Sound recording and digital phonocardiography of cardiac murmurs in dogs by using a sensor-based electronic stethoscope

Use of Digital Stethoscope to Measure Heart Rate in Birds: Comparison of Different Counting Methods Using Phonocardiograms

The high cardiac contractility of birds poses a challenge to traditional cardiac auscultation, particularly for the accurate determination of heart rate (HR). The objectives of this study were to 1) evaluate the feasibility of using phonocardiograms of adequate length and quality to assess HR in different avian species with a commercially available digital stethoscope, 2) compare 5 counting methods, including 2 direct reading methods (manual counting and using a semiautomatic computerized algorithm as a reference method) and 3 listening methods (progressive mental counting, counting by 10s, and counting with a smartphone application tap counter), and 3) obtain the HR in selected birds and identify a correlation between body weight and HR in different avian species. An inverse correlation on a logarithmic scale was identified between the mean body weight and HR in 60 different bird species (n = 211; R = -0.72, P < 0.0001). Manual reading of phonocardiograms was the most reliable method and had the highest agreement with the reference method; this was followed by the counting by 10s method, the tapping method, and the progressive mental counting method, which was the least reliable. The agreement levels for the different methods were comparable for HRs <200 beats per minute (bpm) in birds weighing >1 kg. For HRs >500 bpm in birds weighing <150 g, only the reading method maintained a good agreement level. A digital stethoscope can be a useful tool for accurately determining the HR in birds, including very small species with high HRs.

Evaluation of a new smartphone-based digital stethoscope featuring phonocardiography and electrocardiography in dogs and cats

This study assessed a new smartphone-based digital stethoscope (DS) featuring simultaneous phonocardiographic and one-lead electrocardiogram (ECG) recording in dogs and cats. The audio files and ECG traces obtained by the device were compared with conventional auscultation and standard ECG. A total of 99 dogs and nine cats were prospectively included. All cases underwent conventional auscultation using an acoustic stethoscope, standard six-lead ECG, standard echocardiography and recordings with the DS. All the audio recordings, phonocardiographic files and ECG traces were then blind reviewed by an expert operator. The agreement between methods was assessed using Cohen's kappa and the Bland-Altman test. Audio recordings were considered interpretable in 90% animals. Substantial agreement was found in the diagnosis of heart murmur (κ = 0.691) and gallop sound (k = 0.740). In nine animals with an echocardiographic diagnosis of heart disease, only the DS detected a heart murmur or gallop sound. ECG traces recorded with the new device were deemed interpretable in 88 % animals. Diagnosis of heart rhythm showed moderate agreement in the identification of atrial fibrillation (k = 0.596). The detection of ventricular premature complexes and bundle branch blocks revealed an almost perfect agreement (k = 1). Overall, the DS showed a good diagnostic accuracy in detecting heart murmurs, gallop sounds, ventricular premature complexes and bundle branch blocks. A clinically relevant overdiagnosis of atrial fibrillation was found but without evidence of false negatives. The DS could represent a useful screening tool for heart sound abnormalities and cardiac arrhythmias..

Remote Teaching of Canine Cardiac Auscultation Using Digital Phonocardiograms

Veterinary students often struggle to correctly interpret heart sounds. This study sought to evaluate if additional online training using digital phonocardiograms (DPCGs) improves students' ability to identify normal and pathologic heart sounds in dogs. Thirty-six randomly assigned veterinary students listened to and interpreted 10 audio recordings of normal heart sounds (2), heart murmurs (4), and arrhythmias (4) at the start and the end of a 4-week period. Twenty-two students participated in training with DPCGs, including those created from these recordings during this period, via a self-study website (n = 12) or online webinar (n = 10). Their results were compared with those of a control group (n = 14) that did not undergo additional training. Although pre- and post-training test scores did not differ between groups, both training groups showed within-group improvement between the two tests (p = .024, p = .037); the control group did not (p = .49). Although neither training group showed differences in ability to differentiate normal heart sounds from arrhythmias, both showed increased ability to detect and specify heart murmurs and provide refined diagnoses of detected arrhythmias. These results suggest additional training, even without actual patients, improves students' ability to identify heart murmurs and provide specific diagnoses for arrhythmias. Further study with a larger sample size and an additional group without DPCG-based training would help evaluate the effectiveness of DPCGs regarding arrhythmias. Studying a larger sample size would also allow for a training group participating in both training methods, measuring cumulative effectiveness of both methods.

