• Incidence 3% to 6% of all congenital cardiac defects, increases with age. Congenital bicuspid aortic valve not always recognized in childhood, often presents as valve becomes stenotic in older age.
• Male/female ratio of 4:1.
• Associated cardiac anomalies up to 20%. Most commonly, coarctation of the aorta and patent ductus arteriosus, as well as bicuspid aortic valve. Ventricular septal defect and pulmonary stenosis also occur. Aortic valve stenosis associated with other left heart obstructive lesions; the most severe form is hypoplastic left heart syndrome.

• Acquired aortic valve stenosis also occurs, usually secondary to rheumatic heart disease.
• Acquired aortic stenosis (AS) from rheumatic fever not usually seen in early childhood, rare even in the first decade. Often associated with aortic insufficiency. Mitral valve usually involved.

• Congenital AS most often from decreased commisural separation between cusps of the aortic valve. Fusion results in bicuspid aortic valve with eccentric orifice. Impaired excursion of aortic valve leaflets causes obstruction to left ventricular ejection of cardiac output.
• In infants, aortic valve often unicommisural, associated with severe left ventricular (LV) outflow tract obstruction.

• Hemodynamic significance related to the degree of LV outflow tract obstruction.
• Pressure gradient between LV cavity and aorta directly related to the flow across the aortic valve squared. Elevated LV cavity pressure causes LV hypertrophy (LVH). Pressure load and LVH creates potential subendocardial ischemia. This can be the substrate for ventricular arrhythmias and sudden death.
• Increased risk of subacute bacterial endocarditis, incidence increases with severity of the obstruction.

• Varies with severity of obstruction. Disease in infancy is usually the most severe.
• Frequently progressive over time. Mild AS (<25-mm Hg gradient) often followed medically. A gradient of >50 mm Hg has an increased risk of arrhythmia and sudden death.
• Lifelong requirement for subacute bacterial endocarditis prophylaxis.
• Relief of most LV outflow tract obstruction accomplishable with catheter-based and/or surgical intervention. Treatment may include valve replacement.

• Subvalvar AS
  • Subaortic membrane
  • Abnormal AV valve attachments
  • Malalignment of the infundibular septum
  • IHSS (hypertrophic obstructive cardiomyopathy)
• Supravalvar AS
  • Williams syndrome
  • Idiopathic infantile hypercalcemia (± familial form)
• Chest pain syndromes
  • Coronary abnormalities causing myocardial ischemia, especially with exercise

Question: Mild to moderate AS?
Significance: Usually asymptomatic, normal growth and development.

Question: Fatigue, exertional dyspnea, chest pain, and syncope?
Significance: May develop with severe AS. Less frequently abdominal pain, sweating, and epistaxis. Sudden death, especially with exertion.

Question: Severe cardiac dysfunction?
Significance: In infants, severe cardiac dysfunction associated with non-immune hydrops fetalis. Signs of decreased systemic output including hypotension, tachycardia, cardiomegaly, pulmonary vascular congestion, and respiratory distress. Impaired LV function may be associated with myocardial ischemia and/or infarction.

Question: Critical AS?
Significance: In newborns represents systemic circulation dependent on flow across patent ductus arteriosus. May require urgent catheter or surgical intervention.

Finding: Loud harsh systolic murmurs at base of heart radiating to jugular notch and carotid arteries.
Significance: Turbulent flow past aortic valve

Finding: Palpable thrill
Significance: Associated with a gradient >25 mm Hg from LV to aorta.

• Opening ejection click
• S2 can be narrowly split and may be single with delayed aortic closure.
• A lift or palpable pre-systolic expansion if left atrial pressure is elevated.
• Diastolic murmur with associated aortic insufficiency.
• In infants with critical AS, a systolic murmur may not be audible because of severe LV dysfunction and poor cardiac output.

Test: Electrocardiography
Significance: Left ventricular hypertrophy (large S wave in V1, large R wave in V6). Signs of myocardial perfusion abnormalities with strain pattern (abnormal QRS-T vector angle).

Test: Chest radiograph
Significance: Possible cardiomegaly with LVH, size correlates poorly with gradient. Left atrial enlargement in severe AS. Signs of congestive heart failure such as pulmonary vascular congestion, pulmonary artery dilation, and right ventricular hypertrophy, especially in infants. Post-stenotic dilation of the aortic valve (rare in children). Adults may have calcification of the aortic valve.

Test: Echocardiography
Significance: Defines aortic valve anatomy. Fusion of aortic valve commissures with impaired leaflet excursion. Identifies degree of stenosis and associated regurgitation.

Test: Exercise testing
Significance: Non-invasive modality to test symptoms such as dyspnea, chest pain, dizziness, or palpitations associated with exertion. Cardiovascular response to exercise in terms of heart rate, blood pressure, and electrocardiographic (ST-T) changes measured.

Test: Cardiac catheterization
Significance: Direct measurement of pressure gradient between LV-aorta, and cardiac output. Angiography demonstrates valve anatomy. Potential intervention by transcatheter balloon dilation of the aortic valve. The major risk of aortic valve dilation is the development of aortic insufficiency.

• Balloon dilation via cardiac catheterization
• Surgical valvotomy
• Valve replacement
  • Prosthetic aortic valve
  • Aortic homograft (Does not require systemic anticoagulation, especially desirable in women of childbearing years.)
  • Pulmonary autograft in the aortic position (Ross procedure) (Does not require systemic anticoagulation, especially desirable in women of childbearing years.)
• There is an incidence of homograft degeneration. Right ventricular to pulmonary artery conduit may require replacement with patient growth.

Q: How likely is endocarditis in patients with AS?
A: The presence of aortic valve stenosis represents moderate risk for development of subacute bacterial endocarditis. The Second Natural History Study reported 22 cases in 462 patients with AS, for an incidence of 27.1 per 10,000 person-years. Of these 20/22 occurred in patients with >50 mm Hg gradient across the aortic valve.

Q: Should activity be limited in individuals with aortic stenosis?
A: Recommendations for activity restrictions are based on the degree of AS, extent of symptomatology, and ECG findings. Patients with severe AS should be counseled not to participate in competitive sports.

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