Coarctation of Aorta

Coarctation of Aorta

Coarctation of the aorta is a narrowing of the aorta that occurs near the ligamentum arteriosum just distal to the origin of the left subclavian artery.

The narrowing can be preductal, juxtaductal, or postductal depending on its insertion site relative to the patent ductus arteriosus origin.

It causes an outflow obstruction proximal to the site of the stenosis, which leads to left ventricular pressure overload, hypertrophy, and potentially heart failure. The stenosis can be discrete or long and may have collateral vessels.

It is commonly associated with other cardiac abnormalities such as a bicuspid aortic valve (50%-75%), mitral valve abnormalities, patent ductus arteriosus, or atrial and ventricular septal defect.

Synonyms

  • Postductal coarctation of the aorta
  • Preductal coarctation of the aorta
  • Congenital hypoplasia of aortic arch
  • Coarctation of the aorta

Epidemiology & Demographics

Aortic coarctation has a prevalence of approximately 4 per 10,000 live births and accounts for 4%-8% of all congenital heart defects. It affects predominantly males, with a male to female ratio of 1.5:1.

Risk Factors

The cause for aortic coarctation among most patients is unknown. Genetic mutation and environmental causes are possibilities.

It also can be acquired through inflammatory conditions such as Takayasu arteritis or severe atherosclerosis.

Maternal factors such as drug, alcohol, and radiation exposure, and maternal infection with rubella can contribute to development of coarctation as well.

Genetics

Although most cases are sporadic, several genes are identified, including NOTCH1 gene.

Its association with a number of other conditions, such as DiGeorge, Noonan, Williams-Beuren, and Sturge-Weber syndromes, also suggests a genetic predisposition.

Most notably, up to 30% of patients with Turner syndrome have coarctation of the aorta and carry higher risk for aortic dissection than the general population.

Clinical Presentation & Physical Finding

  • •Clinical presentation:
    • 1.The clinical manifestations of coarctation of the aorta depend on the age of discovery, severity of the aortic narrowing, and adequacy of collateral circulation.
    • 2.Neonates without severe aortic coarctation or with a persistent patent ductus arteriosus may be asymptomatic, and heart failure rarely occurs beyond the neonatal period. Neonates with severe coarctation may present with heart failure and even shock when the ductus arteriosus closes. Patients may present with diaphoresis, dyspnea, and pallor with weak or absent femoral pulses.
    • 3.Beyond infancy, most patients are asymptomatic. Symptoms arise from severe hypertension which may lead to epistaxis, headache, dizziness, heart failure symptoms, or even aortic dissection. There may also be claudication of the lower extremities, especially with exertion and abdominal angina.
  • •Physical exam findings:
    • 1.“Brachial-femoral” delay characterized by diminished or delayed femoral pulses compared to the brachial pulses.
    • 2.Upper extremity systolic hypertension.
    • 3.Low or unobtainable blood pressure in the lower extremities.
    • 4.Systolic ejection murmur at the left upper sternal border and left subscapular region
    • 5.A continuous murmur heard best posteriorly between scapulae may be present if there are large collaterals.
    • 6.Systolic murmurs may be heard if there are coexisting cardiac defects (i.e., systolic ejection murmur with bicuspid aortic valve).

Etiology

  • •The exact pathogenesis is unknown. The two main theories for potential mechanisms are reduced antegrade intrauterine flow leading to underdevelopment of the fetal aortic arch and abnormal extension of tissue from the ductus arteriosus into the wall of the fetal thoracic aorta.
  • •In coarctation of the aorta, the arterial wall of the aorta has several pathologic abnormalities. The cystic medial necrosis and intimal hyperplasia in the wall can lead to increased stiffness and less distensibility. In the prestenotic segment, there is also increased collagen and less smooth muscle mass content.
  • •Coarctation leads to left ventricular pressure afterload causing secondary hypertension in upper extremities and reduced flow to lower extremities. To overcome the obstruction, left ventricle hypertrophies and collateral vessels develop. Degree of symptom severity depends on the severity of coarctation and existing compensatory mechanism.

