In the early stages of fetal development, the vascular ring composed of paired aortas fails to make a normal transition to a single aorta, and the right dorsal aorta degenerates and resorbs incompletely or other segments of the aortic arch develop abnormally, so that the pediatric aortic arch still retains a complete or incomplete annular structure, and the esophagus and trachea, which are walking in the vascular ring, are compressed to varying degrees, and this abnormality in the way that the various segments of the aortic arch are assembled is called vascular malformation of the vascular ring. The incidence of vascular ring malformations is low in Eastern countries, where malformed blood vessels encircle the esophagus and organs, compressing them and causing clinical symptoms, thus requiring surgical management for symptomatic relief. I. Pathologic Anatomy and Pathophysiology The development of the fetal aortic arch is a progression from a circumferential aortic arch to a single aortic arch. The fetal vascular ring is initially formed by six pairs of aortic arches connecting the aortic bursa to the dorsal aortic arch. Later, the first, second, and fifth pairs of aortic arches are absorbed, and the dorsal aorta between the third and fourth pairs of aortic arches is interrupted, leaving the fourth and sixth pairs of aortic arches to form the vascular ring. At this point, the aortic bursa is separated into the ascending aorta and the pulmonary trunk, which is connected to the fourth pair of aortic arches, and the pulmonary trunk is connected to the sixth pair of aortic arches. Later, as the vascular ring shortens and deforms, the intersegmental arterial segments of the dorsal aorta in segments 1 and 2 are completely absorbed, and the arterial planes in segments 3-7 are shortened, so that only the dorsal aorta equivalent to segment 8 in two cases constitutes the lateral margin of the vascular ring. Normally the distal end of the right 6th arch and the resorption of the 8th intersegmental segment of the right dorsal aorta disappeared, and the right edge of the vascular ring was broken and resorbed, forming a single aortic arch on the left side. Thus vascular ring malformations are due to either incomplete resorption of the dorsal aorta in the right 8th intersegmental segment or abnormal resorption of the left-sided arterial arch. The most frequent site of malformation is the dorsal aorta of the dorsal aorta in the 4th arch and 8th intersegmental segment on both sides. There are quite a number of ways to categorize vascular ring malformations, of which the following are common. (I) Double aortic arch Double aortic arch is the most common type of vascular ring. It is due to the simultaneous existence of the left and right 4th aortic arches during embryonic development, both of which originate from the ascending aorta, and converge into the descending aorta from the trachea and esophagus bypassing the dorsum on both sides of the trachea and esophagus, thus forming a true ring. Usually the right arch (dorsal) gives off the right common carotid and right subclavian arteries, while the smaller left arch (anterior) gives off the left common carotid and left subclavian arteries. The right arch is predominant in about 73% of patients, the left arch is predominant in only 20%, and the left and right are of similar size in 2% of patients. (B) Right aortic arch with left arterial ligament During embryonic development, if the left 4th arch degenerates, it can produce a right aortic arch. Depending on the site of degenerative disruption of the left arch and the pattern of branching of the left common carotid artery, left subclavian artery and arterial conduit, the right aortic arch can produce many types of vascular ring malformations. The most common are retrograde esophageal left subclavian artery and mirror-like branches of the aortic arch. The right aortic arch with retrograde esophageal left subclavian artery is due to the presence of the right 4th arch and the interruption of the left arch between the left common carotid and left subclavian arteries, allowing the left subclavian artery to originate from the descending aorta and travel on the left posterior side of the esophagus, and the presence of a ligament between the descending aorta and the left pulmonary artery, which allows for the formation of a complete vascular ring. The right aortic arch with mirror-like branches is then present in the right 4th arch, while the left arch is interrupted between the left subclavian artery and the dorsal descending aorta, forming a ligament. When this ligament originates in the descending aorta, it forms a complete vascular ring, whereas when it originates in the cephalic trunk (innominate artery), it does not form a vascular ring, and the child may be asymptomatic. (C) Pulmonary artery sling In embryonic development, when the left pulmonary artery originates from the right pulmonary artery, the pulmonary artery bypasses the right main bronchus and travels between the trachea and the esophagus, forming a “sling” that presses on the right bronchus (Figure 15-46). This often results in tracheal compression in the neonatal period. (d) Cephaloarterial trunk (unnamed artery) compression syndrome When the cephaloarterial trunk (unnamed artery) travels abnormally, the anterior wall of the trachea is compressed by the cephaloarterial trunk. However, some children with normal travel of the head and arm trunks also have tracheal compression, and the mechanism is not fully understood. It has been suggested that the origin of the head-arm trunk in these children is more posterior to the left side of the aortic arch than in normal subjects, and that when the artery travels posteriorly to the right side up to the thoracic outlet, it can compress the anterior wall of the trachea. (E) Vagus right subclavian artery The left aortic arch with vagus right subclavian artery is caused by the degeneration of the right 4th arch between the subclavian artery and the carotid artery during embryonic development, resulting in the right subclavian artery originating from the descending aorta and traveling upward to the right through the posterior border of the esophagus, which can cause indentation of the left posterior wall of the esophagus, but it doesn’t form a complete vascular ring. The incidence of this malformation is statistically high, while symptoms causing dysphagia are uncommon, and even rarer requiring surgical treatment. (vi) Left aortic arch with right descending aorta This malformation is rare, but if combined with right-sided