1. 4th practice Medical Informatics Biomedical Signal Processing TAMUS, Zoltán Ádám zoltanadam_tamus@yahoo.com

2.  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

3.  Auscultation areas for heart sound

4.  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

5.  Normal cardiac cycle contains two major sounds the first heart sound (S1) and the second heart sound (S2)

6.  S1 occurs at the onset of the ventricular contraction (systole)

7.  S2 occurs at the closure of the semilunar valves (diastole)

8.  The first vibration: contractions in the ventricles blood move toward the atria sealing the atrio- ventricular (AV- mitral and tricuspid) valves

9.  The second component: abrupt tension of the closed AV valves decelerating the blood

10.  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

11.  The forth component: Turbulence in the ejected blood flowing rapidly through the ascending aorta and the pulmonary artery

12.  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

13.  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

14.  In some cases may be heard sudden termination of the ventricular rapid filling phase Low frequency: ventricles filled blood and their walls are relaxed

15.  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

16.  Rangaraj M. Rangayyan: Biomedical Signal Analysis, IEEE Press/Wiley, New York, NY, 2002.

17.  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.huhttp://zoltanadam.fw.hu software: Audacity http://audacity.sourceforge.net/http://audacity.sourceforge.net/