A newborn with transposition of the great arteries and type A coronary anatomy according to Yacoub and Radley-Smith'sReference Yacoub and Radley-Smith¹ classification underwent successful arterial switch operation. At 17 months after surgery, the transthoracic echocardiogram showed normal left ventricular function with mild hyperechogenicity of the papillary muscles with no mitral valve regurgitation. Routine aortic angiography revealed a stenotic and thin left coronary artery (Fig 1). At that time, we decided to follow the child with serial electrocardiograms and echocardiographic examinations.

Figure 1 Stenotic and hypoplastic left coronary artery (white arrow) at aortic angiography.

During follow-up, electrocardiogram, echocardiography, and cardiac stress tests were reported as normal. When the child was 11 years old, informed consent was obtained and the child was included in a prospective study, approved by the local ethics committee, aimed at comparing cardiac computed tomography with conventional angiography. Electrocardiogram-gated computed tomography revealed a hypoplastic left coronary artery with unusual severe stenosis of the proximal segment and aneurysmal dilation of the post-stenotic tract (Fig 2, left panel). This finding was confirmed by selective left coronarography (Fig 2, right panel). After multidisciplinary discussion, revascularisation treatment was offered to the child. Owing to the aneurysmal dilation, the lesion was considered not suitable for percutaneous intervention.

Figure 2 Electrocardiogram-gated computed tomography shows severe stenosis of the proximal segment of the left main coronary artery followed by aneurysmal dilation as visualised by volume rendering reconstruction (left panel). The critical left coronary artery stenosis was confirmed by selective coronary angiography (right panel).

In our centre, we opt for left internal mammary bypass graft in the presence of long coronary stenosis or complete coronary occlusion. In this child, the stenotic lesion was limited to the proximal segment of the left coronary artery. Therefore, we considered that patch arterioplasty was the best surgical option and the child underwent successful surgical left coronary artery angioplasty using saphenous vein graft. After 6 months, cardiac computed tomography showed complete relief of the coronary stenosis (Fig 3).

Figure 3 Multiplanar reconstruction with maximal intensity projection (left panel) and volume rendering reconstruction (right panel) 6 months after surgery shows an excellent surgical result.

This report underlines that coronary stenosis is a major concern after arterial switch operation.Reference Legendre, Losay and Touchot-Koné² These images highlight the capacity of cardiac computed tomography to accurately visualise abnormal coronary anatomy even in children, and the ability of this tool to guide appropriate intervention and assess its outcome.