How do you determine the location of a heart murmur?

Determining the Location of Heart Murmurs

The location of a heart murmur is determined primarily by identifying the area of maximal intensity on the chest wall, which typically corresponds to the anatomical origin of the murmur.

Anatomical Locations for Auscultation

• The primary auscultation areas on the chest correspond to specific cardiac structures 1:

  • Aortic area: Right second intercostal space
  • Pulmonic area: Left second intercostal space
  • Tricuspid area: Left lower sternal border
  • Mitral area: Cardiac apex (fifth intercostal space, midclavicular line)

• The area where the murmur is heard loudest (maximal intensity) typically indicates its origin 1

Characteristics to Assess

• Timing in cardiac cycle: Systolic, diastolic, or continuous 1

• Configuration: Crescendo, decrescendo, crescendo-decrescendo (diamond-shaped), or plateau 1

• Intensity: Graded on a scale of 1 through 6 2

  • Grade 1: Very faint, heard only in quiet room with experienced listener
  • Grade 2: Quiet but clearly audible
  • Grade 3: Moderately loud, no thrill
  • Grade 4: Loud with a palpable thrill
  • Grade 5: Very loud, thrill palpable, audible with stethoscope partly off chest
  • Grade 6: Audible with stethoscope entirely off chest

• Radiation pattern: Direction in which the murmur transmits away from its point of maximal intensity 1

  • Aortic stenosis: Radiates to carotid arteries and neck
  • Mitral regurgitation: Radiates to axilla
  • Aortic regurgitation: Radiates along left sternal border

Specific Murmur Locations and Characteristics

• Aortic valve murmurs 1:

  • Maximal at right upper sternal border
  • Aortic stenosis: Harsh, mid-systolic crescendo-decrescendo murmur
  • Aortic regurgitation: High-pitched early diastolic decrescendo murmur, often loudest along mid-left sternal border

• Mitral valve murmurs 1:

  • Maximal at apex
  • Mitral regurgitation: Holosystolic (pansystolic) murmur radiating to axilla
  • Mitral stenosis: Low-pitched diastolic rumble with presystolic accentuation

• Tricuspid valve murmurs 1:

  • Maximal at left lower sternal border
  • Tricuspid regurgitation: Holosystolic murmur, increases with inspiration
  • Tricuspid stenosis: Diastolic rumble, increases with inspiration

• Pulmonic valve murmurs 1:

  • Maximal at left upper sternal border
  • Pulmonic stenosis: Systolic ejection murmur with possible ejection click
  • Pulmonic regurgitation: Diastolic decrescendo murmur

Dynamic Auscultation Techniques

• Respiratory variation 1:

  • Right-sided murmurs generally increase with inspiration
  • Left-sided murmurs usually are louder during expiration

• Valsalva maneuver 1:

  • Most murmurs decrease in intensity
  • Hypertrophic cardiomyopathy murmurs become louder
  • Mitral valve prolapse murmurs become longer and often louder

• Positional changes 1:

  • Standing: Most murmurs diminish; hypertrophic cardiomyopathy murmurs become louder
  • Squatting: Most murmurs become louder; hypertrophic cardiomyopathy murmurs soften

• Exercise 1:

  • Murmurs due to flow across normal or obstructed valves become louder
  • Murmurs of mitral regurgitation, ventricular septal defect, and aortic regurgitation increase with handgrip exercise

Common Pitfalls in Murmur Localization

• Failing to distinguish between radiation and point of maximal intensity 1
• Not considering patient body habitus which may affect murmur transmission 1
• Overlooking soft diastolic murmurs, which are almost always pathological 1
• Mistaking innocent murmurs (especially in children and young adults) for pathological ones 3, 4
• Assuming that all grade 3 murmurs are pathological when some innocent murmurs can be relatively loud 3

When to Pursue Further Evaluation

• Echocardiography is recommended for 1:

  • Diastolic murmurs
  • Continuous murmurs
  • Holosystolic murmurs
  • Late systolic murmurs
  • Murmurs associated with ejection clicks
  • Murmurs that radiate to the neck or back
  • Grade 3 or louder systolic murmurs
  • Murmurs associated with symptoms or signs of heart disease

• Referral to a cardiologist is warranted for 3, 4:

  • Diastolic murmurs (except confirmed venous hum)
  • Holosystolic murmurs
  • Murmurs associated with other abnormal cardiac findings
  • When a specific innocent murmur cannot be confidently identified

By systematically evaluating the location of maximal intensity, timing, radiation pattern, and response to dynamic maneuvers, clinicians can accurately determine the origin of heart murmurs and identify those requiring further evaluation.