Study of Acoustic Signal of Heart

1. VELTECH
DEPARTMENT OF ECE
PhonoCardiogram-PCG
Prepared By,
V.Mahalakshmi,
Assistant Professor,
Department of ECE,
Veltech

2. Phonocardiogram (PCG)
• Phonocardiography is the study of different heart
sounds.
• The phonocardiograph is the instrument used to
pick up the different heart sound, filter the
required and display.
• The phonocardiogram is the graphic record of
heart sounds.
Two categories
• Heart sound- transient characteristics with short
duration occurs due to opening and closing of the
heart valves.
• Murmurs- noisy characteristics with long duration
occurs due to turbulent blood flow in heart.

3. PIONEERS
• Hippocrates laid the foundation for
auscultation
• Robert Hook realized diagnostic use of cardiac
auscultation
• Biggest breakthrough in auscultation:
Rene Laennec invented stethoscope
• Dr. Jean Bennett Maguire devised a method
of real-time spectral phonocardiography for
the detection and classification of heart
murmurs.

4. Development of stethoscope
Early monaural stethoscope
Modern binaural stethoscope
Modern electronic stethoscope

6. Classifications of heart sounds
• Valve closure sound - This sound occurs at the
beginning of systole and at the beginning of
diastole.
• Ventricular filling sound - This sound is
occurred at the time of filling of the ventricles.
• Valve opening sound - This sound occurs at
the time of opening of atrio- ventricular valves
and semi lunar valves.
• Extra cardiac sound - This sound occur in mid
systole or late systole or early diastole

7. PCG Signal Characteristics
3 factors of PCG Signal
• Frequency – (10 to 1000 Hz)
• Amplitude
• Quality

8. PCG Signal Characteristics
• 1st Heart sound:
• Closure of mitral and tricuspid valves.
• Frequency- 30 to 100Hz and duration 50 to
100ms.
• 2nd Heart sound :
• Closure of aortic and pulmonary valves.
• Frequency- 30 to 100Hz and duration 25 to
50ms.

9. PCG Signal Characteristics
• 3rd heart sound:
• Blood rapid movement into relaxed ventricular
chambers
• Frequency – 10 to 100 Hz and duration 0.04 to
0.08 S.
• 4th heart sound
• Atrial contraction.
• Frequency 10 to 50HZ and duration 0.03 to 0.06S

10. PCG Signal Characteristics

11. HEART CYCLE
Name
EventsPressure(kPa)
PCG
ECG
Time 0 (sec)

12. PCG waveform

13. • Aortic stenosis murmur – This murmur is occurred
when the blood is ejected from the left ventricle
through aortic valve due to resistance to ejection, the
pressure in the left ventricle increased. So turbulent
blood flow occur. This turbulent blood impinging the
aortic valve. So intense vibration is produced. It
produces loud murmur.
• Mitral regurgitation murmur- In this murmur, blood
flows in backward direction through the mitral valve
during systole.
• Aortic regurgitation murmur – During diastole,
sound is heard. In diastole blood flows in the
backward direction from aorta to left ventricles when
valves are damaged, then this sound is heard.
• Mitral stenosis murmur – This murmur is produced
when blood is passed from left atrium to left
ventricle. This sound is very weak.

14. PCG Recording System

15. TYPES OF MICROPHONES USED IN
PCG
1. Air coupled microphone-
• Movement of chest is transferred through the air
cushion.
• It provides low mechanical impedance to the
chest.
2. Contact microphone
• It is directly coupled to the chest wall and provides
high impedance, high sensitivity, and low noise.
• It is light in weight.

16. Amplifier
• Offer selective high pass filter to allow frequency
cutoff
• Bandwidth : 20- 2000Hz
• Amplify signal
Filter
• Permit selection of suitable frequency bands
• Avoid aliasing
• Separate louder low frequency signals from
lower intensity, much informative high frequency
murmurs.