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Page 18 of 43 Rao. Vessel Plus 2022;6:26 https://dx.doi.org/10.20517/2574-1209.2021.93

The CPV may be visualized posterior to the LA [Figure 30A and B]. It may also be imaged superior to the
LA in apical four-chamber view [Figure 30D]. Every attempt must be exerted to show the entrance of all
pulmonary veins into the CPV by means of combined 2D echo and color Doppler [Figure 31] in several
projections. Subcostal, parasternal, and supra-sternal notch views should be scrutinized to accomplish this.
The horizontal or vertical orientation and the size of the CPV should also be demonstrated. The anomalous
draining vein should be shown and the site of its connection established by careful color flow imaging.

Several images of TAPVC with drainage into the infra-diaphragmatic site [Figure 32], left innominate vein
[Figure 33], and coronary sinus [Figure 34] locations stand illustrated below.

Obstruction of the anomalous connecting vein may be present and should be shown by demonstrating the
site of obstruction (segmental obstruction), by an enlarged proximal part of the anomalous connecting vein,
and/or by Doppler flow that is turbulent or continuous. Also, the Doppler flow velocity may be high
[Figure 35]. Non-obstructed forms have low velocities [Figure 36].

If a PDA is present, right to left shunt via the ductus is typically visualized, especially in babies with
obstructed total veins.

Echo-Doppler studies are sufficiently accurate to confirm the diagnosis and guide treatment decisions
without resorting to cardiac catheterization and angiography.

TRUNCUS ARTERIOSUS
Truncus arteriosus is a CHD in which only one blood vessel (truncus) originates from the heart and this
vessel gives origin to the aorta, PAs and coronary arteries. The truncus overrides a large outlet VSD [4,22,28-30] .
In truncus, the formation of atria and ventricles is normal. Collett and Edwards in 1949 described a
[31]
classification of the truncus on the basis of how PAs are connected to the truncus: (1) Type I. A short main
PA comes off of the side of the truncus, which splits into RPA and LPA. Type I is the utmost frequent form
of truncus arteriosus and constitutes 50% to 70% of all truncus cases. (2) Type II. The RPA and LPA
originate as distinct vessels behind (posterior) the truncus. Type II is the second most frequent type
accounting for 30% to 50% cases. (3) Type III. The origin of RPA and LPA is from the side (lateral aspect) of
the truncus. Type III is the least frequent type comprising 6 to 10% of all truncus arteriosus cases. (4) Type
IV. The pulmonary flow is supplied either via a PDA or MAPCAs originating from the aorta. This entity is
also portrayed as pseudotruncus. However, at the present time, Type IV truncus is not considered to be a
variety of truncus arteriosus; instead, it is a form of VSD with pulmonary atresia [28-30] .

Thickening of the truncal valve leaflets may be seen in some patients. The truncal valve is usually tricuspid
with occasional cases exhibiting bicuspid or quadricuspid valve leaflets. Narrowing of the truncal valve in
5% to 10% of cases and regurgitation of the truncal valve in 5% to 20% of cases may be seen. The PAs are not
typically narrowed. The absence of one of the PAs may occur in 16% of cases; such an abnormality is
generally on the same side where the aortic arch descends, or the PA may come off of the descending
portion of the aorta. In unusual patients, one PA comes off of the ascending aorta while the other arises
from the RV; this anomaly has been described a hemi-truncus. In nearly 40% of patients, the aortic arch
descends on the right side. The frequent association of interruption of the aortic arch and DiGeorge
syndrome with truncus is well recognized.