Heart Murmur


Heart Murmur, Heart Murmur Interpretation

  • Physiology
  1. Turbulent Blood Flow results in vibratory changes picked up by stethoscope
  2. Ventricles fill most rapidly in the first third of diastole
    1. Aortic Regurgitation murmur is loudest in early diastole
    2. Mitral Stenosis murmur is also loudest in early diastole (with a slight delay for mitral valve opening)
  3. Ventricles empty most rapidly in the first third of systole
    1. However, the Aortic Stenosis murmur is a crescendo decrescendo Systolic Murmur (increases, peaks and decreases)
  4. Factors that increase murmur intensity
    1. Increased pressure gradients and velocity changes
    2. Increased Cardiac Output
  5. Factors that decrease murmur intensity
    1. Pericardial Effusion
    2. Decreased Cardiac Output
    3. Obesity
  • Images
  1. Cardiac Cycle Volumes and Pressures (Wiggers Diagram)
    1. cvCardiacCycleWiggers.png
  • Exam
  1. Characteristics
    1. Identify beginning of systole and diastole
      1. S1 Heart Sound
      2. S2 Heart Sound
  2. Timing
    1. Determine timing of murmur
      1. Systolic Murmur
      2. Diastolic Murmur
      3. Continuous Murmur
    2. Determine Early, Middle or late in interval
  3. Severity
    1. Grade 1/6: Barely audible
    2. Grade 2/6: Just easily audible
    3. Grade 3/6:
    4. Grade 4/6:
    5. Grade 5/6: Loudest requiring a stethoscope
    6. Grade 6/6: Heard with stethoscope off chest
  4. Location
    1. Identify valve area involved
  5. Pattern
    1. Uniform: Constant
    2. Crescendo: Increasing
    3. Decrescendo (Diminuendo): Decreasing
    4. Crescendo-Decrescendo: Diamond Shaped Murmur
  6. Pitch
    1. Low pitched
      1. Best heard with bell chest-piece at light pressure
    2. High pitched
      1. Best heard with diaphragm at firm pressure
      2. Valve insufficiency murmurs are high pitched due to higher velocity Blood Flow
  7. Dynamic Maneuvers: Affecting Left Ventricular Preload (most useful single set of dynamic tests)
    1. Decreased Left Ventricular Preload (e.g. Valsalva, stand from squat, forced heavy expiration)
      1. Increases Hypertrophic Cardiomyopathy and Mitral Valve ProlapseSystolic Murmurs
      2. Decreases Aortic Stenosis, Mitral Regurgitation and innocent Systolic Murmurs
    2. Increased left Ventricular Preload (e.g. Squat, passive leg raise)
      1. Increases innocent Systolic Murmurs as well as Mitral Regurgitation and Aortic Stenosis
      2. Decreases Hypertrophic Cardiomyopathy and Mitral Valve ProlapseSystolic Murmurs
  8. Dynamic Maneuvers: Other
    1. Increased Afterload (e.g. hand grip, transient arterial Occlusion with Blood Pressure cuff)
      1. Increases Mitral Regurgitation, pulmonic stenosis and Ventricular Septal DefectSystolic Murmurs
      2. Decreases Hypertrophic Cardiomyopathy, Aortic Stenosis and Mitral Valve ProlapseSystolic Murmurs
      3. Increases Aortic Regurgitation, Ventricular Septal Defect (and possibly Mitral Stenosis) Diastolic Murmurs
    2. Increased venous return and increased left Ventricular Afterload (e.g. deep or exaggerated inspiration)
      1. Increases tricuspid regurgitation, pulmonic stenosis Systolic Murmurs
      2. Increases tricuspid stenosis (and possibly pulmonary regurgitation) Diastolic Murmurs
    3. Decreased jugular venous return (Jugular Vein compression, or transition supine from sitting)
      1. Decreases Venous Hum continuous murmur
  9. Consider auscultation in different positions
    1. Supine
    2. Erect
    3. Left lateral decubitus position
  • Interpretation
  1. Benign murmur findings
    1. Murmur characteristics
      1. Crescendo-decrescend character
      2. Musical or vibratory murmur
      3. Quiet murmur (Grade 2 or less)
      4. Timing: Early systolic or mid Systolic Murmur
      5. Location: Left sternal border or pulmonic area
    2. Associated findings absent
      1. Cardiopulmonary symptoms absent
      2. Family History absent
      3. Exam (BP, pulse, auscultation) otherwise normal
      4. Normal physiologic split S2 without gallup or click
  2. Pathologic murmur findings
    1. Murmur characteristics
      1. Timing: Diastolic, mid-late systolic, holosystolic
      2. Loud murmur (Grade 3 or greater)
      3. Murmur exacerbated by Valsalva Maneuver
      4. Murmur radiates to Carotid Artery or axilla
    2. Associated findings present
      1. Arrhythmia present
      2. Symptoms: Chest Pain, Palpitation, Dyspnea, Syncope
      3. Sudden Cardiac DeathFamily History
      4. Jugular Venous Pulsation abnormal
      5. Arterial pulsation abnormal
        1. Wide Pulse Pressure
        2. Water-Hammer Pulse (rapidly rising, bounding)
        3. Weak, slow rising pulse
      6. Other abnormal precordial exam
        1. Other heart sounds (e.g. Loud S1, fixed split S2)
        2. Left ventricular heave
  • Resources
  1. University of Michigan Heart Sound and Murmur Library
    1. http://www.med.umich.edu/lrc/psb/heartsounds/