Effect Of Narrow Paravisceral Aorta On Target Vessel Instability After Fenestrated-Branched Endovascular Aortic Repair

OBJECTIVES To investigate the effect of narrow paravisceral aorta (NPA) on target vessels instability (TVI) after fenestrated-branched endovascular aortic repair (F-BEVAR). METHODS We conducted a single-center retrospective study (2014-2022) on patients treated by F-BEVAR for thoracoabdominal (TAAA) or pararenal aortic aneurysms (PRAA). Paravisceral aorta was defined as the aortic segment limited by the diaphragmatic hiatus proximally and the emergence of lower renal artery distally and was considered “narrow” in case of minimum inner diameter < 25 mm. Minimum aortic diameter, location, longitudinal extension, angulation, calcification, and thrombus thickness of NPA were evaluated at the preoperative computed tomography angiogram. Endpoints were technical success and freedom TVI (target vessel-related death, occlusion, rupture, or reintervention for stenosis, endoleak, or disconnection). Kaplan-Meier estimates and Cox proportional hazards were used for analysis. RESULTS Three-hundred-ninety-four (394) incorporated target arteries were analyzed (112 patients; 51 TAAAs, 60 JRAA/PRAA and 1 chronic dissection), 214 fenestrations (54 %), 101 outer branches (26%) and 79 inner branches (20%). NPA was present in 82 patients (73%) patients accounting for 277 target vessels (193 fenestrations, 50 inner branches, and 34 outer branches); the non-NPA group had 117 target vessels (21 fenestrations, 29 inner branches, 67 outer branches). Overall technical success was 89 % (NPA: 87%, Non-NPA: 97%; P=.1761). Overall freedom form TVI at 5 years was 82±9% (NPA: 81±10%, non-NPA: 84±8%; P=.22). After stratification by endograft design, NPA<20mm was associated with TVI for FEVAR (fenestrations: HR 2.73, 95%CI 0.98-9.64; P=0.06); while there was not association between NPA<25mm and TVI with inner branches: HR 2.25, 95%CI 0.47-16.25; P=.343. For outer branches the same relation was not significant: HR 1.09, 95%CI 0.27-4.17; P=.891). The association of use of outer branches in NPA<25mm plus location at the level of the aortic zone 6 (from the origin of the celiac artery to the superior mesenteric artery), longitudinal extension >25 mm, or aortic wall moderate/severe calcifications, was cause of worsened freedom from TVI (P=.031; P=.043; P=.045; respectively). Thrombus thickness (HR 9.43, 95%CI 3.41-56.4; P=.536) and angulation>30° (HR 1.02, 95%CI 0.94-1.18; P=.602) of NPA were not significantly associated. CONCLUSIONS FEVAR and BEVAR are both feasible in case of NPA, and overall provide satisfactory target vessels durability. The use of outer branches should be avoided in cases with inner aortic diameter < 25 mm at the level of the aortic zone 6, with longitudinal extension >25 mm, or moderate/severe NPA calcifications. In FE-VAR, bridging stent patency may be negatively influenced by NPA< 20 mm.