Right aortic arch

Introduction The right aortic arch is a more common congenital vascular malformation. The aorta does not cross the left main bronchus from the left ventricle, but extends backwards across the right main bronchus, and descends from the descending aorta. The descending aorta descends along the right side of the spine until it approaches the left side. Patients are often accompanied by other congenital cardiovascular malformations such as tetralogy of Fallot, ventricular septal defect, pulmonary atresia, right atrioventricular atresia, permanent aortic stem and aortic dislocation.

Cause

At the 4th week of embryonic development, the front end of the dorsal aorta bypasses the pharynx and forms the first pair of aortic arches and the left and right primordial aorta on the ventral side of the foregut. The latter fuse with each other to form an aortic sac. As the zygomatic arch grows, six pairs of radial arches are issued from the aortic sac and connected to the dorsal aorta. When the third pair of radial artery arches were fully developed, the first and second pairs of radial artery arches disappeared. The third pair of radial artery arches form the common carotid artery and part of the internal carotid artery. The fourth pair forms the aortic arch on the left side of the radial artery arch, and forms the innominate artery and the right subclavian artery on the right side.

The fifth pair of radial arches does not exist constantly or disappears quickly. The sixth pair of radial artery arches form the pulmonary artery, and the right distal segment is disconnected from the dorsal aorta; the left side is persistently called the arterial catheter during the fetal period, and the catheter is closed to become the arterial catheter ligament after birth. The left axillary arch of the left side disappeared, the aortic arch developed on the right side, and the descending aorta was located on the right side of the spine. The order of branches from the aortic arch is normal, that is, the first branch is the left innominate artery, and the left common carotid artery and the left subclavian artery are issued; the second branch is the right common carotid artery; the third branch is the right subclavian bone. artery. Sometimes the aortic arch sends out 4 branches, and the left unknown artery does not exist. The arterial catheter or arterial ligament is located between the left innominate artery or the left subclavian artery and the left pulmonary artery.

Avascular vessels behind the esophagus do not constitute a vascular ring. The right aortic arch generally does not compress the trachea and esophagus, but there are a few cases of arterial catheter or arterial ligament, which is connected to the distal part of the right aortic arch from the left pulmonary artery bypassing the esophagus, or the left subclavian artery originates from the proximal descending aorta. The posterior esophagus enters the left upper limb, and the arterial catheter or arterial ligament may also be located between the left left pulmonary artery and the left subclavian artery of the trachea, or between the left pulmonary artery and the left subclavian artery originating from the descending aorta.

an examination

Related inspection

Contrast magnetic resonance angiography

The right aortic arch itself does not cause significant hemodynamic changes, but with the left aortic or left ulnar ligament, it can form a vascular ring with the arterial catheter, arterial ligament, aortic arch, and pulmonary artery, compressing the esophagus and trachea and causing difficulty in swallowing. Symptoms such as respiratory distress and lung infections sometimes cause hoarseness. Chest X-ray and X-ray examination of the esophagus can suggest the presence of the disease, and aortic angiography can confirm the diagnosis.

Differential diagnosis

Clinically, various types of congenital aortic arch deformities are identified, including obstructive congenital aortic arch deformities such as aortic coarctation and aortic arch interruption, non-obstructive congenital aortic arch deformities such as double aortic arch and right aortic arch with vagus left subclavian artery. Etc., may also include shunt congenital aortic arch malformations such as patent ductus arteriosus.

1, aortic coarctation

The main lesion is aortic localized short-segment stenosis or occlusion leading to aortic blood flow disorders. The vast majority (more than 95%) of the lesions in the aortic constriction are at the junction of the distal aortic arch and the descending thoracic aorta, that is, the aortic isthmus, adjacent to the arterial catheter or arterial ligament. However, in a very small number of cases, the narrowing segment can be located in the aortic arch, the descending thoracic aorta or even the abdominal aorta. Sometimes the aorta can be narrowed in two places. Very few patients have a family history. The disease is more common in men, the ratio of male to female is 3 to 5:1. The clinical manifestations of aortic coarctation vary with the location of the constricted lesion, the degree of constriction, whether there are other cardiovascular vascular malformations, and different age groups.

