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Page 6 of 14 Squizzato et al. Vessel Plus 2023;7:16 https://dx.doi.org/10.20517/2574-1209.2023.05

dependent on the operator pin-pull force, which could ultimately lead to a forward misplacement of the
[24]
graft if not properly and dynamically applied .
The second available mechanism (Gore CTAG, Gore & Associates, Flagstaff-USA) implies a two-stage
[12]
delivery system that enhances stability during deployment . It is also incorporated with an angulation
system that allows angulating the proximal tip of the delivery system to better adapt to the aortic anatomy,
[25]
thereby leading to enhanced wall apposition .

There are no available direct comparisons between the two mechanisms of deployment, but preliminary
data seem to highlight a high precision with the use of the active control system [12,25] .

For devices with a pin-pull deployment, the presence of a proximal bare metal stent (BMS) confers a higher
stability during the deployment, maintaining the proximal end of the device captured to the delivery system
until it is finally released, and helps to promote endograft-to-wall apposition once the device is deployed.
However, the use of endografts with a proximal BMS should be avoided in the treatment of dissections or
[26]
more proximal landing zones (zones 0 and 1) since it is associated with the occurrence of RTAD .
Other endografts without proximal BMS present different adjunctive mechanisms aimed to improve
stability and accuracy of deployment; the Relay® NBS Plus (Terumo Aortic, Sunrise, Florida, USA) has two
nitinol supporting wires that promote the apposition of the endograft to the lesser curvature during the
[27]
deployment. Further data are still necessary to establish the advantages and disadvantages of each different
deployment system.

PROXIMAL SEALING LENGTH
Proximal sealing length
Proximal sealing length is the single most important factor affecting the technical success and durability of
TEVAR in terms of proximal endograft failure. Although a proximal sealing length of 20 mm is usually
recommended for TEVAR, the benefit of adequate sealing also has to be weighed against the possible
technical challenges and complications related to a more proximal coverage, with the associated need for
SAT rerouting, and increased risk for neurological complications in cases with more proximal landing [2,28] .
This concept is corroborated by current series that report the use of a > 2 cm proximal sealing length in just
25%-60% of cases [29-33] [Table 1].

Conversely, the use of a shorter landing zone has been described to be an independent predictor of type I
endoleak and a long PLZ seems to guarantee a higher probability of long-term efficacy of TEVAR .
[29]

In a single-center experience, we aimed to identify the optimal sealing length based on different anatomical
characteristics . We found that overall, the risk of proximal endograft failure is strictly dependent on the
[33]
proximal sealing length, and that for all landing zones in the arch (0, 1, 2 and 3), a 20 mm sealing length can
be considered acceptable only for type I aortic arches. Differently, in type II and III arches, it may be
advisable to obtain a proximal sealing length of 25-30 mm, in order to prevent endograft migration or type
Ia endoleaks during time [Figure 5]. Based on these results, we developed an internal protocol for the
optimization of the proximal landing zone according to the anatomical arch characteristics [Table 2].

The significant role played by the proximal sealing zone emphasizes two crucial aspects of TEVAR
procedures. (1) In order to achieve favorable long-term outcomes, it is essential to preserve the extension in
the aortic arch. However, it is important to carefully consider the benefits of this approach against the