Remodeling of the Proximal Sealing Zone and Sac Shrinkage after Endovascular Aortic Repair or Fenestrated Endovascular Aortic Repair

Background: Variations in sac shrinkage (SS) are noted between endovascular aneurysm repair for abdominal aortic aneurysm (AAA) and fenestrated endovascular aneurysm repair for short neck AAA. These variations may originate from difference in the geometry and length of proximal sealing, which influences the quality and durability of the seal. This study aimed to explore the disparities in aneurysm exclusion and sac remodeling across these 2 scenarios.<br /> Methods: This study involved a retrospective analysis of prospectively collected data from 2014 to 2021. Of 486 endovascular abdominal aortic repair cases, 33 that exclusively used a low permeability expanded polytetrafluoroethylene infrarenal device, strictly adhering to the instructions for use (IFUs), were selected. Concurrently, 30 cases of fenestrated repair that utilized modified polyester woven fabric devices proximally with consistent use of the aforementioned low-permeability devices infrarenally were examined. The quality of both proximal and distal sealing zones in fenestrated repairs was maintained within the range specified in the expanded polytetrafluoroethylene infrarenal device's IFUs, ensuring consistent sealing integrity for reliable group comparisons. Key metrics used for analysis were the detection of endoleaks and measurements of sac dimensions. Additional analyses included comparisons of demographic data and postoperative diameter changes in the proximal sealing zone (PZ) (encompassing 0, 5, 10, 15, and 20 mm below the most proximal sealing stent).<br /> Results: The demographic data and preoperative maximum-minimum diameter of the aneurysms did not differ between the groups. Proximal neck dilatation was similarly observed after both procedures. Immediately after the procedure, the incidence of lumbar arterial type II endoleaks was significantly lower after fenestrated repair than that after endovascular aortic repair (EVAR, 10% vs. 39.4%, P - 0.0094). At the final observation, EVAR substantially reduced the PZ length (-4.73 +/- 15.30%), while fenestrated repair maintained the length (21.98 +/- 24.34%; P < 0.0001). The preservation of the sealing length in fenestrated repairs was attributable to dilation occurring within the sealing range of the proximal device, oversized to accommodate the larger diameters in the more proximal sections of the aorta. The cumulative occurrence of SS (>5 mm) following fenestrated repair increased faster than that after endovascular repair (P = 0.002).<br /> Conclusions: Although aortic neck dilatation progressed similarly in both groups, fenestrated repair maintained the sealing length and demonstrated a greater extent of SS, even under the challenging circumstances in PZ. The superior postoperative results were linked to both the durability of proximal sealing and a lower occurrence of lumbar arterial type II endoleaks, stemming from the effective shuttering of the collateral sources in the proximal lumbar or intercostal arteries.