Coarctation of the Aorta

Coarctation of the aorta is a narrowing of the aorta between the aortic arch and the iliac bifurcation commonly around the point of insertion of the ductus arteriosus. Coarctation of the aorta is typically congenital and the clinical presentation depends on the age of the patient. Neonates present with heart failure upon the closure of the ductus arteriosus, while children and adults present with hypoperfusion and/or hypertension. Classic findings on physical exam include radio-/brachio-femoral delay and decreased blood pressure in the lower limbs. Diagnosis is confirmed by echocardiogram. Patients should be surgically managed as early as possible to avoid complications of hypertension. Close follow-up is required as the risk of hypertension and re-coarctation remain.

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Overview

Definition

Coarctation of the aorta is a narrowing of the aorta caused by the thickening of the medial layer at a localized point, most commonly near the insertion of the ductus arteriosus.

Schematic representation of coarctation of the aorta

Image by Lecturio.

Types

  • Preductal: The narrowing is located proximally to the ductus arteriosus.
  • Postductal: The narrowing is located distally to the ductus arteriosus.

Types of coarctation of the aorta

Image by Lecturio.

Epidemiology

  • Incidence in the United States: 4 per 10,000 live births
  • Accounts for approximately 6% of all congenital heart disease
  • More common in boys (2:1 men:women ratio)
  • Associated conditions:
    • Up to 15% of girls with coarctation of the aorta have Turner syndrome.
    • Accompanied by bicuspid aortic valve in over 70% of cases

Etiology and Pathophysiology

Etiology

  • Congenital: 
    • Accounts for most cases
    • Caused by intrauterine factors or genetic predisposition altering endothelial development and elasticity of the aorta
    • 2 accepted theories of development:
      • Tissue from the ductus arteriosus extends into the aorta.
      • Underdevelopment of the aortic arch results from reduced intrauterine blood flow from the left ventricle (LV) through the aorta to the fetal body.
  • Acquired: This form may be seen in adult patients with aortitis secondary to Takayasu’s arteritis.

Pathophysiology

  • In utero and in neonates, the presence of the foramen ovale and the ductus arteriosus provide a physiological aortic bypass.
  • Heart failure begins to develop when the structures close after birth and the neonate begins to depend on the aorta for systemic circulation.
  • The narrowing of the aorta causes increased afterload increasing systolic pressure in the LV and the proximal aorta.
  • In contrast, there is hypoperfusion of the tissues distal to the narrowing.
  • To compensate, the LV undergoes hypertrophy to maintain the ejection fraction.
  • To bypass the narrowing, collateral blood flow develops through the inferior intercostal, internal mammary, and scapular arteries.

Collateral circulation composed of the inferior intercostal vessels develops to bypass the coarctation, which results in rib notching.

Image by Lecturio.

Clinical Presentation

Neonates

  • Asymptomatic while there is a patent ductus arteriosus (PDA) 
  • When the PDA closes, the patient presents with signs of heart failure (cyanosis, dyspnea, diaphoresis, shock).
  • In the physical exam:
    • Delayed or absent femoral pulses
    • Cyanotic and/or cold lower extremities
    • Systolic ejection murmur at the left sternal border due to an underlying bicuspid aortic valve 
    • Continuous machinery-like murmur of the infraclavicular location due to PDA or collateral circulation

Children

  • Fainting or near-fainting
  • Claudication, weakness, or chest pain on exertion
  • Failure to thrive
  • In the physical exam: 
    • Radio-femoral delay/brachio-femoral delay: Femoral pulses are delayed compared to radial or brachial pulses.
    • Higher blood pressure in the upper vs. the lower extremities (difference of > 20 mm Hg)
    • Presence of continuous murmur due to collateral circulation 
    • Presence of systolic ejection murmur due to a bicuspid aortic valve

Adults

  • Hypertension
  • Stroke secondary to intracranial aneurysm
  • Weak pulses of the lower extremities
  • Higher blood pressure in the upper vs. the lower extremities (difference of > 20 mm Hg)

Diagnosis

Diagnostic test of choice: echocardiogram

Findings:

  • Narrowing of the lumen
  • Any additional cardiac lesions (e.g., bicuspid aortic valve)
  • Doppler: increased velocity and turbulence of blood flow through the narrowing

Supportive noninvasive workup

  • Chest X-ray:
    • Neonates: cardiomegaly with pulmonary congestion
    • Older children:
      • Figure 3 sign: formed by the indentation at the coarctation point along the dilated aorta
      • Rib notching: erosion of the lower surface of the ribs due to increased blood flow through the collateral intercostal arteries
  • ECG shows LV hypertrophy.
  • CT and MRI can be helpful when echocardiogram results are deficient or unclear.

