Characteristic Heart Sounds in Moderate Mitral Regurgitation
In moderate mitral regurgitation, you will typically hear a holosystolic (pansystolic) murmur that is high-pitched, blowing in quality, best heard at the cardiac apex, and radiates to the axilla. 1
Primary Auscultatory Findings
Systolic Murmur Characteristics
- The murmur begins with S1 and extends throughout systole to S2, distinguishing it from the late systolic murmurs seen in mitral valve prolapse 1
- The murmur is high-pitched and blowing in quality, heard best at the left ventricular apex 1
- Intensity increases with expiration since left-sided murmurs are louder during expiration 1
Additional Heart Sounds
- S3 gallop may be present in moderate to severe cases, reflecting increased left ventricular volume load from the regurgitant flow 1
- S1 may be diminished if there is poor leaflet coaptation 1
Dynamic Auscultation Maneuvers
Understanding how the murmur changes with physiologic maneuvers helps confirm the diagnosis:
- Handgrip exercise increases the murmur intensity by increasing afterload and thus increasing the regurgitant volume 1
- Valsalva maneuver decreases murmur intensity (unlike mitral valve prolapse where it becomes longer and louder) 1
- Squatting increases the murmur by increasing preload and afterload 2
Important Clinical Distinctions
Acute vs. Chronic Mitral Regurgitation
- In acute mitral regurgitation, you may hear only an early systolic murmur rather than a holosystolic murmur, as the left atrium is non-compliant and pressures equalize rapidly 1
- This is a critical pitfall—absence of a holosystolic murmur does not exclude significant regurgitation in acute settings 3
Mitral Valve Prolapse Pattern
- If you hear a midsystolic click followed by a late systolic murmur, this suggests mitral valve prolapse rather than primary mitral regurgitation 2
- The click-murmur complex moves earlier toward S1 with standing/Valsalva and later toward S2 with squatting 2
Silent Mitral Regurgitation
- Significant mitral regurgitation can occasionally be "silent" without the characteristic murmur, particularly in combined valvular lesions 3
- Clues include cardiomegaly with marked left atrial dilation disproportionate to other findings 3
Severity Assessment Caveats
- Early systolic murmurs are often associated with milder regurgitation and less left ventricular dilation, while holosystolic murmurs typically indicate more significant regurgitation 4
- Murmur intensity does not reliably correlate with severity—echocardiography is essential for quantifying the degree of regurgitation 1
- In moderate regurgitation, a middiastolic rumble may be audible at the apex due to increased diastolic flow across the mitral valve 1