Differential Diagnosis

  • •Hypoplastic left heart syndrome
  • •Interrupted aortic arch
  • •Pseudo-coarctation
  • •Left ventricular outflow tract obstruction, including subaortic and supravalvular aortic stenosis
  • •Prior surgical ligation
  • •Critical aortic valve stenosis
  • •Obstructive peripheral arterial disease
  • •Aortic dissection

Workup

  • •Bilateral arm and leg blood pressures should be measured to search for a differential pressure (Class I, C).
  • •For patients with suspected aortic coarctation, the physical exam should include simultaneous palpation of the brachial and femoral pulses to assess for “brachial-femoral delay,” which is characteristic of significant aortic coarctation.
  • •An electrocardiogram may show left ventricular hypertrophy, ST-T wave abnormalities, and RV conduction delay.
  • •Transthoracic echocardiogram, including suprasternal notch acoustic windows, should be performed.
  • •Every patient with coarctation should have at least one cardiovascular MRI or CT scan for a complete evaluation of the thoracic aorta and intracranial vessels (Class I, B).
  • •Cardiac catheterization is indicated when associated coronary artery disease is suspected or for therapeutic intervention of the coarctation.

Laboratory Tests

There are no specific laboratory tests are needed for coarctation of the aorta.

Imaging Studies

  • Chest x-ray:
    • 1.Posterior rib notching of ribs 4-8 is due to bony erosion formed by intercostal collateral arteries.
    • 2.The “3 sign,” a double contour seen on the descending aorta, is formed by indentation of the aortic wall at the site of the coarctation with pre- and postcoarctation dilation.
  • •Echocardiography:
    • 1.Generally, echocardiography can establish the diagnosis and severity of coarctation of the aorta, but it is less useful for postoperative patients or for adult patients who may have less favorable acoustic windows compared with children.
    • 2.Aortic narrowing is visualized in the suprasternal notch view.
    • 3.Color flow imaging and pulsed Doppler may localize the area of coarctation.
    • 4.Continuous wave Doppler estimates the severity of coarctation. However, the collateral flow may reduce the gradient across the coarctation, creating a lower gradient than expected for the degree of the obstruction.
    • 5.Associated cardiac defects, chamber sizes, valvular abnormalities, and left ventricular function can be evaluated.
  • •Magnetic resonance imaging and computed tomography:
    • 1.Per the ACC/AHA adult congenital heart disease guidelines, every adult patientwith coarctation should have at least one cardiovascular MRI or CT or a complete evaluation of the thoracic aorta.
    • 2.The modalities have very high diagnostic accuracy (>95%) in detecting coarctation of the aorta and its associated abnormalities.
    • 3.Both provide a large field of view and allow simultaneous visualization of the ascending aorta, aortic arch, descending aorta, aortic valve, and collateral vessels.
    • 4.Compared to MRI, CT can offer higher spatial resolution and can be used in patients with metallic implants, but cannot provide peak gradient assessment across coarctation and degree of collateral circulation.
    • 5.CT and MRI are indicated for serial follow-up imaging after surgical repair to assess for aortic dilatation or aneurysm formation.
    • 6.MRI is preferred to CT to decrease the lifetime exposure to radiation.
  • •Cardiac catheterization:
    • 1.Cardiac catheterization is the gold standard for assessing the peak gradient across the coarctation, but is usually performed in conjunction with a therapeutic intervention (balloon angioplasty or stent placement).

Imaging Evaluation of Coarctation of the Aorta

From Boxt LM, Abbara S: Cardiac imaging: the requisites, ed 4, Philadelphia, 2016, Elsevier.

