How do you classify and manage a newly detected murmur in a patient?

Murmur Classification and Management

Classify murmurs by timing (systolic, diastolic, continuous), then determine which require immediate echocardiography based on specific characteristics: all diastolic and continuous murmurs are pathologic and mandate echocardiography, as do holosystolic, late systolic, and grade ≥3 midsystolic murmurs. 1

Classification by Timing in Cardiac Cycle

Systolic Murmurs

Holosystolic (Pansystolic) Murmurs

• Occur throughout entire systole from S1 to S2, indicating flow between chambers with widely different pressures (left ventricle to left atrium or right ventricle) 1
• Typical causes: mitral regurgitation, tricuspid regurgitation, ventricular septal defect 1
• All holosystolic murmurs require echocardiography regardless of intensity or symptoms 1, 2

Midsystolic (Systolic Ejection) Murmurs

• Crescendo-decrescendo configuration, starting after S1 when ventricular pressure opens semilunar valve 1
• May be innocent (high-flow states: pregnancy, thyrotoxicosis, anemia, arteriovenous fistula) or pathologic (aortic stenosis, pulmonic stenosis) 1
• Grade ≥3 intensity requires echocardiography; grade 1-2 in asymptomatic young patients with normal exam does not 1

Late Systolic Murmurs

• Begin in mid-to-late systole, typically associated with mitral valve prolapse 1, 3
• All late systolic murmurs require echocardiography 1, 4

Diastolic Murmurs

Early Diastolic Murmurs

• High-pitched, decrescendo murmurs indicating aortic or pulmonic regurgitation 1, 3
• All diastolic murmurs are virtually always pathologic and require echocardiography 1, 4

Mid-Diastolic Murmurs

• Lower-pitched, suggesting mitral stenosis or increased mitral valve flow 1, 3

Presystolic Murmurs

• Occur late in diastole 1

Continuous Murmurs

• Occur throughout cardiac cycle, suggesting patent ductus arteriosus or arteriovenous fistula 1
• All continuous murmurs require echocardiography except innocent venous hums and mammary souffles in pregnancy 1, 4

Dynamic Cardiac Auscultation for Classification

Critical Maneuvers to Perform:

• Valsalva maneuver: Most murmurs decrease; hypertrophic cardiomyopathy and mitral valve prolapse increase 1, 3
• Positional changes: Murmurs louder when standing and softer when squatting suggest hypertrophic cardiomyopathy or mitral valve prolapse 1, 3
• Sustained handgrip: Increases intensity in mitral regurgitation and ventricular septal defect 1, 3
• Respiration: Right-sided murmurs increase with inspiration; left-sided with expiration 1, 3
• Post-premature ventricular contraction: Failure to increase suggests mitral regurgitation or ventricular septal defect 1, 3

Management Algorithm

Immediate Echocardiography Required (Class I Recommendations):

1. Any symptomatic murmur (syncope, angina, heart failure, thromboembolism, suspected endocarditis) 1, 2, 4
2. All diastolic murmurs 1, 4
3. All continuous murmurs (except venous hums, mammary souffles) 1, 4
4. All holosystolic murmurs 1, 2, 4
5. All late systolic murmurs 1, 4
6. Grade ≥3 midsystolic murmurs 1, 4
7. Murmurs with ejection clicks 1, 4
8. Murmurs radiating to neck or back 1, 4
9. Abnormal S2 (fixed splitting, reversed splitting, soft/absent A2) 1, 3
10. Murmurs increasing with Valsalva or standing 1, 3

Echocardiography NOT Required:

• Grade 1-2 midsystolic murmurs in asymptomatic young patients with:
  • Normal physical examination 1
  • No other cardiac findings 1
  • Normal exercise capacity 1
  • Identified as innocent by experienced examiner 1

Additional Testing Considerations:

• ECG and chest X-ray: Not routinely needed for grade 1-2 midsystolic murmurs in young asymptomatic patients, but if obtained and abnormal, proceed to echocardiography 1
• Exercise testing: Valuable when symptoms are difficult to assess, safe even in severe aortic stenosis 1
• Cardiac catheterization: Reserved for discrepancies between echocardiography and clinical findings 1

Critical Pitfalls to Avoid

Never dismiss exertional syncope with any murmur as benign - this combination requires immediate echocardiography until structural heart disease is excluded 3

Do not rely on murmur intensity alone - even grade 2/6 holosystolic murmurs can represent severe chronic mitral regurgitation 2

Combined valvular lesions are commonly missed - sensitivity is only 55% for detecting combined aortic and mitral disease on examination alone 5

Severe aortic stenosis may have a softer murmur than expected when left ventricular ejection fraction is severely reduced 1, 3, 5

Elderly patients with severe aortic stenosis may lack the typical parvus et tardus pulse due to vascular aging 1

Doppler echocardiography detects trace regurgitation in many normal patients - interpret findings in clinical context, not all detected regurgitation is pathologic 1