title: Aortic neck enlargement after endovascular aneurysm repair using balloon-expandable versus self-expanding endografts.
abstract: OBJECTIVE
  This study evaluated changes in aortic neck diameter after endovascular aneurysm repair (EVAR) using a balloon-expandable stent (BES) endograft compared with a commercially available self-expanding stent (SES) endograft. We hypothesized that forces applied to the aortic neck by SES endografts may induce aortic neck enlargement over time and that such enlargement may not occur in aneurysm patients treated with a device that does not use a proximal SES.
  
  
  METHODS
  This was a retrospective quantitative computed tomography (CT) image analysis of patients treated with the Nellix (Endologix, Irvine, Calif) BES (n = 49) or the Endurant II (Medtronic, Minneapolis, Minn) SES (n = 56) endograft from 2008 to 2010. Patients with preimplant, postimplant, and at least 1-year serial CT scans underwent quantitative morphometric assessment by two independent vascular radiologists blinded to the outcome results. Changes in the infrarenal neck over time were compared with the suprarenal aorta for each patient.
  
  
  RESULTS
  Follow-up extended to 4.8 years for the BES and to 4.6 years for the SES, with no significant difference in median follow-up time (34 months for BESs and 24 months for SESs; P = .06). There were no differences in preimplant neck diameter (25.2 ± 0.9 mm vs 25.7 ± 1.1 mm; P = .54) or length (27.7 ± 3.7 mm vs 23.6 ± 3.7 mm; P = .12) between BESs and SESs at baseline. After implantation, neck diameter increased by 1.1 ± 0.5 mm in BES patients and 2.6 ± 0.5 mm in SES patients (P = .07) compared with the preoperative diameter. At 3 years, neck diameter increased by 0.5 ± 0.9 mm in BES patients and by 3.8 ± 1.0 mm in SES patients (P = .0002) compared with the first postoperative CT scan. The annual postimplant rate of increase in the infrarenal neck diameter was fivefold greater in SES patients (1.1 ± 0.1 mm/y) than in BES patients (0.22 ± 0.04 mm/y; P < .0001). There were no significant differences in the diameter of the suprarenal aorta at baseline or at 3 years and no differences in the annual rate of change in suprarenal aortic diameter between BES and SES endografts.
  
  
  CONCLUSIONS
  EVAR using SES endografts resulted in progressive infrarenal aortic neck enlargement, whereas EVAR using BES endografts resulted in no neck enlargement over time. These data suggest that infrarenal neck enlargement after EVAR with SES endografts is likely related to the force exerted by SES elements rather than disease progression in the infrarenal neck.
authors.affiliation: Department of Radiology, Pauls Stradins Clinical University Hospital, Riga, Latvia.
authors.forename: Janis
authors.initials: J
authors.lastname: Savlovskis
authors.affiliation: Department of Vascular Surgery, Pauls Stradins Clinical University Hospital, Riga, Latvia.
authors.forename: Dainis
authors.initials: D
authors.lastname: Krievins
authors.affiliation: Department of Vascular Surgery, St. Antonius Hospital, Nieuwegein, The Netherlands.
authors.forename: Jean-Paul P M
authors.initials: JP
authors.lastname: de Vries
authors.affiliation: Department of Interventional Radiology, Auckland City Hospital, Auckland, New Zealand.
authors.forename: Andrew
authors.initials: A
authors.lastname: Holden
authors.affiliation: Department of Vascular Surgery, Pauls Stradins Clinical University Hospital, Riga, Latvia.
authors.forename: Kaspars
authors.initials: K
authors.lastname: Kisis
authors.affiliation: Department of Vascular Surgery, Pauls Stradins Clinical University Hospital, Riga, Latvia.
authors.forename: Marcis
authors.initials: M
authors.lastname: Gedins
authors.affiliation: Department of Radiology, Pauls Stradins Clinical University Hospital, Riga, Latvia.
authors.forename: Natalija
authors.initials: N
authors.lastname: Ezite
authors.affiliation: Department of Surgery, Stanford University Medical Center, Stanford, Calif. Electronic address: zarins@stanford.edu.
authors.forename: Christopher K
authors.initials: CK
authors.lastname: Zarins
mesh_terms: D000368:Aged; D001012:Aorta, Abdominal / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000601:surgery*; D017544:Aortic Aneurysm, Abdominal / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000601:surgery*; D001027:Aortography / Q000379:methods; D001807:Blood Vessel Prosthesis; D019917:Blood Vessel Prosthesis Implantation / Q000009:adverse effects / Q000295:instrumentation*; D057510:Endovascular Procedures / Q000009:adverse effects / Q000295:instrumentation*; D005260:Female; D006801:Humans; D007844:Latvia; D008297:Male; D061330:Multidetector Computed Tomography; D009426:Netherlands; D009520:New Zealand; D011183:Postoperative Complications / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000517:prevention & control*; D011237:Predictive Value of Tests; D011474:Prosthesis Design; D012189:Retrospective Studies; D012307:Risk Factors; D015607:Stents; D013314:Stress, Mechanical; D013997:Time Factors; D016896:Treatment Outcome