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Page 4 of 13 Jubouri et al. Vessel Plus 2023;7:5 https://dx.doi.org/10.20517/2574-1209.2022.49

Table 1. Evaluation of frozen elephant trunk (FET) and conventional (CET) procedures, which both facilitate thoracoabdominal
intervention
FET CET
Advantages 1-stage procedure (risk of reintervention) Simplifies distal aortic arch anastomosis, reducing the risk of visceral
ischemic complications
Minimal graft kinking Lower rates of spinal cord injury
Reduces risk of repeat aortic surgery via better FL
thrombosis
Disadvantages Higher rates of spinal cord injury 2-stage procedure - high cumulative surgical risk
Interval mortality
May fail to address residual FL patency
Graft kinking

the potential to replace OSR via CET and FET. Still, endovascular control of the torque may be severely
limited by the anteroposterior and mediolateral curvature of the proximal aorta. Thus, the accurate
placement and positioning of the device remain challenging and the use of antegrade and retrograde
[27]
guiding wires may be necessary to improve technical control . Several endoarch devices are commercially
available on the market globally, employing both branched and fenestrated TEVAR.

The RELAY™ Branched, developed by Terumo Aortic, is a well-recognized example of branched TEVAR for
treating aortic arch pathologies. The RELAY™ device features a branched system for retrograde
endovascular delivery through femoral or iliac access. The design of the pre-curved inner catheter and dual
sheath conforms to the alignment with the curvature of the arch and ascending aorta. Furthermore,
employing support wires helps to reduce intra-aortic instrumentation and serves to ease positioning during
implantation. The main body of the RELAY™ Branched system has a window situated on the dorsal aspect
of the endograft, which facilitates the cannulation of one, two, or all three supra-aortic vessels using either a
single-, double-, or triple-branched device, respectively. This window is labelled with radiopaque markers to
outline the device’s positioning and orientation in relation to the supra-aortic vessels. Importantly, the
design of TEVAR endoprostheses and their technical considerations during deployment have continually
evolved. The different branch configurations of the RELAY™ endoprosthesis are illustrated in Figure 1.
Examples of other commercially available TER devices are shown in Figure 2.

Careful evaluation of the landing zone is imperative. In cases of dissection, it is measured using the distance
[28]
from the coronary ostia and the sinotubular junction to the proximal entry of the dissection . The
ascending aorta possesses high velocity, consequent shear stress, and four-dimensional rotational and
pulsatile movements during the cardiac cycle. Thus, the proximal and deep implantation of the device into
zone 0 of the arch exposes the endoprosthesis to maximal hemodynamic pressure, which in turn increases
the risk of malorientation as a result of the windsock effect . Therefore, shorter and wider dimensions of
[29]
the endoprosthesis are favoured, and 15% oversizing of the endoprosthesis relative to the native aortic
diameter is recommended to improve FL depressurization and aneurysmal regression .
[30]

The triple-branched RELAY™ endoprosthesis allows for cannulation of the three-supra aortic vessels and is
most suitable for long-term patency. Maintaining the left subclavian artery (LSA) patency after TER is
paramount to circumvent the risk of left arm ischemia as well as SCI. Further, it avoids the subclavian steal
[31]
syndrome and vertebrobasilar insufficiency, thus, leading to lower rates of stroke . In cases where LSA
cannulation is not possible, a single- or double-branched RELAY™ system is used, and prophylactic
[32]
revascularization of the LSA (e.g., subclavian-carotid bypass) prior to TEVAR can be performed . A study
by Bradshaw et al. reported a 1.9% stroke rate in patients who underwent revascularization of the LSA . In
[31]
contrast, a stroke rate of 14.3% was reported in those who underwent TEVAR with total LSA occlusion.