Postnatal Steroids in Preterm Infants: A Narrative Review Series-Part 2: Cardiovascular Impacts.

Postnatal corticosteroids are frequently administered to extremely preterm infants to support respiratory management, yet their effects on the immature cardiovascular system are complex and underexplored. As the second installment in a series on physiology-informed steroid use, this narrative review focuses on the cardiovascular consequences of systemic corticosteroid therapy in preterm neonates. We examine how corticosteroids influence key aspects of cardiovascular physiology, including ductal closure, systemic and pulmonary vascular resistance, myocardial remodeling, and autonomic regulation. Attention is given to the hemodynamic transition of early postnatal life and how steroid exposure may interact with patency of the ductus arteriosus and vascular development. The potential for corticosteroids to contribute to reactive myocardial hypertrophy, systemic hypertension, and pulmonary hypertension is also reviewed in the context of both short- and long-term outcomes. Emerging diagnostic and monitoring tools are discussed for their potential to guide individualized therapy. These include targeted neonatal echocardiography (TnECHO) to assess cardiac function and structure, electrocardiography (ECG) for rhythm and conduction abnormalities, heart rate variability analysis for autonomic function, and circulating biomarkers to evaluate myocardial stress and inflammation. Together, these tools may inform tailored steroid timing and dosing, especially in the research context, while monitoring for signs of cardiovascular side effects in real time. By synthesizing mechanistic insights with evolving clinical evidence, this review highlights the need for a more nuanced understanding of how corticosteroids affect the developing cardiovascular system. It underscores the importance of integrating cardiovascular monitoring into routine care to optimize therapeutic benefit while minimizing unintended harm. Alongside companion reviews addressing respiratory and growth impacts, this installment contributes to a broader framework for individualized, physiology-driven steroid use in extremely preterm infants.