A digitális fonokardiográfia szerepe a kutyák szívhangjainak hallgatózásos vizsgálatának oktatásában

Absztrakt

Sok állatorvostanhallgatónak esik nehezére a szívhangok helyes értelmezése. Kutatásunk célja a digitális fonokardiogramokat felhasználó online, tanterven kívüli oktatás hatásának felmérése volt a hallgatók szívhangok felismerésével kapcsolatos diagnosztikai képességeire. Harminchat véletlenszerűen elosztott állatorvostanhallgató hallgatott meg és értelmezett 10 hangfelvételt élettani szívhangokról (2), szívzörejekről (4) és szívritmuszavarokról (4) egy négyhetes periódus elején és Végén. Huszonkét hallgató vett részt DPCG-ket felhasználó képzésben, egy önképző oldal (n = 12) és egy online webinar (n = 10) keretein belül. A két teszten elért eredményeiket egy kontrollcsoportéval vetettük össze (n = 14), akik nem vettek részt tanterven kívüli képzésben. Bár az elő- és utótesztek pontszámai nem különböztek szignifikánsan a csoportok között, mindkét oktatásban résztvevő csoport szignifikáns csoporton belüli javulást mutatott a két teszt között (p = 0,023, p = 0,037), míg a kontrollcsoport nem (p = 0,49). Bár egyik csoport sem ért el javulást az élettani szívhangok felismerésében és szívritmuszavaroktól való elkülönítésében, mindkét csoportban javulást láttunk a szívzörejek felismerésében és azonosításában, valamint az észlelt szívritmuszavarok azonosításában. Eredményeink alapján a hallgatók hallgatózásos vizsgálattal kapcsolatos diagnosztikai képességei javíthatóak tanterven kívüli oktatással, akár élő álatok igénybevétele nélkül is. További, nagyobb elemszámmal végzett, valamint DPCG-t nem használó oktatómódszereket alkalmazó kutatás szükséges a DPCG-k szerepének pontos meghatározásához. Egy emelt elemszámmal végzett kutatás lehetővé tenné továbbá egy kombinált oktatott csoport létrehozását, mérhetővé téve a két módszer kumulatív hatását.

This translation was provided by the authors. To view the original article visit: https://doi.org/10.3138/jvme-2021-0097

Use of proposed systolic and myocardial performance indices derived from simultaneous ECG and PCG recordings to assess cardiac function in healthy Beagles

Background and Aim:

Cardiac time intervals (CTIs) can provide important information on the electrical and mechanical properties of the heart. We hypothesized that cardiac function can be described using the combined power of electrocardiography (ECG) and phonocardiography (PCG) signals. This study aimed to (1) validate a novel custom device in measuring CTI parameters; (2) compare CTI parameters with a commercially available device and standard transthoracic echocardiography (STE); and (3) compare calculated systolic performance index (SPI) and myocardial performance index (MPI) with Tei index from the STE.

Materials and Methods:

This study determined CTIs based on simultaneous ECG and PCG recordings in 14 healthy Beagle dogs using the custom-built device. These CTI parameters were compared with a commercially available device (Eko DUO ECG + Digital Stethoscope; Eko DUO) and the STE. Agreement of CTI parameters between the custom device and the commercially available device or STE was evaluated. Calculated SPI and MPI based on Wigger’s diagram were proposed, compared with SPI and Tei index, and correlated with STE parameters.

