What is the recommended diagnostic and management approach for a newborn with a suspected right-sided aortic arch?

Echocardiographic Imaging Approach for Right-Sided Aortic Arch in Newborns

Transthoracic echocardiography (TTE) is the essential first-line diagnostic test for evaluating a newborn with suspected right-sided aortic arch, specifically utilizing the 3-vessel view and 3-vessel tracheal view to identify the arch sidedness, branching pattern, and presence of a complete vascular ring. 1, 2

Initial Echocardiographic Assessment

Critical Views and Findings

• The 3-vessel view and 3-vessel tracheal view are mandatory for detecting and characterizing right aortic arch (RAA) anomalies, as routine cardiac views will miss these abnormalities 2

• Look for the "U-shaped" or "V-shaped" appearance at the junction between the ductus arteriosus and aortic arch in the upper mediastinal view 3:

  • U-shaped appearance indicates a complete vascular ring (CVR) in 100% of cases, which occurs in 82% of RAA cases 3
  • V-shaped appearance indicates RAA with right ductus arteriosus and mirror-image branching, not forming a CVR 3

• Assess the relationship of the aortic arch to the trachea to determine arch sidedness and identify aberrant vessel origins 2, 3

Key Anatomic Variants to Identify

The echocardiogram must distinguish between three main RAA patterns 4, 3:

1. RAA with aberrant left subclavian artery (ALSA) and left posterior ductus arteriosus - represents 30-35% of vascular rings and is the second most common vascular ring type 4

2. RAA with mirror-image branching - may or may not form a vascular ring depending on ductus arteriosus position 3

3. Double aortic arch - always forms a complete vascular ring 4, 3

Assessment for Associated Cardiac Defects

• Screen carefully for congenital heart disease (CHD), particularly tetralogy of Fallot, ventricular septal defects, and other conotruncal abnormalities 1, 4

• RAA forming a CVR (U-shaped) is associated with septal defects in only 16% of cases, while RAA not forming a CVR is associated with major CHD in 75% of cases 3

• If intracardiac abnormalities are identified, TTE provides comprehensive evaluation of ventricular function, valve morphology, and hemodynamics 1

When TTE is Inadequate

Advanced Imaging Indications

If TTE provides inadequate visualization of the aortic arch anatomy, proceed with cross-sectional imaging 1:

• CT angiography (CTA) chest is the preferred next study for detailed arch anatomy, branch vessel origins, and surgical planning in children with suspected aortic arch anomalies 1, 5

• CTA provides complete visualization of the aortic arch, branch vessels, presence of Kommerell's diverticulum (present in 20-60% with aberrant subclavian artery), and relationship to trachea and esophagus 1, 4, 5

• MRI/MRA may be preferred for serial follow-up imaging in young patients to minimize cumulative radiation exposure 1, 5, 6

Clinical Risk Stratification

Symptoms Requiring Urgent Evaluation

• Approximately 25% of vascular rings become symptomatic, primarily in the first 2 years of life 4

• Watch for respiratory distress, upper airway obstruction, stridor, dysphagia, and vomiting from tracheal and esophageal compression 4, 7

• Neonates with RAA may present with life-threatening airway complications requiring immediate intervention 4

Physical Examination Priorities

• Examine pulse volume in all four extremities and both carotid arteries to detect differential pulses suggesting arch obstruction 1

• Obtain blood pressure readings in all four extremities to identify coarctation or interruption 1

• Assess respiratory rate while infant is asleep: abnormal if >50 breaths/min in infants <2 years 1

• Look for hepatomegaly, diaphoresis, and mottling as signs of heart failure 1

Management Pathway

Asymptomatic Newborns

• If TTE confirms isolated RAA without CVR and no CHD, clinical observation with parental education about potential symptoms is appropriate 7, 3

• If CVR is present on TTE, obtain CTA for surgical planning even if asymptomatic, as 25% will develop symptoms 1, 4, 7

Symptomatic Newborns

• Moderate-to-severe respiratory or feeding symptoms mandate surgical intervention through left thoracotomy or median sternotomy 7

• Surgery involves division of the left ductal ligamentum; if Kommerell's diverticulum is >1.5 times the subclavian artery diameter, concomitant resection and vessel translocation is required 7

• Tracheomalacia may persist postoperatively and sometimes requires additional tracheal surgery 4

Critical Pitfalls to Avoid

• Do not rely on chest radiography alone - it has limited sensitivity and will miss most arch anomalies 1, 5

• Do not withhold oxygen administration based solely on suspected arch anomaly unless there is confirmed ductus-dependent systemic circulation (e.g., hypoplastic left heart syndrome) 1

• Do not assume RAA is isolated - always complete full cardiac evaluation as CHD associations are common 4, 3

• Recognize that transesophageal echocardiography has limited utility in newborns for arch imaging and is more invasive than CTA 1