What is Pulmonary Atresia with Intact Ventricular Septum?
Pulmonary atresia with intact ventricular septum (i.e. without a ventricular septal defect), occurs when the pulmonary valve fails to form normally while the baby is in the mother’s womb. It is quite rare comprising about 3% of all congenital heart defects. The pulmonary valve is one of four valves in the normal heart. It sits between the right ventricle (1) and the pulmonary artery (2). In babies with pulmonary atresia, the pulmonary valve (3) is so small that blood flow leaving the right heart is completely blocked. Almost all babies with this defect also have an atrial septal defect (4) that allows blue blood to bypass the obstruction, flowing from the right atrium to the left atrium, the left ventricle and out to the body. The only way that blood can reach the lungs is to flow backwards from the aorta through a patent ductus arteriosus (5). This a small blood vessel that, prior to birth, permits the blood to by-pass the baby’s fluid-filled lungs. In most babies, one or two days aft
