Long-Term Enlargement of the Neo-Aortic Root and Aortic Arch Following Arch Reconstruction in Hypoplastic Left Heart Syndrome

Abstract

Long-term enlargement of the aortic arch after aortic arch reconstruction (AAR) in hypoplastic left heart syndrome (HLHS) is not well described. Aortic arch measurements for 50 patients with HLHS who achieved Fontan completion were converted to Pediatric Heart Network z-scores. Dimensions were assessed using linear mixed models and differences among time points were evaluated with F-tests. Sub-analysis was conducted comparing Norwood (n=36) vs hybrid (n=14) strategies. Median time to last imaging was 6.4 (IQR, 3.5-11.3) years. Prior to intervention, the main pulmonary artery was dilated whereas the ascending aorta (AA), transverse arch (TA), and isthmus (ISTH) were hypoplastic. With AAR, there were expected increases in all arch z-scores. The aortic arch continued to dilate after AAR reaching peak values at 7 months [Neo-Aortic Complex (NAC): z= 6.9 (5.6-8.0)] or 12 months following stage I [AAo: z=6.1 (2.9-8.3); TA: z=4.7 (3.0-5.9)]. Following peak values, there was a gradual decline in z-scores with most components still at least mildly dilated at 16 years [NAC: z=3.2 (3.1-3.9), AAo: z=3.9 (3.3-4.2); TA: z=3.1 (2.5-3.7)] with abrupt calibre change at ISTH: z= -0.8 (-1.1- -0.3)]. Norwood and hybrid strategies showed similar enlargement profiles after 7 months of age. Neo-aortic root and aortic arch in HLHS are enlarged early after AAR and continue to enlarge out of proportion to normal controls until 12 months of age, with gradual decline in enlargement up to adolescence. Further work should focus on modifiable surgical factors which may prove important to optimize arch growth and geometry.