Baby With Asthma and Vomitting

at first glance some more probable differentials outshine:
Esophageal Duplication,Esophageal Atresia,Neurogenic Tumor,Vascular Anomaly,Foreign Body


But lets take a look at the patient's CT images:











Now we have a more precise image of the underlying abnormality. 
which is the most likely diagnosis ?
a.Double Aortic Arch
b.Right Aortic Arch with aberrant left subclavian artery
c.Left Aortic Arch with aberrant right subclavian artery
d.Transposition of great vessels
e.Tetralogy of Fallot
-----------------------------------------------------------------------------------------------------------


Findings :


CXR: Mild indentation of the right distal aspect of the trachea. Barium swallow: There is an abnormal indentation of the posterior esophagus. 
CT: Right aortic arch with aberrant left subclavian artery coursing behind the esophagus and compressing it. This is consistent with a vascular ring. The aorta descends on the right and then crosses to the left at the level of the crus. Trachea is mild to moderately narrowed at the level of the vascular ring.


Diagnosis:  Right aortic arch with aberrant left subclavian artery (left SCA)

Discussuion:

• Right arch is present in 0.1% of asymptomatic population
• 10-15% with associated congenital heart disease (tetralogy of fallot most common) compared to patients with mirror image branching type of right aortic arch who have >90% chance of having associated congenital heart disease
• May present with symptoms (stridor, dysphagia, cough), but most are asymptomatic
• Most common congenital anomaly of aortic arch
• Related to embryological persistence of the right fourth aortic arch
• Diverticulum of Kommerell is dilatation of origin of left SCA (occurs in 60% of right arch with aberrant left SCA)
• Left SCA can arise directly from the descending aorta or can arise from diverticulum of Kommerell)
• The left ductus persists as ligamentum arteriosum, which completes the vascular ring
  • Left ligamentum arteriosum connects to subclavian artery= loose vascular ring
  • Left ligamentum arteriosum connects to diverticulum of Kommerell= tight vascular ring (constricting, symptomatic)

Treatment:

• Right arch with aberrant left SCA and constricting (symptomatic) left ligamentum arteriosum: Division of ligamentum via left thoracotomy

Radiological overview:

• Aortic arch located to right of trachea, coursing over right main stem bronchus
• Large vessel arising from the distal aorta and passing behind the esophagus with oblique course to the left
• In 60% there is dilatation of the origin of the aberrant subclavian artery (aortic diverticulum of Kommerell)
• Aorta descends on right and crosses to left before entering abdomen
• 4 branches off aortic arch: Right subclavian artery, right carotid artery, left carotid artery, left subclavian artery
• CXR:
  • Aortic arch indentation on right of trachea, which is deviated to the left
  • Increased right paravertebral soft tissue density
  • Right-sided descending aorta line
  • Lateral shows indentation on the posterior aspect of the trachea
  • There may be prominence of the left mediastinum
• Barium swallow:
  • Frontal view: Oblique filling defect coursing from right-inferior to left-superior
  • Lateral view: Posterior indentation
• CT: Define patency of arch segments, branching patterns, depict constricting effect on tracheal airway, if present
• Indications for additional imaging:
  • Right arch with airway compression and aberrant left SCA on esophagram: Perform cross-sectional imaging
  • Right arch, mirror image branching pattern: Evaluate for congenital heart disease

Key points:

• Most common congenital anomaly of aortic arch
• 10-15% with congenital heart disease
• Most asymptomatic
• Vascular ring formed by ligamentum arteriosum connecting to left subclavian artery or diverticulum of Kommerell
• Aberrant left subclavian courses behind the esophagus
• Right aortic arch courses over right main stem bronchus