Aortic Stenosis Murmur Characteristics
Aortic stenosis produces a midsystolic (systolic ejection) murmur with a crescendo-decrescendo (diamond-shaped) configuration, best heard at the second right intercostal space with radiation to the carotid arteries. 1
Timing and Configuration
- The murmur begins shortly after S1 when ventricular pressure rises sufficiently to open the aortic valve 1
- It has a crescendo-decrescendo pattern that increases as ejection accelerates and diminishes as ejection declines 1
- The murmur is classified as midsystolic (systolic ejection) rather than holosystolic 1
Location and Radiation
- Maximal intensity occurs at the second right intercostal space 1, 2
- The murmur radiates to the carotid arteries in the neck 1, 2
- Radiation over the right clavicle is particularly important—absence of a murmur over the right clavicle effectively rules out aortic stenosis (likelihood ratio 0.10) 2
Associated Physical Findings
Critical accompanying signs that suggest severe aortic stenosis include: 1
- Slow-rising, diminished arterial pulse (parvus et tardus)—though this may be absent in elderly patients due to vascular stiffening 1
- Soft or absent A2 or reversed splitting of S2 1
- Systolic thrill in the suprasternal notch or upper right sternal border 1
- Prominent and sustained apical impulse from left ventricular hypertrophy 1
Dynamic Auscultation
The AS murmur responds predictably to physiologic maneuvers: 1
- Increases with handgrip exercise and after amyl nitrite inhalation (during increased stroke volume phase) 1
- Increases after a premature ventricular beat or during long cycle lengths in atrial fibrillation 1
- Decreases with Valsalva maneuver (like most murmurs) 1
Clinical Pitfalls
Important caveats to avoid missing severe disease:
- Murmur intensity does not reliably correlate with stenosis severity—particularly in larger patients where peak momentum transfer affects perceived loudness 3
- A grade 2/6 murmur can still represent severe AS, especially with reduced cardiac output 1, 4
- Echocardiography is often necessary to distinguish a prominent benign midsystolic murmur from true valvular AS 1
- The presence of three or four associated findings (slow carotid upstroke, reduced carotid volume, maximal intensity at second right intercostal space, reduced S2 intensity) strongly predicts moderate-to-severe AS (likelihood ratio 40) 2