<unk>  is a form of congenital heart disease whereby there is a complete absence of the<unk>  valve. Therefore, there is an absence of right atrioventricular connection. This leads to a hypoplastic (undersized) or absent right ventricle. This defect is contracted during prenatal development, when the heart does not finish developing. It causes the systemic circulation to be filled with relatively deoxygenated blood. Because of this, hypoxia occurs, so other defects must occur to maintain blood flow. Because of the lack of an atrioventricular connection, an atrial septal defect (ASD) must be present to fill the left atrium and the left ventricle with blood. Since there is a lack of a right ventricle, there must be a way to pump blood into the pulmonary arteries, and this is accomplished by a ventricular septal defect (VSD). The causes of<unk>  are unknown. A combined atrial septal defect (ASD) and a ventricular septal defect (VSD) can be present to maintain blood flow-from the right atrium, the blood must flow through the ASD to the left atrium to the left ventricle and through the VSD to the right ventricle to allow access to the lungs. Alternatively, an atrial septal defect (ASD) with a patent ductus arteriosus may also be present, thus causing blood flow from the right atrium to the left atrium to the left ventricle to the aorta and then to the pulmonary artery. In these cases, prostaglandin E1 is used to maintain patency of the ductus arteriosus until emergency corrective surgery can be completed.
Tricuspid atresia
Double aortic arch
Interrupted aortic arch
Persistent truncus arteriosus
Double outlet right ventricle
Double inlet left ventricle
Situs ambiguus
Transposition of the great vessels