Download The Second Heart Sound (S2) Chapter 8

The Third & Fourth (S3 &S4)
Chapter 9
Are G. Talking, MD, FACC
Instructor
Patricia L. Thomas, MBA, RCIS
Outline
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Diastolic Filling
The Third Heart Sound
Summation Gallop
Differential Diagnosis
Absent S3 & S4
The Fourth Heart Sound
Diastolic Filling
• Reflects Ventricular Function
• S3 heard in systolic left ventricular
dysfunction
• S4 heard in diastolic left ventricular
dysfunction
• Two periods of accelerated ventricular filling
– Passive filling early diastole after AV valves open
– Active filling occurring late diastole results from
atrial contraction (A-Kick)
Early or Passive Filling
• Begins when the mitral valve opens
• Rapid filling of the LV follows
• Soft positive wave (RFW) rapid filling can
cause a physiological S3 in young or in high
flow states
• Pathological S3 or ventricular diastolic
gallop in cases of dilated hearts and in CHF
Late or Active Filling
• Atrial systole forces blood into the ventricle
in late diastole
• Forward thrust of blood is normally silent
• If ventricle is stiff/reduced compliance, the
force of blood entering the ventricle is more
vigorous and results in an impact sound in
late diastole know as S4 or atrial gallop
• Hypertension, outlet obstruction,
hypertrophy/infiltrative myopathies
Where To Listen
• Listen with the bell at the PMI after patient
turn to left lateral position
The Third Heart Sound S3
• Originate in either or both ventricles most
commonly in the LV and resulting in vibrations
of the LV wall
• Relates to a sudden deceleration of early
diastolic LV inflow caused by a sudden
limitation of expansion along the longitudinal
axis of the LV wall resulting in a negative jerk
that is transmitted to the skin surface
• High inflow rates with mitral regurgitation
• Incomplete relaxation
Normal S3
• Present in children and well-conditional young
athletes
• Persist in ¼ of individuals until about 40
• Predicted by leanness and high early diastolic
LV inflow velocity which reflects effects of
aging
• Normal disappearance with age due to
increased myocardial mass, larger mass
increase damping factor and less vibrations
Pathological S3 (Gallop Rhythm)
• S3 or S4 produces a triple rhythm
• S3 & S4 produces a quadruple rhythm that
sounds like the galloping of a horse in both
normal/abnormal clinical situations
• Causes
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Mitral Regurgitation
Aortic Stenosis
Acute Myocardial Infarction
Evolving Heart Failure
S3 Induced by Exercise
Differential Diagnosis
• Normal vs. Abnormal S3 or S4
• Right vs. Left Ventricular S3
– Right Ventricular S3 is louder during inspiration
because of increased venous return to the RV and a
larger stroke volume
The Fourth Heart Sound (S4)
• Caused by the vibration created in the ventricles as
they expand in the second phase of rapid diastolic
filling when the atria contract and before the first
heart sound
• Fourth heart sounds seldom occur in normal hearts
• Pathological S4 is a low-frequency, dull or
thudding sound resulting from the sudden
movement of stiff ventricular wall as they respond
to the force delivered through the AV valves by the
enhanced contraction of the atria
Where to Listen/Loudness of S4
• Listen with the bell at the PMI with patient in
the left lateral decubitus position
• It is louder on expiration
• Louder with increased preload or afterload
(squatting, hand grip, leg elevation) increases
the intensity of S4 because it shortens the P-S4
interval
S4 & the PR Interval
• Easily heard when the PR interval is
prolonged
• Interval from the P wave to S4 varies and
influences prognosis
THE END
OF
CHAPTER 9
Tilkian, Ara MD Understanding Heart Sounds and Murmurs,
Fourth Edition, W.B. Sunders Company. 2002, pp. 93-106