Aortic Stenosis Diagnosis and Characteristics

Key Acoustic Features

• The American Heart Association describes the murmur of aortic stenosis as a crescendo-decrescendo (diamond-shaped) systolic ejection murmur that is typically loudest at the apex and radiates to the upper right sternal border and carotid arteries 1
• The murmur is midsystolic (systolic ejection type), starting shortly after S1 when ventricular pressure rises sufficiently to eject blood across the narrowed aortic valve 2
• The murmur has a crescendo-decrescendo pattern, reflecting the flow dynamics across the stenotic valve 1, 3
• The murmur is best heard at the apex with radiation to the upper right sternal border and over the carotid arteries 1

Severity Indicators on Physical Examination

• In severe aortic stenosis, the classic triad includes a loud (grade 4/6) late-peaking systolic murmur radiating to the carotids, single or paradoxically split second heart sound (S2), and delayed and diminished carotid upstroke 3
• A soft or absent A2 component or reversed splitting of S2 may indicate severe AS 4

Diagnostic Approach

• The American College of Cardiology recommends echocardiography when a systolic murmur is grade 3/6 or greater, a single S2 is present, or any symptoms potentially attributable to AS are present 3

Aortic Stenosis Diagnosis and Management

Clinical Significance and Severity Assessment

• The American College of Cardiology suggests that a grade 3/6 or louder systolic murmur is an indication for urgent echocardiography in patients with potential aortic stenosis 5
• The presence of new or changing symptoms in a patient with known aortic stenosis warrants urgent echocardiography, as recommended by the American Heart Association 6

Immediate Diagnostic Approach

• Echocardiography is a crucial diagnostic tool for determining the severity of aortic stenosis and guiding management, with criteria for severe AS including an aortic valve area ≤1.0 cm², peak velocity ≥4 m/sec, and mean gradient ≥40 mmHg, although specific citation is not provided for these criteria, the importance of echocardiography is supported by 5 and 6
• The American College of Cardiology recommends that patients with symptoms potentially attributable to aortic stenosis, such as dyspnea, angina, syncope, or presyncope, undergo urgent echocardiography 5

Diagnostic and Echocardiographic Criteria for Severe Aortic Stenosis

Murmur Acoustic Features

• The classic murmur of aortic stenosis is midsystolic, crescendo‑decrescendo, and begins shortly after the first heart sound when ventricular pressure rises enough to open the narrowed valve【7】【8】.
• It is best auscultated at the cardiac apex and radiates to the upper right sternal border and the carotid arteries【9】.

Physical Examination Findings

• A delayed and diminished carotid upstroke (pulsus parvus et tardus) is typical, although it may be absent in older adults because of age‑related vascular stiffening【8】【10】.
• Severe disease often produces a soft or absent A2 component of S2, or a paradoxically split S2【8】【10】.
• The presence of a systolic ejection click suggests a bicuspid aortic valve morphology【9】.
• A sustained apical impulse reflects left‑ventricular hypertrophy secondary to chronic pressure overload【9】.

Echocardiographic Severity Thresholds

• An aortic valve area ≤ 1.0 cm² (or indexed to body surface area) defines severe aortic stenosis【9】.
• Mean Doppler gradient should be used preferentially to assess severity because the peak instantaneous gradient can overestimate stenosis in certain hemodynamic states【9】.

Stress‑Testing Considerations

• In patients with reduced left‑ventricular ejection fraction and low cardiac output, dobutamine stress echocardiography helps differentiate truly severe anatomic stenosis from low‑gradient functional disease【9】.
• For asymptomatic individuals with a mean gradient > 40 mm Hg or peak velocity > 4 m/s, exercise stress testing is reasonable, especially when evaluating fitness for athletic activity or pregnancy【9】.

All statements are derived from American College of Cardiology (ACC) evidence‑based recommendations.