Simulated Heart Sounds Research Articles

Hemodynamics-driven mathematical model of first and second heart sound generation.

We propose a novel, two-degree of freedom mathematical model of mechanical vibrations of the heart that generates heart sounds in CircAdapt, a complete real-time model of the cardiovascular system. Heart sounds during rest, exercise, biventricular (BiVHF), left ventricular (LVHF) and right ventricular heart failure (RVHF) were simulated to examine model functionality in various conditions. Simulated and experimental heart sound components showed both qualitative and quantitative agreements in terms of heart sound morphology, frequency, and timing. Rate of left ventricular pressure (LV dp/dtmax) and first heart sound (S1) amplitude were proportional with exercise level. The relation of the second heart sound (S2) amplitude with exercise level was less significant. BiVHF resulted in amplitude reduction of S1. LVHF resulted in reverse splitting of S2 and an amplitude reduction of only the left-sided heart sound components, whereas RVHF resulted in a prolonged splitting of S2 and only a mild amplitude reduction of the right-sided heart sound components. In conclusion, our hemodynamics-driven mathematical model provides fast and realistic simulations of heart sounds under various conditions and may be helpful to find new indicators for diagnosis and prognosis of cardiac diseases.New & noteworthyTo the best of our knowledge, this is the first hemodynamic-based heart sound generation model embedded in a complete real-time computational model of the cardiovascular system. Simulated heart sounds are similar to experimental and clinical measurements, both quantitatively and qualitatively. Our model can be used to investigate the relationships between heart sound acoustic features and hemodynamic factors/anatomical parameters.

Outcomes of Using Heart Sound Simulator in Teaching Cardiac Auscultation

Background - Despite continued curriculum reform, the clinical skills competencies of medical graduates at all levels are steadily declining within a training system, where bedside opportunities become a luxury and the laboratory tests prevail over the clinical skills. While high-fidelity expensive simulators are being embraced by high-procedure volume specialties, low-fidelity and relatively inexpensive simulators, such as the heart sounds simulators remain under-utilized in medical training. Methods - We used a commercially available heart sound synthesizer in 2-hour training sessions with students and residents. Pre-post testing was completed at the beginning of the training session and three weeks after the session; participant responses were recorded by audience interactive response system. Results - Data analysis was accomplished with statistical software SPSS 17.0 utilizing paired t-test, and showed a statistically significant difference in learners’ knowledge and skills attainment 3 weeks after completion of the simulation training (p<0.0001). Conclusions - Based on our findings and the review of literature, we recommend that heart sound simulation is introduced at medical student level as the standard for teaching cardiologic auscultation findings and as preparation for auscultation of live patients. We also suggest that training with digitally simulated heart sounds is similarly beneficial in resident training.

Training auscultatory skills: computer simulated heart sounds or additional bedside training? A randomized trial on third-year medical students

BackgroundThe present study compares the value of additional use of computer simulated heart sounds, to conventional bedside auscultation training, on the cardiac auscultation skills of 3rd year medical students at Oslo University Medical School.MethodsIn addition to their usual curriculum courses, groups of seven students each were randomized to receive four hours of additional auscultation training either employing a computer simulator system or adding on more conventional bedside training. Cardiac auscultation skills were afterwards tested using live patients. Each student gave a written description of the auscultation findings in four selected patients, and was rewarded from 0-10 points for each patient. Differences between the two study groups were evaluated using student's t-test.ResultsAt the auscultation test no significant difference in mean score was found between the students who had used additional computer based sound simulation compared to additional bedside training.ConclusionsStudents at an early stage of their cardiology training demonstrated equal performance of cardiac auscultation whether they had received an additional short auscultation course based on computer simulated training, or had had additional bedside training.

