Vascular Rings Treatment & Management

No medical therapy exists for the definitive treatment of vascular rings. Preoperatively, the patient should be given adequate nutritional support as well as general respiratory care and appropriate treatment of any respiratory tract infection. Surgery should not be delayed in the presence of a respiratory tract infection, because the division of the ring allows more adequate and complete clearing of respiratory secretions.

Surgical division of symptomatic vascular rings is the only appropriate form of therapy. Surgery should be performed promptly after the diagnosis is made, especially in patients with stridor, apnea, or other symptoms of respiratory distress. Delay in operative intervention can result in complications of a serious nature. Left thoracotomy is the surgical approach of choice for the division of a vascular ring in the majority of cases. Anomalous left pulmonary artery has been corrected using the left thoracotomy approach in the past. More recently, the use of median sternotomy and cardiopulmonary bypass has been shown to produce better long-term results. The extremely rare configurations associated with left aortic arch and right descending thoracic aorta are the lesions that should be approached via a right thoracotomy for division of the ring.

Division of a double aortic arch

The left chest is entered through the fourth intercostal space. The mediastinal pleura is opened, and the components of the vascular ring are visualized.

The right, or posterior, arch does not require mobilization unless it is the lesser of the 2 arches and is to be divided. In such cases, the proximal descending aorta should be reflected anteriorly to visualize the area where the right arch enters.

In cases of double aortic arch, the nondominant, or smaller, arch is divided. If one arch is atretic, it is the obvious choice for division. A likely site for division of the minor, or atretic, arch is at its point of juncture with the descending aorta.

Division of the chosen arch should be performed between applied vascular clamps. Prior to actual division, the strength of the right and left carotid and the radial pulses should be evaluated with the vascular clamps applied. Diminution or absence of the pulse in one or several of these areas indicates that division of the arch at the chosen location would result in interruption of blood flow to that area. In such cases, another site for division should be chosen.

Perfusion to the lower extremities should be assessed prior to division of 1 of 2 equal-sized patent arches.

The ends of the divided arch should be oversewn with fine, nonabsorbable vascular suture.

The ligamentum arteriosum and any other fibrous bands around the trachea or esophagus in that area should be divided as well.

Identify and avoid the recurrent laryngeal and vagus nerves. Closure of the mediastinal pleura is not performed to avoid the development of adhesive scarring in the already affected area of the trachea and esophagus.

Division of a vascular ring in cases with right aortic arch anatomy

In cases of complete vascular rings with right aortic arch anatomy, the primary structure to be divided is the ligamentum arteriosum.

After left thoracotomy, the anatomy should be dissected out and clearly visualized.

The vagus and recurrent nerves should be visualized and preserved.

The ligamentum is divided between vascular clamps and the ends oversewn. After ligamentum division, any associated fibrous or adhesive bands in the area are also divided.

In cases of right aortic arch with mirror-image branching and retroesophageal ligamentum arteriosum, a prominent or aneurysmal Kommerell diverticulum may be present. If so, it should be resected over a partially occluding vascular clamp and primarily oversewn or mobilized with adjacent descending aorta so that it may be pexed or transfixed to nearby vertebral fascia. If left alone, these diverticula can contribute to the compression on the trachea and esophagus. A few authors have advocated division of the aberrant left subclavian artery in these cases as well, but this is very rarely indicated for relief of the symptoms caused by the ring and may cause symptoms of subclavian steal later.

Repair of anomalous left pulmonary artery

In the past, this abnormality was approached through either a right or a left thoracotomy. Presently, many centers utilize a median sternotomy approach with the aid of cardiopulmonary bypass. Others continue to report excellent results performing the corrective surgery using a left thoracotomy.

In cases using median sternotomy and bypass, aortic and single right atrial cannulation is employed. The infant is cooled to 32°C so that the normal cardiac rhythm is maintained.

The left pulmonary artery is identified at its junction with the right and is dissected out as far to the left as possible, taking care to avoid injury to the membranous portion of the trachea. Its origin is often on the posterior surface of the right pulmonary artery and to the right of the trachea.

The pericardium is opened on the posterior left side near the site where the ligamentum arteriosum meets the pulmonary artery. The left pulmonary artery is identified in this area and freed from surrounding adhesions.

A partially occluding clamp is placed on the right pulmonary artery at the site of its junction with the left, which is then transected. The orifice left in the right pulmonary artery is closed primarily with fine interrupted polypropylene sutures.

The partial occluding clamp is released and replaced on the main pulmonary artery posteriorly where an arteriotomy is made. The location of the clamp on the main pulmonary artery is critical so that the left pulmonary artery is without deformity after the anastomosis.