Comorbidity screening

  • Genetic testing for women suspected of having Turner syndrome
  • For adults, CT angiography to screen for intracranial aneurysms, abdominal aortic aneurysms, and atherosclerotic changes to the coronary arteries

Management and Complications

Management

Neonates: 

  • Prostaglandin E1 IV to keep the ductus arteriosus open
  • Surgical management for patients dependent on PDA

Children and adults:

  • Surgical treatment is indicated in the case of:
    • Heart failure
    • > 20 mm Hg gradient across the coarctation
    • Presence of collateral blood flow
  • Therapeutic procedures include balloon angioplasty, stent placement, or patch aortoplasty.

Complications

A few long-term complications can develop postsurgical repair:

  • Rebound hypertension: 
    • Most common in adults
    • Re-coarctation must be ruled out.
    • Hypertension must be medically managed to reduce the risk of coronary or cerebrovascular disease.
  • Re-coarctation: 
    • Most commonly seen in neonates and children
    • Due to inadequate wall growth
    • Should be suspected in cases where symptoms resurge
  • Aortic aneurysm and dissection: mainly in adults at the site of repair

Postoperative follow-up: Annual consult and imaging, such as an echocardiogram, is required to detect complications.

Prognosis

  • When detected in childhood and not treated, death occurs by 20–40 years old due to hypertensive complications such as coronary heart disease or stroke.
  • If surgery performed prior to age 20, 10-year postrepair survival estimate is 90%.
  • Patients may resume all forms of exercise within a year of uncomplicated repair.

Differential Diagnosis

The differential diagnosis of coarctation of the aorta must be considered depending on the age group of the patients.

Neonates

Since patients present in shock, other causes such as septic shock or hypovolemic shock must be ruled out.

  • Septic shock: organ dysfunction resulting from a dysregulated systemic host response to infection. The etiology is mainly bacterial; pneumonia is the most commonly known source. Presentation includes fever, tachycardia, tachypnea, hypotension, and/or altered mentation. Diagnosis is confirmed during the treatment when vasopressors are necessary to control hypotension. 
  • Hypovolemic shock: a life-threatening condition of organ dysfunction resulting from decreased cardiac output due to reduced preload secondary to hemorrhage, gastrointestinal losses, burns, or polyuria. Presentation includes tachycardia, tachypnea, hypotension, decreased capillary refill time, and cold/clammy skin in the case of compensated shock. Treatment is based on volume resuscitation.

Children

If a young girl is diagnosed with coarctation, karyotyping for Turner syndrome must be performed as it accounts for 15% of cases.

Turner syndrome: a genetic condition in which 1 X chromosome is partly or completely missing, resulting in karyotype 45,X0. Presentation includes primary amenorrhea (characteristic of a woman with short stature), webbed neck, broad chest, and widely spaced nipples. Genetic testing confirms the diagnosis, and treatment is based on hormone replacement.

Adults

A delay in pulse may also be seen in peripheral arterial disease and aortic dissection.

  • Peripheral arterial disease: obstruction of the arterial lumen resulting in decreased blood flow to the distal limbs caused by atherosclerosis or thrombosis. Patients may be asymptomatic, have progressive claudication, skin discoloration, ischemic ulcers, or gangrene. Diagnosis is confirmed with ankle-brachial index measurement and imaging studies to localize and assess the disease. Treatment varies depending on disease severity.
  • Aortic dissection: a tear in the tunica intima of the aortic wall allowing blood to flow into the media and create a “false lumen.” Aortic dissection results from pulsatile pressure shearing stress secondary to uncontrolled hypertension. Presentation includes acute “tearing” chest or back pain. Computed tomography is the diagnostic modality of choice. Type a dissections require surgery, while Type b dissections can be managed medically with impulse control using beta-blockers and calcium channel blockers.

References

  1. Hoffman, J.I.E. & Kaplan, S. (2002). The incidence of congenital heart disease. doi: https://doi.org/10.1016/S0735-1097(02)01886-7
  2. Kliegman, R.M., St. Geme, J.W., Blum, N.J., Shah, S.S., Tasker, R.C., & Wilson, K.M. (2020). Acyanotic congenital heart disease: Obstructive lesions. Nelson textbook of pediatrics (pp. 238-2393.e1). https://www.clinicalkey.es/#!/content/3-s2.0-B9780323529501004545
  3. Eckhauser, A., South, S.T., Meyers, L., Bleyl, S.B., & Botto, L.D. (2015). Turner Syndrome in Girls Presenting with Coarctation of the Aorta. The Journal of pediatrics, 167(5), 1062–1066. DOI:10.1016/j.jpeds.2015.08.002
  4. Hijazi, Z.M. (2018). Clinical Manifestation and diagnosis of coarctation of the aorta. UpToDate. Retrieved January 5, 2021, from https://www.uptodate.com/contents/clinical-manifestations-and-diagnosis-of-coarctation-of-the-aorta

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