Cardiac auscultation: technique, timing and murmur localisation
THE CONTEXT
Cardiac auscultation uses different stethoscope components, pulse timing and patient positions to identify heart sounds and murmurs.
Stethoscope placement
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Use the diaphragm at the apex, lower left sternal border (tricuspid area), upper left sternal border (pulmonary area) and upper right sternal border (aortic area).
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Use the bell for low-pitched sounds, particularly the mid-diastolic murmur of mitral stenosis at the apex.
Timing sounds and murmurs
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Feel the carotid pulse while listening: the first heart sound (S1) just precedes the pulse upstroke, whereas the second heart sound (S2) is out of step with it.
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A third heart sound (S3) immediately follows S2; a fourth heart sound (S4) just precedes S1.
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Systolic murmurs are synchronous with the pulse.
Radiation and patient position
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Listen for radiation of the systolic murmur of aortic stenosis over the base of the neck and that of mitral incompetence in the axilla.
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For aortic incompetence, listen over the left sternal border with the patient sitting forward.
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For mitral stenosis, listen at the apex with the patient rolled onto the left side.
Cardiovascular disease burden
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Cardiovascular disease is described as the commonest cause of death worldwide, with coronary heart disease the leading cause of death.
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The passage reports 3.8 million male and 3.4 million female deaths from coronary heart disease each year. Its incidence is falling in some countries but rising in lower-income countries, which account for more than 60% of the global burden.
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Valvular heart disease is predominantly due to rheumatic fever in South Asia and Africa, whereas calcific aortic valve disease is the commonest valvular problem in high-income countries.
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Treatment and prevention strategies for cardiovascular disease have a strong evidence base supported by randomised trials.