Frequency of Atrioventricular Septal Defect Variants Among Children With Down Syndrome at Tertiary Care Centers

https://doi.org/10.5281/zenodo.18207223

Abstract

Background: Down syndrome is frequently complicated by congenital heart disease, and atrioventricular septal defect (AVSD) is the hallmark lesion. AVSD encompasses a spectrum of anatomical variants with differing haemodynamic burden, surgical complexity, and long-term prognosis. Data from resource-limited settings on the relative frequency of these variants in children with Down syndrome remain scarce.

Objective: To determine the frequency and echocardiographic profile of AVSD variants among children with Down syndrome presenting to tertiary care centers.

Methods: We conducted a hospital-based cross-sectional study over 12 months (July 2023–June 2024) in tertiary pediatric cardiology centers with dedicated echocardiography laboratories. Consecutive children younger than 18 years with clinically diagnosed Down syndrome and transthoracic echocardiographic confirmation of AVSD were included. AVSD was classified as complete, partial, intermediate, or unbalanced according to International Paediatric and Congenital Cardiac Code criteria. The primary outcome was the frequency distribution of AVSD variants. Secondary analyses described age at diagnosis, sex distribution, associated intracardiac lesions, pulmonary hypertension, and left atrioventricular valve regurgitation. Categorical variables were summarized as n (%) and compared using chi-square or Fisher’s exact tests; continuous variables were summarized as mean ± standard deviation or median (interquartile range).

Results: A total of 110 children were enrolled (mean age 21.8 ± 24.2 months; median 10.0 months; 62/110 [56.4%] male). Complete AVSD was the most common variant (60/110, 54.5%), followed by partial (24/110, 21.8%), intermediate (16/110, 14.5%), and unbalanced AVSD (10/110, 9.1%). Two-thirds of complete AVSD cases were diagnosed at ≤12 months of age. Overall, 62/110 (56.4%) had at least one additional intracardiac lesion, 58/110 (52.7%) had Doppler-defined pulmonary hypertension, and 51/110 (46.4%) had moderate–severe left atrioventricular valve regurgitation, with the highest burden in complete and unbalanced variants.

Conclusion: In this tertiary-care cohort of children with Down syndrome, complete AVSD predominated, and a substantial proportion presented with pulmonary hypertension and significant valve regurgitation. These findings support routine early echocardiographic screening in infants with Down syndrome and timely referral to specialized centers to optimize surgical planning and long-term outcomes.