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Alberts et al. Vessel Plus 2023;7:34 https://dx.doi.org/10.20517/2574-1209.2023.37 Page 9 of 24

Sinus of Valsalva aneurysm is a rare congenital or acquired defect, which leads to severe dilatation of one or
more sinuses. It can lead to rupture of nearby structures, in most cases, the right ventricle or the right
atrium. In the event of rupture, CFD shows a continuous positive flow from the aorta to the nearby
structure in both systole and diastole .
[65]

Aortic dissection
Aortic dissection (AD) is a result of a disruption of the intima (tear), leading to the accumulation of blood
between the intima and media. This results in the formation of a second lumen, the so-called false lumen.
Intimal tears typically occur at points of greatest wall stress, most commonly just above the sinotubular
junction on the greater curve or just distal to the origin of the left subclavian artery. AD can be classified
anatomically according to Stanford or DeBakey. AD is classified as Stanford type A or DeBakey I/II if the
ascending aorta is dissected regardless of the location of the intimal tear. If the dissection is limited to the
descending aorta, AD is classified as Stanford type B or DeBakey III. If the aortic arch is involved but not
the ascending aorta, AD is classified as non-A-non-B [66,67] . The indication of surgical treatment depends on
the type of dissection; Stanford type A and non-A-non-B AD usually require (immediate) surgery.

TEE can be used as a diagnostic modality for AD, with sensitivity reaching up to 99% and specificity 89% in
acute cases . The diagnosis of chronic AD can be more difficult to make with TEE, especially in cases
[17]
[55]
where false lumen is completely thrombosed .
The intimal flap, which separates the true and false lumen, appears on TEE as a mobile echodense line [11,68] .
An example of a dissection flap visualized on TEE is shown in Figures 5 and 6. The entry or re-entry tears
appear as a disruption of the intimal flap and CFD shows blood flow over the tear. Imaging artefacts such as
reverberation artefacts or side lobe artefacts can give a false impression of AD. Therefore, it is important to
obtain multiple images of the intimal flap in different views [11,17,68] .

Preoperatively, the proximal extension of the intimal flap should be demonstrated precisely to guide surgical
decision making for aortic reconstruction. If possible, the distal extension of AD should be demonstrated as
well. Studies indicate that the use of 3D TEE improves the location and size of the entry tear compared to
2D echocardiography . Furthermore, 3D TEE has been shown to enhance the visualization of the extent of
[69]
[70]
the dissection flap .
[11]
After visualizing the dissection flap, it is essential to differentiate the true and the false lumen . Important
criteria include:

The false lumen is most often larger than the true lumen, especially further distal in the aortic arch and
descending aorta.

PWD displays higher blood flow velocities in the true lumen in systole compared to the false lumen . Low
[11]
blood flow velocities can be displayed as spontaneous echo contrast or thrombosis in the false lumen.The
true lumen expands in systole, while the false lumen is compressed. M-mode can help to visualize the
extension and compression.

At the entry tear, CFD displays blood flow from true to false lumen in systole.

The direction of flow is anterograde in the true lumen, whereas it can be retrograde in the false lumen.