How congenital heart disease originates in fetal life

Knowledge of the early development of the heart has increased rapidly in recent years as microscopic techniques, experimental models using animal, avian and insect species, and various genetic techniques have been brought to bear on the mysteries of human fetal cardiac development. The development of the heart occurs rapidly from embryonic day 18 in humans to the twelfth week of fetal life. The stages include gastrulation and formation of the primitive heart tube with rhythmic contractions appearing at day 21, segmentation of the primitive heart tube, looping, realignment of inflow and outflow segments, septation of the atria, ventricles and outflow segments, formation of atrio-ventricular valves, and development of aortic and pulmonary trunks and aortic arches. The genes and factors currently known to be involved in cardiac development are reviewed, but much is still to be determined as the field is evolving with extraordinary rapidity.