Double aortic arch
Encyclopedia
Double aortic arch is a relatively rare congenital cardiovascular malformation. DAA is an of the aortic arch
Aortic arch
The arch of the aorta or the transverse aortic arch is the part of the aorta that begins at the level of the upper border of the second sternocostal articulation of the right side, and runs at first upward, backward, and to the left in front of the trachea; it is then directed backward on the left...

 in which two aortic arches
Aortic arches
The aortic arches or pharyngeal arch arteries are a series of six paired embryological vascular structures which give rise to several major arteries...

  form a complete vascular ring
Vascular ring
A vascular ring is a congenital defect in which there is an abnormal formation of the aorta and/or its surrounding blood vessels. The trachea and esophagus are completely encircled and sometimes compressed by a "ring" formed by these vessels, which can lead to breathing and digestive...

 that can compress the trachea
Vertebrate trachea
In tetrapod anatomy the trachea, or windpipe, is a tube that connects the pharynx or larynx to the lungs, allowing the passage of air. It is lined with pseudostratified ciliated columnar epithelium cells with goblet cells that produce mucus...

 and/or esophagus
Esophagus
The esophagus is an organ in vertebrates which consists of a muscular tube through which food passes from the pharynx to the stomach. During swallowing, food passes from the mouth through the pharynx into the esophagus and travels via peristalsis to the stomach...

. Most commonly there is a larger (dominant) right arch behind and a smaller (hypoplastic) left aortic arch in front of the trachea/esophagus. The two arches join to form the descending aorta
Descending aorta
The descending aorta is part of the aorta, the largest artery in the body. The descending aorta is the part of the aorta beginning at the aortic arch that runs down through the chest and abdomen. The descending aorta is divided into two portions, the thoracic and abdominal, in correspondence with...

 which is usually on the left side (but maybe right-sided or in the midline). In some cases the end of the smaller left aortic arch closes (left atretic arch) and the vascular tissue
Vascular tissue
Vascular tissue is a complex conducting tissue, formed of more than one cell type, found in vascular plants. The primary components of vascular tissue are the xylem and phloem. These two tissues transport fluid and nutrients internally. There are also two meristems associated with vascular tissue:...

 becomes a fibrous cord. Although in these cases a complete ring of two patent aortic arches is not present, the term ‘vascular ring’ is the accepted generic term even in these anomalies.

The symptoms are related to the compression of the trachea, esophagus or both by the complete vascular ring. Diagnosis can often be suspected or made by chest x-ray
Chest X-ray
In medicine, a chest radiograph, commonly called a chest X-ray , is a projection radiograph of the chest used to diagnose conditions affecting the chest, its contents, and nearby structures...

, barium esophagram, echocardiography. Computed tomography (CT) or magnetic resonance imaging (MRI) show the relationship of the aortic arches to the trachea and esophagus and also the degree of tracheal narrowing. Bronchoscopy can be useful in internally assessing the degree of tracheomalacia
Tracheomalacia
Tracheomalacia is a condition characterized by flaccidity of the tracheal support cartilage which leads to tracheal collapse especially when increased airflow is demanded....

. Treatment is surgical and is indicated in all symptomatic patients. In the current era the risk of mortality or significant morbidity after surgical division of the lesser arch is low. However, the preoperative degree of tracheomalacia
Tracheomalacia
Tracheomalacia is a condition characterized by flaccidity of the tracheal support cartilage which leads to tracheal collapse especially when increased airflow is demanded....

 has an important impact on postoperative recovery. In certain patients it may take several months (up to 1-2 years) for the obstructive respiratory symptoms (wheezing) to disappear.

Classification

Double aortic arch is a subtype of complete vascular ring
Vascular ring
A vascular ring is a congenital defect in which there is an abnormal formation of the aorta and/or its surrounding blood vessels. The trachea and esophagus are completely encircled and sometimes compressed by a "ring" formed by these vessels, which can lead to breathing and digestive...

. There are three types of double aortic arch:
  • Right dominant arch (about 70% of surgical cases)
  • Balanced or codominant (about 5%): both arches are of equal size
  • Left dominant (about 25%)


Double aortic arch with right dominant arch:
Normally there is only one (left) aortic arch. In patients with double aortic arch the ascending aorta
Ascending aorta
The ascending aorta is a portion of the aorta commencing at the upper part of the base of the left ventricle, on a level with the lower border of the third costal cartilage behind the left half of the sternum; it passes obliquely upward, forward, and to the right, in the direction of the heart’s...

 arises normally from the left ventricle but then divides into two arches, a left and a right aortic arch which join posteriorly to become the descending aorta.

