|Year : 2022 | Volume
| Issue : 4 | Page : 91-93
Hostile neck anatomy of abdominal aortic aneurysms: Is it time for a solid up-to-date definition?
Christos F Pitros, Stavros K Kakkos
Department of Vascular Surgery, Medical School, University of Patras, Patras, Greece
|Date of Submission||09-Sep-2022|
|Date of Decision||01-Jan-2023|
|Date of Acceptance||02-Jan-2023|
|Date of Web Publication||15-May-2023|
Dr. Christos F Pitros
Department of Vascular Surgery, Medical School, University of Patras, Patras
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Pitros CF, Kakkos SK. Hostile neck anatomy of abdominal aortic aneurysms: Is it time for a solid up-to-date definition?. Vasc Invest Ther 2022;5:91-3
|How to cite this URL:|
Pitros CF, Kakkos SK. Hostile neck anatomy of abdominal aortic aneurysms: Is it time for a solid up-to-date definition?. Vasc Invest Ther [serial online] 2022 [cited 2023 Jun 8];5:91-3. Available from: https://www.vitonline.org/text.asp?2022/5/4/91/376922
Hostile neck anatomy (HNA) is a common consideration for vascular surgeons for about three decades. It is a major determinant of endovascular aneurysm repair (EVAR) patient eligibility for treating an abdominal aortic aneurysm (AAA) and directing the decision traditionally toward open repair. Nevertheless, the definition of HNA remains somewhat controversial since there is no consensus specifically describing it.
One of the first attempts to define HNA was made in 2003 by Dillavou et al. describing it as the presence of one of the following: (1) neck length ≤10 mm, (2) focal bulge in the neck >3 mm, (3) >2 mm reverse taper within 1 cm below the renal arteries, (4) neck thrombus ≥50% of circumference, and (5) angulation ≥60° within 3 cm below renals. Another study from 2011 suggests that the proximal neck diameter >28 mm should also be a factor. In more recent studies, it is believed that a hostile neck's length limit should not be <15 mm, thus giving the chance to more endografts to be labeled as appropriate in treating AAAs with an HNA according to their instructions for use (IFU). According to the 2019 Delphi consensus,which is based on reported predictors of failure and/or complications, an agreement was reached on the five parameters that need to be defined to describe HNA, namely, aortic neck length, aortic neck angulation, aortic neck diameter, reverse tapered (conical) neck, and presence of circumferential calcification. Each of these parameters is considered a standalone criterion of divergence from the EVAR treatment option. These are only some of the many examples of heterogeneity in the HNA definition, which leads to heterogeneity in the studies' results regarding the EVAR option for HNA and the inability of comparison to provide the scientific community with robust results. The variety of definitions considering HNA in the aforementioned reports raises the question, is it time to find common ground on what HNA is and classify different types of it?
Many different adjunctive surgical procedures have emerged during recent years promising to counteract unfavorable necks, such as funnel, chimney, kilt techniques, and/or the use of EndoAnchors. New-generation endografts with a variety of positioning and sealing mechanisms show promising results in the battle against AAAs; many of those also showing good results against HNA – in the way we choose to define it in each study. For instance, a new study concerning a new-generation endograft reveals promising outcomes of treating unruptured AAAs with HNA, which shows the safety and efficacy of newer-generation endografts against HNA. The patient eligibility for EVAR is rapidly broadening through the continuous introduction of new devices., The eligibility of each endograft and its capability of countering HNA are solely based on its IFU introduced by the company manufacturing the device. However, it has been shown that some of those devices provide positive results despite being used outside the IFU., A recent study has shown that the AAA proximal neck anatomy had no effect on sac reduction following EVAR. Especially, regarding sac shrinkage, patients with an HNA before EVAR may have comparable results with those that had friendly neck anatomy. Lack of comparative investigations of different endografts for HNA as well as clinical indications for each endograft, has led to the abuse of IFU as the sole qualifying criterion. We have witnessed a significant increase in the capabilities of endografts and their remarkable evolution, which makes us wonder nowadays which necks are deemed hostile and whether all hostile necks are of the same “hostility.”
In a recent study, we have shown that the individual characteristics of endografts are frequently based on different engineering structures and features to ensure adaptation to varied anatomies and demands. It would be useful to categorize hostile neck types and each endograft capable of treating HNA according to the individual hostile neck type each endograft can treat. In an attempt to do so, a common classification of the devices may be based on what they can treat: angulated necks (>60°), reverse taper (conical) aortic necks, and short aortic necks (<15 mm). There is not a single endograft designed against severe neck thrombus and also calcification; in addition, as these conditions are considered a risk factor, they are also outside the IFU of most devices if they exceed 50% of the focal aortic circumference [Table 1].
|Table 1: Hostile neck anatomy categories and endografts against each category|
Click here to view
In conclusion, there is a genuine need for defining HNA through a consensus of experts which will provide the scientific community with a rigorous definition, on which further studies will be based, as well as for facilitating appropriate classification of different types of HNA. In addition, clinical trials are required to examine the treatment of various types of HNA and determine each type's suitability for EVAR. Moreover, comparative studies could be conducted on the efficacy of various endografts in treating different types of HNA. If these studies are based on a common HNA definition, the results will be comparable, and thus, solid conclusions regarding HNA treatment options using EVAR will be established.
All authors have contributed with writing, reading, and correction of the editorial.
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