title: Aortic side branch perfusion alone does not account for high intra-sac pressure after endovascular repair (EVAR) in the absence of graft-related endoleak.
abstract: OBJECTIVE
  to examine the effect of stent-graft deployment on pressure within an aneurysm sac and to investigate the potential sources of intra-sac pressure.
  
  
  METHODS
  intra-sac pressure was monitored during and immediately after endovascular repair via an indwelling catheter. Intra-sac pressure was also monitored during conventional open repair and was compared with the pressure measured within patent lumbar and inferior mesenteric side-branches, both before and after restoration of iliac arterial blood flow. Intra-sac and side-branch pressures were recorded and expressed as ratios of simultaneously measured radial artery pressure.
  
  
  RESULTS
  in the absence of a graft-related endoleak (23/25 patients), endovascular repair resulted in a significant reduction in intra-sac pulse pressure (median ratio 0.31 IQR 0.10-0.46). There was no corresponding reduction in mean intra-sac pressure (median ratio 0.91; IQR 0.83-1.00). Application of clamps at conventional open repair resulted in a fall in both intra-sac pressure (median ratio 0.39, IQR 0.32-0.64) and pressure within side-branches (median ratio 0.45, IQR 0.33-0.64). Restoration of iliac blood flow resulted in a modest recovery of the side-branch pressure (median ratio 0.63, IQR 0.57-0.81), which nonetheless remained significantly less than the intra-sac pressure recorded after EVAR (p=0.01).
  
  
  CONCLUSIONS
  reperfusion of the aneurysm sac through patent side-branches seems insufficient to account for persistent pressurisation of the aneurysm after endovascular repair. This finding supports the hypothesis that pressure may be transmitted directly through stent-graft fabric.
authors.affiliation: Department of Vascular Surgery, and Regional Vascular Unit, Royal Liverpool University Hospital, Liverpool, UK.
authors.forename: S R
authors.initials: SR
authors.lastname: Vallabhaneni
authors.forename: G L
authors.initials: GL
authors.lastname: Gilling-Smith
authors.forename: T V
authors.initials: TV
authors.lastname: How
authors.forename: J A
authors.initials: JA
authors.lastname: Brennan
authors.forename: D A
authors.initials: DA
authors.lastname: Gould
authors.forename: R G
authors.initials: RG
authors.lastname: McWilliams
authors.forename: P L
authors.initials: PL
authors.lastname: Harris
mesh_terms: D001014:Aortic Aneurysm / Q000503:physiopathology* / Q000601:surgery*; D001019:Aortic Rupture / Q000209:etiology* / Q000503:physiopathology*; D001794:Blood Pressure / Q000502:physiology*; D019917:Blood Vessel Prosthesis Implantation / Q000009:adverse effects*; D002408:Catheters, Indwelling / Q000009:adverse effects; D003326:Coronary Circulation / Q000502:physiology*; D006439:Hemodynamics / Q000502:physiology; D006801:Humans; D011183:Postoperative Complications; D011475:Prosthesis Failure; D014654:Vascular Patency / Q000502:physiology