A Novel Classification System for Autogenous Arteriovenous Fistula Aneurysms in Renal Access Patients

Introduction: Arteriovenous fistulae (AVFs) constructed for hemodialysis access are prone to aneurysmal degeneration. This can lead to life-threatening sequelae such as aneurysmal rupture. The literature includes various guidelines on the management of certain aspects of access-related aneurysm formation; however, no classification system exists to guide reporting or prognostication. We aimed to create a universally acceptable classification for these aneurysms and establish guidance about their management. Methods: We clinically examined, duplex scanned, and photographed all of the autologous arteriovenous fistulae in our local renal failure population in January 2010 in order to categorize morphology. We then followed up the cohort for 2 years prospectively to assess outcomes, primarily of rupture or surgical intervention for bleeding. Results: A total of 344 patients were included (292 currently needling their fistula and 52 with low creatinine clearance awaiting dialysis). In all, 43.5% of dialyzed patients had aneurysmal fistulae. We propose a classification system as follows: type 1a: dilated along the length of the vein; type 1b: postanastomotic aneurysm; type 2a: classic “camel hump”; type 2b: combination of type 2a and 1b; type 3: complex; and type 4: pseudoaneurysm. Six fistulae needed emergency surgery for bleeding in the 2-year follow-up period and 5 of these were type 2 aneurysms. The remaining one was in the nonaneurysmal group, although it had become aneurysmal by the time it bled. Conclusion: Type 1 aneurysms are much commoner in patients who have not yet needled their fistula and have a relatively innocuous course although type 1a aneurysms should be monitored for high flow and physiological consequences thereof. Type 2 aneurysms are associated with needling of AVFs. They are at significant risk of rupture and need to be monitored carefully or treated prophylactically.