How do you characterize a heart murmur?

How to Characterize a Heart Murmur

Characterize every heart murmur systematically by assessing six key features: timing in the cardiac cycle, intensity (grade 1-6), configuration, location and radiation, pitch, and duration—with timing and intensity being the most critical determinants of whether further evaluation is needed. 1

Essential Characteristics to Document

Timing in the Cardiac Cycle

• Systolic murmurs occur between S1 and S2 and are subdivided into:

  • Holosystolic (pansystolic): Begin with S1 and continue throughout systole, indicating flow between chambers with widely different pressures (e.g., mitral regurgitation, tricuspid regurgitation, ventricular septal defect) 1
  • Midsystolic (ejection): Start shortly after S1 when ventricular pressure opens the semilunar valve, typically crescendo-decrescendo in shape 1
  • Early systolic: Begin with S1 but end in midsystole, often due to tricuspid regurgitation without pulmonary hypertension 1
  • Late systolic: Start well after ejection begins and end before or at S2, commonly from mitral valve prolapse 1

• Diastolic murmurs occur between S2 and S1 and virtually always represent pathological conditions requiring cardiac evaluation 1

• Continuous murmurs extend through both systole and diastole; most require evaluation except venous hums and mammary souffles 1

Intensity Grading

• Grade systolic murmurs on a 1-6 scale: Grade 1 (very faint), Grade 2 (soft but readily heard), Grade 3 (moderately loud), Grade 4 (loud with palpable thrill), Grade 5 (very loud, heard with stethoscope partially off chest), Grade 6 (extremely loud, heard with stethoscope off chest) 2

• Grade diastolic murmurs on a 1-4 scale 2

• Clinical significance: Grade 3 or louder systolic murmurs typically warrant echocardiography as they are more likely to represent organic heart disease 2

Configuration (Shape)

• Crescendo: Progressively increasing intensity 1
• Decrescendo: Progressively decreasing intensity 1
• Crescendo-decrescendo (diamond-shaped): Increases then decreases, typical of midsystolic ejection murmurs 1
• Plateau: Constant intensity throughout, characteristic of holosystolic murmurs 1

Location and Radiation

• Document the point of maximal intensity (apex, left lower sternal border, left upper sternal border, right upper sternal border) 1
• Note radiation patterns (to axilla, carotids, back, neck) 1

Pitch

• High-pitched murmurs suggest high-velocity flow 1
• Low-pitched murmurs suggest lower-velocity flow 1
• Medium-pitched with vibratory quality suggests Still's murmur (innocent) 1

Duration

• Document whether the murmur occupies the entire phase (holosystolic) or only part of it (early, mid, or late) 1

Dynamic Maneuvers to Further Characterize Murmurs

Perform dynamic auscultation to differentiate pathologic from innocent murmurs and identify specific conditions:

• Valsalva maneuver/standing: Murmurs that increase suggest hypertrophic cardiomyopathy or mitral valve prolapse and require workup 2

• Squatting: Murmurs that decrease with squatting (after increasing with standing) suggest hypertrophic cardiomyopathy 2

• Handgrip exercise: Murmurs that increase during sustained handgrip require workup 2

• Post-premature ventricular contraction: Murmurs that do NOT increase after a PVC or long R-R interval in atrial fibrillation suggest mitral regurgitation or ventricular septal defect 2

• Position changes: Innocent murmurs often decrease or disappear when upright 1

Critical Pitfalls to Avoid

• Never dismiss diastolic murmurs: All diastolic murmurs require echocardiographic evaluation regardless of intensity, as they virtually always represent pathology 1, 2

• Don't overlook holosystolic or late systolic murmurs: These require echocardiography even if soft, as they indicate regurgitant lesions 2

• Grade 3+ systolic murmurs are not innocent: Any midsystolic murmur of grade 3 or greater intensity requires echocardiography 2

• Symptoms override murmur characteristics: Any systolic murmur accompanied by syncope, angina, heart failure, or thromboembolism requires echocardiography regardless of grade 2

• Abnormal second heart sound is a red flag: Wide splitting or abnormal intensity of S2 with any murmur warrants further evaluation 2

• In older patients with hypertension: Grade 1-2 midsystolic murmurs may relate to sclerotic aortic valve leaflets or flow into tortuous vessels, but this is a diagnosis of exclusion 2