Endovascular aneurysm repair in abdominal aortic aneurysms with hyperangulated necks: Staying on the straight and narrow

We were interested to note this study by Bonvini et al., ¹ describing short-term results (five months) with the new Gore Excluder Conformable AAA Endoprosthesis (W. L. Gore & Associates, Flagstaff, USA) and its active control system for endovascular aneurysm repair (EVAR) in five patients with hyperangulated necks (HAN). The use of a routine brachiofemoral pullthrough wire (PTW) makes sense in straightening out the neck anatomy allowing for more accurate deployment; the renal artery should then project in a more appreciable fashion negating the need for pre-cannulation. However, the default advantage of the Gore device is in allowing for repeat proximal constraining and then reopening and release at the proximal landing zone, which can potentially be done without the additional need for a PTW.

The main concern is that of eventual loss of seal along the outer curve; the EUROSTAR registry ² correlated HAN to neck dilatation, proximal type I endoleakage and reinterventions, and historical series report complications as high as 70% where neck angulation is >60°. ³ We advocate routine endostapling at EVAR undertaken in the HAN scenario; ⁴ as the authors know, a successful procedure must be supplemented by durability of the results, with migration and type I endoleakage the relevant problems.

The authors make a valid point in ‘starting high’; our experience also mimics theirs wherein slight distal migration is noted at initial deployment, wherein even redo deployments may be ineffective; this improves with experience. The ‘drop’ is likely due to suboptimal engagement of device barbs along the outer curve of the neck. Our approach of routinely reinforcing the proximal sealing zone with Heli-FX EndoAnchors (Medtronic Ltd., Minneapolis, USA), particularly along the outer curve, provides robust mid-term results at >18 months. ⁴

Examining a similar subset of cases undertaken with Gore C3 devices, including the previous (n = 5) and current (n = 4) iterations, we undertook nine procedures (seven males, two females, mean age 76 ± 10.7 years) with mean neck angulation 77 ± 17°. Eight such were lateral angulations and one sagittal (not highlighted by the authors), four necks were conical; mean 6 ± 2 EndoAnchors were deployed per patient. Due to neck length and angulation effects, cuffs were necessary in two patients (thoracic endoprosthesis pre-emptively used as a cuff in a Marfan Syndrome patient with a long neck,^4,5 and standard cuffs ×2 in another patient). PTWs, renal pre-cannulation were not used in any case.

The interesting finding from our series was that neck angulation reduced (mean 60 ± 16°, p < 0.03, paired T-test) after endostapled EVAR and was maintained throughout follow-up; ⁴ it would have been interesting to note if that happened in the series presented, or did the aortic endoprosthesis conform to the neck anatomy? This aspect has potential implications for integrity of proximal seal in the long term.

The authors are to be congratulated on their success with such HAN anatomy including in short necks. Further cases will indicate if a PTW is actually compulsory to straighten out HAN; long-term results will inform us of device durability in such hostile neck anatomy.