The cardiac chambers adapt in configuration and mass to the external work requirements. In
utero right and left ventricular size and configuration are relatively similar. With an infant's
first breath dramatic changes in pulmonary and systemic vascular resistances occur so that
the workload of the right ventricle becomes proportionally lower than that of the left ventricle.
After birth, the proportional growth of the left ventricle exceeds the right in concert with their
respective evolving hemodynamic patterns. The differential growth pattern of these …