P4371Right ventricular remodeling during the first weeks of life in healthy neonates

Abstract

Abstract Background The right ventricle (RV) serves as the dominant ventricle in utero. The transition from fetal to post-natal circulation at birth involves marked structural and functional cardiac changes including a large increase in pulmonary blood flow and closure of fetal shunts. Little is known about how the transitional circulation influences RV structure and function in healthy neonates during the first weeks of life. The purpose of this study was to systematically assess RV remodeling in a large, unselected cohort of healthy neonates. Methods Transthoracic echocardiograms of unselected neonates <26 days old without any signs of structural cardiac abnormalities performed between April 1st, 2016 and August 12th, 2017, were consecutively included from the Copenhagen Baby Heart study until at least 90 neonates per day were included. Left parasternal long-axis RV anterior end-diastolic wall thickness and short-axis RV outflow tract end-diastolic diameter were measured offline by one sonographer according to recommendations by the American Society of Echocardiography. RV parameters were corrected for body surface area (BSA). Comparisons were made by T-tests and correlations were computed using univariate linear regression. Results A total of 3,412 echocardiograms were assessed, of which 414 were excluded due to age ≥26 days (n=159), presence of cardiac abnormality (n=179), or suboptimal parasternal views (n=76). Thus, a total of 2,998 (48% male) were included for analysis. Age, weight, and length at examination were (mean±SD) 11.1±7.5 days, 3.6±0.6 kg, and 52±2.6 cm, respectively. BSA-corrected mean (95% CI) end-diastolic outflow tract diameter and end-diastolic anterior wall thickness according to age are presented (Figure). There was a small age-related reduction in end-diastolic RV outflow tract diameter (r2=0.018, p<0.001), whereas the BSA-corrected end-diastolic anterior wall thickness decreased by 35% (from 14.2 to 9.2 mm/m2, p<0.001) from birth to day 25. Figure 1. Mean (95% CI) BSA-corrected end-diastolic RV anterior wall thickness and end-diastolic RV outflow tract diameter. P-value for correlation. Conclusion RV remodeling during the first 25 days of life in unselected neonates included a small decrease in RV outflow tract diameter and a 35% decrease in anterior wall thickness.