DESCRIPTION

• Narrowing or obstruction along the course of the aorta, typically located at the aortic isthmus opposite the ductal insertion, sometimes referred to as the “juxtaductal” thoracic aorta
• The lesion is most often discrete but may be a long segment or tortuous. It may occur at other sites, such as the abdominal aorta.
• Various types
  • Infantile
  • Childhood
• The prevalence of associations with other lesions like bicuspid aortic valve and long-term complications like hypertension indicates that this lesion may be part of a broader arteriopathy and/or endothelial disorder.

EPIDEMIOLOGY

• 0.3/1,000 of all children born
• 4–10% of liveborn children with congenitally malformed hearts
• More prevalent in males

ETIOLOGY

• Histologically, there is protrusion of intimal and medial ridges into the posterior portion of the aortic lumen.
  • Disruption of natural formation of 4th and 6th aortic arches during the 6th to 8th weeks’ gestation
  • 4th arch becomes the thoracic aortic arch and aortic isthmus
  • 6th arch becomes proximal pulmonary arteries, and distal portion becomes patent ductus arteriosus (PDA).
• Potential mechanisms of coarctation
  • Ductal tissue wrapped around or migrates into aorta and contracts postnatally leading to coarctation
  • Reduction of blood flow through the isthmus in the fetus leads to decreased growth and coarctation.

RISK FACTORS

PATHOPHYSIOLOGY

• Decreased blood flow to the lower body distal to the obstruction; relative underperfusion of the renal vessels, baroreceptors, and multiple other mechanisms combine to induce compensatory hypertension.
• Leads to elevated pressures within the left ventricle, ascending aorta and branches, including the coronary arteries, and ultimately left ventricular (LV) hypertrophy. Diastolic flow in coronaries decreases as the LV hypertrophy leads to increased LV diastolic pressure.
• In Infancy
  • If the coarctation is severe in infants, LV dysfunction and congestive heart failure (CHF) result, with low cardiac output and increased LV end-diastolic pressure.
  • Results in decreased perfusion distal to the obstruction, leading to renal acidosis, renal failure, necrotizing enterocolitis, and ultimately shock and potentially death
• In older patients
  • Long-term development of collaterals through intercostal and internal mammary arteries
  • Long-term elevated blood pressure (BP) in the coronary and carotid arteries is a risk factor for atherosclerosis.

COMMONLY ASSOCIATED CONDITIONS

• Intracardiac lesions
  • Bicuspid aortic valve 50–85%
  • Aortic Valve Stenosis 29%
  • Mitral Valve stenosis 20%
  • Ventricular septal defects in 17–33%
• Extracardiac lesions: Berry aneurysms of circle of Willis (3–10%)