- Clinical science
Aortic valve stenosis (AS) is a valvular heart disease characterized by narrowing of the aortic valve. As a result, the outflow of blood from the left ventricle into the aorta is obstructed. This leads to chronic and progressive excess load on the left ventricle and potentially left ventricular failure. The patient may remain asymptomatic for long periods of time; for this reason, AS is often detected late when it first becomes symptomatic (dyspnea on exertion, angina pectoris, or syncope). Auscultation reveals a harsh, crescendo-decrescendo murmur in systole that radiates to the carotids, and pulses are delayed with diminished carotid upstrokes. Echocardiography is the noninvasive gold standard for diagnosis. Patients with mild asymptomatic aortic stenosis are treated conservatively with monitoring and medical management of related conditions (e.g, hypertension). Symptomatic patients, or those with severe aortic valve stenosis, require immediate aortic valve replacement (AVR) as definitive treatment. Options for valve replacement include surgical AVR or transcatheter AVR (TAVR) for patients with high operative risk. Patients with severe AS have a high risk of developing acute complications such as heart failure and cardiogenic shock, which are challenging to manage and often require critical care interventions and expedited surgery or TAVR.
The most common etiologies of valvular aortic stenosis include:
- Aortic valve sclerosis: calcification and fibrosis of aortic valve leaflets 
Bicuspid aortic valve (BAV): fusion of two of the three aortic-valve leaflets in utero 
- Most common congenital heart valve malformation , predominantly affects males (3:1) 
- Predisposes the valve to and degeneration
- Patients present with symptoms of aortic stenosis earlier than in regular aortic valve calcification. 
- Congenital aortic stenosis is rare and usually features a unicuspid or bicuspid valve. 
- Narrowed opening area of the aortic valve during systole → obstruction of blood flow from left ventricle (LV) → increased LV pressure → left ventricular concentric hypertrophy, which leads to:
- Initially, cardiac output (CO) can be maintained (see “Compensation mechanisms” in “ ”)
- Later, the decreased distensibility of the left ventricle reduces cardiac output and may then cause backflow into the pulmonary veins and capillaries → higher afterload (pulmonic pressure) on the right heart → right heart failure
Aortic stenosis may remain asymptomatic for years; , particularly with mild or moderate stenosis. Symptoms usually start to develop when the disease progresses to severe AS, and may present at rest or on exertion.
- Signs and symptoms
- Physical examination
- Harsh crescendo-decrescendo (diamond-shaped), late systolic ejection murmur that radiates bilaterally to the carotids
- Soft S2
- S4 is best heard at the apex.
- Early systolic ejection click
- Used to monitor disease progression and determine the need for intervention
- Based on echocardiographic criteria of valve anatomy and hemodynamics
|AHA staging for aortic valve stenosis |
|Stage||Definition||Aortic valve area (AVA)||Transaortic velocity||Mean aortic pressure gradient|
|Stage A aortic valve stenosis||At risk of AS||3–4 cm2||< 2.0 m/second||< 10 mm Hg|
|Stage B aortic valve stenosis||Progressive AS||Mild: 1.5–2.9 cm2||2.0– 2.9 m/second||10–19 mm Hg|
|Moderate: 1.0–1.4 cm2||3.0–3.9 m/second||20–39 mm Hg|
|Stage C1 aortic valve stenosis||Asymptomatic severe AS (LVEF normal)||≤ 1.0 cm2||≥ 4.0 m/second||≥ 40 mm Hg|
|Stage C2 aortic valve stenosis||Asymptomatic severe AS (LVEF < 50%)|
|Stage D aortic valve stenosis||Symptomatic severe AS|
Indication: Assessment of aortic valve structure, function, and stenosis severity, left ventricle and other heart valves (see )
- TTE: recommended primary test and noninvasive gold standard used to confirm diagnosis and determine AS severity 
- TEE: second-line modality for confirmation of TTE findings or operative planning 
- Calcification and narrowing of the aortic valve
- Increased mean aortic pressure gradient and transvalvular velocity
- Signs of cardiac remodeling, e.g.,
- Laboratory studies: usually nonspecific and therefore not routinely indicated; however, they can be useful for the evaluation of other possible etiologies.
