THE CONTEXT
Murmur timing, intensity, location, radiation and quality help identify its nature and underlying cause.
Features of an innocent murmur
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An innocent murmur is soft and mid-systolic, and is heard at the left sternal border.
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It has no radiation and is accompanied by no other cardiac abnormalities.
Radiation and sound quality
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Radiation follows the direction of turbulent blood flow and is detectable only when a high-velocity jet is present.
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Mitral regurgitation produces a blowing murmur that radiates from the apex to the axilla.
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Aortic stenosis produces a rasping murmur that radiates from the base to the neck.
Timing within the cardiac cycle
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Time a murmur against the heart sounds, carotid pulse and apex beat to establish its position in the cardiac cycle.
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Ejection systolic murmurs are associated with ventricular outflow tract obstruction and occur in mid-systole.