2, aortic arch interruption

Aortic arch interruption refers to luminal atresia or a part of the aortic arch. The anatomical aortic arch is dissected, and the proximal and distal lumens are discontinuous, resulting in blood between the two parts of the aortic arch or between the aortic arch and the descending aorta. The flow is interrupted. Abdominal arch interruptions are almost always combined with large PDA and VSD, and can also be combined with other intracardiac malformations and abnormalities in the relationship between large vessels and ventricles. Combined PDA is a condition in which the aortic arch interrupts the child's survival after birth. The blood flow from the aortic arch and descending aorta at the site of the interruption is provided by the right atrium or/and the right ventricle through ASD or VSD via PDA. After the child is born, because the pulmonary circulation resistance is reduced, the pressure gradient between the left and right ventricles increases, and the left-to-right shunt is generated by VSD, resulting in congestive heart failure. If combined with PDA small or left ventricular outflow obstruction, can lead to refractory heart failure, most cases die in the neonatal period, a small number of survivors have pulmonary vascular secondary lesions, leading to pulmonary hypertension, gradually to right heart failure.

3, double aortic arch

The bilateral axillary arches remain and develop to form an aortic arch. The ascending aorta is normal and is divided into left and right aortic arches outside the pericardium. The left aortic arch walks from right to left in front of the trachea, over the left main bronchus, and merges with the right aortic arch on the left side of the spine to synthesize the descending aorta. The right aortic arch spans the right main bronchus in front of the spine, behind the esophagus, across the midline to the left, and the left aortic arch merges to form the descending aorta. The left and right aortic arches each divided two branches, that is, the left aortic arch issued the left common carotid artery and the left subclavian artery, and the right aortic arch issued the right common carotid artery and the right subclavian artery. The arterial catheter or arterial ligament is located between the left aortic arch, the lower edge of the left subclavian artery, and the left pulmonary artery. In most cases, the diameter of the aortic arch on both sides is not equal, and the right side is generally thicker.

In a few cases, the descending aorta is located on the right side, the left arterial arch crosses the left main bronchus, and the posterior to the right is passed the posterior esophagus. The right side of the spine and the right aorta are combined to form the descending aorta. Regardless of whether the descending aorta is located on the left or right side, the vascular ring formed by the bilateral aortic arch surrounds the trachea and esophagus, such as the narrow space between the two arterial arches, and clinically, compression symptoms can be produced.

4, right aortic arch with vagus left subclavian artery

This is the most common type of right aortic arch deformity. This abnormality rarely causes symptoms and complicated other cardiac malformations, so adults have almost the right aortic arch. However, in elderly patients, esophageal or tracheal compression symptoms may occur due to the hardening of large blood vessels. Its development process is the interruption of the left bow of this embryo between the left subclavian artery and the left common carotid artery, and the distal part of the left arch of the embryo develops into an arterial diverticulum. When the vagus left subclavian artery originates from this time, Often a large mass effect occurs behind the esophagus. The descending aorta can descend to the left or right side of the spine, and is more common on the right side. At this time, the esophageal indentation is not obvious. Esophageal angiography only shows that there is a posterior wall of the esophagus. A small transverse line of compression, which is caused by the vagus left subclavian artery crossing the spine. In a small number of cases, the posterior segment of the right aortic arch crosses the midline through the esophagus and descends to the left side of the spine. The chest radiograph is misinterpreted as a double aortic arch. Esophageal angiography shows that the esophagus advances. CT scans are mainly used to exclude mediastinal masses or to further understand their vascular types.

CT showed that the position of the right aortic arch was usually higher, mostly at the level of the left forearm vein, and it was closer to the sagittal direction than the oblique direction. There are four branches on the arch, and the order from the proximal end to the distal end of the aortic arch is the left common carotid artery, the right common carotid artery, the right subclavian artery, and the left subclavian artery. The left subclavian artery is usually larger, rising from the back of the esophagus across the spine to the left to the left of the trachea.

5, patent ductus arteriosus

Patent ductus arteriosus is one of the most common congenital heart diseases in children. The arterial catheter is the main physiological blood flow channel for fetal blood circulation. Normally, it is functionally closed after birth, and then anatomically closed, but under the influence of certain pathological conditions, the arterial catheter remains open, which becomes the patent ductus arteriosus. Because the aortic pressure is higher than the pulmonary artery pressure, blood is shunted from the aorta through the patent ductus to the pulmonary artery during systolic or diastolic phase, resulting in excessive left ventricular volume overload and pulmonary blood flow, resulting in pulmonary hypertension. And the right ventricle is overloaded. Pulmonary hypertension begins to develop from motility to resistance, eventually resulting in a right-to-left shunt.

Small catheters, small flow rate, no symptoms, no difficulty in breathing during the movement of the catheter to the upper body, easy to fatigue on weekdays, repeated respiratory infections or heart failure, or complicated with bacterial endocarditis, systemic infection symptoms Such as fever, chest pain and peripheral blood vessel embolism symptoms.

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