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Uppu. Vessel Plus 2021;6:21 https://dx.doi.org/10.20517/2574-1209.2021.101 Page 5 of 19

pulmonary veins and lower portion of the RA in IVC type SVD [Figure 5]. The pulmonary venous orifice to
the left atrium (LA) is commonly preserved, the pulmonary venous flow destined to LA empties into the
right atrium, there is an additional left to right shunting across the pulmonary venous orifice into the RA
across the SVC, as such there is significant right heart dilatation that is out of proportion to the size of the
defect. SVC type SVD is often associated with partial anomalous pulmonary venous connections [4,6,7,17] .

Coronary sinus defect
Coronary sinus defect (CSD) is rare and results from incomplete fusion of the left horn of sinus venosus
with the septum primum. CSDs are almost always associated with Left SVC draining into the LA results
from the partial or complete unroofing of the coronary sinus (CS) where the wall separating the CS from
the left atrium may be partially or completely deficient, there is a coronary sinus opening in the right atrium
that functions as an atrial septal communication (Raghib syndrome) [14,18,19] [Figure 6]. This results in
desaturated blood entering the systemic circulation and cyanosis. If the degree of cyanosis is not clinically
[20]
obvious, these patients can present with polycythemia, paradoxical emboli, stroke, or brain abscess .
IMAGING ATRIAL SEPTAL DEFECT
Knowledge of atrial septal anatomy is crucial to understanding and visualizing the ASDs. Given the complex
three-dimensional (3D) structure of the atrial septum, one has to image it from multiple views to have a
global perspective. Two-dimensional (2D) transthoracic echocardiography (TTE) is still the diagnostic
modality of choice and often helps with the diagnosis. In subjects with good acoustic windows, the atrial
septum can be better evaluated from the subcostal and high right parasternal windows, where the atrial
septum is profiled perpendicular to the ultrasound beam. Thus false dropouts seen from traditional apical
views can be avoided. Slow, long sweeps help with better visualization of the entire septum. Identifying the
location, size, rims, the number of defects, surrounding structures, and evaluation for possible associated
lesions help tailor the management plan [7,21] .

Three-dimensional echocardiography is being utilized more frequently given the immediate access to the
technology along with fast post-processing capability of the 3D datasets that helps with better visualization
of the defect in relation to its surroundings and check rims and device placement [22,23] [Figure 7]. However,
3D TTE technology has the same setbacks as traditional 2D echocardiography as they both require good
acoustic windows.

In patients with poor acoustic windows, one can consider transesophageal echocardiography (TEE)
[24]
[Figure 8] or alternative imaging such as cardiac magnetic resonance imaging (CMR) .

Patients with OS ASD who are deemed to be potential candidates for device closure need proper
measurement of the defects from all the imaging views [25,26] . In addition, it is also important to measure the
rims, total septal length, which helps to choose the device. This can be achieved pre-procedure or at the
time of the intervention using TEE [8,27,28] .

OS ASDs are better visualized from the parasternal short axis, subcostal short and long axis, and high right
parasternal windows. Therefore, it is important to notify the operator of a prominent Eustachian valve in
patients undergoing surgical closure, especially in those with IVC confluent OS ASD, so that it is not
mistaken for the inferior rim of the ASD [29-31] .

Cross-sectional imaging with CMR and cardiac computed tomography (CT) can be considered in a select
group of patients where echocardiography is suboptimal or vascular/venous anomalies are suspected as they