Signal processing of heart signals for the quantification of non-deterministic events.
BACKGROUND
Heart signals represent an important way to evaluate cardiovascular function and often what is desired is to quantify the level of some signal of interest against the louder backdrop of the beating of the heart itself. An example of this type of application is the quantification of cavitation in mechanical heart valve patients.


METHODS
An algorithm is presented for the quantification of high-frequency, non-deterministic events such as cavitation from recorded signals. A closed-form mathematical analysis of the algorithm investigates its capabilities. The algorithm is implemented on real heart signals to investigate usability and implementation issues. Improvements are suggested to the base algorithm including aligning heart sounds, and the implementation of the Short-Time Fourier Transform to study the time evolution of the energy in the signal.


RESULTS
The improvements result in better heart beat alignment and better detection and measurement of the random events in the heart signals, so that they may provide a method to quantify nondeterministic events in heart signals. The use of the Short-Time Fourier Transform allows the examination of the random events in both time and frequency allowing for further investigation and interpretation of the signal.


CONCLUSIONS
The presented algorithm does allow for the quantification of nondeterministic events but proper care in signal acquisition and processing must be taken to obtain meaningful results.
Department of Mechanical Engineering, 161 Louis Pasteur, University of Ottawa, K1N 6N5, Ottawa, Ontario, Canada. nbaddour@uottawa.ca.
Véronique
V
Millette
Natalie
N
Baddour
D000465:Algorithms; D016477:Artifacts; D006321:Heart / Q000502:physiology*; D006334:Heart Function Tests / Q000379:methods*; D006350:Heart Valve Prosthesis; D006801:Humans; D008955:Models, Cardiovascular; D012815:Signal Processing, Computer-Assisted; D013997:Time Factors
Annu Int Conf IEEE Eng Med Biol Soc. 2008;2008:334-7
19162661
ASAIO J. 2003 May-Jun;49(3):304-8
12790381
J Heart Valve Dis. 2002 Sep;11(5):736-44
12358413
J Med Eng Technol. 2008 Nov-Dec;32(6):456-65
18663636
IEEE Trans Biomed Eng. 1998 Aug;45(8):962-71
9691571
Biomed Eng Online. 2011 Jan 26;10:10
21269508
Comput Methods Programs Biomed. 2010 Jul;99(1):43-8
20036439
J Heart Valve Dis. 2004 Jul;13(4):651-8
15311874
Philos Trans A Math Phys Eng Sci. 2009 Jan 28;367(1887):277-96
18977726
Comput Methods Programs Biomed. 2010 May;98(2):140-50
19854530
Expert Rev Med Devices. 2004 Sep;1(1):95-104
16293013
Philos Trans A Math Phys Eng Sci. 2009 Jan 28;367(1887):255-75
18936017
IEEE Trans Biomed Eng. 1998 Aug;45(8):972-9
9691572
ASAIO J. 1998 Sep-Oct;44(5):M475-9
9804476
Med Biol Eng Comput. 1998 May;36(3):302-8
9747569
Philos Trans A Math Phys Eng Sci. 2009 Jan 28;367(1887):391-409
18940775
J Biomech Eng. 2003 Oct;125(5):663-70
14618925
Med Biol Eng Comput. 2001 Nov;39(6):644-8
11804170
Ann Thorac Surg. 2006 Jan;81(1):34-41
16368331
J Heart Valve Dis. 2005 Jul;14(4):551-8
16116884
J Heart Valve Dis. 2003 Nov;12(6):790-6
14658822
J Heart Valve Dis. 1994 Apr;3 Suppl 1:S8-22; discussion S22-4
8061873
J Biomech Eng. 2006 Apr;128(2):217-22
16524333