ductus arteriosus or arterial ligament, it can form a complete vascular ring. Left aortic arch with right descending aorta is due to embryonic development of the aortic arch of the third arch is not degraded and absorbed, forming a large cervical aortic arch, so some children do not have a right-sided arterial conduit can also produce the symptoms of the anterior wall of the trachea compression. Second, the natural regression of congenital vascular ring malformation children are generally found in the hospital physical examination or esophageal, tracheal compression symptoms, for the absence of symptoms of the child can be followed and observed, the child can be well tolerated and do not need surgical treatment. For children with obvious symptoms of esophageal and tracheal compression, surgery is needed, and the results are better. Clinical manifestations and diagnosis The clinical manifestations of children with vascular ring malformations vary according to the location and degree of compression on the trachea and esophagus. Typical symptoms are: respiratory distress and rales in early life, rales are louder after activity and feeding, and can be heard during sleep, coughing like “barking” or “gong”, and recurrent respiratory tract infections. Older children have difficulty swallowing, especially when eating solid food, and may even have difficulty breathing or bruises. Some children prefer to tilt their heads back when they sleep, a position that can reduce the obstruction of the airway. There are many ways to diagnose vascular ring malformations, but the most common and simplest diagnostic method is chest x-ray. Frontal and lateral chest radiographs are used to visualize the position of the aortic arch. Poor visualization of the normal aortic arch often suggests the possibility of a double aortic arch malformation. Lateral radiographs can show whether there is tracheal and bronchial stenosis at the level of the aortic arch, and high-kilovoltage photography can be helpful in this regard. Chest radiographs show hyperventilation of the right lung, often suggesting the possibility of pulmonary artery sling; esophageal barium swallow imaging is also extremely helpful in the diagnosis of vascular ring anomalies, in the aortic arch or the right aortic arch with the left arterial ligament of the patient, esophageal barium swallow can be seen in the examination of the posterior wall of the back wall there is a clear compression of the trace. In recent years, the emergence of high-speed spiral CT has provided superior conditions for the diagnosis of this disease, which has led to the diagnosis of many previously missed patients. Echocardiography should be used as a routine means of examination, while cardiovascular angiography can be used as a supplement. Surgery All symptomatic children, once the diagnosis is clear, there are surgical indications, delayed surgery can lead to further damage to the trachea and bronchus, or even sudden death. Surgical methods vary according to the diagnosis, the following introduces several common vascular ring malformation surgical treatment principles. (I) Double aortic arch: Enter the chest at the 4th intercostal space of the left posterior lateral side, and expose the relationship between the vascular ring, ligament and descending aorta after separation. A smaller aortic arch (usually the left arch) is cut at the junction with the descending aorta, and the arterial ligaments are cut at the same time, with care taken to preserve the normal blood supply of the carotid and subclavian arteries bilaterally. (ii) Right aortic arch with left arterial ligament Enter the chest at the left posterior lateral 4th intercostal space, separate and expose the arterial ligament, cut and suture it, and loosen the adherent ligaments to avoid injury to the nearby laryngeal recurrent and vagus nerves. (C) Cephalic trunk (unnamed artery) compression syndrome: Enter the chest at the right or left anterolateral 3rd-4th intercostal space, excise the right thymus tissue, use three-needle padded sutures to make mattress sutures in front of the aortic arch at the beginning of the cephalic trunk, at the point where the cephalic trunk connects with the arch and at the point where the cephalic trunk emanates from the chest, and then fix it to the back of the sternum. It is advisable to perform a tracheoscopy at the same time as the surgery to understand the release of tracheal compression. Recently, some authors have proposed a median sternotomy, which is cut off at the beginning of the head-arm trunk, closed proximally, and re-fixed distally to the normal position of the aortic arch against the right anterior aspect. (iv) Pulmonary artery sling Often operated on in infants and neonates. Sternal median incision, the establishment of extracorporeal circulation, the beginning of the left pulmonary artery will be cut off, the proximal end is closed, the distal end is moved to the front of the trachea and the trunk of the pulmonary artery for end-side anastomosis, such as at the same time combined with tracheal ring deformity, the need to use the pericardial patch for tracheoplasty. In recent years, with the development and application of thoracoscopic technology, many hospitals have adopted thoracoscopic technology to treat pediatric vascular malformations with success. V. Postoperative monitoring and complications The key to pediatric vascular ring malformation surgery is respiratory care. In addition to the tracheoplasty patients need to stay a long time tracheal intubation, generally advocate early extubation, give the respiratory tract sufficient wetting, strengthen the back patting sputum, to ensure that the respiratory tract is open. In some cases, the symptoms of respiratory compression may not be completely relieved in the early postoperative period, but the symptoms often disappear after a few months or a year. Sixth, the results of surgery and follow-up Backer et al. reported a group of 251 cases due to respiratory and digestive tract compression symptoms, suspected of vascular ring deformity of the child, including double aortic arch accounted for 76 cases; the right aortic arch with the left arterial ligament in 66 cases; head and arm trunk compression syndrome in 79 cases; the pulmonary artery sling with or without tracheal ring deformity in 30 cases. The total operative mortality rate was 7.6%, and most of the fatal cases were associated with cardiac and tracheal malformations. In the last 30 years, there has been no operative mortality rate for simple vascular ring malformations.