title: Does drainage hole size influence adhesion on ventricular catheters?
abstract: OBJECTIVE
  Ventricular catheter drainage holes of shunt systems used to treat hydrocephalus obstruct with tissue commonly comprising monocytes/macrophages, astrocytes, and giant cells. Despite high rates of obstruction, very few studies have manipulated drainage hole orientation, number, position, or diameter. By altering the hole diameter but maintaining a constant hole surface area, we manipulated shear stress through the holes, which we hypothesized would change the degree of macrophage and astrocyte attachment.
  
  
  METHODS
  First, a hole fabrication method was chosen from two fabrication techniques including punched holes in catheter tubing and constructed holes using nanofabrication techniques.
  
  
  RESULTS
  Punched holes were chosen to vary hole size from 282 to 975 μm because (1) samples were geometrically similar to commercially available ventricular catheters without significant microscopic differences in roughness values and (2) total macrophage and astrocyte adhesion on the punched holes was not significantly different from adhesion on the commercially available catheters. Overall adhesion from least to most adherent appeared to follow 975 < 754 ≈ 500 < 282-μm hole diameter for macrophages and 975 < 500 < 754 < 282 for astrocytes with an obvious dependency on catheter orientation with respect to the horizontal; a dependency to the proximity of the hole to the catheter tip was not observed.
  
  
  CONCLUSIONS
  This study suggests that macrophage and astrocyte adhesion generally decreases with increasing hole diameter under flow conditions and underscores the necessity for future work to examine how hole diameter impacts inflammatory-based shunt obstruction.
authors.affiliation: Department of Bioengineering, University of Utah, Salt Lake City, UT, 84112, USA. carolyn.harris@hsc.utah.edu
authors.forename: Carolyn A
authors.initials: CA
authors.lastname: Harris
authors.forename: James P
authors.initials: JP
authors.lastname: McAllister
mesh_terms: D000818:Animals; D001253:Astrocytes / Q000166:cytology; D002408:Catheters, Indwelling / Q000009:adverse effects*; D002448:Cell Adhesion; D002557:Cerebrospinal Fluid Shunts / Q000009:adverse effects* / Q000295:instrumentation*; D004867:Equipment Design; D004868:Equipment Failure; D008264:Macrophages / Q000166:cytology; D051379:Mice; D051381:Rats