The so-called chimney technique for the endovascular treatment of aortic aneurysms involving reno-visceral vessels was first described in 2003 as a "bailout" procedure and further developed in 2007 as an alternative endovascular therapy method [1, 2]. The first series with more than five abdominal cases were reported by Ohrlander et al. in 2008, by Hiramoto et al. in 2009, and by Donas et al. in 2009 [3, 4, 5]. These publications demonstrate the feasibility of the procedure with good results regarding 30-day morbidity and mortality.
In 2013, two centres reported on the results of a CT angiography follow-up after 24 months in 124 high-risk patients, in whom the pararenal aneurysms had been successfully excluded using the chimney technique in 90% of cases [6]. A further two-centre study demonstrated that the combination of two different materials (Excluder (Gore) stent graft with Viabahn (Gore) and the Endurant prosthesis (Medtronic) with the Advanta V12 (Getinge)) also achieves a good patency rate of 95% and a low incidence of type Ia endoleaks (2%) [7]. An in-vitro study from 2012 reached the same conclusion [8].
Numerous publications on this topic emerged from the PERICLES Registry ("Collected World Experience About the Performance of the Snorkel/Chimney Endovascular Technique in the Treatment of Complex Aortic Pathologies"). Thus, in 2015, the world's largest experience with this technique was published based on 517 cases. The patency rate of the chimney grafts was 94.1%, and the regression of the diameter of the treated aneurysms averaged 6.5 cm. To minimise the risk of endoleak, the group recommended creating a new landing zone of 20 mm [9]. In the meantime, numerous further publications have emerged from the registry [10-19].
The occurrence of type Ia endoleak has been regarded by some authors as the "Achilles' heel" of chimney treatment [20]. A distinction is made between "high flow" (HF) and "low flow" (LF) endoleaks. In HF, the contrast medium exits outside the aortic graft immediately after application, whereas in LF it appears only markedly delayed in the late phase after contrast medium application. Studies show that LF endoleaks are no longer present after a short time and thus have no clinical relevance [21 - 24]. A study from Zurich (conservative with close-meshed CT monitoring) reaches a similar conclusion [25]. HF endoleaks, in contrast, represent an absolute indication for intervention.