x the normal diameter of the vessel

• Main complications include rupture, infection, and erosion of the overlying skin

• Risks of rupture include nonhealing ulcer, spontaneous bleeding, and rapid expansion of the size

• Requires surgical revision prior to rupture

• Localized infection of an AV graft is also surgical 

Vascular steal

• Most commonly affects the distal extremity due to shunting of blood flow through the AV fistula and away from said extremity

• Often worse during dialysis sessions due to increased shunting

• Symptoms are related to ischemic changes (e.g., pain, paresthesias, numbness, weakness) 

• On physical exam, above symptoms may improve with manual compression of the AV fistula

• Digital waveforms and pressures with and without AV fistula compression can also be used as a screening test to rule out the diagnosis of vascular steal

• Vascular duplex ultrasound is indicated to evaluate for distal arterial stenosis or flow reversal that could be contributing to vascular steal

• Treatment options vary and depend on the severity of symptoms. If mild and intermittent, close observation over weeks to allow for collateral vessels to form is possible. If ischemic symptoms are severe or persistent, vascular surgery should be consulted to evaluate for revascularization options.

• Special case: if a patient has an internal mammary coronary artery bypass graft on the same side as their AV fistula, shunting from the fistula can result in coronary steal with subsequent myocardial ischemia.

Heart failure

• AV fistula placement results in decreased systemic vascular resistance, which lowers blood pressure and results in a compensatory increase in sympathetic tone. The fistula also results in increased venous return, which can lead to right ventricular (RV) overload.

• The above effects can result in high output heart failure with associated RV dysfunction and dilation

• Initial treatment is medical and targeted towards volume control with diuretics and dialysis, blood pressure control, and correction of anemia

• Surgical options include closing unused fistula sites, decreasing flow through an active high flow fistula, or when all else fails closing a fistula

Neuropathy

• Caused by local amyloid deposition

• Usually causes median nerve dysfunction (i.e., carpal tunnel)

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Joel M Topf, MD, FACP

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References:

1) UpToDate Arteriovenous fistula creation for hemodialysis and its complications. https://www.uptodate.com/contents/arteriovenous-fistula-creation-for-hemodialysis-and-its-complications?search=fistula%20dialysis&source=search_result&selectedTitle=2~150&usage_type=default&display_rank=2#H3359368070

2) UpToDate Arteriovenous graft creation for hemodialysis and its complications. https://www.uptodate.com/contents/arteriovenous-graft-creation-for-hemodialysis-and-its-complications?search=av fistula&topicRef=115151&source=see_link - H1354144314

3) UpToDate Thoracic central vein occlusion associated with hemodialysis access. https://www.uptodate.com/contents/thoracic-central-vein-occlusion-associated-with-hemodialysis-access?search=fistula%20dialysis&topicRef=1917&source=see_link#H204766401

4) UpToDate Primary failure of the hemodialysis arteriovenous fistula. https://www.uptodate.com/contents/primary-failure-of-the-hemodialysis-arteriovenous-fistula?search=av fistula&topicRef=1917&source=see_link - H60151140

5) UpToDate Failure of the mature hemodialysis arteriovenous fistula. https://www.uptodate.com/contents/failure-of-the-mature-hemodialysis-arteriovenous-fistula?search=av fistula&topicRef=1917&source=see_link - H24

6) Lok CE, Foley R. Vascular access morbidity and mortality: trends of the last decade. Clin J Am Soc Nephrol 2013; 8: 1213–19

7) UpToDate Evaluation and management of heart failure caused by hemodialysis arteriovenous access. https://www-uptodate-com/contents/evaluation-and-management-of-heart-failure-caused-by-hemodialysis-arteriovenous-access?search=av fistula&topicRef=1917&source=see_link - H4285282968

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How to Cite this Post

[Peer-Reviewed, Web Publication] Akhetuamhen, AT; Maivelett, J. (2020, Mar 9). AV Fistulas and Grafts. [NUEM Blog. Expert Commentary by Topf, J]. Retrieved from https://www.nuemblog.com/blog/av-fistulas

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