Aims Cor-triatriatum is a rare congenital cardiac malformation with a reported incidence of 0.1%–0.4% of all congenital cardiac disease. Its literal meaning is “three atria”. In this condition, the atrium is divided into two compartments by a fibro-muscular membrane. We present two cases of children presenting unwell with respiratory distress, who were later diagnosed with this rare condition.

Methods Descriptive case reports of two patients with cor-triatriatum.

Results Patient 1: A seven month old boy presented with reduced feeding. He was born at 34+5 weeks gestation and had been reviewed for faltering growth. Despite high energy feeds, there had been no improvement. On examination he was apyrexial, tachypnoeic with intermittent grunting and subcostal recessions. On auscultation he had good air entry with no added sounds. Cardiovascular and abdominal examinations were unremarkable. A CXR showed bilateral haziness in all lung fields and no cardiomegaly. He was treated for suspected bronchopneumonia. Despite treatment he showed no improvement. Unexplained tachypnoea and persistent tachycardia on Paediatric Early Warning Scores (PEWS) prompted an echocardiogram revealing a cor-triatriatum. Findings were supra-mitral membrane with severe stenosis with peak gradient of 23 mmHg, mean 13 mmHg and a dilated left atrium (Figure 1). The child underwent surgical resection of the supra-mitral membrane at a cardiac centre.

Patient 2: A one year old previously healthy girl presented unwell, with lethargy, reduced feeding and dehydration. She was tachypnoeic and had left-sided bronchial breathing. She had normal heart sounds and no murmurs. CXR showed a mildly enlarged heart but no consolidation. Bloods tests were normal. She was treated for a presumed pneumonia. Her clinical condition worsened despite treatment and myocarditis was considered due to persistent tachycardia. She was transferred to a tertiary cardiac centre where the diagnosis of cor-triatriatum was made.

Conclusion In both cases, the patients presented unwell with persistent tachypnoea and no significant respiratory signs. Chest radiographs showed bilateral diffuse haziness, no consolidation and no significant cardiomegaly. Unexplained tachypnoea and Paediatric Early Warning Score (PEWS) showing persistent tachycardia were the only indications to undertake echocardiogram. Cor-triatriatum should be considered with similar clinical presentations.