title: Access recirculation in a native fistula in spite of a seemingly adequate access flow.
abstract: True access recirculation (AR) measured by ultrasound dilution technique is usually absent in well-working shunts. It occurs with low access flows (Qa). High access flow rates are assumed to prevent AR. Two major exceptions to these rules are known: presence of intra-access strictures and inadvertently reversed blood lines. We present an additional exception in which true access recirculation occurred in a native arteriovenous (AV) fistula with correct placement of bloodlines. Surprisingly, access blood flow exceeded pump blood flow (Qb) almost threefold. The situation was clarified by a magnetic resonance angiogram showing a collateral forming a functional loop. This loop led to true access recirculation in one branch, although overall blood flow through both branches appeared to be adequate. The different findings in this shunt over time give insight into the often complex pathophysiology of native fistulae. This case proves that seemingly adequate access flow does not necessarily prevent access recirculation in native AV fistulae. We suggest monitoring both access flow and recirculation in hemodialysis accesses on a regular basis.
authors.affiliation: Department of Internal Medicine, Division of Nephrology, the Department of Radiology, Division of MR Imaging, the Department of Surgery, and the Department of Physiology, University of Graz, Austria. peter.krisper@kfunigraz.ac.at
authors.forename: P
authors.initials: P
authors.lastname: Krisper
authors.forename: M
authors.initials: M
authors.lastname: Aschauer
authors.forename: K
authors.initials: K
authors.lastname: Tiesenhausen
authors.forename: G
authors.initials: G
authors.lastname: Leitner
authors.forename: H
authors.initials: H
authors.lastname: Holzer
authors.forename: D
authors.initials: D
authors.lastname: Schneditz
mesh_terms: D000328:Adult; D002408:Catheters, Indwelling / Q000009:adverse effects; D006801:Humans; D018810:Magnetic Resonance Angiography; D008297:Male; D008991:Monitoring, Physiologic; D012039:Regional Blood Flow; D006435:Renal Dialysis / Q000009:adverse effects*; D018616:Ultrasonography, Doppler, Duplex; D016157:Vascular Fistula / Q000000981:diagnostic imaging*