Results:

We found that the ECG and PCG parameters measured from the custom-built device did not differ from the commercially available device and the STE. By combining ECG and PCG signals, we established CTI parameters in healthy dogs including indices for systolic function (SPI: QS1/S1S2) and global cardiac function {F1 ([QS1+S2]/S1S2), F2 ([RS1+S2]/S1S2), and F3 (RS1 + [QS2-QT]/S1S2)}. The SPI, F2, and F3 were comparable with echocardiographic parameters describing systolic (Pre-ejection period/left ventricular ejection time [LVET]) and Tei index ([MCOdur-LVET]/LVET), respectively. Only SPI and F3 were correlated significantly with MCOdur and heart rate, respectively.

Conclusion:

We have validated the use of the custom-built device to describe CTIs that are comparable to the commercially available device and STE in healthy Beagles. The proposed SPI and MPI derived from CTI parameters can be useful in clinical practice to describe the cardiac function, especially in areas where access to STE is constrained.

Digital phonocardiography of cardiac arrhythmias in dogs - Preliminary experiences

Electronic stethoscopes and digital phonocardiograms (DPCGs) can be applied when diagnosing cardiac murmurs, but their use for cardiac arrhythmias is not described in veterinary medicine. Data of 10 dogs are presented in this preliminary study, demonstrating the applicability of these techniques. Although the number of artefacts and the amount of baseline noise produced by the two digitising systems used did not differ, the Welch Allyn Meditron system or similar ones capable of simultaneous recording of electrocardiograms (ECGs) and DPCGs provide a better option for clinical research and education, whilst the 3M Littmann 3200 system might be more suitable for everyday clinical settings. A combined system with simultaneous phonocardiogram and ECG, especially with wireless transmission, might be a solution in the future.

Stretchable Composite Acoustic Transducer for Wearable Monitoring of Vital Signs

A highly flexible, stretchable, and mechanically robust low-cost soft composite consisting of silicone polymers and water (or hydrogels) is reported. When combined with conventional acoustic transducers, the materials reported enable high performance real-time monitoring of heart and respiratory patterns over layers of clothing (or furry skin of animals) without the need for direct contact with the skin. The approach enables an entirely new method of fabrication that involves encapsulation of water and hydrogels with silicones and exploits the ability of sound waves to travel through the body. The system proposed outperforms commercial, metal-based stethoscopes for the auscultation of the heart when worn over clothing and is less susceptible to motion artefacts. The system both with human and furry animal subjects (i.e., dogs), primarily focusing on monitoring the heart, is tested; however, initial results on monitoring breathing are also presented. This work is especially important because it is the first demonstration of a stretchable sensor that is suitable for use with furry animals and does not require shaving of the animal for data acquisition.

Correlation of blood pressure and the ratio of S1 to S2 as measured by esophageal stethoscope and wireless bluetooth transmission

Objective : Esophageal stethoscope has the advantage of being non-invasive, easily placed and capability to monitor the heart sound. This study was designed to determine whether the ratio of S1 to S2 analyzed by esophageal stethoscope and wireless bluetooth transmission can be accurate indicator that express the correlation with blood pressure.

METHODS

Total 33 adult male and female without cardiac disorder and with normal heart rhythm were selected randomly as the subjects of this Study. Two microphones were used with one for acquisition of heart sound by connecting it to the esophageal stethoscope while the other was used to measure the background noise in the operating room. After having transmitted the heart sound measured with the esophageal stethoscope to the receiver by using bluetooth module, it was saved in PC and outputted, following removal of noise in the operating room and the respiratory sound. S1 and S2 were measured with computation of the ratio of S1 to S2. Correlations between the systolic blood pressure with each of the S1, S2 and ratio of S1 to S2 were examined by using correlation analysis.

RESULTS

The ratio of S1 to S2 displayed the highest correlation with the systolic blood pressure, with S1 and S2 also displaying positive correlation with the systolic blood pressure.

