Abstract
Like every muscle in the body, the heart adapts its structure and mass to functional requirements, which are primarily determined by loading conditions. These can be classified as pressure loading (increased afterload, as in hypertension or banding of an artery), or volume loading (preload, which could be increased by creating an arterio-venous shunt, valve regurgitation, or shifting the blood streams).
While numerous models exist for modifying the loading conditions postnatally, this chapter focuses on those few created in the developing heart, chiefly during prenatal development. As the reactions of the early postnatal heart are somewhat similar to the response of the fetal one, discussion of early postnatal models is also included.
Principal findings from these studies are considered in the light of clinical scenarios of abnormal loading in congenital heart malformations and their optimal surgical management.