Patency of the Ductus Arteriosus

Closed

Patent

Flow from aorta to pulmonary artery (typically postductal coarctation)

Flow from pulmonary artery to aorta (preductal coarctation or pulmonary hypertension)

Collateral Pathways

Scarce (typical of patients under 2 yr of age)

Abundant

Bridging the coarctated segment

Internal mammary to intercostal to distal aorta

Circumscapular pathways to distal aorta

Other Arch Anomalies and Stenoses

Arch interruption

Double aortic arch with stenosis in either or both arches

Coarctation proximal to left subclavian artery

Takayasu aortitis, rubella, Williams syndrome, neurofibromatosis, mucopolysaccharidosis, and other causes of stenoses not in the aortic isthmus

Subclavian Artery Anomalies

Atresia or stenosis of the left subclavian artery

Aberrant retroesophageal right subclavian artery

Proximal to the coarctation

Distal to the coarctation

Origin of both subclavian arteries distal to the coarctation

Associated Lesions

Cardiac, such as ventricular septal defect or bicuspid aortic valve

Aneurysms:

In aorta adjacent to coarctation

In the ductus

In the intercostal arteries

In the circle of Willis

Anomalies Associated with Aortic Coarctation

From Boxt LM, Abbara S: Cardiac imaging: the requisites, ed 4, Philadelphia, 2016, Elsevier.

Common

Bicuspid aortic valve with stenosis and regurgitation

Patent ductus arteriosus

Ventricular septal defects

Turner syndrome

Rare

Transposition of the great arteries

Double-outlet right ventricle

Shone syndrome (parachute mitral valve, supramitral ring, aortic valve stenosis, and aortic coarctation)

Treatment

Acute General Treatment

  • •Infants with critical coarctation are at risk for heart failure and death once the ductus arteriosus closes. Treatments include:
    • 1.Continuous intravenous infusion of prostaglandin E1 to keep the ductus arteriosus patent.
    • 2.Dopamine and/or dobutamine to increase contractility for those with heart failure.
    • 3.Once stabilized, surgical repair is preferred over balloon angioplasty due to higher patency with reduced need for reintervention in neonates.

Chronic Treatment

  • •Systemic hypertension should be treated with angiotensin-converting enzyme inhibitors, angiotensin-receptor blockers, or beta-blockers.
  • •All patients with aortic coarctation should have long-term follow up with a congenital heart disease specialist.
  • •After repair, a CT or MRI of the repair site should be obtained at 1 yr postoperatively and then every 5 yr or less depending on anatomy to monitor for long-term complications such as recoarctation.
  • •Monitoring for intracranial aneurysms with MRA or CTA is reasonable.
  • •Endocarditis prophylaxis is not necessary except for previous history of endocarditis, conduit placement, and 6 mo after repair with stent or prosthesis.
  • •After a successful coarctation repair especially done early in life, both quality of life and life expectancy are same as normal population.

Nonpharmacologic Therapy

Aortic coarctation can be repaired surgically or percutaneously by balloon angioplasty and/or stent placement. The choice of intervention is made on an individual basis based on aortic morphology and should be determined by a multidisciplinary team including cardiologists, interventionalists, and cardiac surgeons who are experienced in treating patients with congenital heart disease.

