Analysis of phonocardiogram
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Transcript Analysis of phonocardiogram
4th practice
Medical Informatics
Biomedical Signal Processing
TAMUS, Zoltán Ádám
[email protected]
The
most traditional biomedical signal
(stethoscope)
The PCG is generated by the contractile
activity of the cardiohemic system (the
heart and blood together)
Recording: microphones, pressure
transducers or accelerometers placed on
the chest surface
Auscultation
areas for heart sound
The
heart sound are NOT caused by
valve leaflets movements
Vibrations of the whole cardiovascular
system
As the fluid filled balloon when
stimulated any location
Normal
cardiac cycle contains two major
sounds
• the first heart sound (S1) and the second heart
sound (S2)
S1
occurs at the onset of the ventricular
contraction (systole)
S2
occurs at the closure of the semilunar
valves (diastole)
The
first vibration:
• contractions in the
ventricles
• blood move toward
the atria
• sealing the atrioventricular (AVmitral and tricuspid)
valves
The
second
component:
• abrupt tension of the
closed AV valves
• decelerating the
blood
The
third
component:
• the semilunar valves
(aortic and
pulmonary) open
• the blood is ejected
out of the ventricles
• oscillation of blood
between the root of
the aorta and the
ventricular walls
The
forth
component:
• Turbulence in the
ejected blood
flowing rapidly
through the
ascending aorta and
the pulmonary artery
The
S2 is caused by
the closure of the
semilunar valves
• Vibrations in the
arteries due to the
deceleration of blood
• Ventricles and atria
also vibrate due to the
transmission of
vibrations through
blood, valves and the
valve rings
S2
has two components
• First: closure of the aortic valve (A2)
• Second: closure of the pulmonary valve (P2)
A2
precedes P2 by few miliseconds
Phatologic conditions could cause this
gap widen or may also reverse the order
of A2 and P2
In
some cases may
be heard
• sudden termination
of the ventricular
rapid filling phase
• Low frequency:
ventricles filled
blood and their walls
are relaxed
The
intervals between S1 and S2, and S2
and S1 are normally silent
Murmurs are caused by certain
cardiovascular defects and diseases
Murmurs are high frequency, noise-like
sounds
Turbulence in blood flow
Rangaraj
M. Rangayyan: Biomedical
Signal Analysis, IEEE Press/Wiley, New
York, NY, 2002.
1. Analysis of the heart sound
• Observation of the parts of heart sound
Parts of S1 and S2
• Determination of the heart rate (pulse)
2. Examination of heart sound in frequency
domain
3. Examination of murmurs in time and
frequency domain
sample files: http://zoltanadam.fw.hu
software: Audacity http://audacity.sourceforge.net/