The smaller left arch passes anteriorly and to the left of the trachea in the usual position. It is often joined by the ligamentum arteriosum
Ligamentum arteriosum
The ligamentum arteriosum is a small ligament attached to the superior surface of the pulmonary trunk and the inferior surface of the aortic arch...

 (or patent ductus arteriosus
Patent ductus arteriosus
Patent ductus arteriosus is a congenital disorder in the heart wherein a neonate's ductus arteriosus fails to close after birth. Early symptoms are uncommon, but in the first year of life include increased work of breathing and poor weight gain...

) where it forms the descending aorta. The left arch gives first origin to the left common carotid artery
Common carotid artery
In human anatomy, the common carotid artery is an artery that supplies the head and neck with oxygenated blood; it divides in the neck to form the external and internal carotid arteries. - Structure :...

 and then the left subclavian artery
Subclavian artery
In human anatomy, the subclavian arteries are two major arteries of the upper thorax , below the clavicle . They receive blood from the top of the aorta...

.

The right aortic arch is completing the vascular ring by passing to the right and then behind the esophagus and trachea to join the usually left-sided descending aorta. The first vessel coming off the right arch is usually the right common carotid artery
Common carotid artery
In human anatomy, the common carotid artery is an artery that supplies the head and neck with oxygenated blood; it divides in the neck to form the external and internal carotid arteries. - Structure :...

 followed by the right subclavian artery
Subclavian artery
In human anatomy, the subclavian arteries are two major arteries of the upper thorax , below the clavicle . They receive blood from the top of the aorta...

.

Double aortic arch with left dominant arch:
In this less common condition, as the name indicates, the left arch is the larger of the two aortic arches. The origins of the arm and head vessels are identical to the anatomy of double aortic arch with right dominant arch

Balanced or codominant double aortic arch:
In this rare condition both aortic arches are of the same diameter.

Signs and symptoms

Symptoms are caused by vascular compression of the airway, esophagus or both. Presentation is often within the first month (neonatal period) and usually within the first 6 months of life. Starting at birth an inspiratory and expiratory stridor
Stridor
Stridor is a high pitched wheezing sound resulting from turbulent air flow in the upper airway. Stridor is a physical sign which is produced by narrow or obstructed airway path. It can be inspiratory, expiratory or biphasic . Inspiratory stridor is common...

 (high pitch noise from turbulent airflow in trachea) may be present often in combination with an expiratory wheeze
Wheeze
A wheeze is a continuous, coarse, whistling sound produced in the respiratory airways during breathing. For wheezes to occur, some part of the respiratory tree must be narrowed or obstructed, or airflow velocity within the respiratory tree must be heightened...

. The severity of the stridor may depend on the patient’s body position. It can be worse when the baby is lying on his back rather than its side. Sometimes the stridor can be relieved by extending the neck (lifting the chin up). Parents may notice that the baby’s cry is hoarse and the breathing noisy. Frequently a persistent cough
Cough
A cough is a sudden and often repetitively occurring reflex which helps to clear the large breathing passages from secretions, irritants, foreign particles and microbes...

 is present. When the airway obstruction
Airway obstruction
Airway obstruction is a respiratory problem caused by increased resistance in the bronchioles that reduces the amount of air inhaled in each breath and the oxygen that reaches the pulmonary arteries...

 is significant there may be episodes of severe cyanosis
Cyanosis
Cyanosis is the appearance of a blue or purple coloration of the skin or mucous membranes due to the tissues near the skin surface being low on oxygen. The onset of cyanosis is 2.5 g/dL of deoxyhemoglobin. The bluish color is more readily apparent in those with high hemoglobin counts than it is...

 (“blue baby”) that can lead to unconsciousness. Recurrent are common and secondary pulmonary secretions can further increase the airway obstruction.

Secondary to compression of the esophagus babies often feed poorly. They may have difficulties in swallowing liquids with choking or regurgitating and increased respiratory obstruction during feeding. Older patients might refuse to take solid food, although most infants with severe symptoms nowadays are operated upon before they are offered solid food.

Occasionally patients with double aortic arches present late (during later childhood or adulthood). Symptoms may mimic asthma.

Causes

Little is known regarding the exact causes of aortic arch anomalies. However, the association with chromosome 22q11 deletion (CATCH 22) implies that a genetic
Genetics
Genetics , a discipline of biology, is the science of genes, heredity, and variation in living organisms....

 component is likely in certain cases.

Diagnosis

Prenatal diagnosis (fetal ultrasound):
Today the diagnosis of double aortic arch can be obtained in-utero in experienced centers. Scheduled repair soon after birth in symptomatic patients can relieve tracheal compression early and therefore potentially prevent the development of severe tracheomalacia.

