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Differing morphological changes following endovascular AAA repair using balloon-expandable or self-expanding
1Endovascular Unit, University College London Hospitals, England, UK.
Purpose:
To determine whether changes in aneurysm morphology after endovascular abdominal aortic aneurysm (AAA) repair differ according to the type of endograft (self-expanding versus balloon-expandable).
Methods:
Among 88 patients with AAA treated with either homemade polytetrafluoroethylene (PTFE) aortomonoiliac endografts or Talent stent-grafts, 30 patients (24 males; mean age 73 years, range 55-93) were selected for this study based on a >2-year follow-up and freedom from endoleak or conversion. Of these, 12 had PTFE endografts and 18 Talent devices. All patients had spiral computed tomographic angiography with 3-dimensional reconstruction at 5 days posttreatment and 6-month intervals thereafter. Neck dimensions (length and diameters at 3 levels) were measured, along with volumes and maximal diameters of the sac and lengths of the aneurysm and endograft. Intra- and interobserver errors were <5% for linear and volume measurements.
Results:
Both groups had an initial 20-mL increase in median volume (p = 0.02) followed, only in Talent patients, by marked shrinkage at 6 months (-87.4 mL; p = 0.09). PTFE patients had no further changes in sac volume. Maximal sac diameters reflected volumes, but only after day 5. PTFE patients had an immediate increase (p = 0.03) in aneurysm neck diameters, which then remained stable. Talent patients had continuing increases in diameter to 6 months (p < 0.05), with no change thereafter. Length changes were not significant in either group. PTFE patients had an increase in median aneurysm length at day 5 (+3.2 mm, p = 0.04) and again at 1.5 years (+6.4 mm, p = 0.03). Endograft length slowly increased (+18.7 mm) over 1.5 years (p = 0.02). Talent patients had no length changes in the device or aneurysm.
Conclusions:
Aneurysm morphology appeared to alter according to the type of endograft deployed. With PTFE endografts, aneurysm volume does not change, whereas impressive sac shrinkage occurs in conjunction with the Talent system. Aneurysm/graft lengths increase with unsupported stent-grafts. Neck diameter increases immediately with balloon-expandable endografts and then remains constant. In the self-expanding models, neck diameter increases at 6 months but not thereafter.