Treatment of Thoracic Aortic Disease with the Chimney Procedure
The proximal and distal landing zones represent the most critical anatomic feature in the short- and long-term stability and success of endovascular aortic repair. Short and/or angulated necks can lead to “bird-beaking,” type 1 endoleak, and late migration. Chimney (snorkel) stenting is a technique used to maintain perfusion to a branch vessel when coverage of its origin is planned during endovascular aortic repair. The technique is most often utilized during intentional branch vessel coverage in order to gain additional landing zone, but is occasionally useful post hoc as a rescue technique during inadvertent branch occlusion. Basically, the branch vessel (chimney) stent is deployed alongside the endograft (parallel position between the inside of the aortic wall and outside the endograft). Since its original descriptions to treat a juxtarenal abdominal aortic aneurysm and maintain left subclavian artery perfusion during thoracic endografting, the technique has been refined and modified with respect to the number of chimney stents, types of stents, and configuration of the stents relative to the endograft. Variations have included a multilayered (“terraced,” “sandwich”) technique for three- to four-vessel repairs and down-going (“periscope”) stents used to treat thoracoabdominal aortic aneurysms. Similar to the back-table fenestrations of endografts, the chimney technique has emerged as a potential “off-the-shelf” alternative to custom-manufactured advanced endograft technologies. This chapter focuses on the use of the chimney technique for endovascular treatment of aortic arch pathologies.
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