CONCLUSION

As the result of analysis of the heart sound and the systolic blood pressure measured by using the esophageal stethoscope, the radio of S1 to S2 displayed greater correlation with the systolic blood pressure in comparison to the S1.

Clinical evaluation of the 3M Littmann Electronic Stethoscope Model 3200 in 150 cats

Detection of murmurs and gallops may help to identify cats with heart disease. However, auscultatory findings may be subject to clinically relevant observer variation. The objective of this study was to evaluate an electronic stethoscope (ES) in cats. We hypothesized that the ES would perform at least as well as a conventional stethoscope (CS) in the detection of abnormal heart sounds. One hundred and fifty consecutive cats undergoing echocardiography were enrolled prospectively. Cats were ausculted with a CS (WA Tycos Harvey Elite) by two observers, and heart sounds were recorded digitally using an ES (3M Littmann Stethoscope Model 3200) for off-line analysis. Echocardiography was used as the clinical standard method for validation of auscultatory findings. Additionally, digital recordings (DRs) were assessed by eight independent observers with various levels of expertise, and compared using interclass correlation and Cohen's weighted kappa analyses. Using the CS, a heart murmur (n = 88 cats) or gallop sound (n = 17) was identified in 105 cats, whereas 45 cats lacked abnormal heart sounds. There was good total agreement (83-90%) between the two observers using the CS. In contrast, there was only moderate agreement (P <0.001) between results from the CS and the DRs for murmurs, and poor agreement for gallops. The CS was more sensitive compared with the DRs with regard to murmurs and gallops. Agreement among the eight observers was good-to-excellent for murmur detection (81%). In conclusion, DRs made with the ES are less sensitive but comparably specific to a CS at detecting abnormal heart sounds in cats.

Comparison of traditional and sensor-based electronic stethoscopes in beagle dogs

The objective of this study was to compare the auscultatory findings using traditional and electronic sensor-based stethoscopes. Thirty-three adult healthy Beagles (20 females, 13 males, mean age: 4.8 years, range 1.4-8 years) were auscultated by four investigators with different experiences (INVEST-1, -2, -3 and -4) independently with both stethoscopes. Final cardiological diagnoses were established by echocardiography. Mitral murmurs were heard with both stethoscopes by all investigators and echocardiography revealed mild mitral valve insufficiency in 7 dogs (21%, 4 females, 3 males). The statistical sensitivity (Se) in recognising cardiac murmurs proved to be 82% using the traditional stethoscope and 75% using the electronic one in the mean of the four examiners, whilst statistical specificity (Sp) was 99% by the traditional and 100% by the electronic stethoscope. The means of the auscultatory sensitivity differences between the two stethoscopes were 0.36 on the left and 0.59 on the right hemithorax, demonstrating an advantage for the electronic stethoscope being more obvious above the right hemithorax (P = 0.0340). The electronic stethoscope proved to be superior to the traditional one in excluding cardiac murmurs and especially in auscultation over the right hemithorax. Mitral valve disease was relatively common in this clinically healthy research Beagle population.

A comparison of different feature extraction methods for diagnosis of valvular heart diseases using PCG signals

This article presents a novel method for diagnosis of valvular heart disease (VHD) based on phonocardiography (PCG) signals. Application of the pattern classification and feature selection and reduction methods in analysing normal and pathological heart sound was investigated. After signal preprocessing using independent component analysis (ICA), 32 features are extracted. Those include carefully selected linear and nonlinear time domain, wavelet and entropy features. By examining different feature selection and feature reduction methods such as principal component analysis (PCA), genetic algorithms (GA), genetic programming (GP) and generalized discriminant analysis (GDA), the four most informative features are extracted. Furthermore, support vector machines (SVM) and neural network classifiers are compared for diagnosis of pathological heart sounds. Three valvular heart diseases are considered: aortic stenosis (AS), mitral stenosis (MS) and mitral regurgitation (MR). An overall accuracy of 99.47% was achieved by proposed algorithm.