Early Childhood Emotional, Relational, and Stress-Related Outcomes Following Infant Cardiac Surgery.

Children with congenital heart disease (CHD) experience significant early-life stress through medical interventions and hospitalization, shaping physiological and psychological development. This study examined emotional and behavioral regulation and salivary cortisol responses in preschool-aged children who underwent cardiac surgery in infancy, and explored the parent-child relationship as a source of co-regulation and buffering support. In this prospective cohort, 22 preschoolers with CHD and their parents participated in a hospital-based laboratory visit. Child salivary cortisol was collected at three time points. Observed parent-child interactions were coded using the Emotional Availability Scales, and parent-reported Child Behavior Checklist (CBCL) scores assessed emotional and behavioral regulation. Mixed-effects models examined associations between cortisol response, CBCL scores, and relationship quality. Significant individual variability in cortisol response was observed. Lower cortisol levels were associated with greater emotional and behavioral difficulties and higher parent-reported traumatic stress at the time of their child's surgery. Longer hospital stays predicted blunted cortisol responses. Children in lower quality relationships displayed flatter cortisol profiles. Findings highlight the impact of early medical stress on stress physiology and suggest emotionally available relationships may buffer HPA axis dysregulation. Results identify potential intervention targets to support psychosocial development and parent-child relationships and contribute to the emerging use of stress biomarkers in CHD research.