Atrial septal defect is the most common congenital heart disease, which is divided into two kinds: 1, secondary foramen ovale type atrial septal defect, is due to the left and right atrial septum at the stage of embryonic development, there are remnants of the left and right atrial septum did not completely grow into the closure, resulting in left and right atrial septal defect, resulting in left and right atrium direct pressure difference and formation of loss of circulation, the flow of oxygenation of the blood through the left atrium will be a small portion of the flow of oxygenation of the blood through the right atrium, resulting in the should be A small portion of the oxygenated blood flowing through the left atrium will flow through the right atrium, resulting in a decrease in the oxygenated blood that should flow through the left atrium, thus causing a decrease in the blood flow in the body circulation, which results in an atrial septal defect.2. Primary foramen ovale-type atrial septal defects are caused by the lack of development of the heart’s central endothelial cushion in the embryonic stage, resulting in the emergence of the defect.