The original abdominal Excluder (W.L. Gore & Associates, Flagstaff, Ariz) endoprosthesis has been associated with late aneurysm sac expansion over time from transgraft ultrafiltration of serous fluid. This has been treated by relining the graft with original or low-permeability components. We asked whether additional component overlap of the original graft material resulting from proximal or distal extensions placed at the time of initial repair would influence the rate of late aneurysm sac expansion in the absence of endoleak.Methods
Computed tomography (CT) scans from subjects (n = 120) receiving the original endoprosthesis from the Excluder pivotal trial were measured for total distance of original graft overlap (including contralateral gate, proximal extension, or distal extension overlap) based on reformatted CT scans. This was compared to change in aneurysm sac diameter and volume (as measured in independent laboratories) at the latest time point available. Patients were omitted if they were missing CT scan data (n = 10), their graft was explanted for endoleak (n = 2), they underwent an intervention for endoleak and did not have diameters available after their intervention (n = 3), or if they had a continued endoleak that could account for an increase in aneurysm sac diameter (n = 11). This left 27 patients with more overlapping components than the required contralateral limb/gate overlap (mean follow-up time 40.6 ± 17.0 months) and 67 patients with required gate overlap (mean follow-up time 46.2 ± 15.9 months).Results
Subjects with increased component overlap (mean overlap 87.1 mm ± 57.4 mm) were not protected from aneurysm sac expansion when compared to those with the minimum required gate overlap (mean overlap 31.2 mm ± 3.4 mm). There was no association of total distance of overlap with aneurysm sac size change by diameter or volume (r2 = 0.00034,P= .86 for diameter and r2 = 0.0019,P= .68 for volume). Increasing percentage of overlap within the aneurysm sac was likewise not associated with aneurysm sac decrease in diameter (r2 = 0.0028,P= .61). Few patients had large percentages of original graft overlap (mean 26.2% ± 14.1% for the increased overlap group and 18.6% ± 5.5% for the required overlap group,P= .0097).Conclusion
Partial graft overlap involving multiple original components from proximal and distal extensions is not protective against aneurysm sac expansion due to transgraft ultrafiltration. This suggests that transgraft ultrafiltration is not impeded by having partial double layers of original material. All patients who received the original Excluder and have late aneurysm sac expansion in the absence of endoleak should have as complete relining as feasible with low permeability components if sac shrinkage is the surrogate goal.