Heart Sounds in Aortic Stenosis
In aortic stenosis, the characteristic heart sound finding is a harsh, crescendo-decrescendo (diamond-shaped) systolic ejection murmur best heard at the right upper sternal border with radiation to the carotid arteries, accompanied by a soft or absent aortic component (A2) of the second heart sound in severe disease. 1, 2
Key Acoustic Characteristics
The murmur of aortic stenosis has several defining features:
Timing and Pattern: The murmur is midsystolic, starting shortly after S1 when left ventricular pressure rises sufficiently to eject blood across the narrowed valve, creating the classic crescendo-decrescendo pattern that reflects flow dynamics across the stenotic valve 2
Location and Radiation: Best heard at the apex with radiation to the upper right sternal border and over the carotid arteries 2
Intensity: In severe disease, the murmur is typically grade 4/6 or louder and late-peaking 2
Critical Second Heart Sound Changes
The second heart sound provides crucial diagnostic information about severity:
Soft or Absent A2: Valve calcification and immobility prevent normal rapid, forceful closure of the aortic valve leaflets, resulting in diminished or absent A2 1
Progressive Dampening: As stenosis progresses from mild to severe, the aortic valve becomes increasingly rigid and immobile, progressively dampening the closure sound 1
Single S2: In severe aortic stenosis, A2 may become so soft that a single S2 is heard, or paradoxical (reverse) splitting may occur 1, 3, 2
Diagnostic Specificity: The disappearance of the second aortic sound is specific to severe aortic stenosis, though not sensitive 1
Physical Examination Triad for Severe Disease
The classic triad indicating severe aortic stenosis includes:
- Loud (grade 4/6) late-peaking systolic murmur radiating to the carotids 2
- Single or paradoxically split S2 2
- Delayed and diminished carotid upstroke (pulsus parvus et tardus) 1, 2
Critical Diagnostic Pitfall
A normally split S2 reliably excludes severe aortic stenosis 1. This is an important bedside finding that can help risk-stratify patients. Conversely, if physical examination strongly suggests severe aortic stenosis but echocardiography shows only mild stenosis, the echocardiogram has likely underestimated disease severity 1
When to Obtain Urgent Echocardiography
Echocardiography is indicated when:
- Systolic murmur is grade 3/6 or greater 2
- Single S2 is present 2
- Any symptoms potentially attributable to AS (dyspnea, angina, syncope, presyncope) are present 2
- New or changing symptoms in a patient with known aortic stenosis 2
Management Based on Severity
For older adults with severe aortic stenosis presenting with hemodynamic compromise:
Transcatheter aortic valve replacement (TAVR) should be considered if the patient's burden of geriatric syndromes is not prohibitive and life expectancy exceeds 1 year 4
Percutaneous balloon valvuloplasty may serve as a bridge to TAVR in patients with pulmonary edema or cardiogenic shock, though immediate TAVR is now possible in most circumstances 4
Valve replacement decisions must incorporate patient preferences, values, and patient- and procedure-specific risk assessments, acknowledging the inherent higher risk for morbidity and mortality in older adults 4
For younger patients with mobile, noncalcified bicuspid aortic valve stenosis (typically age <25 years), balloon valvuloplasty may improve stenosis and symptoms, though restenosis will occur over time 4
Surveillance Intervals for Asymptomatic Patients
Follow-up echocardiography intervals based on severity 1, 5:
- Mild AS (Vmax 2.0-2.9 m/s): Every 3-5 years 4, 1
- Moderate AS (Vmax 3.0-3.9 m/s): Every 1-2 years 4, 1
- Severe AS (Vmax ≥4.0 m/s): Every 6-12 months 4, 1, 5
Prognostic Significance
Untreated symptomatic severe aortic stenosis carries a mortality rate approaching 50% at 1-2 years 6, 7, 5. However, timely aortic valve intervention returns the mortality curve to that normal for the population 4, 5