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Page 16 of 24 Alberts et al. Vessel Plus 2023;7:34 https://dx.doi.org/10.20517/2574-1209.2023.37

descending aorta in the descending aorta SAX (0-10°). The guidewire will show up as a small, echogenic dot
in the lumen. If the guidewire lies close to the aortic wall, it may be difficult to visualize. Simultaneous bi-
plane mode or 3D imaging can demonstrate the guidewire in SAX and LAX, which aids in the visualization
and can exclude potential artifacts [Figure 11]. It is noteworthy that during endovascular repair of the
ascending aorta, the guidewires are placed across the aortic valve into the ventricular lumen.

In cases of AD, the standard imaging modalities used during TEVAR (fluoroscopy and angiography) cannot
directly verify the correct positioning in the true lumen. However, with TEE, the true lumen can be
identified and correct guidewire positioning can readily be confirmed [101,102] . Figure 12 shows an example of
confirmation with TEE of the correct placement of a guidewire in the descending aorta.

During the procedure, TEE is suited as an imaging modality in addition to fluoroscopy and angiography for
the guidance of the stent positioning. The presence of atherosclerotic plaque may complicate correct stent
placement, and scanning the aorta on the site of stent deployment may detect or rule out its presence .
[103]
Ideally, stent grafts require a 20-25 mm landing zone proximal and distal to the lesion to acquire an
adequate seal [99,104,105] . This landing zone can be determined by TEE. Subsequently, the tip of the probe can be
set facing the most ideal landing zone, serving as a reference point for fluoroscopy [101,103] . For endovascular
ascending aorta repair, the determination of the landing zone can be challenging and smaller distances may
be accepted. The most common site for the entry tear in AD is just distal to the sinotubular junction, and in
these cases, the sinotubular junction has been used as the proximal landing zone in several cases [104,106] . Even
more proximal placement of the stent graft within the sinus of Valsalva has been described [104,107] . While
visualizing the aorta in LAX, the correct stent graft positioning can be confirmed before and during stent
graft deployment [Figure 13].

In TEVAR after aortic arch replacement with (Frozen) Elephant Trunk, TOE can be used to confirm the
correct placement of guidewires and the endovascular stent in the Elephant Trunk, especially in challenging
cases. The same applies to the positioning of an endo-prosthesis for the extension of a previous TEVAR.
Moreover, recently developed hybrid grafts for thoracoabdominal aortic repair, such as the Toracoflo®
(Terumo, Tokyo, Japan), rely completely on intraoperative TEE for the correct positioning of the
endovascular part of the hybrid graft [108,109] .

After stent deployment, the echocardiographist should confirm correct positioning and search for gross
endoleaks. In addition, TEE can be used to detect flow in the stent graft excluded zone, the aneurysmal or
false lumen. Exclusion from the blood pool leads to an initial “smoke phenomenon”, caused by initial
thrombosis in this lumen. This can serve as a confirmation that the aneurysm or the primary entry is
correctly stented [101,103] . CFD with the Nyquist limit reduced to 25 cm/s can be used to detect residual flow in
[101]
the aneurysmal or false lumen . Anterograde flow in the aneurysmal or false lumen indicates endoleak,
while retrograde flow suggests flow from a re-entry tear. These findings may indicate extra stent graft
placement or additional balloon dilatation. Studies have shown that the findings on TEE contributed to an
alternation of the procedures in 38%-59% of cases [101,102] .

After the procedure, TEE can be used to detect any new lesions, such as intimal tears proximal or distal
from the stent graft. Furthermore, if the distance between the stent graft and aortic branches and the stent is
small, TEE can be used to confirm adequate flow in these branches after stent deployment . In ascending
[101]
aorta stent grafting, TEE can be used to detect or rule out several specific complications. The AV could be
damaged from stiff guidewire placement near or across the valve. Therefore, it should be evaluated for
structural changes and functional abnormalities such as (worsening of) aortic regurgitation. Entrapment of