The recording of heart vibrations: a problem of vibration measurement on soft tissue

Vermariën, H.; Vollenhoven, E. Van

doi:10.1007/bf02446821

Cited by 46 publications

(17 citation statements)

References 14 publications

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“…Both techniques use a small acoustic detector unit to record and capture biological sounds under the premise that abnormal sounds will be signi®cantly dierent from normal sounds [13]. The ®eld of phonocardiography, researched since the beginning of the 20th century [14], oers some unique insights into the issues of (1) calibration of acoustic detector units, (2) airborne-noise-rejecting characteristics of acoustic detector units, (3) coupling of the acoustic unit to the skin surface, and (4) site of placement.…”

Section: Acoustic Detector Unit: Airborne-noise-rejecting Characterismentioning

confidence: 99%

Detection of Swallowing Sounds: Methodology Revisited

Cichero

Murdoch

2002

Dysphagia

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Cervical auscultation is in the process of gaining clinical credibility. In order for it to be accepted by the clinical community, the procedure and equipment used must first be standardized. Takahashi et al. [Dysphagia 9:54-62, 1994] attempted to provide benchmark methodology for administering cervical auscultation. They provided information about the acoustic detector unit best suited to picking up swallowing sounds and the best cervical site to place it. The current investigation provides contrasting results to Takahashi et al. with respect to the best type of acoustic detector unit to use for detecting swallowing sounds. Our study advocates an electret microphone as opposed to an accelerometer for recording swallowing sounds. However, we agree on the optimal placement site. We conclude that cervical auscultation is within reach of the average dysphagia clinic.

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Section: Acoustic Detector Unit: Airborne-noise-rejecting Characterismentioning

confidence: 99%

Detection of Swallowing Sounds: Methodology Revisited

Cichero

Murdoch

2002

Dysphagia

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“…It has a metal housing from which a unipolar esophageal electrocardiogram (eECG) can be derived. For chest surface transducers it has been reported that with increasing mass of the microphone attenuation of heart sounds occurs in sPCG [13,14]. Although the situation of the microphone positioned in the esophagus basically differs from the one of a surface transducer applied to the chest wall, we decided to construct the esophageal type with a mass as small as possible; the result in this case is 1.5 g.…”

Section: Methodsmentioning

confidence: 99%

“…This can only be appropriately performed if a much stiffer cable were used, which would present more discomfort to the patient. For this reason an electronic device has been built [12] (FYSParl, Laboratory of Physiology and Physiopathology, Univer sity of Brussels VUB) which enables axis rotation on the recorded orthogonal vibratory vector components ( fig. 3a, b).…”

Section: Axis Rotationmentioning

confidence: 99%

“…During the investigations it was established that obser vations might be influenced by the directional property of the microphone [11,12], The uniaxial type of microphone first used had the disadvantage of an unsensitive axis (perpendicular to the main, sensitive axis); some informa tion could therefore be underestimated or even over looked. It was actually found that some cardiovascular vibrations are characterized by a specific direction whereas others do not appear to be so.…”

Section: Introductionmentioning

confidence: 99%

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Investigation of Cardiovascular Sound with Esophageal Phonocardiography

Chin¹,

Vermariën²,

Vollenhoven³

et al. 1987

Am J Noninvas Cardiol

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Esophageal phonocardiography (ePCG) has the advantage that certain heart sounds are picked up near their sites of origin, whereas in conventional surface phonocardiography (sPCG) attenuation of the vibration occurs in the pathway to the microphone. The disadvantage of directional sensitivity of an accelerometer-type microphone has been eliminated by constructing biaxial microphones; with the aid of an electronic axes rotation, optimal recording of heart vibrations in the horizontal plane is achieved. ePCG has clinical value because of diagnosing mitral valve regurgitation (MR) better than conventional PCG, especially in patients having prosthetic valves in both mitral and aortic orifices where left ventricular angiography is not easily accomplished. Regarding the level of the microphone in the esophagus it has been established that various significant vibration patterns can be recorded at different heights. This variety of patterns is also explained by the distance to specific sources: heart sounds generated in the vicinity of the microphone are better detected with respect to others having a more distant origin. In this way the method contributes to the discussion about valvular components contained in the first heart sound. In the investigation simultaneous recordings with M-mode echocardiogram and pulsation curves have been obtained. More than 60 patients and normal subjects were examined. In 9 patients with prosthetic valves in both mitral and aortic orifices and 8 patients with mitral valve prolapse, MR was proved by ePCG in respectively 4 and 2 cases while sPCG failed to do so.

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“…Although the mechanical behaviours of piezoelectric contact sensors and condenser microphones have been examined with reference to an accelerometer, the mechanical variable characteristics (i.e. acceleration, velocity or displacement) of the MMG signals detected with an accelerometer have not been verified, in addition, transducer weight, which induces serious distortion of the body surface, has not been examined as a potential contributor to the mechanical variability (VERMARIEN and VAN VOLLENHOVEN, 1984). Recently, a laser distance sensor was used to record the MMG signal from the cat gastrocnemius muscle during electrical stimulation (ORIZIO et al, 1999;2000).…”

Section: Introductionmentioning

confidence: 99%

Reliability of the mechanomyogram detected with an accelerometer during voluntary contractions

Watakabe

Mita

Akataki

et al. 2003

Med. Biol. Eng. Comput.

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The accelerometer is used for mechanomyogram (MMG) recordings of muscle contractions. Although the mechanical characteristics of other MMG transducers have been determined with reference to the accelerometer, mechanical aspects of the accelerometer itself, including the weight of the transducer, have not been verified. This study was designed to reinvestigate the mechanical variable of the MMG signal detected with an accelerometer, with reference to a laser distance sensor (LDS), and then to clarify the influence of the accelerometer weight on the MMG recording during muscle contractions. The study was performed during mechanical sinusoidal vibrations and during voluntary contractions of the quadriceps muscle. Maximum differences in the amplitude spectral density functions between the LDS signal and the double integral of the accelerometer signal were approximately 4 microm. The results verified that the MMG signal from the accelerometer accurately reflected the acceleration of body surface vibration. However, the MMG signal was gradually distorted when weight was added to the accelerometer: the addition of 4.0 g (total 6.0 g, including 2.0 g of accelerometer) substantially attenuated the MMG signal. The results suggest that the appropriate weight for the accelerometer should be less than 5.0 g for measurements of the quadriceps muscle and indicate that the transducer weight must be taken into account for accurate measurement of muscles of different sizes.

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The recording of heart vibrations: a problem of vibration measurement on soft tissue

Cited by 46 publications

References 14 publications

Detection of Swallowing Sounds: Methodology Revisited

Detection of Swallowing Sounds: Methodology Revisited

Investigation of Cardiovascular Sound with Esophageal Phonocardiography

Reliability of the mechanomyogram detected with an accelerometer during voluntary contractions

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