Congenital Coarctation of the Aorta

Definition

Coarctation of the aorta (CoA) is a congenital heart defect characterized by a pathological narrowing of the aortic arch, typically located at the aortic isthmus, between the origin of the left subclavian artery and the ductus arteriosus. This condition obstructs blood flow from the left ventricle to the systemic circulation, leading to hypertension in the upper body and hypoperfusion of the lower extremities.

Embryology and Pathogenesis

Coarctation of the aorta develops during fetal life and can be attributed to various embryological abnormalities, including:

Abnormal closure of the ductus arteriosus: Persistence of ductal tissue in the aortic isthmus may lead to progressive narrowing of the aortic wall.
Defects in neural crest cell migration: Abnormalities in the conotruncal septum can affect aortic arch remodeling.
Genetic factors: Mutations in the NOTCH1 and NKX2-5 genes have been associated with isolated CoA or CoA combined with other congenital heart anomalies.

Classification

Coarctation of the aorta can be classified based on the morphology and location of the narrowing:

Pre-ductal coarctation: The narrowing is located before the ductus arteriosus; common in Turner syndrome.
Ductal coarctation: The narrowing coincides with the ductus arteriosus and may manifest upon its closure.
Post-ductal coarctation: The stenosis is distal to the ductus arteriosus and often presents in adulthood.

Pathophysiology

The aortic narrowing creates a significant pressure gradient between the proximal and distal circulation, leading to:

Hypertension above the coarctation: Affects the carotid and subclavian arteries, predisposing to left ventricular hypertrophy.
Hypoplasia of the distal circulation: Reduced perfusion to the lower limbs can cause claudication and muscle hypotrophy.
Development of collateral circulation: Blood bypasses the stenosis via intercostal and internal mammary arteries to compensate for the hemodynamic deficit.

Clinical Manifestations

The severity of symptoms depends on the degree of stenosis and the patient’s age at presentation:

Neonates with critical coarctation: May present with acute heart failure, cardiogenic shock, and metabolic acidosis after ductus arteriosus closure.
Children and adolescents: Often asymptomatic but may have hypertension and heart murmurs audible in the thoracic area.
Undiagnosed adults: May develop intracranial aneurysms, hemorrhagic stroke, and congestive heart failure.

Diagnosis

Diagnosis of CoA relies on clinical and imaging studies:

Physical examination: Weak or absent femoral pulses, blood pressure differential between upper and lower extremities.
Doppler echocardiography: First-line modality to assess pressure gradients and associated anomalies.
CT angiography and cardiac MRI: Advanced imaging techniques for detailed anatomical evaluation of the aorta.
Cardiac catheterization: Used in patients undergoing percutaneous correction.

Treatment

The management of CoA depends on the severity of the obstruction and patient age:

Prostaglandins (PGE1): Administered in neonates with critical CoA to keep the ductus arteriosus open and ensure systemic perfusion.
Balloon angioplasty with stenting: A minimally invasive technique used in older children and adults.
Surgical repair: The primary option in neonates and young children, including end-to-end anastomosis, patch aortoplasty, or interposition of a prosthetic graft.

Prognosis

If treated early, coarctation of the aorta has an excellent prognosis, with normal life expectancy. However, long-term follow-up is necessary due to the risk of residual hypertension, restenosis, and aortic aneurysms.

Conclusion

Coarctation of the aorta is a potentially severe congenital defect, but with early diagnosis and proper treatment, prognosis can be significantly improved. Advances in echocardiography, cardiac MRI, and interventional cardiology have revolutionized the management of this condition, reducing mortality and improving long-term outcomes.

Bibliografia

Beerman LB et al. "Coartazione dell'aorta." *Children's Hospital of Pittsburgh of the University of Pittsburgh School of Medicine*.
Kim YY et al. "Aortic Coarctation." *Cardiology Clinics*, 2020;38(3):337-351.
Abbruzzese PA et al. "Aortic coarctation: an overview." *Journal of Cardiovascular Medicine*, 2007;8(2):123-8.
Graziano S et al. "Coartazione aortica: definizione, diagnosi e trattamento." *Tesi di Laurea*, Università degli Studi di Padova, 2024.
Ballerini L et al. "Il trattamento della coartazione dell'aorta." *Centro Lotta Infarto*, Atti del Convegno 2013.