The divided left pulmonary artery is brought through the path created for it behind the trachea and into the pericardium through the left-sided pericardial opening. It is sewn to the arteriotomy with interrupted fine polypropylene sutures.

Tracheal anomalies associated with anomalous left pulmonary artery

As many as 50% of patients with aberrant left pulmonary artery may have the associated anomaly of complete tracheal rings. In these infants, the membranous portion of the trachea is congenitally absent. This abnormality results in tracheal stenosis/malacia and significantly adds to the morbidity of surgery.

The diagnosis of tracheal/bronchial malacia is made using rigid bronchoscopy.

The choice of repair depends upon the length of the trachea involved and may involve resection and end-to-end anastomosis in cases with short segment involvement to a variety of tracheoplasty procedures for long segment abnormalities.

When tracheal stenosis secondary to complete tracheal rings is found in association with an aberrant pulmonary artery, the 2 abnormalities may be repaired during the same operative procedure. The approach for this is median sternotomy, and cardiopulmonary bypass is used.

Congenital cardiac defects associated with anomalous left pulmonary artery

Intracardiac defects are commonly associated with an anomalous left pulmonary artery. Depending on the type of intracardiac pathology, the surgeon must use discretion in deciding to correct or palliate the cardiac defect at the same setting or at a later time.

Anomalous innominate artery

Tracheal compression from an aberrant innominate artery is most often approached via an anterolateral right thoracotomy. The right lobe of the thymus is removed, avoiding injury to the phrenic nerve. The pericardium immediately beneath this area is opened, and the innominate artery is identified near its junction with the aorta.

The treatment of this condition simply involves tacking the innominate artery to the posterior sternal surface. The innominate artery is affixed to the posterior periosteal layer of the sternum using interrupted polypropylene sutures with pledgets. The sutures are each passed through the adventitia of the innominate artery and then through the periosteal layer of the sternum. Usually about 3 sutures are used and placed at intervals along the length of the artery, with the most proximal one placed at the junction of the innominate artery and the aorta. When these sutures are tied, the innominate artery is pulled away from the anterior surface of the trachea, relieving the compression.

Left aortic arch with right descending aorta lesions

These are extremely rare lesions, but they are the lesions that must be approached via a right thoracotomy.

Division of the ring in these cases is accomplished by dividing the right-sided ligamentum arteriosum.

Patients having this anomaly often have associated congenital cardiac defects and commonly receive extensive preoperative workup.

Although left thoracotomy can be used as the surgical approach for the vast majority of vascular rings, the surgeon must have exact delineation of the type of vascular ring present as well as associated tracheal or intracardiac abnormalities so that the proper surgical approach can be made.

Although a large percentage of vascular rings can be diagnosed using a simple and inexpensive barium esophagram, additional studies should be performed if any question about the exact configuration of the abnormality exists prior to surgery.

Because the airway problems associated with vascular rings can cause the most severe complications, preoperative airway management is of paramount importance in these patients, especially those presenting with severe respiratory problems very early in life.

The infant with a vascular ring who requires intubation for respiratory distress prior to surgery should not be considered completely safe from airway complications simply because he/she is intubated. Small amounts of flexion or extension of the neck in these infants can cause the position of the endotracheal tube to change in relation to the area of tracheal constriction, producing difficulties with ventilation and oxygenation. The endotracheal tube position and ventilatory status of the patient must be carefully monitored in the operating room, especially during the positioning of the patient for surgery.

When a thoracotomy approach is chosen, a muscle-sparing incision is preferred.

In the thorax, delineating all of the anatomic features of the vascular ring before dividing the appropriate structure is important. In all cases, the phrenic, vagus, and recurrent laryngeal nerves should be identified and preserved intact.

Good communication between the surgeon and anesthesiologist is essential during the operative procedure. This is especially true when vascular clamps are applied to a portion of an arch to be divided or to a ligamentum arteriosum prior to division. The constricting effect of the vascular ring is increased temporarily by the placement of the clamps, and airway constriction may be transiently more severe. The surgeon should announce the time of clamp application, forewarning the anesthesiologist that oxygenation may worsen or ventilation may become more difficult. The anesthesiologist may then be able to compensate with other supportive measures.

Monitoring pulse oximetry and blood pressure in both upper extremities and one lower extremity is important in the case of a double aortic arch in which a patent arch is divided. These measurements help to confirm the vascular anatomy and verify that no difference in blood pressure is produced when the arch to be divided is temporarily occluded.

Immediate postoperative management after division of a vascular ring is performed in an intensive care unit. The majority of patients are able to be extubated immediately or within a short time after surgery. Oxygen with high humidity should be administered, and chest physiotherapy should be provided as needed. For those infants with ongoing wheezing or stridor, nebulizer treatment is helpful. Pulse oximetry should be monitored.

