Evidence Based Strategies: To Catch a Coarct: Recognizing Heart Defects Missed by CCHD Screening

Coarctation of the aorta (CoA) is a narrowing of the descending aorta that results in decreased blood flow and lower blood pressure in the lower body, while the upper body experiences higher pressures. This obstructive lesion can present with devastating effects in the newborn period. However, other children may have subtle or delayed signs and go undiagnosed for years.

In 2011, the U.S. Department of Health and Human Services recommended that newborns undergo critical congenital heart disease (CCHD) screening before discharge. The screening was adopted by all U.S. states by 2018. This initiative has been highly effective at identifying many congenital heart lesions; however, the sensitivity of CCHD screening to detect CoA has been reported to be as low as 21%.¹ In 2025, the American Academy of Pediatrics updated the CCHD screening recommendations. Based on the new recommendations, the screen is concerning if either of two scenarios are true: 1) the right upper extremity or the lower extremity oxygen saturation is less than 90%, or 2) the right upper extremity or the lower extremity oxygen saturation is less than 95% and there is a difference of greater than 3% between them. Additionally, the new recommendations specifically highlight the need for education on the limitations of screening.¹ It is key for pediatricians to be aware that a normal CCHD screen and weeks or even years without symptoms of an obstructive heart lesion does not rule out CoA.

Unlike congenital heart conditions that cause significant oxygen desaturation, heart murmurs, or cyanosis, CoA may not be evident during screening during a newborn’s initial hospital stay. One key reason is that the patency of the ductus arteriosus can mask an obstruction. As long as the ductus remains open, lower extremity oxygen saturations may appear normal,² leading to a reassuring, yet misleading, screening result. In some infants, a muscular component of the ductus arteriosus encircles part of the aorta, and as the ductus closes, this tissue contracts resulting in a CoA that could not have been diagnosed with prior screening or imaging.³ Thus, a true hemodynamic obstruction resulting from a CoA may not manifest until the ductus has fully closed.⁴ Because of this, many cases of CoA are not diagnosed until well after the newborn period, with many of these infants presenting in extremis. While some infants are identified prenatally by ultrasound or during CCHD screening, the majority are recognized later,⁵ often when abnormal vital signs, growth concerns, or clinical deterioration bring the infant to medical attention.

Given the limitations of screening, the first outpatient newborn visit is a critical opportunity for pediatricians to evaluate for possible CoA. Unlike many congenital heart diseases, CoA typically does not produce a murmur in the newborn period.³ Therefore, careful attention to other exam findings and history is essential. The hallmark clinical clue is diminished or difficult-to-palpate femoral pulses compared with brachial pulses. Every newborn visit should include assessment of both upper and lower extremity pulses.³ If femoral pulses are weak, delayed, or absent, the next step should be to obtain upper- and lower-extremity blood pressures.⁵ A systolic blood pressure gradient of more than 20 mmhg between the upper and lower extremities is concerning for CoA. Repeating pre- and post-ductal pulse oximetry can also be informative, although saturation differences may not always be present. Additional red flags include respiratory distress or tachypnea, feeding difficulty or poor weight gain, decreased urine output, and lethargy.⁶ When such findings are present, further evaluation is warranted. Chest radiography may reveal cardiomegaly, pulmonary venous congestion, or pulmonary edema, while an electrocardiogram may show right ventricular hypertrophy or right bundle branch block.⁷ Although these are supportive findings, the absence of abnormalities on chest radiography or electrocardiography should not delay definitive testing. The diagnostic standard remains echocardiography, and any infant with concerning signs should be referred urgently to cardiology for this study as well as for possible initiation of prostaglandin infusion.⁷ 

CoA exemplifies the limitations of standard prenatal CCHD screening. While pulse oximetry has greatly improved detection of many critical heart defects, CoA often escapes notice because it may not be present until after the ductus arteriosus closes. It is vital to remember that critical heart lesions may be present in patients with a normal CCHD screening. For pediatricians at newborn visits, vigilance is key. Pediatricians are often the first to evaluate infants once they have transitioned out of the immediate newborn period, and this visit represents a crucial safety net for identifying a potentially life-threatening condition. By maintaining a high index of suspicion, carefully assessing pulses, and promptly investigating concerning clinical features, pediatricians can play a decisive role in catching undiagnosed CoA. Early recognition and referral to a cardiologist for echocardiography is essential to prevent delayed diagnosis and the potentially catastrophic consequences of untreated CoA.

References:

1. Oster ME, Pinto NM, Pramanik AK, et al. Newborn Screening for Critical Congenital Heart Disease: A New Algorithm and Other Updated Recommendations: Clinical Report. Pediatrics. 2025;155(1):e2024069667. doi:10.1542/peds.2024-069667
2. Karatza AA, Fouzas S, Gkentzi D, et al. Missed or Delayed Diagnosis of Heart Disease by the General Pediatrician. Children (Basel). 2025;12(3):366. Published 2025 Mar 15. doi:10.3390/children12030366
3. Hoffman JI. The challenge in diagnosing coarctation of the aorta. Cardiovasc J Afr. 2018;29(4):252-255. doi:10.5830/CVJA-2017-053
4. Lin Y, Thakur V. How Small Is Too Small? The Challenge of Accurate Prenatal and Postnatal Detection of Coarctation of the Aorta. CJC Pediatr Congenit Heart Dis. 2022;1(4):163-166. Published 2022 Jun 17. doi:10.1016/j.cjcpc.2022.05.005  
5. Geggel RL. Coarctation of the Aorta: Delay in Diagnosis and Referral Basis from Infancy to Adulthood. J Pediatr. 2022;242:57-62. doi:10.1016/j.jpeds.2021.11.066
6. Raza S, Aggarwal S, Jenkins P, et al. Coarctation of the Aorta: Diagnosis and Management. Diagnostics (Basel). 2023;13(13):2189. Published 2023 Jun 27. doi:10.3390/diagnostics13132189
7. Park, M., & Salamat, M. (2022). Obstructive Lesions. In Park’s The Pediatric Cardiology Handbook (pp. 137–158). essay, Elsevier.