Characteristics of Aortic Regurgitation Murmur
The murmur of aortic regurgitation is characteristically a high-pitched, early diastolic decrescendo murmur best heard at the left parasternal border, beginning immediately after S2 and diminishing throughout diastole. 1
Primary Characteristics
- Timing: Early diastolic, begins with or shortly after S2 2
- Quality: High-pitched 2, 1
- Pattern: Decrescendo (diminishing throughout diastole) 2, 1
- Location: Best heard at the left parasternal border 1
- Posture: Often better heard when the patient leans forward and holds breath in expiration
Associated Findings
Austin-Flint Murmur
- A low-pitched, rumbling middiastolic or presystolic murmur heard at the LV apex in severe, chronic aortic regurgitation 2, 1
- Results from regurgitant flow causing functional mitral stenosis 1
- No opening snap is present, which helps differentiate it from true mitral stenosis 2
Associated Physical Findings
- Widened pulse pressure (systolic hypertension with normal or low diastolic pressure) 1
- Bounding peripheral pulses (water-hammer or Corrigan's pulse) 1
- Forceful apical impulse due to left ventricular enlargement 1
Pathophysiological Basis
The murmur occurs due to diastolic reflux of blood from the aorta into the left ventricle 3. The high-pitched quality and decrescendo nature reflect the rapid decline in the volume or rate of regurgitation during diastole as the pressure gradient between the aorta and left ventricle decreases 2.
Clinical Pearls
- The intensity of the murmur does not always correlate with severity of aortic regurgitation 1
- Echocardiography is required for accurate assessment of severity 1, 3
- In acute aortic regurgitation, the murmur may be shorter and less audible due to rapid equilibration of aortic and ventricular pressures 4
- The murmur's duration correlates with severity - longer murmurs typically indicate more severe regurgitation
Common Pitfalls
- Mistaking the Austin-Flint murmur for mitral stenosis (remember: no opening snap in AR) 2
- Underestimating severity based on murmur intensity alone 1
- Failing to differentiate between acute and chronic aortic regurgitation, which have different clinical presentations and management approaches 4
- Missing aortic regurgitation in patients with tachycardia (shortened diastole makes the murmur harder to appreciate)
By understanding these characteristics, clinicians can better identify aortic regurgitation on physical examination, though definitive diagnosis and assessment of severity require echocardiography 1, 3, 5.