Chest X-ray:
Plain chest x-rays of patients with double aortic arch may appear normal (often) or show a dominant right aortic arch or two aortic arches . There might be evidence of tracheal deviation and/or compression. Sometimes patients present with radiologic findings of pneumonia.

Barium swallow (esophagraphy):
Historically the esophagram used to be the gold standard for diagnosis of double aortic arch. In patients with double aortic arch the esophagus shows left- and right-sided indentations from the vascular compression. Due to the blood-pressure
Blood pressure
Blood pressure is the pressure exerted by circulating blood upon the walls of blood vessels, and is one of the principal vital signs. When used without further specification, "blood pressure" usually refers to the arterial pressure of the systemic circulation. During each heartbeat, BP varies...

 related movement of the aorta and the two arches, moving images of the barium-filled esophagus can demonstrate the typical pulsatile nature of the obstruction. The indentation from a dominant right arch is usually deeper and higher compared to the dent from the left arch.

Bronchoscopy:
Although bronchoscopy is not routinely done in patients with suspected or confirmed double aortic arch, it can visualize sites and severity of pulsatile tracheal compression.

Echocardiography:
In babies under the age of 12 months, echocardiography is considered to be sensitive and specific in making the diagnosis of double aortic arch when both arches are open. Non-perfused elements of other types of vascular rings (e.g. left arch with atretic (closed) end) or the ligamentum arteriosum might be difficult to visualize by echocardiography.

Computed tomography (CT):
Computed tomography
Computed tomography
X-ray computed tomography or Computer tomography , is a medical imaging method employing tomography created by computer processing...

 after application of contrast media
Radiocontrast
Radiocontrast agents are a type of medical contrast medium used to improve the visibility of internal bodily structures in an X-ray based imaging techniques such as computed tomography or radiography...

 is usually diagnostically accurate. It shows the relationship of the arches to the trachea and bronchi.

Magnetic resonance imaging (MRI):
Magnetic resonance imaging
Magnetic resonance imaging
Magnetic resonance imaging , nuclear magnetic resonance imaging , or magnetic resonance tomography is a medical imaging technique used in radiology to visualize detailed internal structures...

 provides excellent images of the trachea and surrounding vascular structures and has the advantage of not using radiation for imaging compared to Computed tomography.

Cardiac catherization/aortography:
Today patients with double aortic arch usually only undergo cardiac catherization
Cardiac catheterization
Cardiac catheterization is the insertion of a catheter into a chamber or vessel of the heart. This is done for both investigational and interventional purposes...

 to evaluate the hemodynamics and anatomy of associated congenital cardiac defects. Through a catheter in the ascending aorta contrast media is injected and the resulting aortography may be used to delineate the anatomy of the double aortic arch including sites of narrowing in the left aortic arch. Aortography can also be used to visualize the origin of all head and arm vessels originating from the two arches.

Treatment

Surgical correction is indicated in all double aortic arch patients with obstructive symptoms (stridor, wheezing, pulmonary infections, poor feeding
Dysphagia
Dysphagia is the medical term for the symptom of difficulty in swallowing. Although classified under "symptoms and signs" in ICD-10, the term is sometimes used as a condition in its own right. Sufferers are sometimes unaware of their dysphagia....

 with choking). If symptoms are absent a conservative approach (watchful waiting) can be reasonable. Children with very mild symptoms may outgrow their symptoms but need regular follow-up.

Anesthesia and intraoperative monitoring

The procedure is performed in general anesthesia. It is useful to place pulse oximeter
Pulse oximeter
A pulse oximeter is a medical device that indirectly monitors the oxygen saturation of a patient's blood and changes in blood volume in the skin, producing a photoplethysmograph. It is often attached to a medical monitor so staff can see a patient's oxygenation at all times...

 probes on both hands and one foot so that test occlusion of one arch or its branches will allow confirmation of the anatomy. In addition blood pressure cuffs should also be placed on one leg and both arms to confirm the absence of a pressure gradient
Pressure gradient
In atmospheric sciences , the pressure gradient is a physical quantity that describes in which direction and at what rate the pressure changes the most rapidly around a particular location. The pressure gradient is a dimensional quantity expressed in units of pressure per unit length...

 when the intended point of division of the lesser arch is temporarily occluded with forceps.

Open division of vascular ring

Isolated double aortic arch without associated intracardiac defects is a vascular anomaly that can be corrected without the support of cardiopulmonary bypass.

