Early Postnatal Changes in Left Heart Dimensions in Infants Undergoing Neonatal Repair of Coarctation of the Aorta.

The transition from prenatal to postnatal life involves major changes in cardiac loading conditions, including increased left ventricular preload and afterload, potentially affecting left heart size during the neonatal period. We hypothesized that early postnatal hemodynamic changes would significantly impact left heart size and derived Z-scores. We report serial data from infants with prenatally suspected coarctation of the aorta who underwent coarctation repair. We retrospectively studied 51 infants with a prenatal diagnosis of suspected coarctation of the aorta who underwent repair before 30 days of age. Sequential echocardiography was performed at less than 48 h (US1), 48 h to seven days (US2) and over seven days or last pre-operative scan (US3). Cardiac dimensions were assessed on two-dimensional ultrasound and Z-scores computed. Across US1, US2, and US3 groups, significant median Z-score increases from US1 to US3 were observed for LV length (1.3), AoV (1.0), and DTAA (Distal transverse aortic arch) (0.6). Paired data (US1 vs. US2) showed significant increases in LV length Z-score (0.3), AoV Z-score (0.7), and mitral valve Z-score (1.0). Changes in dimensions and Z-scores inversely correlated with initial Z-scores, meaning infants with the smallest initial left heart dimensions exhibited the largest increases. Infants with prenatally suspected coarctation of the aorta demonstrate postnatal changes in absolute measurements and Z-scores of left heart structures. The infants with the smallest initial size of left heart structures showed the greatest increase in size during the neonatal period.