  • •Repair should be performed in infancy or early childhood to prevent the common complications of unrepaired coarctation, including systemic hypertension, accelerated coronary artery disease, stroke, heart failure, and aortic dissection.
  • •The indications for intervention according to the ACC/AHA guidelines for the management of adults with congenital heart disease are:
    • 1.Peak-to-peak coarctation gradient >20 mm Hg or mean Doppler systolic gradient >20 mm Hg between upper and lower extremities.
    • 2.Upper and lower extremity gradient >10 mm Hg or mean Doppler gradient >10 mm Hg with either reduced left ventricular systolic function or aortic regurgitation.
    • 3.Upper and lower extremity gradient >10 mm Hg or mean Doppler gradient >10 mm Hg with collateral follow.
  • •Surgery:
    • 1.Early surgical intervention is preferred with mortality rate of <1%, which increases significantly in adulthood due to coronary artery disease and end-organ damage from chronic hypertension.
    • 2.Options include resection of coarctation with either direct or extended end-to-end anastomosis, a bypass graft across the area of coarctation, and subclavian flap or prosthetic patch aortoplasty.
    • 3.Surgery compared with balloon angioplasty has been shown to be equally effective in reducing the peak systolic pressure gradient early after intervention.
    • 4.Surgery is indicated in the presence of a long re-coarctation segment, aortic aneurysm or pseudoaneurysm, or aortic arch hypoplasia.
  • •Balloon angioplasty and/or stent placement:
    • 1.Balloon angioplasty is the preferred intervention for adult patients with native or recurrent stenosis, not amendable to stent placement or surgery. There are higher risks for intimal tears and aneurysm formation compared to stenting.
    • 2.Stenting improves luminal diameter to diminish the gradient, and reduces dissection and aneurysm risks. Due to risk for recoarctation after stenting, it is often combined with simultaneous balloon angioplasty.
    • 3.Stent placement is not recommended in children <25 kg due to potential vascular complications from the large sheath size and the need for repeated interventions to expand the stent as they grow.
    • 4.Potential complications of percutaneous intervention include immediate residual pressure gradients, recoarctation, aneurysm formation, dissection, and femoral artery complications.

Coarctation and Pregnancy

Women with coarctation should receive pre-pregnancy counseling with input from an adult congenital heart disease specialist to determine maternal cardiac, obstetric, and fetal risks. Women with severe coarctation have an extremely high risk for maternal mortality and severe morbidity, and if pregnant, the option of pregnancy termination should be discussed.

Referral

  • •All patients with coarctation of the aorta, with or without repair, should be referred to a congenital heart specialist.
  • •Intervention should involve a multidisciplinary team of cardiologists, interventionalists, and surgeons at an adult congenital heart disease center.

Pearls & Considerations

  • •Aortic coarctation is most commonly found distal to the origin of the left subclavian artery.
  • •The pathognomonic physical exam finding of aortic coarctation is the brachial-femoral delay.
  • •Systemic hypertension is the most common long-term complication of untreated aortic coarctation, but it is also associated with accelerated coronary artery disease, stroke, aortic dissection, and heart failure.
  • •An adult congenital heart disease specialist should monitor all patients with aortic coarctation.

Suggested Readings

  • Alkashkari W., et al.: Management of coarctation of the aorta in adult patients: state of the art. Korean Circ J 2019; 49 (4): pp. 298-313.
  • Baumgartner H., et al.: Task Force on the Management of Grown-up Congenital Heart Disease of the European Society of Cardiology (ESC), Association for European Paediatric Cardiology (AEPC), ESC Committee for Practice Guidelines (CPG), ESC Guidelines for the management of grown-up congenital heart disease (new version 2010). Eur Heart J 2010; 31 (23): pp. 2915-2957.
  • Brown M., et al.: Coarctation of the aorta lifelong surveillance is mandatory following surgical repair. J Am Coll Cardiol 2013; 62 (11): pp. 1020-1025.
  • Feltes T.F., et al.: Indications for cardiac catheterization and intervention in pediatric cardiac disease: s scientific statement from the American Heart Association. Circulation 2013; 123 (22): pp. 2607-2652.
  • Silversides C.K., et al.: Canadian Cardiovascular Society 2009 Consensus Conference on the management of adults with congenital heart disease: outflow tract obstruction, coarctation of the aorta, tetralogy of Fallot, Ebstein anomaly and Marfan’s syndrome. Can J Cardiol 2010; 26 (3): pp. e80.
  • Stout K.K., et al.: 2018 AHA/ACC Guideline for the management of adults with congenital heart disease: s report of the American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines. J Am Coll Cardiol 2019; 73 (12): pp. e81. Epub 2018 Aug 16.
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