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Murmurs
Murmurs are produced by turbulent blood flow, and are
described according to their location, intensity, timing, frequency,
and radiation (Tables 15.1 to 15.3 and Figure 15.1).
Innocent murmurs are due to pulmonary flow and can be
heard in children, pregnancy, and high-flow states, such
as hyperthyroidism and anaemia. They are heard over the
left sternal edge and are ejection systolic, and there are
no added sounds or thrill. The cervical venous hum is a
continuous murmur, common in children and typically reduced
by turning the head laterally or bending the elbows
back. The mammary soufflé is a continuous murmur that
may be heard in pregnancy.
Dynamic auscultation manoeuvres may help bedside diagnosis
of systolic murmurs (Table 15.2). 4, 5 Murmurs originating
within the right-sided chambers of the heart can
be differentiated from all other murmurs by augmentation
of their intensity with inspiration and diminution with
expiration. The murmur of hypertrophic cardiomyopathy
is distinguished from all other systolic murmurs by an increase
in intensity with the Valsalva manoeuvre and during
squatting-to-standing, and by a decrease in intensity
during standing-to-squatting action, passive leg elevation,
and handgrip. The murmurs of MR and VSD have similar
responses but can be differentiated from other systolic
murmurs by augmentation of their intensity with handgrip
and during transient arterial occlusion.