DISCUSSION and TEACHING POINT
Sinus-venosus ASD complicated by PAPVC is rare, anatomically complex,
and difficult to detect by means of TTE alone, particularly in adults
with limited echo window. As ASD exists at the ceiling of the atrial
septum near the SVC, it is occasionally difficult to evaluate the
superior defect type completely. In a report [3] verifying the
diagnostic accuracy of TTE and TEE in 41 patients with ASD, 33 cases of
them could be identified by TTE, whereas TEE could detect all cases.
Meanwhile 6 cases of the 8 ASDs that TTE could not detect were
sinus-venosus ASDs, which indicates how difficult it is to identify
sinus-venosus ASD with TTE alone. Furthermore, in 7 of these 8 patients
with PAPVC coexisting with ASD, PAPVCs were visualized by TEE, but TTE
could not visualize the PAPVCs for all. Turner et al reported a case in
which the etiology could not be clarified, while dilatation of the right
heart became a clue for the final diagnosis as in our case. They
reported that re-examination of TTE performed even after CT could
visualize neither sinus-venosus ASD nor PAPVC; however, CT scanning
clearly showed a sinus-venosus ASD complicated by PAPVC[4]. Inferior
sinus-venosus ASD is rarer than the superior type, but technical points
have been reported to improve the diagnostic accuracy in TTE. The
complete lack of posterior rim in the modified parasternal short axis
view is considered to be an effective finding that can distinguish
inferior sinus-venosus ASD from ostium secundum type and other
ASDs[6].
In this case report, we identified a sinus-venosus ASD complicated by
two separately connected anomalous pulmonary veins at the modified right
ventricular inflow view projected at the apical long-axis view.
Sinus-venosus ASD may also be visualized in the bicaval view in the
right thoracic or subcostal approach. Prior study however has indicated
that TTE even if with such approach was able to detect only 44% of
sinus-venosus ASD [7]. In this case, it was impossible because the
patient was obese.