Interrupted aortic arch (IAA) is a rare congenital malformation of the cardiovascular system in which the continuity of the aortic arch is disrupted, resulting in a complete loss of luminal connection between the ascending and descending aorta. The condition is typically diagnosed in the neonatal period and requires prompt medical and often surgical intervention to ensure systemic perfusion.
Classification
IAA is most commonly classified into three anatomic types based on the site of interruption relative to the arterial branches of the aortic arch:
- Type A – interruption distal to the left subclavian artery.
- Type B – interruption between the left common carotid artery and the left subclavian artery (the most frequent type, accounting for about 60–70 % of cases).
- Type C – interruption proximal to the left common carotid artery, a very rare form.
Epidemiology
- Incidence is estimated at 0.007–0.02 % of live births, corresponding to roughly 1–3 cases per 100,000 newborns.
- Approximately 50–70 % of cases are associated with other congenital heart defects, most notably ventricular septal defect, atrial septal defect, or patent ductus arteriosus.
- A strong association exists with certain genetic syndromes, especially DiGeorge (22q11.2 deletion) syndrome; up to 40 % of patients with IAA have this chromosomal abnormality.
Pathophysiology
During embryonic development, the aortic arch forms from a series of paired dorsal and ventral aortic arches. Failure of fusion or regression of specific arch segments leads to a segmental discontinuity. In the absence of a patent ductus arteriosus (PDA) or other collateral pathways, systemic blood flow to the lower body is severely compromised.
Clinical Presentation
- Neonates often present within hours to days after birth with:
- Marked differential cyanosis or pallor (upper extremities pink, lower extremities cyanotic) when the PDA closes.
- Weak or absent femoral pulses.
- Low blood pressure in the lower extremities.
- Respiratory distress or signs of heart failure if associated lesions are present.
- Older children may exhibit exercise intolerance, hypertension in the upper extremities, and development of collateral circulation.
Diagnosis
- Physical examination revealing absent lower‑extremity pulses and blood pressure gradient.
- Chest radiography may show a "figure‑of‑8" or “egg‑on‑a‑string” sign.
- Echocardiography is the primary non‑invasive imaging modality, allowing visualization of the arch interruption, associated defects, and assessment of cardiac function.
- Cardiac magnetic resonance imaging (MRI) or computed tomography (CT) angiography provide detailed anatomic delineation, especially useful for surgical planning.
- Genetic testing for 22q11.2 deletion and other chromosomal abnormalities is recommended.
Management
- Prostaglandin E₁ (PGE₁) infusion is initiated emergently to maintain ductal patency and systemic perfusion until definitive repair.
- Surgical repair is the definitive treatment and usually performed within the first few weeks of life. Options include:
- End‑to‑end anastomosis of the aortic segments.
- Extended end‑to‑end or interposition grafts.
- Use of the PDA or a conduit to bridge the interruption in complex cases.
- In selected patients, hybrid approaches combining surgical and catheter‑based techniques have been employed.
- Post‑operative care involves monitoring for recurrent coarctation, hypertension, and neurodevelopmental outcomes.
Prognosis
- Survival rates have markedly improved with advances in neonatal intensive care and surgical techniques; contemporary 30‑day mortality is reported at 5–10 % in high‑volume centers.
- Long‑term outcomes depend on the presence of associated cardiac lesions, genetic syndromes, and the adequacy of repair.
- Hypertension and recoarctation may develop in adolescence or adulthood, necessitating lifelong follow‑up.
History
The condition was first described in the early 20th century through autopsy series. Systematic classification into Types A‑C was introduced in the 1970s, facilitating standardized reporting and surgical planning. The introduction of prostaglandin therapy in the 1970s and the evolution of cardiopulmonary bypass techniques in the 1980s significantly improved survival.
Research Directions
Current investigations focus on:
- Genetic and molecular mechanisms underlying aortic arch morphogenesis.
- Optimizing timing and technique of surgical repair to minimize neurodevelopmental sequelae.
- Long‑term vascular health, including surveillance for aortic root dilation and hypertension.
References
- Hoffman, J. I. E., & Kaplan, S. (2002). The incidence of congenital heart disease. Journal of the American College of Cardiology, 39(12), 1890–1900.
- McGowan, D. J., Emani, S. M., Musa, Y., et al. (2018). Contemporary outcomes after repair of interrupted aortic arch. Annals of Thoracic Surgery, 105(1), 104–110.
- Bassett, A. S., Glavac, D., & McDonald-McGinn, D. (2004). Interruption of the aortic arch and 22q11.2 deletion syndrome. British Journal of Cardiology, 11(3), 101‑107.