Right And Double Aortic Arch

Right Aortic Arch And Double Aortic Arch – Genetics, Diagnosis, Prognosis

Embryology

  • Normal anatomy results from persistence of the left 4th arch and regression of the right.
  • Right Aortic Arch (RAA): persistence of the right 4th arch with regression of the left.
  • Double Aortic Arch (DAA): persistence of both arches, forming a complete vascular ring around trachea and esophagus.

Right Aortic Arch (RAA)

Definition

Aortic arch courses to the right of the trachea.

Subtypes

1. RAA with aberrant left subclavian artery (ALSA)

  • Often forms a vascular ring with the ligamentum arteriosum
  • Most common subtype

2. RAA with mirror-image branching

  • Branching mirrors normal left arch
  • Usually no vascular ring
  • Often associated with intracardiac CHD

3. RAA with isolated left subclavian artery (rare)

  • Strongly associated with 22q11.2 deletion

Prenatal Ultrasound Diagnosis

Three-vessel–trachea (3VT) view

Findings:

  • Aortic arch seen to the right of the trachea
  • V-shaped configuration with ductus depends on subtype

Subtype clues:

  • RAA + left ductus → U-shaped ring (suggests vascular ring)
  • RAA + right ductus → mirror-image branching

Associated Cardiac Anomalies (RAA)

  • Tetralogy of Fallot (most common)
  • Truncus arteriosus
  • Pulmonary atresia with VSD
  • Ventricular septal defect

CMA is recommended for all prenatally diagnosed RAA, even if isolated.

Prognosis (RAA)

  • Isolated RAA, no vascular ring: Excellent, often asymptomatic
  • RAA with vascular ring: Possible postnatal feeding or respiratory symptoms
  • RAA with CHD: Prognosis driven by cardiac lesion

Most isolated cases have normal neurodevelopment.

Double Aortic Arch (DAA)

Definition

Persistence of both right and left aortic arches, forming a complete vascular ring.

Prenatal Ultrasound Diagnosis

3VT view:

  • Trachea encircled by two arches
  • Classic “O-shaped” ring around trachea

Genetic

  • Lower association with 22q11.2 deletion compared with RAA
  • Most cases are sporadic

Postnatal Course and Prognosis (DAA)

  • High likelihood of postnatal symptoms:
    • Stridor
    • Recurrent respiratory infections
    • Feeding difficulties
  • Symptoms often appear in infancy

Surgical correction (division of the smaller arch) is usually required and is highly effective.

Long-term prognosis after surgery is excellent.

RAA vs DAA

Take-Home Points

  • RAA ≠ DAA biologically or prognostically
  • 3VT view is the cornerstone of prenatal diagnosis
  • 22q11.2 deletion testing is critical for RAA
  • Long-term outcomes are generally very good with appropriate follow-up