3. Learning objectives
At the end of this lecture, all the students should be able to;
• Define heart sounds
• Enumerate various types of heart sounds
• Describe the formation of first heart sound
• Describe the formation of second, third and fourth heart
sound
10. Heart sounds
• Mechanical activities of heart during each cardiac cycle
produce sounds which are called heart sounds
11. Cardiac Cycle
• The cardiac events that occur from the beginning of one
heart beat to the beginning of the next are called cardiac
cycle
Systole
Diastole
15. What do we need to know
about these heart sounds????
How are they produced?
At which stage of cardiac cycle they are produced?
What are the characteristics?
What is correlation with ECG?
16. During each cardiac cycle, four heart sounds are produced
First heart sound Second heart sound
Third heart sound Fourth heart sound
18. First and second heart
sound can be listened
with stethoscope in a
healthy person with
healthy heart
19.
20. First heart sound
• Produced due to sudden closure of atrioventricular valves
• Closure of atrioventricular valves set up vibrations in the
valvular leaflets and chordae tendineae
• These vibrations are mainly responsible for production of
the first heart sound
26. Characteristics
• First heart sound is a long, soft and low-pitched sound
• It resembles the spoken word ‘LUBB’
• The duration of this sound is 0.10 to 0.17 second with a
frequency of 25 to 45 cycles/second
27.
28. First Heart Sound and ECG
• First heart
sound
coincides
with peak of
‘R’ wave in
ECG
30. Second heart sound
• Second heart sound is
produced due to the sudden
and synchronous closure of the
semilunar valves
• It is produced at the end of
early diastole of ventricles
35. Characteristics
• Second heart sound is a short, sharp and high-pitched
sound
• It resembles the spoken word ‘DUBB’ (or DUP)
• Duration of second heart sound is 0.10 to 0.14 second with
a frequency of 50 cycles/second
36. Second Heart Sound and ECG
• Second heart sound
coincides with the ‘T’ wave
in ECG. Sometimes, it may
precede the ‘T’ wave or it
may commence after the
peak of ‘T’ wave
37. Third heart sound Fourth heart sound
Heard sounds recorded on phonocardiogram
(Additional heart sounds)
A specially designed microphone
amplifies these sounds and is
attached to a sound recorder to give
phonocardiogram
38.
39. Third heart sound Fourth heart sound
Heard sounds recorded on phonocardiogram
(Additional heart sounds)
40. Third heart sound
• Third heart sound is a low-pitched sound that is produced
during rapid filling period of the cardiac cycle
• May be normally present in children, adolescents and
young adults but generally indicates systolic heart failure in
older adults
41. Third heart sound is produced due to rapid ventricular
filling
Which part of the cardiac cycle it is being generated?????
44. Cause
Third heart sound is produced by the rushing of blood into
ventricles and vibrations set up in the ventricular wall during
rapid filling phase
45. Characteristics
Third heart sound is a short and low-pitched sound. Duration
of this sound is 0.07 to 0.10 second with a frequency of 1 to 6
cycles/second
46. Third Heart Sound and ECG
• Third heart
sound appears
between ‘T’
and ‘P’ waves
of ECG
47. Conditions when Third Heart Sound becomes Audible
Third heart sound can be heard by stethoscope in
• Children and athletes(Physiological sound)
• Pathological conditions such as
• Aortic regurgitation
• Cardiac failure and
• Cardiomyopathy with dilated ventricles
48. Third heart sound Fourth heart sound
Heard sounds recorded on phonocardiogram
(Additional heart sounds)
49. Fourth heart sound
• An atrial heart sound (fourth heart sound) can sometimes
be recorded in the phonocardiogram, but it can almost
never be heard by stethoscope because of weakness and
very low frequency
• It is recorded in perhaps one fourth of all people
50. • This sound is produced during atrial systole and it is
considered as the physiologic atrial sound if recorded on
phonocardiogram but if heard on stethoscope ,it is
considered to be pathological
• It is also called atrial gallop or presystolic gallop
Fourth heart sound
52. Cause
• Fourth heart sound is produced by contraction of atrial
musculature and vibrations are set up in atrial musculature,
flaps of the atrioventricular valves during systole
• It is also due to the vibrations set up in the ventricular
myocardium because of ventricular distention during atrial
systole
53. Characteristics
• Fourth heart sound is a short and low-pitched sound
Duration of this sound is 0.02 to 0.04 second with a
frequency of 20 cycles/second or less
54. Fourth Heart Sound and ECG
• Fourth heart
sound coincides
with the interval
between the
end of ‘P’ wave
and the onset of
‘Q’ wave
55. Conditions when Fourth Heart Sound becomes Audible
Fourth heart sound becomes audible by stethoscope when
the ventricles become stiff
• Ventricular stiffness occurs in conditions like
• Ventricular Hypertrophy
• Long Standing Hypertension
• Aortic Stenosis
56. Summary
First heart sound
Isovolumetric contraction and early part
of ejection period
Second heart
sound
Early part of isovolumetric relaxation
Third heart sound Rapid filling phase
Fourth heart sound Atrial systole
57.
58. Mitral area
Left fifth intercostal
space
Left midclavicular line
Tricuspid area
Left fourth,fifth
intercostal space
Lower left sternal
border
Pulmonary area
Left second intercostal
space
Upper left sternal
border
Aortic area
Right second
intercostal space
Upper right sternal
border
