title: Low-flow polytetrafluoroethylene accesses: ultrasound surveillance and preemptive interventions ensure long-term patency.
abstract: BACKGROUND
  Vascular accesses (especially polytetrafluoroethylene grafts) with a permanently low flow (Qa <600 ml/min) are prone to thrombosis and thus have short patency. The reason for a permanently low flow is usually medial calcinosis of the inflow artery in diabetics. We retrospectively studied the long-term patency of low-flow grafts with careful ultrasound surveillance and preemptive interventions.
  
  
  METHODS
  Twenty subjects with Qa permanently <600 ml/min were included. Ultrasound surveillance was performed every 3 months in addition to classical monitoring techniques. Significant stenosis was strictly defined as the combination of B-mode narrowing >50% + >2-fold peak systolic velocity increase + 1 additional criterion (residual diameter <2.0 mm or flow volume decrease by >20%). Such stenoses were treated by preemptive percutaneous intervention. Primary and secondary patencies were calculated.
  
  
  RESULTS
  The primary patency was 357 ± 316 days and the secondary (cumulative) patency was 996 ± 702 days. The number of interventions was 2.09/patient year, but >10 in 6 (33%) subjects. 93 and 80% of grafts were patent 1 and 2 years after access creation, respectively.
  
  
  CONCLUSIONS
  Low-flow accesses undergoing ultrasound surveillance with strict diagnostic criteria and preemptive interventions had patencies similar to accesses with normal Qa in our study. This was enabled by a relatively high rate of interventions.
authors.affiliation: Third Department of Internal Medicine, General University Hospital, Prague, Czech Republic.
authors.forename: Jan
authors.initials: J
authors.lastname: Malik
authors.forename: Vladimir
authors.initials: V
authors.lastname: Tuka
authors.forename: Eva
authors.initials: E
authors.lastname: Chytilova
authors.forename: Magdalena
authors.initials: M
authors.lastname: Mokrejsova
authors.forename: Martin
authors.initials: M
authors.lastname: Masek
authors.forename: Marcela
authors.initials: M
authors.lastname: Slavikova
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001783:Blood Flow Velocity / Q000502:physiology; D001807:Blood Vessel Prosthesis / Q000592:standards* / Q000639:trends; D002318:Cardiovascular Diseases / Q000000981:diagnostic imaging* / Q000601:surgery; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011138:Polytetrafluoroethylene / Q000592:standards*; D012189:Retrospective Studies; D014463:Ultrasonography
chemical_list: D011138:Polytetrafluoroethylene