creation date: 2025-10-23 16:27
tags: Pathologies
Aortic Stenosis
Background
Definitions
Aortic stenosis is a valvular disorder characterized by left ventricular outflow obstruction.
Etiology
Etiology is categorized by congenital or acquired.
Congenital
An abnormal valve congenitally with superimposed calcification can result in aortic stenosis. The most common cause is the bicuspid aortic valve. Suspect this in patients under the age of 70 with aortic stenosis.
Acquired
- Rheumatic valve disease (leaflets fuse to leave small orifice)
- Calcification
- Alkaptonuria (genetic)
- Systemic lupus erythematosus
- Ochronosis
- Irradiation
- Homozygous type II lipoproteinemia
- Metabolic diseases (eg. Fabry disease)
Pathophysiology
The stenosis creates left ventricular obstruction which:
- Increases LV systolic pressure
- Increases LV ejection time
- Decreases aortic pressure
- Increases LV end-diastolic pressure
The increased afterload and volume overload increases LV mass. This eventually leads to LV dysfunction and failure.
Myocardial oxygen consumption increases due to these factors while myocardial perfusion decreases (both decrease in time in diastole due to ejection time increase and pressures decreasing coronary perfusion pressure) which can lead to injury.
Clinical Presentation
Signs & Symptoms
The most common presenting symptoms of severe aortic stenosis are:
- Dyspnea on exertion or decreased exercise tolerance
- Exertional presyncope or syncope
- Exertional angina
In the final form, AS can manifest as heart failure.
In more mild/moderate forms, symptoms are unlikely to have symptoms due to obstruction. There are also no uniform set of values that can predict when symptoms may occur.
Classical signs (may not be appreciated until severe/late-stage disease) are:
- Systolic late-peaking murmur (moderate-severe AS often have grade 3/6)
- Murmur radiates to the carotids
- Single soft second heart sound
- Delayed and diminished carotid upstroke
History & Physical Exam
History may elicit symptoms suggestive of disease. However, symptoms often manifest late in the disease course and thus may not be suspected without incidental findings.
Physical exam should include thorough cardiovascular exam including auscultation and palpation of the carotid pulse.
Risk factors
Symptoms typically begin between age 50-70.
Diagnosis
Criteria
Diagnosis if made through echocardiogram. Initial assessment may be made by POCUS but transthoracic echocardiogram is used for diagnosis.
Findings that support a diagnosis include:
- Thickened and calcified aortic leaflets
- Reduced systolic leaflet motion
- Small aortic orifice during systole
- Increased transaortic velocity and calculation of left ventricular-aortic gradient
Cardiac catheterization to the left ventricle can also be used to quantify the flow definitively.
Aortic stenosis can be staged using TTE findings but is not commonly used:
Stage A
- Asymptomatic
- Transvalvular aortic velocity <2 m/s
- At risk of AS (eg. congenital valve anomaly, aortic sclerosis)
Stage B - Progressive AS with mild-moderately calcified valve leaflets, mild-moderately reduced valve leaflet mobility, and mild or moderate AS
- Murmur on exam but asymptomatic
- Mild AS: aortic Vmax 2.0-2.9 m/s or transvalvular pressure gradient <20 mmHg
- Moderate AS: aortic Vmax 3.0-3.9 m/s or transvalvular pressure gradient 20-39 mmHg
Stage C - Severe valve obstruction with no symptoms
- Severe leaflet calcification/thickening and reduced leaflet motion
- Aortic velocity ≥4 m/s
- Stage C1: LVEF normal
- Stage C2: LVEF <50%
Stage D - Symptomatic
- Stage D1: severe high-gradient
- Aortic Vmax ≥4 m/s OR mean transvalvular pressure gradient ≥40 mmHg
- Stage D2: low flow, low gradient with reduced LVEF (<50%)
- Aortic Vmax <4 m/s or mean pressure gradient <40 mmHg
- Stage D3: low gradient AS with normal LVEF
Work-up
Work-up can include:
- ECG - to detect concomitant conditions
- Chest XR - to assess for pulmonary edema in patients with HF
Serial evaluation may be indicated for asymptomatic patients with normal LV function for evidence of progression
Differential
The differential diagnoses for the classical symptoms are broad and varied and are discussed separately.
Systolic ejection murmurs may also be due to:
- Subvalvular AS (eg. fixed lesions)
- Supravalvular AS (eg. constriction of ascending aorta)
Red Flags / Complications
Complications of aortic stenosis include:
- Pulmonary hypertension
- Heart failure
- Sudden cardiac death
- Arrhythmias
- Endocarditis
- Increased risk of bleeding
- Embolic events
Management
Asymptomatic
Management of asymptomatic patients who are not indicated for aortic valve intervention primarily focuses on monitoring for progression and treatment of comorbidities.
Risk stratification is used for eligibility for valve replacement.
Symptomatic
The mainstay treatment of aortic stenosis is aortic valve replacement. This is done through:
- Surgical aortic valve replacement
- Transcatheter aortic valve implantation (TAVI)
Medical management generally consist of optimizing hemodynamics for operation.
In patients who are unable to undergo valve replacement, goal of management is to treat symptoms, manage concurrent cardiovascular conditions, and prevent diseases that can exacerbate symptoms.
Following valve replacement, management includes:
- Annual echocardiographic surveillance for valve dysfunction
- Antithrombotic therapy with warfarin (DOACs are contraindicated); this is lifelong with mechanical valves or short-term with bioprosthetic valves
A temporary intervention can be done via balloon valvuloplasty but is generally not useful and mainly to delay until definitive treatment.