Malformation of the Aortic Arch
Vascular Rings
Definition:
Term used to describe those aortic arch of pulmonary artery malformations that exhibit abnormal relation with esophagus and trachea, causing compression, dysphagia, and/or respiratory symptoms).Embryology and Anatomy
1) Total of 6 aortic arches may develop from the distal truncus arteriosus or aortic sac.
2) Arches desappear at various times during development but terminate in the two dorsal aortae.
3) First 2 arches form maxillary, hyoid, and stapedial arteries.
4) 2nd pair forms carotid arteries.
5) 3rd pair leaves aortic sac and forms right and left horns, the right horn becomes the brachiocephalic trunk and the left horn along with the 4th aortic arch becomes the arch of the aorta.
6) 6th right arch becomes right PA and the 6th left arch persists as ductus arteriosus.Pathophysiology
Trachea compression
Trachea compression is grouped as:
1) complete vascular ring
2) partial vascular ring
3) compression by innominate artery or left carotid artery
Complete vascular ring
1) Double Aortic Arch
Most common vascular ring where ascending aorta arises normally. As ascending aorta leaves pericardium it divides into right and left aortic arch that join to form descending aorta. Left arch passes anteriorly and to the left of trachea and the right aortic arch passes to the right and posterior of esophagus. Right arch becomes right common carotid and right subclavian. Left arch becomes left common carotid and left subclavian.2) Right Aortic Arch with Retroesophageal Component
1) Aorta ascends anterior to trachea and continues to right and posteriorly. Left arch is interrupted proximally to ductus arteriosus. Left sided ligamentum arteriosus extends from diverticulum on upper descending thoracic aorta behind esophagus forward to the left PA.
Interruption may also occur between left common carotid and right arch. This is common intetralogy of fallot and truncus arteriosus. Left arch can also cross behind esophagus and form a ring in combination with right patent ductus arteriosus or ligamentum arteriosus.Partial vascular ring
Left aortic arch and anomalous right subclavian artery. In this case, right subclavian artery arises as the 4th branch in an otherwise normal aortic arch, passes upward and to the right behind esophagus.Symptoms
Symtoms manifest as harsh cry, inspiratory stridor, dysphagia, chronic cough, bronchopneumonia, poor growth, failure to thrive, difficulty feeding, respiratory distress, wheezing, cyanosis, and hyperinflation of the lungs.Surgical Intervention
Surgical intervention is indicated when symptoms are severe. Approach is left posterolateral thoracotomy in most cases, identification and division of rings usually corrects the problem. Right thoracotomy is used for left sided aortic arch and right sided ligamentum arteriosus.
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