Diagnosing Neonatal Aortic Coarctation in the Setting of Patent Ductus Arteriosus

In neonates, it is challenging to diagnose aortic coarctation in the setting of a patent ductus arteriosus (PDA). Frequently, serial echocardiograms are performed, and diagnosis is delayed until the PDA closes. The purpose of this study was to identify echocardiographic predictors of neonatal coarctation in the presence of a PDA in cases in which diagnosis is uncertain.

We retrospectively identified neonates diagnosed with possible but not definitive coarctation in the presence of a PDA by echocardiography (January 2004 through August 2013). The carotid-subclavian artery index (CSAi) was defined as the distal transverse arch diameter divided by the distance between the left common carotid and left subclavian arteries. Medical records were reviewed to identify patients who underwent coarctation repair within 1 year. A separate validation group was identified with the same methodology (September 2013 through April 2015).

Thirty-three patients were identified (median age 1, range 0-8 days). Twelve patients (36%) underwent coarctation repair. The coarctation group had smaller aortic and mitral valves, distal transverse arch, and isthmus z scores, larger right innominate artery, and longer transverse arch compared with the remaining group (p < 0.05). The CSAi was lower in the coarctation group (p = 0.014), and a cutoff of less than 0.85 yielded a sensitivity of 0.83 and specificity of 0.86 for coarctation (area under the receiver operating characteristic curve, 0.91). In the validation group (n = 12; median follow-up, 316 days), none of the 8 patients with a CSAi of greater than 0.85 have required surgery. The intraclass correlation coefficient for CSAi was 0.79 (95% confidence interval, 0.18 to 0.95).

The CSAi, a simple and reproducible measure, can identify neonates at risk for aortic coarctation even in the presence of a PDA, prevent multiple echocardiographic evaluations, and hence guide appropriate resource utilization.