Obstructed infracardiac total anomalous pulmonary venous drainage

Clinical History

A full-term infant with uneventful delivery presented with respiratory distress, difficulty in feeding and cyanosis. The oxygen saturation by pulse oximeter was 50% in room air. Septic screen was negative and there was no history of haemoptysis.

Imaging Findings

After an uncomplicated birth at term and discharge home well at day two of life, the patient presented with gradual shortness of breath and difficulty in feeding due to tiredness over a 10-day period. At a routine postnatal check it was noticed that he was dusky and in mild respiratory distress. On transfer to the Casualty department, the oxygen saturation was found to be 50% in room air. He was apyrexial and the white cell count was normal. An initial chest radiograph demonstrated a normal-sized heart with normal pulmonary vascularity and clear lungs.

The patient deteriorated over the next few hours, requiring intubation and ventilation. There was no history of haemoptysis or of visualised blood during intubation. A repeat chest radiograph was obtained (Fig. 1). It demonstrated a normal-sized heart and diffuse bilateral airspace opacification consistent with pulmonary oedema. Pleural effusions were not present. The upper mediastinum was not widened. In view of the history of cyanosis and respiratory distress with an oxygen saturation of 50% and the rapid onset of airspace opacification with a normal heart size a provisional diagnosis of obstructed total anomalous pulmonary venous return was made. An echocardiogram was performed and confirmed the presence of a common pulmonary venous chamber, behind the left atrium, which accepted all four pulmonary veins and which connected to the infradiaphragmatic IVC by an obstructed vertical vein. A small 6mm restrictive ASD shunting from right to left was also found. The ventricular septum was normal; mild tricuspid regurgitation was noted. The main pulmonary artery was enlarged, a PDA was also present, again with right to left shunting. The aortic arch was left sided and normal. The left ventricular outflow tract was normal. The IVC and SVC were connected to a morphologic right atrium.

Supportive medical therapy was instigated and the patient underwent cardiac surgery within 24 hours. At surgery the findings on echo were confirmed and repaired. The common chamber receiving all four pulmonary veins was anastomosed to the left atrium and the ASD was sutured closed. The patient was discharged home well on full feeds on day 20 post-op.

Discussion

The aim of this case is to demonstrate that the presentation of a neonate with cyanosis combined with pulmonary oedema and a normal-sized heart should ring alarm bells for the possibility of obstructed total anomalous pulmonary venous return (TAPVR). The chest radiographic findings of rapid onset (within several hours) bilateral diffuse air space opacification in this patient has a very limited differential. Acute massive aspiration and pulmonary haemorrhage are possible causes, however, the profound cyanosis with saturations of 50% when the chest radiograph did not demonstrate any initial pulmonary pathology and the lack of history of haemoptysis or finding of blood on intubation make these possibilities less likely. The low oxygen saturation makes a cardiac cause more likely. Left heart obstructive lesions will present as pulmonary oedema, however moderate cyanosis is not a feature and the heart is usually enlarged. The combined presentation with cyanosis and heart failure in a neonate is rare and includes obstructed TAPVR, truncus arteriosus (in which the heart is usually enlarged and there is pulmonary plethora prior to pulmonary oedema) and tricuspid atresia with a large VSD resulting in pulmonary plethora. Confirmation of the diagnosis can be made with echocardiography and in some cases with magnetic resonance imaging.

Total anomalous pulmonary venous drainage has been conventionally divided into supracardiac, cardiac, infracardiac and mixed types. The supracardiac type is the most common. The infracardiac type accounts for 21% of all types. Classically the connection is below the diaphragm via a long vessel which arises from a common chamber, as in this case.The common vein descends anterior to the oesophagus and then joins the IVC, hepatic or portal venous system. Obstruction to drainage is often present due to passage through the diaphragm as well as resistance to flow through the liver sinusoids.

The pulmonary venous obstruction results in back pressure through the pulmonary circulation resulting in a right to left shunt through an often associated ASD. The resultant pressure in the right side of the heart can result in tricuspid regurgitation, enlargement of the main pulmonary artery together with a normal-sized heart. The back pressure in the lungs causes pulmonary oedema. The right to left shunt results in cyanosis. The cardiac output is often markedly reduced. The outcome in these patients is invariably poor if not diagnosed early; for this reason it is important that these chest radiographic findings in combination with the clinical picture should alert to the possibility of this diagnosis. In particular, a cardiac cause should not be excluded on the basis of a normal heart size.

Differential Diagnosis List

Final Diagnosis

Obstructed infracardiac total anomalous pulmonary venous return

URL:	https://www.eurorad.org/case/1687
DOI:	10.1594/EURORAD/CASE.1687
ISSN:	1563-4086