Aortic Stenosis Murmur Characteristics
The murmur of aortic stenosis is 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
Key Acoustic Features
- Timing and Configuration: The murmur is midsystolic (systolic ejection type), starting shortly after S1 when ventricular pressure rises sufficiently to eject blood across the narrowed aortic valve 1
- Shape: Crescendo-decrescendo pattern, reflecting the flow dynamics across the stenotic valve 1
- Location: 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 1
- Single or paradoxically split second heart sound (S2) 1
- Delayed and diminished carotid upstroke 1
Important Caveats
- In elderly patients, the carotid upstroke may appear normal due to vascular aging effects, and the murmur may be soft or radiate to the apex rather than the carotids 1
- The only reliable physical finding to exclude severe AS is a normally split second heart sound 1
- A soft or absent A2 component or reversed splitting of S2 may indicate severe AS 1
Associated Findings
- Systolic ejection sound (click): Usually present in younger patients (until the fourth decade), heard loudest at the apex but radiating to the base; this disappears as valve calcification restricts cusp mobility 1
- Palpable systolic thrill: May be present in the suprasternal notch or upper right sternal border 1
- Prominent and sustained apical impulse: Reflects left ventricular hypertrophy from chronic pressure overload 1
Clinical Pitfalls
Detection challenges in real-world practice:
- The AS murmur is missed by clinicians in approximately 61% of encounters, even in patients with moderate-to-severe disease 2
- Detection improves significantly in outpatient settings, when AS diagnosis is already known, in female patients, and when symptoms are present 2
- Murmur intensity correlates with peak momentum transfer and body size, meaning loud murmurs predict severe disease less reliably in larger patients 3
- In patients with severely diminished left ventricular ejection fraction, the degree of stenosis may be underestimated on clinical examination due to reduced flow across the valve 4
Diagnostic Approach
Echocardiography is mandatory when:
- A systolic murmur is grade 3/6 or greater 1
- A single S2 is present 1
- Any symptoms potentially attributable to AS are present 1
No single bedside maneuver reliably identifies the AS murmur, but the diagnosis can be made by exclusion when the murmur does not augment with inspiration (excluding right-sided lesions), does not increase with Valsalva or squatting-to-standing (excluding hypertrophic cardiomyopathy), and does not increase with handgrip or transient arterial occlusion (excluding mitral regurgitation and ventricular septal defect) 5