For surgical division of the narrower left aortic arch in a typical double arch patient with a dominant right arch, the patient is placed on the right side. After prepping and draping of the left chest a posterolateral thoracotomy
Thoracotomy
Thoracotomy is an incision into the pleural space of the chest. It is performed by a surgeon, and, rarely, by emergency physicians, to gain access to the thoracic organs, most commonly the heart, the lungs, the esophagus or thoracic aorta, or for access to the anterior spine such as is necessary...

 is performed. The chest cavity
Thoracic cavity
The thoracic cavity is the chamber of the human body that is protected by the thoracic wall ....

 is entered between the fourth and fifth rib (fourth intercostal space
Intercostal space
The intercostal space is the space between two ribs . Since there are 12 ribs on each side, there are 11 intercostal spaces, each numbered for the rib superior to it.-Structures in intercostal space:* several kinds of intercostal muscle...

) (as in the operation for patent ductus arteriosus
Patent ductus arteriosus
Patent ductus arteriosus is a congenital disorder in the heart wherein a neonate's ductus arteriosus fails to close after birth. Early symptoms are uncommon, but in the first year of life include increased work of breathing and poor weight gain...

 or coarctation). After pulling the left lung aside, the layer (mediastinal pleura
Mediastinal pleura
Different portions of the parietal pleura have received special names which indicate their position: thus, that portion which lines the inner surfaces of the ribs and Intercostales is the costal pleura; that clothing the convex surface of the diaphragm is the diaphragmatic pleura; that which rises...

) above the left arch is incised and the left arch and the ligamentum arteriosum
Ligamentum arteriosum
The ligamentum arteriosum is a small ligament attached to the superior surface of the pulmonary trunk and the inferior surface of the aortic arch...

 are dissected out and separated from the surrounding structures. The ligamentum is divided and two vascular clamps are placed on the junction of the left arch with the descending aorta. After division the two aortic ends are oversewn with 2 running layers of non-absorbable sutures. The end of the left arch is now further dissected from the mediastinal tissues for relief of any remaining constricting mechanism. The medial surface of the descending aorta and the distal end are also carefully dissected away from the esophagus. Additional relief can be obtained by stitching the lateral wall of the aorta to the adjacent rib to pull it away from the esophagus.

After insertion of a chest tube
Chest tube
A chest tube is a flexible plastic tube that is inserted through the side of the chest into the pleural space. It is used to remove air or fluid , or pus from the intrathoracic space...

 to prevent hemothorax
Hemothorax
A hemothorax is a condition that results from blood accumulating in the pleural cavity.-Cause and presentation:Its cause is usually traumatic, from a blunt or penetrating injury to the thorax, resulting in a rupture of the serous membrane either lining the thorax or covering the lungs...

 and/or pneumothorax
Pneumothorax
Pneumothorax is a collection of air or gas in the pleural cavity of the chest between the lung and the chest wall. It may occur spontaneously in people without chronic lung conditions as well as in those with lung disease , and many pneumothoraces occur after physical trauma to the chest, blast...

, the fourth and fifth rib are approximated by an absorbable suture. The surgery is completed by closure of the left thoracotomy wound in layers.

In most centers, the mortality
Death
Death is the permanent termination of the biological functions that sustain a living organism. Phenomena which commonly bring about death include old age, predation, malnutrition, disease, and accidents or trauma resulting in terminal injury....

 risk for surgery is between zero and 2%. A specific risk of open surgical repair of double aortic arch is injury to the recurrent laryngeal nerve
Recurrent laryngeal nerve
The recurrent laryngeal nerve is a branch of the vagus nerve that supplies motor function and sensation to the larynx . It travels within the endoneurium...

, which can cause vocal cord paralysis. Injury to the lymphatic system
Lymphatic system
The lymphoid system is the part of the immune system comprising a network of conduits called lymphatic vessels that carry a clear fluid called lymph unidirectionally toward the heart. Lymphoid tissue is found in many organs, particularly the lymph nodes, and in the lymphoid follicles associated...

 can lead to postoperative chylothorax
Chylothorax
A chylothorax is a type of pleural effusion. It results from lymphatic fluid accumulating in the pleural cavity.-Causes:...

. Additional risks include lung injury, bleeding with the need for blood transfusion
Blood transfusion
Blood transfusion is the process of receiving blood products into one's circulation intravenously. Transfusions are used in a variety of medical conditions to replace lost components of the blood...

s and wound infection.

