title: Outcomes of original and low-permeability Gore Excluder endoprosthesis for endovascular abdominal aortic aneurysm repair.
abstract: OBJECTIVE
  Because of concern about the percentage of enlarging abdominal aortic aneurysms (AAAs) after endovascular repair with the Excluder device (W.L. Gore & Assoc, Inc, Sunnyvale, Calif), the graft material was modified to reduce its permeability and released for commercial use in mid-2004. We studied all AAA repairs with Excluder endografts performed at our institution, including the original-permeability (OP) version (n = 99) and the low-permeability (LP) version (n = 48).
  
  
  METHODS
  All patients were followed up with serial computed tomography (CT) angiography and three-dimensional (3D) reconstruction. Morphologic measurements, including AAA diameter and 3D volume, were prospectively entered into a database to evaluate changes in AAA size over time. Owing to the length of available follow-up for the LP version, the primary end point was AAA size change at 6 and 12 months, evaluated by Mann-Whitney U test for unpaired samples.
  
  
  RESULTS
  Preoperative and postoperative anatomy was similar in the two groups, including AAA diameter (OP, 5.6 +/- 1 cm; LP, 5.8 +/- 2 cm; P = .3), aortic neck length (OP, 21 +/- 1 mm; LP, 22 +/- 2 mm; P = .9), postoperative aortic seal zone (OP, 18 +/- 1 mm; LP, 16 +/- 1 mm, P > .1) and iliac seal zone (OP, 33 +/- 1 mm, LP 31 +/- 1 mm, P = .2). The rate of sac shrinkage differed significantly. Orthogonal diameter measurements showed a significant difference in the rate of shrinkage by 12 months postoperatively (OP, -2.1 +/- 1 mm; LP, -5.1 +/- 1 mm; P = .01). By 3D volume, the rate of shrinkage was considerably different between the two groups at both 6 and 12 months (12 months: OP, -6% +/- 1%; LP, -20 +/- 4%; P = .0006). There was no enlargement by diameter in either group at 6 or 12 months postoperative. By standard volume criteria, however, 12 of 99 patients in the OP group and one of 48 patients in the LP group had significant AAA enlargement < or =12 months (P = .04). Of these, four of 12 patients in the OP group had enlargement without apparent endoleak, even on delayed-contrast CT. The remainder had persistent type II endoleaks (8/12 in the OP group and 1/1 in the LP group). Multivariate analysis revealed graft permeability (P < .0001) and endoleak (P < .0001) as independent factors in aneurysm size change. In the OP group long-term, the average AAA enlarged at later time points compared with the prior scan: 24 months, -0.2%; 36 months, +0.2%; 48 months, +2%; and 60 months, +2% (P < .0002).
  
  
  CONCLUSIONS
  In early follow-up, the low-permeability Excluder device is associated with a significantly greater aneurysm shrinkage rate than the original version. Clinically important enlargement also appears significantly different within 1 year of implantation. Despite these promising results, longer follow-up is needed to determine whether these differences will persist.
authors.affiliation: Section of Vascular Surgery, Dartmouth-Hitchcock Medical Center, Lebanon, NH 03756, USA.
authors.forename: William
authors.initials: W
authors.lastname: Tanski
authors.forename: Mark
authors.initials: M
authors.lastname: Fillinger
mesh_terms: D000368:Aged; D017130:Angioplasty / Q000009:adverse effects; D017544:Aortic Aneurysm, Abdominal / Q000000981:diagnostic imaging / Q000601:surgery*; D019917:Blood Vessel Prosthesis Implantation / Q000009:adverse effects; D005260:Female; D005465:Fluorocarbon Polymers / Q000737:chemistry*; D005500:Follow-Up Studies; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D021621:Imaging, Three-Dimensional; D016015:Logistic Models; D008297:Male; D010539:Permeability; D016062:Porosity; D011446:Prospective Studies; D011474:Prosthesis Design; D011475:Prosthesis Failure; D012086:Reoperation; D013997:Time Factors; D036542:Tomography, Spiral Computed; D016896:Treatment Outcome
chemical_list: D005465:Fluorocarbon Polymers; C010946:polytetrafluoroethane