title: Embolic protection filters for carotid stenting: differences in flow obstruction depending on filter construction.
abstract: OBJECTIVE
  To investigate the pressure gradient and degree of flow reduction associated with embolus protection filters for carotid stenting in an in vitro experiment.
  
  
  METHODS
  Three filter devices with a perforated membrane design and one wire mesh type filter were tested. At a pressure of 70 mmHg, the flow reduction and pressure gradient were measured in a 5-mm tube using blood-mimicking fluid.
  
  
  RESULTS
  The pressure gradient in the wire mesh filter was 1.65+/-0.49 mmHg (95% CI 1.32 to 1.86). The mean pressure gradient in the perforated membrane filters was 6.88+/-2.62 mmHg (95% CI 6.22 to 7.55, p<0.0001). There was also a significant correlation between pressure gradient and flow reduction (r=-0.77, p<0.01).
  
  
  CONCLUSIONS
  Embolic protection filters cause a pressure gradient and obstruct blood flow. This effect is marked in perforated membrane filters and almost absent in the wire mesh filter.
authors.affiliation: Department of Vascular Surgery, Erasmus Medical Center, Rotterdam, The Netherlands. j.m.hendriks@erasmusmc.nl
authors.forename: Johanna M
authors.initials: JM
authors.lastname: Hendriks
authors.forename: Jaap D
authors.initials: JD
authors.lastname: Zindler
authors.forename: Aad
authors.initials: A
authors.lastname: van der Lugt
authors.forename: Peter M T
authors.initials: PM
authors.lastname: Pattynama
authors.forename: Marc R H M
authors.initials: MR
authors.lastname: van Sambeek
authors.forename: Johanna L
authors.initials: JL
authors.lastname: Bosch
authors.forename: Lukas C
authors.initials: LC
authors.lastname: van Dijk
mesh_terms: D001783:Blood Flow Velocity; D001794:Blood Pressure; D002343:Carotid Artery, Internal / Q000601:surgery*; D005069:Evaluation Studies as Topic; D020766:Intracranial Embolism / Q000209:etiology / Q000517:prevention & control; D008955:Models, Cardiovascular; D015607:Stents / Q000009:adverse effects; D014160:Transducers, Pressure; D014656:Vascular Surgical Procedures / Q000295:instrumentation*; D016306:Vena Cava Filters