What is the approach to evaluating abnormal heart sounds?

Approach to Evaluating Abnormal Heart Sounds

A comprehensive echocardiogram with Doppler flow studies is the single most useful diagnostic test for evaluating abnormal heart sounds, as it can determine whether abnormalities of myocardium, heart valves, or pericardium are present and which chambers are involved. 1

Initial Assessment of Heart Sounds

Classification of Abnormal Heart Sounds

• Systolic murmurs: Occur between S1 and S2 heart sounds

  • Midsystolic (ejection) murmurs: Begin after S1, end before S2 1
  • Holosystolic (pansystolic) murmurs: Begin with S1, continue through systole 1
  • Late systolic murmurs: Begin in mid-to-late systole, continue to S2 1

• Diastolic murmurs: Occur between S2 and S1 heart sounds 2

  • Early diastolic murmurs: Begin with S2 1
  • Mid-diastolic murmurs: Begin after S2 1
  • Presystolic murmurs: Occur just before S1 1

• Continuous murmurs: Begin in systole and continue through S2 into diastole 1

• Extra heart sounds

  • S3 (ventricular gallop): Early diastolic sound associated with rapid filling 2
  • S4 (atrial gallop): Late diastolic sound associated with atrial contraction 2

Evaluation Based on Murmur Characteristics

Timing

• Determine precise timing within cardiac cycle (systolic vs. diastolic) 1
• Note relationship to S1 and S2 heart sounds 1

Location and Radiation

• Identify where the murmur is best heard (apex, left sternal border, right sternal border, etc.) 1
• Note radiation pattern (neck, axilla, back) 1

Intensity (Grading)

• Grade 1: Very faint, heard only in quiet setting with special effort 1
• Grade 2: Quiet but readily audible 1
• Grade 3: Moderately loud, no thrill 1
• Grade 4: Loud with associated thrill 1
• Grade 5: Very loud, thrill, audible with stethoscope partially off chest 1
• Grade 6: Audible with stethoscope off chest 1

Quality and Configuration

• Note pitch (high, medium, low) 1
• Describe configuration (crescendo, decrescendo, crescendo-decrescendo) 1
• Assess response to physiologic maneuvers (Valsalva, standing, squatting) 1

Diagnostic Algorithm

Step 1: Determine Clinical Significance

Based on initial assessment, categorize the abnormal heart sound:

• Requires immediate echocardiography:

  • Any diastolic murmur 1
  • Any continuous murmur (not due to venous hum or mammary souffle) 1
  • Holosystolic or late systolic murmurs 1
  • Systolic murmurs grade 3 or louder 1
  • Murmurs associated with symptoms (dyspnea, syncope, chest pain) 1
  • Murmurs with abnormal ECG or chest X-ray findings 1
  • Murmurs with specific responses to dynamic maneuvers (e.g., increasing with Valsalva) 1

• May not require immediate testing:

  • Grade 1-2 midsystolic murmurs with:
    • Normal S1 and S2 1
    • No other abnormal sounds 1
    • No symptoms 1
    • No evidence of ventricular hypertrophy or dilatation 1
    • No change with Valsalva maneuver or positional changes 1

Step 2: Diagnostic Testing

Echocardiography

• Class I indications (strongly recommended): 1

  • Diastolic murmurs, continuous murmurs, holosystolic murmurs, late systolic murmurs
  • Murmurs associated with ejection clicks
  • Murmurs that radiate to neck or back
  • Murmurs in patients with symptoms/signs of heart failure, myocardial ischemia, syncope
  • Grade 3 or louder systolic murmurs

• Class IIa indications (reasonable): 1

  • Murmurs associated with abnormal ECG or chest X-ray
  • Murmurs in patients with symptoms likely non-cardiac but cardiac basis cannot be excluded

• Class III indications (not recommended): 1

  • Grade 2 or softer midsystolic murmurs identified as innocent by experienced observer

Additional Testing

• Electrocardiography: Useful to assess for ventricular hypertrophy, atrial enlargement, arrhythmias, conduction abnormalities, prior infarction 1

• Chest X-ray: Provides information on cardiac chamber size, pulmonary blood flow, venous pressure, cardiac calcification 1

• Exercise testing: Consider when exercise limitation is a symptom but contribution of heart disease is uncertain 1

• Specialized testing: For specific clinical scenarios:

  • Cardiac catheterization with coronary angiography for patients with chest pain 1
  • Maximal exercise testing with respiratory gas exchange for transplant candidates 1

Step 3: Interpretation of Findings

Common Pathologic Findings

• Systolic murmurs:

  • Aortic stenosis: Harsh midsystolic murmur at right upper sternal border with radiation to neck 1
  • Mitral regurgitation: Holosystolic murmur at apex radiating to axilla 1
  • Hypertrophic cardiomyopathy: Midsystolic murmur that increases with Valsalva and standing 1

• Diastolic murmurs:

  • Aortic regurgitation: High-pitched early diastolic decrescendo murmur at left sternal border 1
  • Mitral stenosis: Low-pitched mid-diastolic rumble at apex 1

• Extra heart sounds:

  • S3: May indicate volume overload, heart failure 2
  • S4: May indicate decreased ventricular compliance, hypertension 2

Special Considerations

Innocent Murmurs

Characteristics of innocent murmurs in adults: 1

• Grade 1-2 intensity at left sternal border
• Systolic ejection pattern
• Normal S1 and S2
• No other abnormal sounds
• No evidence of ventricular hypertrophy
• No change with Valsalva or positional changes

Pediatric Evaluation

In children, echocardiography is indicated for: 1

• Cyanosis, respiratory distress, abnormal pulses, or cardiac murmur in neonates
• Loud or abnormal murmurs in infants or children
• Failure to thrive with abnormal cardiac findings
• Syndromes associated with heart disease

Common Pitfalls to Avoid

• Don't miss diastolic murmurs: Always listen carefully in quiet settings with patient in left lateral position for aortic regurgitation murmurs 1

• Don't overinvestigate innocent murmurs: Grade 1-2 midsystolic murmurs with normal S1 and S2 in asymptomatic young adults often require no further evaluation 1

• Don't forget physiologic maneuvers: Dynamic auscultation with maneuvers like Valsalva, standing, and squatting can help differentiate murmurs 1

• Don't ignore extra heart sounds: S3 and S4 gallops may provide important diagnostic information about ventricular function 2

• Don't overlook systemic conditions: Heart murmurs may be the first sign of systemic conditions like anemia, thyrotoxicosis, or pregnancy 1