About 10% of infants may continue to have noisy breathing for a while after surgery. Communicating this fact to the child's parents is important. Total relief of symptoms may take several months to a year in some cases. Many of these residual postoperative symptoms are related to the presence of some degree of malacotic change of the trachea or major bronchi at the site where the tightest constriction occurred. In the vast majority of cases, growth and appropriate stiffening of the tracheal cartilages takes place.

Infants who must undergo tracheal reconstruction in addition to repair of a vascular ring have the trachea stented with an endotracheal tube for at least 1 week. When the infant is extubated, bronchoscopy is performed first to eliminate excess granulation tissue and any secretions present. Dilation may be performed at this time if necessary.

Most patients are essentially asymptomatic within a few weeks after surgery and can resume activity and feedings as tolerated.

A small group continues to have some symptoms postoperatively; however, these findings are less prominent than those noted preoperatively in the majority of cases. These patients should show gradual improvement over 6-12 months, and most eventually become asymptomatic. This group may require closer follow-up in the immediate postoperative outpatient period so that early diagnosis and treatment of common forms of pediatric airway infections that result in epiglottitis or tracheobronchitis may be performed.

Patients who undergo more extensive surgery, especially tracheal reconstruction, require long-term follow-up. They may require bronchoscopy at regular intervals for elimination of encroaching granulation tissue and for tracheal or bronchial stenosis.

Patients who have associated congenital cardiac disease require regular follow-up with a pediatric cardiologist.

Serious surgical complications are rare in most reported surgical series of vascular ring division. Most complications associated with these problems occur in the preoperative setting and may even occur before the diagnosis is known. The majority of these are related to airway obstruction. Postoperatively, atelectases and pneumonias can and do occur. Pain from the thoracotomy incision can be long-lasting in some patients and can hamper breathing efforts.

Complications related to surgery itself are uncommon in most cases. Injury to the phrenic, vagus, or recurrent laryngeal nerve may occur. Disruption of the thoracic duct is also possible. Late vascular complications, such as subclavian steal, may be noted in cases in which division of a brachiocephalic vessel, such as a retroesophageal subclavian artery, was deemed necessary.

Rare cases in which symptoms of airway obstruction persist may require resection of a severely malacotic segment of trachea or bronchus or a more complex tracheoplasty procedure.

One series reported 2 very rare cases in which a vascular ring that was originally identified as right arch with retroesophageal left subclavian artery and left ligamentum arteriosum was divided via left thoracotomy with no postoperative improvement in symptoms. These patients were described as having a circumflex aorta in which it appeared that the posterior arch itself made up a portion of the obstructing ring. Additional surgery was required in these patients. A second procedure was performed via median sternotomy with cardiopulmonary bypass support in which the posteriorly positioned aortic arch was divided at the point where it traveled around the right side of the trachea and esophagus. The divided leftward portion was brought anterior to the trachea and esophagus on the left and reanastomosed to the portion from which it was originally divided. Fortunately, such cases are extremely rare.

About 95% of patients who undergo surgical correction of a vascular ring survive long term, and most of these are soon relieved of their symptoms. In those infants with no intracardiac or extracardiac defects, surgery for vascular rings carries essentially no mortality.

Among those with less optimal long-term results are patients with an anomalous left pulmonary artery with and without complete tracheal rings and those with severe associated congenital cardiac defects. In those patients with a severely deformed trachea or tracheomalacia, additional reconstruction procedures may be required in the future.

A number of patients continue to show evidence of some pulmonary function abnormalities years after surgery. Several studies report that measured pulmonary function studies show some degree of airway obstruction in as many as 50% of patients 7-8 years postoperatively. Also, a large number of patients appear to have a pronounced bronchial responsiveness to histamine.

Video-assisted thoracic surgical (VATS) techniques have been used for some pediatric thoracic surgical procedures. Several centers have successfully employed this technology for patent ductus arteriosus ligation.

While some reported use of VATS for vascular ring division exists, this remains a controversial area. Most of the cases reported are those in which an atretic arch or a ligamentum arteriosum was divided.

Use of this technology for division of a patent arch remains in question. The main objection to its use in such cases is the increased intraoperative risk of bleeding. The concern is that if vascular clips are applied to a patent arch and the arch is then divided, the amount of recoil of the divided ends that usually occurs may cause one of the clips to dislodge, resulting in severe hemorrhage. Because of the constraints of video-assisted techniques, the surgeon may have difficulty ascertaining when complete occlusion of the arch by the vascular clips has occurred. Because present open techniques provide excellent operative results with extremely low mortality rates and low morbidity, minimally invasive methods will have to provide the same assurance of safety and efficacy to be applicable.