- ECG signs of LVH (e.g., positive )
- Nonspecific ST-segment and T-wave abnormalities
- Chest x-ray: Used to assess for pulmonary edema or other causes of dyspnea. 
Additional evaluation 
- Indication: stage C1 AS and stage C2 AS to provoke possible exertional symptoms
- Interpretation: Exertional findings indicate stage D AS.
Exercise stress testing is contraindicated in patients with severe symptomatic AS (stage D).
Diagnostic hemodynamic cardiac catheterization: definitive diagnostic test to evaluate aortic valve area, cardiac output, and mean aortic pressure gradient
- Consider in symptomatic patients with inconclusive noninvasive testing or discrepancy between symptoms and noninvasive testing. 
- Findings: similar to echocardiographic findings
- Coronary angiography
- Complications: See “Complications” in cardiac catheterization.
Advanced imaging 
Consider the following noninvasive imaging options in the perioperative assessment of patients with severe AS, along with expert consultation. 
- Cardiac CT
- Provides precise information on anatomy and hemodynamics
- Can be helpful in evaluating severity of AS but is not always available
- See for an overview of other cardiac valvulopathies.
- See and .
- See .
- See .
General principles 
- Aortic valve stenosis is a progressive condition and definitive management requires valve replacement.
- Urgency of valve repair/replacement depends on staging.
- Management of acute complications requires individualized and specialized care.
Management of medical comorbidities 
All patients should be screened and treated for other cardiac risk factors.
- Hypertension: Follow standard hypertension guidelines; medication should be carefully titrated to avoid hypotension.
- Hyperlipidemia: Statins are not useful in preventing AS progression.
- Diabetes mellitus: See “Treatment” in diabetes mellitus. 
- Atrial fibrillation: See “Management of acute complications” below.
Management of acute complications 
Prompt critical care specialist consultation and rapid surgical referral are recommended. Patients should receive AVR as soon as possible.
Afterload reduction (e.g., with vasodilators or diuretics) in severe AS may reduce cardiac output enough to compromise systemic and myocardial perfusion. Careful titration is recommended with specialist guidance.
Severe AS compromises coronary perfusion (due to high LV pressure and low pressure in the aortic root). Avoid hypotension as it can cause cardiac ischemia.
Monitoring and prophylactic antibiotics 
- Regular follow-up imaging is indicated for asymptomatic patients with:
- On-demand imaging is indicated for patients with:
- Any change in signs or symptoms
- Conditions that have high hemodynamic/metabolic demands
- Prophylactic antibiotics
Aortic valve replacement (AVR) and repair
- Symptomatic patients with severe, high-gradient AS (stage D AS)
- Asymptomatic patients with severe AS and:
- AVR can also be beneficial for certain patients with moderate (stage B AS) to severe (stage D AS) with specific characteristics.
- Recommended for patients with: 
- Low to moderate surgical risk
- Higher surgical risk AND severe multivessel coronary artery disease
- Recommended for patients with: 
Transcatheter AVR (TAVR)
- Recommended for patients with high or prohibitive surgical risk and predicted survival of > 12 months 
- Reasonable alternative for patients with intermediate surgical risk 
- Emergency TAVR may be considered in certain patient groups. 
Percutaneous balloon valvuloplasty
- Indicated in children, adolescents, and young adults without AV calcification 
- Can consider as a bridging intervention in high-risk patients with stage D AS but overall benefit is questionable. 
Complications of aortic valve replacement 
Antithrombotic therapy after aortic valve replacement
|Antithrombotic therapy for patients with prosthetic aortic valves |
|Choice of agent||Target INR||Duration of therapy|
|Mechanical valve and no risk factors for|| || |
OR older generation mechanical valves
Bioprosthetic valve with low risk of bleeding