System for simultaneously producing and synchronizing spectral patterns of heart sounds and an ECG signal

#The present invention relates to a system and a process for detecting, assessing, grading and diagnosing heart conditions in human beings. In accordance with the system and process of the present invention, a spectral phonocardiogram signal and a corresponding electrocardiogram signal are displayed simultaneously, preferably in a synchronized relationship, to facilitate the detection, assessment, grading and diagnosis of a heart condition.

#U.S. Pat. Nos. 4,967,760 and 5,012,815, both to Bennett et al., illustrate dynamic spectral phonocardiogram (DSP) systems for generating a spectral phonocardiogram which summarizes time dependent changes in the heart sounds through a heart cycle. The systems are based on the projection of spectral surfaces of the Fourier transform of heart sounds as a function of time. They have been used to screen people for heart disease.

#U.S. Pat. No. 4,905,706 to Duff et al. illustrates a similar method and apparatus for detecting coronary artery disease. The Duff et al. system records and analyzes that portion of the phonocardiogram lying between about 100 to 600 Hz. An electrocardiogram is recorded and examined in order to pinpoint the diastolic window of PCG data. This window of data is subjected to autocorrelation analysis and spectral analysis to yield a partial correlation coefficient index and a power density index. A linear combination of these two indices is then used to generate yet another index, termed a Cardiac Screening Index, which is indicative of the presence or absence of coronary artery disease.

#FIG. 1 is a schematic drawing of the human heart showing the basic geometry, direction of blood flow, and valve locations;

#FIG. 2 is an illustration of areas of auscultation of the chest and for placement of a microphone to detect cardiac sounds and murmurs;

#FIG. 3 is an illustration of a human patient connected to an electrocardiograph;

#Referring now to the drawings, FIG. 1 is a cross-sectional drawing of a human heart. The path of blood flow through the normal heart is shown by the heavy arrows and the four valves are indicated in large bold print. Blood flows in through the vena cava to the right atrium, through the tricuspid valve to the right ventricle, and through the pulmonary valve to the lungs. Blood returning from the lungs enters the left atrium, flows through the mitral valve to the left ventricle, and through the aortic valve to the aorta.

#The "First Sound" (S1) in the heart cycle is normally strongest in the apex region, occurs when the heart contracts, and is primarily due to the near simultaneous closing of the tricuspid and mitral valves. During this contraction, blood flows from the right ventricle through the pulmonary valve to the lungs and from the left ventricle through the aortic valve to the aorta. The width of the pulse varies with spectral response function, but typically ranges from about 70 to 100 msecs with A-weighing.

#The "Second Sound" (S2) is strongest in the base region, occurs when the heart expands, and is primarily due to the aortic and pulmonary valves closing. During this expansion, blood flows from the right atrium through the tricuspid valve to the right ventricle and from the left atrium through the mitral valve to the left ventricle. The width of the pulse again varies with spectral response function, but typically about 25 to 60 msecs with A-weighing.