Background Coarctation of aorta is a very common congenital heart malformation occurring in 6%–8% of all congenital heart diseases. However in neonates coarctation may be missed or underestimated by echocardiography, especially with patent ductus arteriosus or severe concurrent illness. The carotid-subclavian artery index has been proposed in previous studies for establishing the diagnosis of coarctation of the aorta.

Methods Echocardiographic evaluations was retrospectively reviewed in patients with coractation of the aorta as well as control group admitted at a tertiary cardiac centre in the period between January 2010 to December 2014. All patients admitted with coarctation of aorta either had surgery or catheter intervention which confirmed the diagnosis. 39 patients with Coarctation as well as 20 patients in controls were included in the study. End systolic measurements were obtained from 6 different sites of the aortic arch.

Results The median age of diagnosis was 5 days (Range 0–24 days) with presence of Bicuspid aortic valve in 9 patients (21%). In all patients the arch was left sided and ductus artersious was patent at the time of evaluation. The distance between the origins of the great vessels were longer in patients with coarctation than in controls and the dimension of the proximal transverse arch(Z score: median 4.21, range 0.28 to 7) and distal transverse arch (Z score: median 3.4, range 2.8 to 9) were significantly smaller in the coarctation group. Carotid-subclavian artery index: The ratio of the aortic arch diameter at the left subclavian artey to the distance between left carotid artery and the left subclavian artery was significantly smaller (Mean 0.65, Range 0.35 2.05) with Index <1 in 92% in patients with coarctation.

Conclusion The carotid-subclavian artery index is a simply obtainable noninvasive screening parameter, showing high sensitivity and specificity for coarctation and may be useful in unstable patients or in those with a patent ductus artersious in which coarctation may be overlooked. Neonates with large patent ductus artersious and any of these findings need close observation until the patent ductus ateriosus closes.