Postoperative care

After the surgery, some patients require intubation
Intubation
Tracheal intubation, usually simply referred to as intubation, is the placement of a flexible plastic or rubber tube into the trachea to maintain an open airway or to serve as a conduit through which to administer certain drugs...

 and mechanical ventilation
Mechanical ventilation
In medicine, mechanical ventilation is a method to mechanically assist or replace spontaneous breathing. This may involve a machine called a ventilator or the breathing may be assisted by a physician, respiratory therapist or other suitable person compressing a bag or set of bellows...

 for several days to allow adequate tracheal toilet, but most patients can have the tubes removed soon after the surgery. The obstructive airway symptoms may be worse in the first postoperative weeks. Only a few patients have immediate relief of stridor, but many obtain immediate relief of problems with swallowing (dysphagia). After extubation, it might be necessary to maintain positive airway pressure by appropriate flows of a humidified oxygen/air mixture.

Epidemiology

Complete vascular rings represent about 0.5-1% of all congenital cardiovascular malformations. The majority of these are double aortic arches.
There is no known gender preference, i.e. males and females are about equally affected. There is also no known ethnic or geographic disposition.

Associated cardiovascular anomalies are found in 10-15% of patients. These include:
  • Atrial septal defect
    Atrial septal defect
    Atrial septal defect is a form of congenital heart defect that enables blood flow between the left and right atria via the interatrial septum. The interatrial septum is the tissue that divides the right and left atria...

     (ASD)
  • Ventricular septal defect
    Ventricular septal defect
    A ventricular septal defect is a defect in the ventricular septum, the wall dividing the left and right ventricles of the heart.The ventricular septum consists of an inferior muscular and superior membranous portion and is extensively innervated with conducting cardiomyocytes.The membranous...

     (VSD)
  • Patent ductus arteriosus
    Patent ductus arteriosus
    Patent ductus arteriosus is a congenital disorder in the heart wherein a neonate's ductus arteriosus fails to close after birth. Early symptoms are uncommon, but in the first year of life include increased work of breathing and poor weight gain...

     (PDA)
  • Tetralogy of Fallot
    Tetralogy of Fallot
    Tetralogy of Fallot is a congenital heart defect which is classically understood to involve four anatomical abnormalities...

     (ToF)
  • Transposition of the great arteries (D-TGA)

History

Congenital abnormalities of the aortic arch have been known for a long time. The first postmortem description of double aortic arch was in 1737 by Hommell. In 1837 von Siebold published a case report
Case report
In medicine, a case report is a detailed report of the symptoms, signs, diagnosis, treatment, and follow-up of an individual patient. Case reports may contain a demographic profile of the patient, but usually describe an unusual or novel occurrence....

 in the German medical literature
Medical journal
A public health journal is a scientific journal devoted to the field of public health, including epidemiology, biostatistics, and health care . Public health journals, like most scientific journals, are peer-reviewed...

 entitled "Ringfoermiger Aortenbogen bei einem neugeborenen blausuechtigen Kinde" (Ring-shaped aortic arch in a cyanotic neonate).

With the use of barium esophagography it became possible to diagnose aortic arch anomalies during life in the 1930s. The first open surgical correction via thoracotomy was performed by Robert E. Gross
Robert E. Gross (surgeon)
Robert E. Gross was a surgeon famous for being the first to cure patent ductus arteriosus by ligating it.-Sources:...

 at Children’s Hospital Boston in 1945. Gross is one of the pioneers of cardiovascular surgery
Cardiothoracic Surgery
Cardiothoracic surgery is the field of medicine involved in surgical treatment of diseases affecting organs inside the thorax —generally treatment of conditions of the heart and lungs .-Cardiac / Thoracic:...

, who also performed the first successful ligation of a patent ductus arteriosus
Patent ductus arteriosus
Patent ductus arteriosus is a congenital disorder in the heart wherein a neonate's ductus arteriosus fails to close after birth. Early symptoms are uncommon, but in the first year of life include increased work of breathing and poor weight gain...

 7 years earlier. The basis for the radiologic diagnosis by barium swallow
Barium meal
A barium meal, also known as an upper gastrointestinal series is a procedure in which radiographs of the esophagus, stomach and duodenum are taken after barium sulfate is ingested by a patient...

 (esophagram) of double aortic arch (and other forms of vascular rings) was described in 1946 by Neuhauser from the same institution.

Certain types of double aortic arch with a left arch that is small in diameter (less than 2 or 3mm patent) or atretic might be suitable for a so called minimally invasive video-assisted thoracoscopic surgery
Video-assisted thoracoscopic surgery
Video-assisted thoracoscopic surgery is a type of thoracic surgery performed using a small video camera that is introduced into the patient's chest via a scope. The surgeon is able to view the instruments that are being used along with the anatomy on which the surgeon is operating...

(VATS) approach.
The source of this article is wikipedia, the free encyclopedia.  The text of this article is licensed under the GFDL.
 
x
OK