Evaluation of Suspected Outflow Stenosis in an Aneurysmal AVF

Abstract

Infographics

Case Description

A 72-year-old man with ESKD, requiring maintenance hemodialysis three times a week, was referred for a fistulogram to our access center. The patient had a 4-year-old, left forearm, radial artery to cephalic vein arteriovenous fistula (AVF). An outflow vein stenosis was suspected by the patient’s nephrologist on dialysis rounds because of the visibly distended and aneurysmal body of the AVF. Despite the absence of other clinical indications associated with flow dysfunction of an arteriovenous access (such as prolonged bleeding, low clearance, high venous pressures), the patient was referred to our access center for a fistulogram and possible intervention. On examination, the patient had a large, left-forearm AVF with aneurysmal dilations in the body of the AVF when the arm was in the normal resting position (Figure 1A). The arm elevation test was performed by lifting the patients arm above the shoulder level. The AVF collapsed nicely (Figure 1B). On auscultation, a soft bruit was heard all throughout the fistula. This ruled out significant stenosis in the outflow tract, and we deemed that a fistulogram was not warranted. A limited ultrasound of the AVF was also performed, and this confirmed that there was no stenosis in the body of the AVF or the draining forearm and upper arm veins. The patient was informed that the AVF was working well and that no further intervention was required at that point, other than monitoring of the aneurysms.

Figure 1.: Arm elevation test. (A) Left forearm (radial artery to cephalic vein) arteriovenous fistula (AVF) in a patient on hemodialysis.The AVF is visibly raised, well distended, and aneurysmal. (B) Elevation of the arm above the heart level leads to the collapse of the AVF. Full collapse of the most distal aneurysm is clearly seen while the proximal aneurysms partially collapse.

Physical examination of the arteriovenous access is an accurate diagnostic tool that can be quickly performed at patient’s bedside and can provide valuable information to detect or rule out stenosis in a vast majority of AVFs (¹). The latest Kidney Disease Outcomes Quality Initiative vascular access guidelines recommend regular physical examinations to monitor and detect any flow dysfunction of the AVF (²). Several studies have shown that physical examination of access correlates well with access ultrasound, intra-access pressures, and even to angiography—the gold-standard test (^34–5). A thorough access examination helps in screening patients and in detecting early stenosis in patients with clinical indications, who may need to be referred for interventions to prevent access thrombosis (¹,²).

The arm elevation or fistula collapse test is performed by elevating the patient’s access arm above the level of the heart. Gravity causes the blood within the AVF body to drain, thus causing the fistula to collapse. In the presence of a significant stenosis, blood drainage is hampered and the AVF may not collapse and usually becomes hyperpulsatile. This simple, noninvasive test is a quick, convenient, and low-cost tool that can be easily taught and used by nephrologists, nurse practitioners, dialysis providers, and even the patients themselves to rule out major stenosis. It can help save unnecessary referrals and unwarranted invasive procedures in such patients.

Teaching Points

• Elevation of the arm above the heart level leads to the collapse of the AVF in those without a significant outflow stenosis.
• The arm elevation test is a no-cost, simple, noninvasive, bedside test that can be performed quickly to assess any outflow vein stenosis in an AVF circuit.

Disclosures

V.D. Niyyar reports receiving honoraria from Albert–Einstein Montefiore and KidneyCon (for being invited faculty); from the American Society of Diagnostic and Interventional Nephrology (ASDIN), American Society of Nephrology, American Society of Nephrology Highlights, National Kidney Foundation (for being for being an invited speaker); from Ardea Biosciences (for random surveys and questionnaires); from Ironwood Pharmaceuticals (for serving on the Renal Event Adjudication Committee); and from Lesinurad (as advisory board member). V.D. Niyyar also reports having previous consultancy agreements with Ardea Biosciences and Lesinurad, and with Ironwood Pharmaceuticals (finished in December 2018); serving as a scientific advisor for, or member of, American Society of Nephrology (continuous cycler assisted peritoneal dialysis; 2018), American Society of Nephrology (interventional nephrology advisory group), and on the graft committee of Kidney Health Initiative–American Society of Nephrology/Food and Drug Administration; serving as the president-elect, and previous secretary treasurer and councilor, of ASDIN, and chair of the ASDIN hemodialysis vascular access Certification Committee and ASDIN US Certification Committee; and having other interests in/relationships with Commdex Consulting. M.K. Sharma reports serving on the editorial board of Annals of Internal Medicine; serving as a medical review board member of ESRD Network 15; serving on a speakers bureau for Relypsa; and having other interests in/relationships with University of Arkansas for Medical Sciences (Little Rock, AR) as adjunct faculty.

Funding

None.