Noninvasive diagnostic system for coronary artery disease
First Claim
1. An apparatus for noninvasive detection of coronary artery disease comprising:
- an acoustic transducer for detecting heart sounds from a patient'"'"'s chest cavity and providing a heart sound signal representative of said detected heart sounds;
frequency analyzer means for providing a parametric model for parametrically modeling said detected heart sounds based on said heart sound signal;
turbulent flow detector means for detecting the presence of auditory component in said parametric model, said component being associated with turbulent blood flow in a partially occluded coronary artery, said turbulent flow detector means including means for applying a decision criterion based on one or more parameters of said parametric model, said decision criterion being indicative of the presence of said auditory component in the range of about 300 to about 1200 Hz; and
display means for presenting diagnostic information based on the detected presence of said auditory component.
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Accused Products
Abstract
A method and system for non-invasively detecting Coronary Artery Disease. The method comprises analyzing the diastolic heart sounds detected from a patient'"'"'s chest cavity during the diastolic portion of the heart cycle in order to identify a low level auditory component associated with turbulent blood flow in partially occluded coronary arteries. These diastolic heart sounds are modeled using advanced signal processing techniques such as Autoregressive (AR), Autoregressive Moving Averaging (ARMA) and Eigenvector methods, so that the presence of such an auditory component may be reliably indicated even under high noise conditions. The system includes an acoustic transducer, pulse sensor device, signal processor means and a diagnostic display. Additionally, the system includes a controller for automatically sequencing data collection, analysis and display stages, therefore requiring a minimum of operator interaction. The system further discloses a piezoelectric type low mass accelerometer for use as an acoustic transducer providing higher sensitivity at the high frequencies necessary for detecting coronary artery disease, specifically between 300 to 1200 Hz. In addition, the system discloses a method for automatically identifying and isolating a diastolic segment of a heart sound recording through a "window" placement technique. A window is placed relative to the second heart sound and various criteria are implemented to evaluate the recording for artifacts, i.e., data due to breath sounds, stomach growls, external ambient noise.
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Citations
33 Claims
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1. An apparatus for noninvasive detection of coronary artery disease comprising:
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an acoustic transducer for detecting heart sounds from a patient'"'"'s chest cavity and providing a heart sound signal representative of said detected heart sounds; frequency analyzer means for providing a parametric model for parametrically modeling said detected heart sounds based on said heart sound signal; turbulent flow detector means for detecting the presence of auditory component in said parametric model, said component being associated with turbulent blood flow in a partially occluded coronary artery, said turbulent flow detector means including means for applying a decision criterion based on one or more parameters of said parametric model, said decision criterion being indicative of the presence of said auditory component in the range of about 300 to about 1200 Hz; and display means for presenting diagnostic information based on the detected presence of said auditory component. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. An apparatus for noninvasive detection of coronary artery disease comprising:
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an acoustic transducer for detecting heart sounds from a patient'"'"'s chest cavity and providing a heart sound signal representative of said detected heart sounds, said transducer comprising; a double cantilever beam configuration, the unsupported end of each beam having an equal mass attached thereto; a bending moment sensor affixed to one side of each beam which produces an electrical output signal in relation to its bending moment; support means for supporting said beam; a contact plate affixed to said support means, for mounting against a patient'"'"'s chest such that chest vibrations couple through said contact plate and support means causing said beam to bend in accordance with such vibrations; and the transducer having a resonant frequency slightly about 1200 Hz, and increased sensitivity in the frequency band of 300 to 1200 Hz; frequency analyzer means for parametrically modeling said detected heart sounds based on said heart sound signal; turbulent flow detector means for detecting the presence of an auditory component in said parametric model, said component being associated with turbulent blood flow in a partially occluded coronary artery, said detector means applying a decision criterion based on one or more parameters of said parametric model; display means for presenting diagnostic information based on the detected presence of said auditory component.
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16. A method for noninvasive detection of coronary artery disease, said method comprising the steps of:
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detecting heart sounds from a patient'"'"'s chest cavity; providing a parametric model for parametrically modeling said detected heart sounds; detecting the presence of an auditory component in said parametric model by applying a decision criteria based on one or more parameters of the parametric model being indicative of said component being in the range of about 300 to about 1200 Hz, said component being associated with turbulent blood flow in a partially occluded coronary artery; and presenting diagnostic information based on the detected presence of said auditory component. - View Dependent Claims (17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28)
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29. A method for automatically isolating the diastolic segment of a heart sound signal and editing the selected segment to determine if it is substantially free of artifacts resulting from other body sounds, said method comprising the steps of:
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establishing a preliminary data window of a predetermined width upon an indication of the onset of diastole in a cardiac cycle, said preliminary data window comprising three zones, the first of which (zone
1) includes the expected trailing edge of a second heart sound, the third of which (zone
3) includes the expected leading edge of a succeeding first heart sound, and the second of which (zone
2) is approximately centered in the diastolic segment of said heart sound;establishing a threshold level within said preliminary data window for discriminating the occurrence of said second or first heart sound; establishing a test window within said preliminary data window, said test window width being significantly smaller than said preliminary data window width; evaluating a RMS value of said heart sound signal within said test window for a plurality of test window locations within said zones of the preliminary data window; locating a lower diastolic boundary which is defined by the latest in time location of said test window in zone 1 where said RMS value exceeds the value of said threshold level; locating an upper diastolic boundary which is defined by the earliest location in time of said test window in zone 3 where said RMS value exceeds said threshold level; positioning a diastolic window of a predetermined width at the approximate center between said lower and upper diastolic boundaries, said diastolic window thereby isolating the heart sound signal within for subsequent analysis; and rejecting said heart sound signal data within said diastolic window if a window defined by said lower and upper diastolic boundaries is smaller in width than said predetermined width of the diastolic window. - View Dependent Claims (30, 31, 32, 33)
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Specification