Download heart sounds

INTRODUCTION
 Heart sounds are sounds produced by the
mechanical activities of the heart during each
cardiac cycle. They are due to movements of
 Blood flow through the chambers of the heart
 Cardiac muscle
 Valves of the heart.
These are heard by placing the ear over the
chest or by using stethoscope or microphone.
Heart sounds
 There are four heart sounds produced during each
cardiac cycle.
First & second heart sounds are more prominent,
appear as “LUB & DUB” these sounds are heard by
stethoscope.
Third heart sound is mild it cannot be heard by
stethoscope in normal conditions, but can be heard by
microphone.
Fourth heart sound is an inaudible, become audible in
pathological conditions only by phonocardiogram.
Importance of heart sounds
 The study of heart sounds has important
diagnostic value in clinical practice b/c the
alteration in heart sounds indicates the
cardiac diseases involving the valves of
heart.
First heart sound:
 It is produced due to the simultaneous closure of both
the atrioventricular (mitral & tricuspid) valves.
 It is produced during isometric contraction period &
earlier part of ejection period or at the start of
ventricular systole.
Characteristics:
 This is long, soft & low pitched sound
 It resembles the spoken word “LUBB”
 The duration of sound is about 0.15 sec
 Frequency is 25-45 Hz.
ISOVOLUMETRIC CONTRACTION
1st Heart Sound
 The first heart sound (S1, "lub") is due to the closing AV
valves and associated blood turbulence.
CAUSES:
Along with closure of A/V valves some other
factors also involved to produce 1st heart sound these
are,
1. Valvular factor; Synchronous closure of
atrioventricular valves set up the vibrations in the
valvular leaflets & chordae tendinae.
2. Vascular factor; The distension of aorta &
pulmonary artery due to the rush of blood from
ventricles into these vessels during ejection period.
3. Muscular factor;
The myocardial tension & contraction of ventricular
muscle during Isometric contraction & the ejection
period.
4. Atrial factor;
The residual vibrations produced by the atrial systole
also play a role in the production of 1st heart sound.
Reduplication of 1st heart sound:
This is the splitting of the 1st heart sound, this is due
to the asynchronous closure of A/V valves, may occur
in normal conditions but rare.
1st heart sound & ECG: coincides with peak R wave
in ECG.
Second heart sound:
 It is produced during the onset of diastole.
 This sound is due to the simultaneous closure of both
the semilunar valves.
 Characteristics:
 The 2nd heart sound is a short, sharp & high pitched
sound.
 It resemble the spoken word “DUBB”
 The duration of the 2nd heart sound is 0.10 to 0.14sec.
 Frequency is about 50 cycles/sec
ISOVOLUMETRIC RELAXATION
2nd Heart Sound
 The second heart sound (S2, "dup") occurs
when the semilunar (aortic and pulmonary)
valves close. S2 is normally split because the
aortic valve closes slightly earlier than the
pulmonary valve.
Reduplication of 2nd heart sound:
This is the splitting of this sound. It occurs due to
asynchronous closure of both the semilunar valves.
Physiological splitting:
occurs during deep inspiration. Aotic valve close
prior to pulmonary valve & interval widening during
inspiration.
Pathological splitting:
occurs during pulmonary stenosis, right bundle
branch block & right ventricular hypertrophy.
2nd heart sound & ECG:
It coincide with T wave in ECG
Third heart sound:
 It is produced during rapid filling period of the cardiac
cycle.
 It is also called ventricular gallop or protodiastolic gallop as
produced during earlier part of diastole.
 Characteristics:
 The 3rd heart sound is short & low pitched
 Its duration is 0.07-0.1 sec
 Frequency is about 1-6 cycles/sec.
Cause:
It is due to rush of blood into ventricles. When blood flows
rapidly, vibrations are set up in ventricular wall resulting in
production of sound.
3rd heart sound is not audible by stethoscope, can be
heard by microphone.
Physiologically can be audible in children & athletes.
Pathological conditions: aortic regurgitation or mitral
incompetence , cardiac failure & cardiomyopathy with
dilated ventricles, severe hypertension, myocardial
infarction.
3rd heart sound & ECG: it appears b/w T and P waves.
RAPID VENTRICULAR FILLING
3rd Heart Sound
 A third heart sound (S3) is usually abnormal and is
due to rapid passive ventricular filling.
 Fourth heart sound:
 This sound produced during atrial systole (late
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diastole).
Characteristics:
Short & low pitched sound
Duration is 0.02-0.04 sec
Frequency is 1-4 cycles/sec.
Cause:
During atrial systole vibrations are set up in the atrial
musculature & in the flaps of A/V valves.
ATRIAL SYSTOLE
4th Heart Sound
 A fourth heart sound (S4) is abnormal and is
associated with the end of atrial emptying after atrial
contraction.
Conditions when 4th heart sound is audible:
 It occurs with hypertrophic congestive heart
failure, massive pulmonary embolism, tricuspid
incompetence, or cor pulmonale & aortic stenosis
4th heart sound & ECG:
 It coincides with the interval b/w the end of P
wave & onset of Q wave.
Methods of study of heart sounds:
Heart sounds are studied by three methods:
1. By using stethoscope
2. By using microphone
3. By phonocardiogram.
1. BY STETHOSCOPE: 1st & 2nd heart sounds are heard on
auscultation areas by stethoscope. Chest piece is placed
over 4 auscultation areas. The 4 auscultation areas are:
a. Mitral areas (Bicuspid Area or apex beat area)= 1st heart
sound is audible
b. Tricuspid area= 1st heart sound
c. Pulmonary area= 2nd heart sound
d. Aortic area= 2nd heart sound
4 auscultation areas
 By Microphone:
 It is highly sensitive microphone is placed over the
chest. The heart sounds are amplified by means of
amplifier & heard by using loud speaker.
 1st, 2nd & 3rd heart sounds are heard by this method.
 By Phono cardiogram:
 Phonocardiography is the technique used to record
the heart sounds. phonocardiogram is the graphical
record of the heart sounds .It is done by placing an
electronic sound transducer over the chest. This
transducer is connected to a recording device like
poly graph. All the 4 heart sounds can be recorded in
phonocardiogram. It helps to analyze the frequency of
the sound waves.
Cardio Microphone:
Phonocardiogram