Overview
Definition:
Aortic stenosis (AS) in adolescents is a narrowing of the aortic valve orifice, impeding blood flow from the left ventricle to the aorta
It can be congenital or acquired, with bicuspid aortic valve being the most common congenital cause.
Epidemiology:
Congenital AS is the most common form of left-sided outflow tract obstruction in children
While many cases are diagnosed in infancy, some adolescents present with milder forms or progression of previously diagnosed AS
The prevalence of bicuspid aortic valve is estimated at 1-2% of the general population, often leading to AS development later in life.
Clinical Significance:
Untreated or inadequately managed AS in adolescents can lead to left ventricular hypertrophy, diastolic dysfunction, myocardial ischemia, arrhythmias, and potentially sudden cardiac death
Proper management of activity restrictions and diligent follow-up are crucial to prevent these adverse outcomes and optimize quality of life.
Clinical Presentation
Symptoms:
Many adolescents with mild AS are asymptomatic
When symptoms occur, they can include exertional dyspnea
Chest pain or angina
Syncope or presyncope, especially with exertion
Palpitations
Fatigue.
Signs:
A characteristic systolic ejection murmur, often best heard at the right upper sternal border, radiating to the carotid arteries
A palpable thrill may be present
In severe cases, signs of heart failure may emerge: diminished peripheral pulses, pulsus alternans, and signs of pulmonary congestion.
Diagnostic Criteria:
Diagnosis is primarily based on echocardiography
Echocardiographic criteria include: Aortic valve area (AVA) less than 1.5 cm²/m²
Mean transvalvular gradient greater than 20 mmHg
Peak transvalvular velocity greater than 2.0 m/s
Severely symptomatic patients with moderate AS may also warrant intervention.
Diagnostic Approach
History Taking:
Detailed family history for congenital heart disease
History of previous cardiac evaluation or intervention
Onset and progression of any exertional symptoms
Red flags include syncope, severe dyspnea, or chest pain with minimal exertion.
Physical Examination:
Auscultation for the characteristic murmur (timing, location, radiation, intensity)
Palpation for thrills
Assessment of peripheral pulses and blood pressure in all four extremities
Examination for signs of left ventricular hypertrophy and heart failure.
Investigations:
Echocardiography: Transthoracic echocardiogram (TTE) is the cornerstone for assessing valve morphology, stenosis severity (gradients, AVA), and LV function
Transesophageal echocardiogram (TEE) may be used for more detailed assessment if TTE is inconclusive
ECG: May show LVH, ST-T wave changes
Chest X-ray: Can reveal cardiomegaly and signs of pulmonary venous congestion in severe AS
Cardiac MRI/CT: May be useful for complex anatomy or pre-operative planning
Cardiac Catheterization: Invasive assessment of gradients and AVA, particularly if non-invasive studies are discordant with clinical findings.
Differential Diagnosis:
Other causes of systolic murmurs: hypertrophic cardiomyopathy, innocent flow murmurs, pulmonary stenosis, ventricular septal defect
Conditions mimicking syncope: vasovagal syncope, orthostatic hypotension, arrhythmias.
Activity Restriction
Assessment Of Risk:
Activity recommendations depend on the severity of AS and presence of symptoms
Mild AS (<1.0 cm²/m² AVA, mean gradient <20 mmHg): Generally, no significant restrictions are needed
Moderate AS (1.0-1.5 cm²/m² AVA, mean gradient 20-40 mmHg): May require limitation of vigorous, prolonged, or competitive activities, especially in symptomatic individuals
Severe AS (<1.0 cm²/m² AVA, mean gradient >40 mmHg): Vigorous isometric and strenuous aerobic activities are generally contraindicated
Contact sports should be avoided due to the risk of chest trauma potentially precipitating fatal arrhythmias.
Guidelines For Different Severities:
For mild AS, most adolescents can participate in all sports
For moderate AS, participation in low-to-moderate intensity activities is usually permissible, with careful consideration of symptoms
For severe AS, participation in low-intensity activities may be allowed, but high-risk sports are prohibited
The cardiologist’s evaluation and consensus guidelines (e.g., AHA/ACC) should be followed.
Role Of Symptoms And Exercise Testing:
Symptom development (syncope, dyspnea, chest pain) is a critical indicator for intervention and may necessitate stricter activity restrictions, even with moderate AS
Exercise stress testing can help assess functional capacity and identify exertional ischemia or arrhythmias, aiding in risk stratification and activity recommendations.
Follow Up
Frequency Of Monitoring:
Follow-up frequency is determined by the severity of AS and whether the patient is symptomatic or has undergone intervention
Mild AS: Annual or biannual echocardiographic follow-up
Moderate AS: Echocardiography every 6-12 months
Severe AS: More frequent monitoring, typically every 6 months, and often requires consideration for intervention.
Elements Of Follow Up Visits:
Clinical assessment: Detailed review of symptoms, including any new or worsening exertional limitations
Physical examination: Focus on murmur characteristics, peripheral pulses, and signs of heart failure
Echocardiography: To assess valve morphology, stenosis severity (AVA, gradient), and LV function
ECG: To monitor for arrhythmias or LVH progression.
Indications For Intervention:
Intervention (balloon valvuloplasty or surgical aortic valve replacement) is indicated for symptomatic severe AS
Asymptomatic severe AS with LV dysfunction or significant LVH
Asymptomatic severe AS with abnormal exercise testing
Moderate AS with rapid progression of stenosis or significant symptoms may also be considered for intervention.
Complications
Early Complications:
Complications related to intervention, such as valve rupture, dissection, or restenosis after valvuloplasty
Bleeding or infection post-surgery.
Late Complications:
Progressive aortic regurgitation
Re-stenosis of the native or prosthetic valve
Infective endocarditis
Left ventricular dysfunction
Arrhythmias
Thromboembolic events
Sudden cardiac death.
Prevention Strategies:
Diligent medical follow-up
Strict adherence to activity guidelines
Prophylaxis against infective endocarditis
Early consideration for intervention when indicated
Lifestyle modifications including smoking cessation and maintaining a healthy weight.
Key Points
Exam Focus:
Understand the grading of AS severity using AVA and gradients
Differentiate between congenital and acquired AS
Recognize common symptoms and physical exam findings
Key indications for intervention in AS
Principles of activity restriction based on severity.
Clinical Pearls:
A diminished or absent S2 can be a sign of severe AS
Always check for associated findings in bicuspid aortic valve, such as aortic root dilation
The murmur of AS increases with inspiration due to increased venous return
Consider AS in any adolescent with unexplained syncope or exertional chest pain.
Common Mistakes:
Underestimating the severity of AS based on murmur intensity alone
Failing to adequately assess LV function and size
Inappropriate activity recommendations for symptomatic patients
Delaying intervention in severe AS, leading to irreversible LV damage.