II. Epidemiology

  1. Overall Murmur Prevelance: 50% of all children
  2. Innocent murmurs more common than pathologic 10:1
  3. Age of murmur onset related to pathology
    1. Murmur onset at 24 hours of life: 8% pathologic
    2. Murmur onset at 6 months of life: 14% pathologic
    3. Murmur onset at 12 months of life: 2% pathologic

III. Causes: Innocent Murmurs

  1. Still's Murmur (Aortic Vibratory Systolic)
    1. Most common innocent murmur
  2. Venous Hum of late infancy and early childhood
    1. Second most common innocent murmur
  3. Septal hypertrophy due to myocardial fat deposition
    1. Resolves over six months
  4. Pulmonary Flow Murmur
  5. Neonatal Pulmonary branch murmur
  6. Physiologic Peripheral Pulmonary Stenosis
  7. Supraclavicular Murmur (Brachiocephalic Systolic Murmur)
  8. Aortic Systolic Murmur
  9. Mammary artery souffle

IV. Causes: Pathologic Murmurs

  1. Ventricular Septal Defect (VSD) 20-25%
  2. Atrial Septal Defect (ASD) 8-13%
  3. Patent Ductus Arteriosus (PDA) 6-11%
  4. Tetralogy of Fallot: 10%
  5. Pulmonary Stenosis: 9%
  6. Pulmonary Artery Stenosis: 7%
  7. Aortic Coarctation: 5-8%
  8. Aortic Stenosis: 5-6%
  9. Transposition of Great Vessels: 5%
  10. Mitral Valve Prolapse 4%
  11. Total anomalous pulmonary venous congestion (2-3%)
  12. Tricuspid Atresia: 1-2%
  13. Hypoplastic Left Heart: Rare
  14. Truncus Arteriosus: rare

V. Signs: Innocent Murmurs

  1. Precaution: These signs are unreliable in under age 1 year due to higher Incidence of Congenital Heart Disease
  2. Auscultation (Seven S's - key reassuring findings in innocent murmurs)
    1. Sensitive
      1. Murmur accentuates with position changes, activity - see below
    2. Short duration
      1. Not holosystolic
    3. Single
      1. Isolated murmur without click, gallup or other extra heart sounds
    4. Small
      1. Murmur limited to small, focal distribution without radiation
    5. Soft
      1. Low amplitude (e.g. II/VI murmur)
    6. Sweet
      1. Non-harsh quality
    7. Systolic
      1. Limited to systole (Diastolic Murmurs are typically pathologic)
  3. Accentuation maneuvers (innocent murmurs become louder in this position)
    1. Sitting forward
    2. Exercise or increased Heart Rate
    3. Fever
    4. Anxiety, Restlessness, or crying

VI. Signs: Pathologic Murmur

  1. See Congenital Heart Disease
  2. Red flag general exam findings
    1. Evidence of Failure to Thrive
    2. Lethargy
    3. Cyanosis
    4. Shortness of Breath
    5. Parasternal heave or thrill
    6. Murmur radiates to back or neck
    7. S3 Heart Sound
  3. Auscultation (6 Cardinal signs of pathology)
    1. Harsh murmur
    2. Pansystolic murmur
    3. Loud Murmur Grade III or more
    4. Murmur at high Left sternal border
    5. Early or Midsystolic click or murmur
    6. Abnormal S2 Heart Sounds

VII. Diagnosis: Innocent Murmur (all 4 criteria required)

  1. No abnormal physical findings
  2. No symptoms suggestive of Congenital Heart Disease
  3. No increased risk of Congenital Heart Disease by history
  4. Auscultation findings consistent with innocent murmur and no red flags suggesting pathologic murmur (see above)

VIII. Management: Approach

  1. Murmurs in newborns and children under age 1 year
    1. Higher risk for Congenital Heart Disease
    2. Echocardiogram
    3. Refer to pediatric cardiology
  2. Murmurs in older children and teens
    1. An innocent murmur that definately meets all above criteria does not require further evaluation or referral
    2. Other murmurs should be referred for evaluation by cardiology and/or Echocardiogram (depending on local protocols)
      1. Pediatric cardiology can often make diagnosis without Echocardiogram and may prevent unnecessary testing.

IX. Management: Pathologic murmur suspected

  1. Newborn to eight weeks
    1. See Congenital Heart Disease for evaluation
  2. Pediatric Cardiology Referral
    1. Do not create preconceived notions of evaluation
    2. Not every Pediatric Murmur will need Echocardiogram

X. Management: Innocent Murmur suspected

  1. Trust skilled clinical evaluation
  2. Study of clinical exam by pediatric cardiolgists
    1. Exam is as accurate as Echocardiogram
    2. Exam is more accurate than Electrocardiogram
    3. Test Sensitivity: 96%
    4. Test Specificity: 95%
    5. Positive Predictive Value: 88%
    6. Negative Predictive Value: 98%
  3. Reference
    1. McCrindle (1996) Arch Pediatr Adolesc Med [PubMed]

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