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hypoplastic right heart syndrome
Hypoplastic right heart syndrome is a congenital heart defect in which the right atrium and right ventricle are underdeveloped. This defect causes inadequate blood flow to the lungs and thus, a blue or cyanotic infant.()
==Anatomy==
A healthy heart has four valves, separated by flaps that open and close to control blood flow between the chambers. When the heart beats, oxygen-poor blood enters the right atrium. The blood then flows into the right ventricle, where it enters the pulmonary artery to travel to the lungs for oxygen. Oxygen-rich blood returns to the left atrium, where it then travels into the left ventricle. The left ventricle pushes the oxygenated blood into the aorta to be circulated to the rest of the body.〔(Heart Contraction and Blood Flow ). National Institutes of Health.〕
The heart is a mesoderm-derived organ; Mesoderm is the middle germ layer of an embryo, whose formation is regulated by various genes. Initially, the most important is expression of Nkx2.5, CR1, pitx2, anf and mhc2a, is responsible for differentiation of the types of cardiomyocytes to determine which part of the heart they go to.() In a later in differentiation, activation of hand1, hand2 and other genes was revealed to help in development. () Expression of these genes expression is regulated by various processes, including transcription and growth factors, as well as proteins like fibrillin, Wnt, BMP2, BMP 4, BMP5, BMP7, which aid in different heart development features like the valves and septum, and other substances, such as retinoid and folic acid.()
Crucial steps in heart formation are development of the ventricles and atrium formation, as well as septation and valve formation. Any disturbances of such processes may lead to various congenital heart diseases and defects that could be initiated by various genetic, epigenetic or environmental factors. The most common heart malformations from genetic or epigenetic problems are: stenosis of the aorta and pulmonary trunk, which is a narrowing of the vessels, atrial and/or ventricular septal defect, tricuspid atresia, hypoplastic left and right heart. When you have hypoplastic right or left heart more than one of these problems occur together ()
抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』
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