What is coarctation of the aorta?

What is Coarctation of the Aorta?

Coarctation of the aorta is a congenital narrowing of the aorta—typically occurring just distal to the left subclavian artery at the ligamentum arteriosum—that obstructs blood flow, causing upper extremity hypertension and lower extremity hypoperfusion, requiring lifelong surveillance even after successful repair. 1

Anatomic Characteristics

• The narrowing can be discrete (short-segment stenosis) or diffuse (hypoplastic segment), most commonly located in the juxtaductal region where the ductus arteriosus inserts 2, 1, 3
• The lesion may extend to involve the aortic arch or isthmus in some cases 1
• An intrinsic abnormality exists in the aortic wall itself, predisposing patients to dissection or rupture at the coarctation site or in the ascending aorta 1
• Extensive collateral vessels develop proximal to the obstruction to bypass the narrowed segment, which can reduce measured gradients and mask true severity 1

Epidemiology and Incidence

• Coarctation accounts for 6-8% of all congenital heart diseases 2
• The incidence is approximately 3-4 per 10,000 live births 4, 5
• The prevalence is approximately 7% per million live births 2

Associated Cardiac Abnormalities

• Bicuspid aortic valve occurs in 50-85% of coarctation patients and requires concurrent lifelong surveillance 2, 1
• Other associated lesions include aortic arch hypoplasia, aberrant aortic branch vessels, ventricular septal defect, patent ductus arteriosus, and subaortic stenosis 2, 1, 6
• Complex associations can occur with hypoplastic left heart syndrome, transposition of the great arteries, or truncus arteriosus 2
• Intracranial (circle of Willis) aneurysms occur in approximately 10% of patients 1
• Ascending aortic aneurysms are also associated with coarctation 1
• Turner syndrome is present in up to 12.6% of females with coarctation, and coarctation occurs in 7-18% of Turner syndrome patients 1

Clinical Presentation

Neonatal Presentation

• Neonates may present in critical distress with metabolic acidosis and respiratory failure at the time of ductal closure if the lesion is ductal-dependent 2
• These infants require prostaglandin infusion and supportive measures until definitive treatment 2
• Coarctation is the critical cardiac lesion most likely to go undetected on pulse oximetry-based newborn screening 7

Older Children and Adults

• Presentation typically occurs with hypertension, heart murmur, and diminished lower extremity pulses 2
• Mild cases may only become evident in adulthood when hypertension is detected 3
• Chest X-ray may demonstrate rib notching from large collateral vessels in older patients 2

Pathognomonic Physical Examination Findings

• The hallmark finding is brachial-femoral pulse delay with decreased amplitude or absent femoral pulses compared to brachial pulses 1
• Hypertension is present in the right arm relative to the lower extremities (unless anomalous origin of the right subclavian artery exists) 1
• A blood pressure differential >20 mmHg between upper and lower extremities suggests significant coarctation 1
• Every patient with systemic arterial hypertension should have brachial and femoral pulses palpated simultaneously to assess for brachial-femoral delay 1

Natural History and Complications

• The natural course is driven by hypertension-related complications including heart failure, intracranial hemorrhage, premature coronary/cerebral artery disease, and aortic rupture/dissection 3
• Aortic dissection can occur both above and below the coarctation site, typically in the third decade of life or later in untreated cases 3
• Hypertension remains an important complication even after successful treatment, particularly when initial repair is performed in adulthood 1, 3
• Pregnancy represents a period of increased risk for aortic complications including dissection 3

Diagnostic Approach

Initial Evaluation

• Transthoracic echocardiography is the first-line imaging modality for suspected coarctation 2, 1, 6
• Blood pressure measurements at both arms and one lower extremity are mandatory in all suspected cases 8, 1, 3

Advanced Imaging

• Every patient with coarctation (repaired or not) should have at least one cardiovascular MRI or CT scan for complete evaluation of the thoracic aorta 1
• CMR or cardiac CT should visualize the entire thoracic aorta, define coarctation anatomy, assess for arch hypoplasia, identify collateral vessels, and detect aneurysms 8
• CTA chest is complementary after echocardiography and assists with surgical planning, particularly for identifying arch hypoplasia severity and aortic branch vessel origins 2
• MRA chest can be combined with MRI heart function to quantify collateral flow, estimate pressure gradients, and assess associated cardiac abnormalities 2

Hemodynamic Assessment

• Invasive catheterization with manometry remains the gold standard for confirming hemodynamic significance (peak-to-peak gradient >20 mmHg) before intervention 8
• Cardiac catheterization is primarily used when catheter-based interventions such as balloon angioplasty or stent insertion are being considered 2

Treatment Approaches

Indications for Intervention

• Intervention is indicated when hypertension (>140/90 mmHg in adults) and a non-invasive arm-to-leg gradient >20 mmHg are present, confirmed with invasive peak-to-peak measurement >20 mmHg 8, 1, 3
• Hypertensive patients with >50% aortic narrowing relative to the diameter at the diaphragm level should be considered for endovascular treatment even if the invasive gradient is <20 mmHg 8, 1
• Normotensive patients with invasive peak-to-peak gradient >20 mmHg should be considered for endovascular treatment when technically feasible 8

Treatment by Age and Anatomy

• For older children (>25 kg) and adults, transcatheter treatment with covered stent placement is the first-choice treatment for native coarctation and re-coarctation 8, 1, 3, 6
• Surgical resection is the treatment of choice in neonates, infants, and young children 6
• Surgical techniques include resection with end-to-end anastomosis, extended end-to-end anastomosis, subclavian flap aortoplasty, and patch aortoplasty 5
• Balloon angioplasty without stenting may be considered if stent placement is not feasible and surgical intervention is not an option, though it carries higher recurrence rates and risk of aneurysm formation 8

Lifelong Surveillance Requirements

• All coarctation patients require lifelong follow-up regardless of treatment success 8, 3
• CMR or cardiac CT imaging every 3-5 years is required to monitor for re-coarctation, aneurysms, pseudoaneurysms, and dissection 8, 3
• 24-hour ambulatory blood pressure monitoring or exercise testing better detects hypertension than office measurements alone 8, 1, 3
• Surveillance for bicuspid aortic valve dysfunction and ascending aortic dilation is required 8, 1
• Screening for intracranial aneurysms by MRA or CTA may be reasonable, though routine screening in asymptomatic patients is not currently evidence-based 8, 1

Medical Management

• Hypertension should be controlled with beta-blockers, ACE inhibitors, or angiotensin-receptor blockers as first-line medications 1
• Hypertension in coarctation patients should be treated according to standard hypertension guidelines 8, 1, 3