Cardiac murmurs are assessed by their timing, intensity, location, radiation and acoustic characteristics. Their relationship to the cardiac cycle helps identify associated valve lesions.
Pansystolic and late systolic murmurs
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Pansystolic murmurs maintain constant intensity from the first heart sound throughout systole to the second heart sound, which they may obscure.
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They result from blood leaking from a ventricle into a low-pressure chamber at an even or constant velocity.
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The stated causes of a pansystolic murmur are mitral regurgitation, tricuspid regurgitation and ventricular septal defect.
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Late systolic murmurs may occur in mitral valve prolapse when regurgitation is confined to late systole, or in hypertrophic obstructive cardiomyopathy when dynamic obstruction occurs late in systole.
Other murmur patterns
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Mid-diastolic murmurs are associated with mitral stenosis, tricuspid stenosis, and mitral or tricuspid flow murmurs.
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Early diastolic murmurs are associated with aortic or pulmonary regurgitation.
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Ejection systolic murmurs are associated with aortic stenosis, pulmonary stenosis, and aortic or pulmonary flow murmurs.
Bedside assessment
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Use heart sounds, the carotid pulse and the apex beat to determine whether a murmur is systolic or diastolic and whether it occupies the whole phase or only part of it.
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Listen over the apex and base, including the aortic and pulmonary areas, to identify where the murmur is loudest. Assess radiation at the neck, axilla and back.
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Describe pitch and whether intensity is constant or variable. High pitch indicates high-velocity flow.
Intensity grading
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Grade 1 is very soft and audible only in ideal conditions; grade 2 is soft; grade 3 is moderate.
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Grade 4 is loud with an associated thrill; grade 5 is very loud; grade 6 can be heard without a stethoscope.
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Diastolic murmurs very rarely exceed grade 4.
Associated cardiac sounds
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An opening snap may occur with mitral stenosis or a mitral prosthesis.
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An ejection click or opening sound may be associated with an aortic prosthesis.