Download Normal Heart Sounds

Abnormal S3 and S4 heart sounds
S3
Sound:
Cause:
Affected mechanism:
Clinical significance:
Ventricular
gallop: dull, faint
thud heard after
S2.
Rapid refilling
or overfilling of
the ventricles
Possibly caused by stiff valve
leaflets and/or ventricular
walls vibrating as diastolic
filling abruptly slows down,
but may be the sound of the
ventricle hitting the inner
chest wall or the apex
suddenly reaching the limit of
its ability to expand
lengthwise.
May indicate:
1. Most
commonly due
to increased
resistance as
blood is forced
into a stiff
(usually left)
ventricle.
Although it is called atrial
gallop, the sound originates
in the ventricles during
diastolic filling, which has two
phases. The first is rapid and
passive, and occurs when the
atrioventricular valves open.
S4 is associated with the
second phase, which occurs
in late ventricular diastole
when the atria contract,
actively forcing blood into the
ventricles. The sound is
thought to be that of the
ventricular wall vibrating as a
result of a sudden decrease
in the rapid flow of blood into
the ventricles.
1. Usually indicates increased resistance to blood flowing into the
ventricles, which is known as reduced compliance, commonly as a
result of ventricular hypertrophy (eg. systemic hypertension, aortic
stenosis, hypertrophic cardiomyopathy) or coronary heart disease
(previous myocardial infarction or acute ischaemia). Right
ventricular S4 is typical of pulmonic valve stenosis and pulmonary
artery hypertension.
Cycle sound:
lub-DUP-da or
lub-DU-bub
S4
Atrial gallop:
low-pitched
dull or thudding
sound heard
shortly before S1
Cycle sound:
bla-lub-DUP or
belub-DUP
2. Increased
atrial pressure
(atrioventricula
r valves may
also vibrate).
S3 & S4
Quadruple
gallop
Cycle sound:
bla-lub-DUP-da

Ventricular dysfunction (eg. ischaemic heart disease, dilated or
hypertrophic cardiomyopathy, myocarditis);
 Heart failure;
 Too much blood or fluid in the ventricles – eg. high cardiac
output (anaemia, pregnancy or thyrotoxicosis), valve
regurgitation or intracardiac shunt, heart block, renal failure, or
excess transfused fluid or blood.
Note: Important indicator of relatively advanced heart disease and
almost always abnormal over the age of 40. May not appear so the
absence of S3 does not rule out the above conditions.
2. Overfilling of a normal ventricle (eg. anaemia, thyrotoxicosis or
acute mitral regurgitation)
Note: Almost always abnormal if clearly heard and palpable, but
may be heard in healthy people aged over 50 – possibly reflecting
a normal decrease in ventricular compliance with ageing.
The creation of this sound depends upon effective atrial contraction
and blood flow through the atrioventricular valves, so S4 does not
occur in patients with atrial fibrillation, or advanced mitral (no S4
sound on left) or tricuspid (no S4 sound on right) stenosis.
Note: In patients with a rapid heart rate it may be difficult to distinguish S3 from S4, and in patients with tachycardia S3
and S4 may occur at almost the same time and be heard as a loud three-beat gallop.