Interrupted Aortic Arch — #1 Anatomy and Classification

Date
November 7, 2025
URL
https://x.com/WithAScalpel/status/1986780344419340651
Categories
Interrupted Aortic Arch

Interrupted Aortic Arch — #1 Anatomy and Classification

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Definition & core physiology.

Interrupted aortic arch (IAA) is a congenital lesion marked by true loss of luminal continuity between the ascending and descending aorta, rendering systemic (lower-body) perfusion ductal-dependent in the newborn. When pulmonary pressures are high, the PDA delivers right-to-left flow into the descending aorta; constriction of the ductus precipitates rapid hemodynamic collapse without prompt therapy [1,2].

Anatomic landmarks.

The proximal aorta (from the LV) supplies the coronaries and head–neck vessels up to the level of interruption; the distal aorta is continuous with the ductus arteriosus. A ventricular septal defect (VSD) is present in most infants and provides obligatory mixing that modulates systemic oxygen content and pulmonary flow [2].

Classification (Celoria–Patton).

Definition is by the level of interruption relative to the arch branches [1,2]:

  • Type A — distal to the left subclavian artery.
  • Type B — between the left common carotid and left subclavian arteries (most common) [3].
  • Type C — between the innominate (brachiocephalic) and left common carotid arteries.

Type B predominates in surgical series and imaging cohorts (≈ two-thirds to >80%), with Type A less frequent and Type C rare, reflecting segmental patterns of arch remodeling failure during weeks 4–8 of gestation [3,7].

Associations and pathophysiology.

IAA is frequently complex, most often accompanied by VSD and a PDA; left-ventricular outflow tract hypoplasia/stenosis and conotruncal anomalies may coexist [2,7]. Clinically, differential blood pressure/oxygenation favoring the upper body, weak/absent femoral pulses, and a single second heart sound are typical signals of a ductal-dependent systemic circulation.

Initial stabilization.

Management priorities are to maintain ductal patency and secure adequate mixing until definitive repair. Prostaglandin E1 (PGE1) is lifesaving in ductal-dependent lesions and should be initiated promptly (e.g., 0.01–0.05 µg/kg/min, titrated to effect) [4]. Contemporary data support low-dose PGE1 (0.01 µg/kg/min) as an effective starting/maintenance dose in many neonates, reducing adverse effects while preserving patency [5]. Without intervention, natural history is dismal—untreated IAA with VSD is nearly uniformly lethal in early infancy [6].

Key takeaways.

  • IAA is a true anatomic disconnection of the arch with ductal-dependent systemic flow.
  • Celoria–Patton A/B/C classification anchors description; Type B is most common [1–3,7].
  • VSD and PDA are the rule, not the exception; stabilization hinges on PGE1 and supportive care pending definitive reconstruction [2,4,5].

References

[1] Celoria GC, Patton RB. Congenital absence of the aortic arch. Am Heart J. 1959;58:407-413. PubMed

[2] Reardon MJ, Hallman GL, Cooley DA. Interrupted aortic arch: brief review and summary of an eighteen-year experience. Tex Heart Inst J. 1984;11(3):250-259. PubMed+1

[3] Dillman JR, Yarram SG, D’Amico AR, Hernandez RJ. Interrupted aortic arch: spectrum of MRI findings. AJR Am J Roentgenol. 2008;190(6):1467-1474. PubMed

[4] Akkinapally S, Chirla D, Aradhya AS, et al. Prostaglandin E1 for maintaining ductal patency in neonates with ductal-dependent cardiac lesions. Children (Basel). 2018;5(6):87. PMC

[5] Vari D, Gray C, Panesar S, et al. Low-dose prostaglandin E1 is safe and effective for critical congenital heart disease: is it time to revisit the dosing guidelines? Cardiol Young. 2021;31(2):191-197. PubMed

[6] Kron IL, Rheuban KS, Nolan SP, et al. Interrupted aortic arch. A conservative approach for the sick neonate. Ann Thorac Surg. 1983;36(1):19-24. PubMed

[7] Schreiber C, Mazzitelli D, Haehnel JC, Lorenz HP, Meisner H. The interrupted aortic arch: an overview after 20 years of surgical treatment. Eur J Cardiothorac Surg. 1997;12(3):466-469. PubMed