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      A color spectrographic phonocardiography (CSP) applied to the detection and characterization of heart murmurs: preliminary results

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          Abstract

          Background

          Although cardiac auscultation remains important to detect abnormal sounds and murmurs indicative of cardiac pathology, the application of electronic methods remains seldom used in everyday clinical practice. In this report we provide preliminary data showing how the phonocardiogram can be analyzed using color spectrographic techniques and discuss how such information may be of future value for noninvasive cardiac monitoring.

          Methods

          We digitally recorded the phonocardiogram using a high-speed USB interface and the program Gold Wave http://www.goldwave.com in 55 infants and adults with cardiac structural disease as well as from normal individuals and individuals with innocent murmurs. Color spectrographic analysis of the signal was performed using Spectrogram (Version 16) as a well as custom MATLAB code.

          Results

          Our preliminary data is presented as a series of seven cases.

          Conclusions

          We expect the application of spectrographic techniques to phonocardiography to grow substantially as ongoing research demonstrates its utility in various clinical settings. Our evaluation of a simple, low-cost phonocardiographic recording and analysis system to assist in determining the characteristic features of heart murmurs shows promise in helping distinguish innocent systolic murmurs from pathological murmurs in children and is expected to useful in other clinical settings as well.

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          Most cited references 11

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          Assessing housestaff diagnostic skills using a cardiology patient simulator.

          To assess the cardiovascular physical examination skills of internal medicine housestaff. Cross-sectional assessment of housestaff performance on three valvular abnormality simulations conducted on the cardiology patient simulator, "Harvey." Evaluations were done at the beginning (session I) and end (session II) of the academic year. Duke University Medical Center internal medicine training program. Sixty-three (59%) of 107 eligible internal medicine housestaff (postgraduate years 1 through 3) agreed to participate and completed session I; 60 (95%) completed session II. All volunteers were tested on three preprogrammed simulations (mitral regurgitation, mitral stenosis, and aortic regurgitation). The overall correct response rates for all housestaff were 52% for mitral regurgitation, 37% for mitral stenosis, and 54% for aortic regurgitation. No difference was noted in correct response rates between sessions I and II. For mitral regurgitation, correct assessment of the contour of the holosystolic murmur predicted a correct diagnosis (P = 0.002). For mitral stenosis, identification of an opening snap and proper characterization of the mitral area diastolic murmur predicted a correct diagnosis (P < 0.0001). No individual observations were noted for the aortic regurgitation simulation, whose identification by the housestaff was associated with a correct diagnosis. Housestaff had difficulty establishing a correct diagnosis for simulations of three common valvular heart diseases. Accurate recognition of a few "key" observations was associated with a correct diagnosis in two of the three diseases. Teaching housestaff to elicit and interpret a few critical signs accurately may improve their physical diagnosis abilities.
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            The accuracy and interobserver agreement in detecting the 'gallop sounds' by cardiac auscultation.

            To determine the observer accuracy and interobserver agreement in identifying S4 and S3 by cardiac auscultation and whether they improve with increasing observer experience. Prospective, blinded study. Cardiology and general internal medicine wards in a university-affiliated teaching hospital. Forty patients with a cardiac diagnosis and 6 patients without were studied. Two cardiologists, one general internist, three senior and two junior postgraduate internal medicine trainees, blinded to the patients' characteristics, examined the patients and documented their findings on a questionnaire. Computerized phonocardiogram was obtained in all patients as a gold standard and was interpreted by a blinded, independent cardiologist. The mean positive predictive values for S4 and S3 were 51% (range, 24 to 100%) and 71% (range, 50 to 88%), respectively. The mean negative predictive values for S4 and S3 were 82% (range, 67 to 94%) and 64% (range, 56 to 85%), respectively. The overall interobserver agreements for detecting S4 was K = 0.05 (95% confidence interval [CI], 0.01 to 0.09) and S3 was K = 0.18 (95% CI, 0.13 to 0.24). There was no apparent trend in the accuracy or interobserver agreement with regard to the level of observer experience. The agreement between observers and the phonocardiographic gold standard in the correct identification of S4 and S3 was poor and the lack of agreement did not appear to be a function of the experience of the observers. The overall interobserver agreement for the detection of either S4 or S3 was little better than chance alone.
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              Phono-spectrographic analysis of heart murmur in children

              Background More than 90% of heart murmurs in children are innocent. Frequently the skills of the first examiner are not adequate to differentiate between innocent and pathological murmurs. Our goal was to evaluate the value of a simple and low-cost phonocardiographic recording and analysis system in determining the characteristic features of heart murmurs in children and in distinguishing innocent systolic murmurs from pathological. Methods The system consisting of an electronic stethoscope and a multimedia laptop computer was used for the recording, monitoring and analysis of auscultation findings. The recorded sounds were examined graphically and numerically using combined phono-spectrograms. The data consisted of heart sound recordings from 807 pediatric patients, including 88 normal cases without any murmur, 447 innocent murmurs and 272 pathological murmurs. The phono-spectrographic features of heart murmurs were examined visually and numerically. From this database, 50 innocent vibratory murmurs, 25 innocent ejection murmurs and 50 easily confusable, mildly pathological systolic murmurs were selected to test whether quantitative phono-spectrographic analysis could be used as an accurate screening tool for systolic heart murmurs in children. Results The phono-spectrograms of the most common innocent and pathological murmurs were presented as examples of the whole data set. Typically, innocent murmurs had lower frequencies (below 200 Hz) and a frequency spectrum with a more harmonic structure than pathological cases. Quantitative analysis revealed no significant differences in the duration of S1 and S2 or loudness of systolic murmurs between the pathological and physiological systolic murmurs. However, the pathological murmurs included both lower and higher frequencies than the physiological ones (p < 0.001 for both low and high frequency limits). If the systolic murmur contained intensive frequency components of over 200 Hz, or its length accounted for over 80 % of the whole systolic duration, it was considered pathological. Using these criteria, 90 % specificity and 91 % sensitivity in screening were achieved. Conclusion Phono-spectrographic analysis improves the accuracy of primary heart murmur evaluation and educates inexperienced listener. Using simple quantitative criterias a level of pediatric cardiologist is easily achieved in screening heart murmurs in children.
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                Author and article information

                Journal
                Biomed Eng Online
                BioMedical Engineering OnLine
                BioMed Central
                1475-925X
                2011
                31 May 2011
                : 10
                : 42
                Affiliations
                [1 ]Department of Biomechanics, Science and Research Branch, Islamic Azad University, Tehran, Iran
                [2 ]Department of General Anaesthesiology, Cleveland Clinic Lerner College of Medicine of Case Western Reserve University, Ohio, USA
                [3 ]Mechanical Engineering Department of Iran University of Science & Technology, Tehran, Iran
                Article
                1475-925X-10-42
                10.1186/1475-925X-10-42
                3126734
                21627809
                Copyright ©2011 Sarbandi et al; licensee BioMed Central Ltd.

                This is an Open Access article distributed under the terms of the Creative Commons Attribution License ( http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

                Categories
                Research

                Biomedical engineering

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