Page 168 - Read Online

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

After ascending aorta or aortic arch replacement, the aortic lumen and the aortic branches can be visualized
to assess adequate blood flow. If, during aortic arch replacement, a so-called (frozen) Elephant Trunk is
[49]
placed, TEE can evaluate the position and blood flow over the Elephant Trunk [Figure 3]. Elephant Trunk
kinking is a rare complication, resulting in reduced blood flow in the descending aorta [50,51] .

TEE and specific aortic diseases
Atherosclerosis
Atherosclerosis is the most common aortic disease and is characterized by the accumulation of lipids,
inflammatory cells, and connective tissue within the arterial wall. It leads to thickening of the intima and
may progress to the formation of atherosclerotic plaques [17,18] . The incidence of atherosclerotic plaques
[52]
increases in the course of aorta, being lowest in the ascending aorta and highest in the descending aorta .
Several classification systems have been proposed for grading the severity of aortic atheroma. Based on the
results of most studies, atherosclerosis severity depends on the level of intimal thickening. It is considered
mild with 2-3 mm (grade 1), moderate < 4 mm (grade II), severe 4 mm (grade III), and complex, when any
grade is associated with mobile or ulcerated components (grade IV) [17,53,54] . Progression of the atherosclerotic
plaques can lead to a penetrating aortic ulcer or aortic dissection.

The presence of aortic atherosclerosis is associated with perioperative stroke. The risk of stroke rises with
increased severity of atherosclerosis, especially in the presence of protruding atheroma ≥ 4 mm, the presence
of a mobile component (mural thrombosis), and if the atherosclerotic plaques are located in the ascending
aorta or aortic arch [52-55] . We recommend scanning the aorta prior to incision, but particularly before
cannulation and cross-clamping to identify any atherosclerotic plaques. Their presence may prompt a
[56]
change in surgical strategy .

On TEE, aortic atherosclerosis is characterized as intimal thickening with an irregular border, often with
reverberation artefacts known as comet-artefact due to aortic wall calcifications [Figure 4]. Compared to
two-dimensional (2D) imaging, 3D TEE provides superior visualization of the number, morphology,
volume, and spatial extent of aortic atherosclerosis . Furthermore, the use of simultaneous multiplane
[54]
imaging (bi-plane) can lead to more rapid imaging of atherosclerotic plaques, especially in cases with
complex plaque formation .
[57]

Epi-aortic ultrasound may be considered in cases where atherosclerosis is suspected but the cannulation site
cannot be visualized with TEE. EUS guidance on surgical manipulation can lead to a change in cannulation
or aortic clamping strategy in up to 36% of the cases and may reduce the incidence of postoperative
stroke [58-60] .

Aortic dilatation and aneurysm
Aortic dilatation is defined as an enlargement of the diameter of the aorta to more than two standard
deviations from the mean predicted diameter . An aneurysm is defined as an artery dilated more than 50%
[17]
of the normal diameter. While this applies well for the descending thoracic aorta, it is noteworthy that for
the ascending aorta and aortic arch, the risk of rupture increases before this limit is reached . Therefore,
[61]
several authors recommend to use the term aneurysm for diameters > 45 mm [17,62] .

The most common site of thoracic aortic aneurysm is the aortic root and ascending aorta (60%), followed by
the descending aorta (35%) and the aortic arch (< 10%) . Approximately 20% of the thoracic aortic
[62]
aneurysms are related to a genetic disorder, such as Marfan’s syndrome or Ehler Danlos .
[63]