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Cardiology was called to review a neonate with cyanosis at 6 hours of life. The oxygen saturations averaged 70% at baseline with no preductal and postductal difference. No cardiac murmurs were heard, but the chest X-ray showed an enlarged heart. Transthoracic echocardiography (TTE) demonstrated a small patent arterial duct and a patent oval foramen, both with left-to-right flow across. TTE also showed dilatation of the left atrium (LA) and left ventricle (LV) (figure 1A), suggesting increased flow to the left—heart (figure 1B). The atrioventricular and ventriculoarterial connections were normal.
Image panel outlining the diagnostic approach to the echocardiographic evaluation of the patient. (A) Transthoracic echocardiogram demonstrating a dilated LA and LV. (B) Subcostal modified bicaval view demonstrating additional flow into the LA, not typical of pulmonary venous return. (C) Agitated saline injected into a left-hand intravenous cannula showing microbubbles in the LA and LV in the early phase. (C) Colour Doppler imaging demonstrating a large venous structure draining into the infant's LA. LA, left atrium; LV, left ventricle.
Agitated saline was administered via an intravenous cannula over the infant’s left hand, and microbubbles were seen to enter the LA and LV in the early phase1 (figure 1C) (video 1), through the right superior caval vein (RSCV) (figure 1D). There was no left superior caval vein. A diagnosis of RSCV to LA was thus confirmed.1 2 CT angiogram, ordered to demonstrate pulmonary venous return, showed drainage of the RSCV into the LA (figure 2A,B), with the right upper lobe pulmonary veins draining into the RSCV–LA junction.3 As the infant’s saturations were persistently low, surgical anastomosis of RSVC to the right atrial appendage was performed.
Image panel of the CT angiogram performed to confirm the position of the pulmonary veins. (A) Coronal view of a 3D reconstructed CT angiogram demonstrating the brachiocephalic vein draining into the RSVC, which then drains into the morphological LA. (B) The abnormal systemic venous drainage is better seen in this projection. The morphological right atrium is seen to receive the inferior caval vein (demonstrated in emerald green silhouette). The right upper pulmonary vein drains into the RSVC just above the RSVC–LA junction. LA, left atrium; RSVC, right superior caval vein.
We highlight an unusual case of neonatal cyanosis and outline our diagnostic approach. In our patient, the presence of LA and LV dilatation pointed to a cardiac anomaly with increased flow to the left heart when pulmonary pressures were still expectedly high. This anomaly also carries an increased risk of embolism due to the right-to-left shunt.4
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Contributors NHYW wrote the manuscript. MVF performed the CT scan and critically reviewed the manuscript and images. DZZ critically reviewed the manuscript and images. SAA-G wrote the manuscript with NHYW. JTLC performed the echocardiogram and critically reviewed the manuscript and images.
Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.
Competing interests None declared.
Provenance and peer review Not commissioned; internally peer reviewed.