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The embryological development of the heart is an awesome and complex process. The heart is formed from groups of cells that coalesce into sheets of tissue. These sheets fuse to form a tube that grows into the atria and ventricles. The twists and turns of the developing heart tissue and the simultaneous septation of atria, ventricles, and truncus, along with a shifting of the atrioventricular canal and conus then position the portions of the heart in alignment to allow normal blood flow. Errors at any stage of embryological formation can result in specific congenital defects. Understanding the development of the heart in utero can provide the pediatric nurse a basis for understanding the physiological effects of embryological failures that result in congenital heart defects in the infant and child.
Acknowledgments: The authors would like to thank Roger N. Ruckman, MD, Pediatric Cardiologist, and Mary A. Meyer for editorial review.
The embryological development of the heart is an awesome and complex process that occurs between the third and ninth weeks of gestation. Understanding this complicated process gives the pediatric nurse insight into the embryological failures that produce congenital heart disease. This basic science review will assist the pediatric nurse in envisioning each congenital defect and, thereby, understanding its impact on the child.
Development of the Heart Tube
Cell to cell diffusion initially provides nutrient and oxygen supply to the fetus. As the fetus grows, however, the stored food supply in the yolk sac no longer supports fetal life, and the cardiovascular system must develop to transfer cellular nutrition from the maternal umbilical cord. This process begins when small groups of blood-forming cells known as the angiogenetic cell clusters come together to form blood pools, or islands, which eventually fuse into sheets of endothelial tissue. These sheets of tissue move together and fuse along their midline to produce a single heart tube (Van Mierop & Kutsche, 1990) (see Figure 1).
Embryological research conducted on chick embryos using surgical implantation of radioactive cells and mapping of cell growth shows differential growth patterns. Analysis of the patterns reveals that stretching, folding, and outgrowths of tissue transform the heart tube (see Figure 1) into the heart itself. This research shows that while the two ends of the heart tube...