The septum that appears first is the primary septum or the first septum, and the septum that appears later is the secondary septum or the second septum. The primary septum grows in a semilunar shape from the dorsal wall of the atrial midline, grows toward the atrioventricular canal and fuses with the endocardial cushion, leaving a small hole with the caudal end of the atrioventricular septum, which is called the primary foramen. Before the primary foramen is closed, a hole is formed in the proximal cephalic portion of the primary septum, called the secondary foramen, which is the normal channel for blood during fetal life. At the same time, a sickle-shaped septum grows on the right side of the first septum from the atrial wall, called the secondary septum or the second septum, which does not continue to grow to separate the atrium midway to stop, the sickle-shaped depression is oval-shaped called the oval fossa, the primary septum and secondary septum at the oval fossa fail to adhere and fuse leaving a small cleft called the oval foramen. At birth, with the first cry, the pressure in the left atrium rises, causing the primary septum on the left to partially adhere to the secondary septum on the right, resulting in functional closure, which is achieved anatomically within 1 year. If the foramen ovale remains unclosed in a child >3 years of age, it is called foramen ovale non-closure. Ovular foramen nonocclusion is mostly asymptomatic, murmurs are difficult to hear, and electrocardiograms and chest X-rays are normal. Therefore, it is not easily detected and is not taken seriously. The Valsalva maneuver or cough test can increase the detection rate of unclosed foramen ovale up to 60%-78% because of the transient increase in right atrial pressure, at this time, the injection of microbubble contrast can increase the detection rate of unclosed foramen ovale. The detection rate of unclosed foramen ovale. Transesophageal ultrasound is three times more likely to detect foramen ovale noncompaction than transthoracic ultrasound. Previously, closure of patent foramen ovale relied on surgical procedures. The success rate of surgical treatment is high and the morbidity and mortality rate is very low, but it is highly traumatic and may result in complications such as atrial fibrillation, pericardial effusion, postoperative bleeding and wound infection; therefore, it has been rarely used in recent years. With the advancement of technology, especially the development of cardiac catheterization technology, a considerable proportion of left-to-right shunt congenital heart diseases (such as patent ductus arteriosus and atrial septal defect) can be radically cured by interventional treatment. Clinical practice in recent years has demonstrated that this technique is also safe, effective, and feasible for permanent closure of open patent foramen ovale.