Relative effectiveness of high- versus low-fidelity simulation in learning heart sounds

Although there are increasing numbers of studies of outcomes of high-fidelity patient simulators, few contrast their instruction with that provided by equivalent low-fidelity, inexpensive simulators. Further, examination of decays in learning and application (transfer) to real patient problems is rare. In this study, we compared the effects of training using a high-fidelity heart sound simulator (Harvey) and a low-fidelity simulator (a CD) on recognition of both simulated heart sounds and those in actual patients. A pilot study with 10 students was conducted to show the feasibility of the methods and some evidence of modality-specific learning (the Harvey-trained group scored 72% correct on Harvey and 36% correct on CD test examples; the CD-trained group scored 60% correct on both CD and Harvey test examples). A main study was then initiated involving 37 Year 3 medical students from the University of Leeds. They received 1 hour of common instruction, after which one group received 3 hours of specific instruction on Harvey. The second group received 3 hours of instruction using a CD. Six weeks later, both groups were tested blind with real patients with stable heart sounds. Stations were observed by an examiner who scored communication skills and examination skills using 5-point scales. The Harvey-trained group was slightly but not significantly better than the CD-trained group at identifying heart sounds (3.11 versus 2.47, respectively; P = 0.06). However, there was no difference between the Harvey and CD-trained groups in diagnosis (2.94 versus 2.84, respectively), communication skills (18.9 versus 19.6, respectively) or examination skills (17.4 versus 17.5, respectively). The study found little evidence that students trained with a high-fidelity simulator were more able to transfer skills to real patients than a control group. Although there was some suggestion that the Harvey-trained group was better at recognising heart sounds, there was no difference between groups in diagnostic accuracy or clinical skills.

Characteristics of normal lung sounds after adaptive filtering.

Lung sounds were recorded from five normal male subjects during tidal breathing. Simultaneous electrocardiograms were recorded and used as index signals to generate simulated heart sounds for digital subtraction from recorded lung sounds to obtain purer lung sounds. Five random breaths from each subject were analyzed. Sound signals were band-pass filtered 25 to 1,000 Hz (antialiasing), digitized at 3,000 Hz, and then subjected to (1) direct fast Fourier transform (FFT) without filtering (NF); (2) digital high-pass filtering at 75 Hz and subsequent FFT (75 HzF); (3) adaptive filtering and subsequent FFT (AF). The FFT algorithms of all lung sounds were characterized by mean, median, and mode frequencies. The mean, median, and mode of NF were lower than those of 75 HzF (64.98 +/- 4.04 versus 150.42 +/- 17.49, mean +/- SE, p less than 0.003; 44.57 +/- 2.06 versus 111.81.5.78, p less than 0.0003; 36.81 +/- 1.77 versus 86.16 +/- 3.13, p less than 0.0001) and those of AF (64.98 +/- 4.04 versus 96.87 +/- 11.58, p less than 0.01; 44.57 +/- 2.06 versus 68.23 +/- 10.44, p less than 0.05; 36.81 +/- 1.78 versus 52.24 +/- 8.97, p less than 0.06). The mean, median, and mode of AF were lower than those of 75 HzF (96.87 +/- 11.58 versus 150.42 +/- 17.49, p less than 0.02; 68.23 +/- 10.44 versus 111.81 +/- 5.77, p less than 0.007; 52.24 +/- 8.97 versus 86.16 +/- 3.73, p less than 0.01). The results indicated that by filtering out low frequency heart sounds, the frequency spectrum of lung sounds was moved upward.(ABSTRACT TRUNCATED AT 250 WORDS)

A New Audiovisual Aid to Heart-Sound Instruction

The use of audiovisual aids to supplement clinical experience in auscultation continues to be studied and evaluated by medical educators. Early audiovisual aids, such as long-playing tapes and phonograph records, were of limited value because they presented a large amount of information at a fixed rate and sequence, and did not actively engage the student in the learning process. Devices incorporating single-example magnetic disks or electronically simulated heart sounds, coupled with oscilloscopic display, have been major advances but are expensive and often complex to operate. This communication describes a new audiovisual instrument for heart-sound instruction which is inexpensive, simple to operate, and useful both as a self-instructional device and as a classroom aid. It is multidimensional in that it incorporates simultaneous audio and visual representation of heart sounds and a correlative text. <h3>Method</h3> The basic unit is a two-channel tape recorder, unique in that the magnetic tape is mounted on