title: Assessment of stenosis in vascular access grafts.
abstract: The major complication that occurs with grafts used as vascular access for hemodialysis, is stenosis at the venous anastomosis or in the draining vein. 75% area stenosis is considered significant as thrombotic occlusion may occur. The aim of this experimental study was to evaluate invasive and noninvasive indices to detect significant stenoses in a vascular access graft. A compliant underarm loop graft in vitro model was built and studied with 50, 65, 80, and 90% stenosis at flow rates of 500, 1000, and 1500 mL/min. Flow in the system was pulsatile. Velocity was measured with ultrasound Doppler and the pressure was measured invasively. The resistance index (RI), p(venous line)/MAP, and the newly introduced pressure ratio (PR) were calculated and compared. A stenosis can be suspected when a high frequency ultrasound velocity signal develops at the venous anastomosis. RI > 1 confirms a very severe stenosis (90%). The parameter PR < 8% confirms significant stenoses showing its clinical relevancy.
authors.affiliation: Hydraulics Laboratory, Institute Biomedical Technology, Ghent University, Ghent, Belgium. Vantricht@ugent.be
authors.forename: Ilse
authors.initials: I
authors.lastname: Van Tricht
authors.forename: Dirk
authors.initials: D
authors.lastname: De Wachter
authors.forename: Daniel
authors.initials: D
authors.lastname: Vanhercke
authors.forename: Jan
authors.initials: J
authors.lastname: Tordoir
authors.forename: Pascal
authors.initials: P
authors.lastname: Verdonck
mesh_terms: D000714:Anastomosis, Surgical; D001166:Arteriovenous Shunt, Surgical; D001794:Blood Pressure; D001807:Blood Vessel Prosthesis; D003251:Constriction, Pathologic; D006439:Hemodynamics; D006801:Humans; D008955:Models, Cardiovascular; D011138:Polytetrafluoroethylene; D018608:Ultrasonography, Doppler; D014655:Vascular Resistance
chemical_list: D011138:Polytetrafluoroethylene