title: Endotension is influenced by wall compliance in a latex aneurysm model.
abstract: OBJECTIVE
  Even though endovascular aneurysm repair (EVAR) creates a closed chamber except for patent branches, the intra-sac pressure is never zero. This study was designed to investigate whether, and to what extent, aneurysm wall compliance influences intra-sac pressure.
  
  
  METHODS
  In vitro experimental study.
  
  
  METHODS
  Aneurysm models with six and 12 latex layers were produced, resulting in elastic and stiff circumferential compliance (3.5 +/- 0.5 and 0.9 +/- 0.3%/100 mmHg, respectively). The models with an 18 mm internal neck and maximum aneurysm diameter of 60 mm were inserted into an in vitro circulation system. The systemic mean pressure (SPmean) was varied from 50 to 120 mmHg. After the aneurysm was excluded with a knitted polyethylene graft, aneurysm sac mean pressure (ASPmean) and aneurysm sac pulse pressure (ASPpulse) were measured. Data are presented as mean +/- SD. Statistics were performed using repeated measurements of variance; p<0.05 was considered significant.
  
  
  RESULTS
  In the model EVAR created a closed chamber without endoleak, but with an aneurysm sac pressure related to wall compliance. In the elastic aneurysm model with six latex coats the aneurysm sac mean pressure (ASPmean) and the aneurysm sac pulse pressure (ASPpulse) at all systemic pressures were significantly lower than they were in the stiffer model with 12 latex coats (p<0.05). At a SPmean of 90 mmHg, the ASPmean was 21.0 +/- 0.9 mmHg (six latex coats) and 26.0 +/- 0.2 mmHg (12 latex coats) (p<0.05), the ASPpulse was 5.7 +/- 0.2 mmHg (six latex coats) and 8.8 +/- 0.3 mmHg (12 latex coats) (p<0.05).
  
  
  CONCLUSIONS
  This in vitro model demonstrated that the aneurysm sac mean pressure (ASPmean) and the aneurysm sac pulse pressure (ASPpulse) were significantly influenced by the compliance of the aneurysm wall. These data highlight the need for further studies regarding endotension.
authors.affiliation: Division of Vascular Surgery, Department of Visceral and Vascular Surgery, University of Cologne, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Gawenda
authors.forename: P
authors.initials: P
authors.lastname: Knez
authors.forename: St
authors.initials: S
authors.lastname: Winter
authors.forename: G
authors.initials: G
authors.lastname: Jaschke
authors.forename: G
authors.initials: G
authors.lastname: Wassmer
authors.forename: Th
authors.initials: T
authors.lastname: Schmitz-Rixen
authors.forename: J
authors.initials: J
authors.lastname: Brunkwall
mesh_terms: D017544:Aortic Aneurysm, Abdominal / Q000503:physiopathology* / Q000601:surgery*; D019917:Blood Vessel Prosthesis Implantation; D003187:Compliance; D007840:Latex; D008954:Models, Biological; D013314:Stress, Mechanical
chemical_list: D007840:Latex