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The Virtual Cardiac Patient: A Multimedia Guide to Heart Sounds and Murmurs
... For further validation, five clinical stethoscopic signals from online databases (e.g., [74], and [75]) are acquired. The five clinical cases have been assessed by an experienced cardiologist (using a stethoscope) as severe, moderate or mild. ...
In this study a frequency scaling law for 3D anatomically representative supravalvular aortic stenosis (SVAS) cases is proposed. The law is uncovered for stethoscopy's preferred auscultation range (70-120 Hz). LES simulations are performed on the CFD solver Fluent, leveraging Simulia's Living Heart Human Model (LHHM), modified to feature hourglass stenoses that range between 30 to 80 percent (mild to severe) in addition to the descending aorta. For physiological hemodynamic boundary conditions the Windkessel model is implemented via a UDF subroutine. The flow-generated acoustic signal is then extracted using the FW-H model and analyzed using FFT. A preferred receiver location that matches clinical practice is confirmed (right intercostal space) and a correlation between the degree of stenosis and a corresponding acoustic frequency is obtained. Five clinical auscultation signals are tested against the scaling law, with the findings interpreted in relation to the NHS classification of stenosis and to the assessments of experienced cardiologists. The scaling law is thus shown to succeed as a potential quantitative decision-support tool for clinicians, enabling them to reliably interpret stethoscopic auscultations for all degrees of stenosis, which is especially useful for moderate degrees of SVAS. Computational investigation of more complex stenotic cases would enhance the clinical relevance of this proposed scaling law, and will be explored in future research.
... In some applications, the cardiac signal is monitored by using pulse oximetry [15] and the use of phonocardiography (PCG) is also extended. The sensors used in PCG are electronic stethoscopes or piezoelectric contact sensors that are sensitive to displacement or acceleration of the skin surface [16]. New approaches are also being used, such as X-rays, left and right cardiac catheterization, angiographic studies, external and intracardiac PCG and echocardiography, and PCG correlations [17]. ...
This paper presents a body-fixed-sensor-based approach to assess potential sleep apnea patients. A trial involving 15 patients at a sleep unit was undertaken. Vibration sounds were acquired from an accelerometer sensor fixed with a noninvasive mounting on the suprasternal notch of subjects resting in supine position. Respiratory, cardiac, and snoring components were extracted by means of digital signal processing techniques. Mainly, the following biomedical parameters used in new sleep apnea diagnosis strategies were calculated: heart rate, heart rate variability, sympathetic and parasympathetic activity, respiratory rate, snoring rate, pitch associated with snores, and airflow indirect quantification. These parameters were compared to those obtained by means of polysomnography and an accurate microphone. Results demonstrated the feasibility of implementing an accelerometry-based portable device as a simple and cost-effective solution for contributing to the screening of sleep apnea-hypopnea syndrome and other breathing disorders.
... Our works started from this point, introducing more sophisticated computer application, and expanding the patients data set with digital phonocardiograms (dPCG), electrocardiograms (dECG), and the traditional transesophageal echocardiograms (TTE) [3,4]. From the first work on spectral analysis of the PCG [5] to the last [6], many efforts were made [7][8][9][10], mainly in pediatrics [11][12][13], without any significant change in everyday clinical use. The aim of our studies was to expand the clinical use of dPCG with advanced computer technique (signal pre-, and post-processing, 3D visualization of the heart sounds and murmurs, communication) combined with telemedicine application. ...
Three studies were performed assessing the clinical value of digital electro- and phonocardiography (dECG, dPCG) with telemedicine application. In the first study, some Doppler echocardiographic parameters (ejection fraction, aortic Vmax, the grade of mitral and tricuspid regurgitation) were estimated from the spectral amplitude value of 170 time-frequency cells of the TriTest dPCG using multivariate discriminant analysis of 584 cardiac patients (292 for the training, and 292 for the test set). A cost analysis of heart failure (HF) screening in various populations was performed on 452 subjects. The greatest cost-savings (Euro / one HF patient) was found in the combined use of dECG and dPCG compared with the TE screening alone (mean: 82.4 CI-95%: 69.5-96.4 versus mean: 230.1 CI-95%: 196.5-254.4; p<0.001). In the third study, during the 24 months telemonitoring of serious heart failure patients, 124 hospital days charge was saved, comparing the two, 29-29 patientspsila groups.
For almost 170 years, since the discovery of the first stethoscope, cardiac auscultation has been an essential component of medical/cardiological observation; in the last 20 years, its relevance has progressively been reducing, even among medical students and university staff, in favor of new technologies that are generally believed to be more “objective”.
As a result, observations made in different Countries demonstrated that doctors are able to correctly recognize only a small percentage of pathological heart sounds. Some years ago, a review of auscultatory skills was conducted among medical students, interns and residents, and also among family doctors; none of them was able to correctly identify more than 40% of the pathological heart sounds presented, while only experienced cardiologists were able to identify 80% or more of the same sounds.
In the meantime, studies of psychoacoustics as well as observational studies on medical students and practitioners, demonstrated that at least 500 (and up to 2000) repetitions are needed to allow a correct memorization of a single new sound.
At present, the availability of patients of adequate type is low in our medical schools (fast turnover of patients), and is clearly insufficient to allow such a heavy auscultatory load; the number of hours spent in the clinical wards is reduced as compared to lessons and meetings; fewer teachers dedicate enough time to teach auscultatory topics: traditional training is so far insufficient and alternative means of teaching cardiac auscultation are needed. In the past years, sound recordings on vinyl disks or audiocassettes have been produced; more recently, training materials on CD-ROMs have become available, as well as simulators, and some forms of web-based training. These alternatives could offer an opportunity for a more adequate exposition of the student to didactic materials and their availability “on-demand”.
This work analyzes the most relevant web resources currently available, and tries to evaluate if some of them could be considered an adequate e-Learning system, in accordance to the “student centered” learning model.
None of the resources available on the Internet responds to the essential characteristics to be considered as an e-Learning site, with the partial exception of the site of the American College of Cardiology “Heart Songs” and the site of Blaufuss Medical Multimedia Laboratories.
A proposal is presented for the organization of an e-Learning teaching/training course on cardiac auscultation. Its general objective and the proposed target groups, along with its main features, some activities and main indicators are presented.
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