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Journal ArticleDOI

A comparison between ultralow-frequency ballistocardiograms and those secured by an improved high-frequency technique, with studies to explain remaining differences.

01 Jul 1962-American Heart Journal (Elsevier)-Vol. 64, Iss: 1, pp 79-100
TL;DR: The advance in ballistocardiographic instrumentation which has been so rapid and so encouraging in recent years has been due primarily to the use of certain physical principles, but on the assumption that well-known physical formulae could be properly applied to the vibration problems of the human body, a new viewpoint emerged.
About: This article is published in American Heart Journal.The article was published on 1962-07-01 and is currently open access. It has received 11 citations till now.

Summary (2 min read)

Instruments

  • Because their room had a low ceiling, their bed---like Rappaport's instrument, and like Henderson's table of 50 years agois displaced laterally by a pair of pins (AC, Pig. 3), sharp at each end and 13.7 cm. long.
  • This system renders their records almost altogether free of building vibration.
  • Of great value has been a secondary electrical circuit, with dry cells and a milliammeter, which indicates when one of the magnets touches the inside of its coil, an error of technique very likely to pass unnoticed without this warning device, and capable of causing marked distortion of the ballistocardiogram.
  • On the assumption that the body moves methods of tightening the subject the as a unit, the physical characteristics of restoring force and damping are about the coupling between body and table can doubled.

Results

  • Comparison of the ULF and HF force records ift healthy persons.
  • The measurements secured in the 30 men were used to construct a grand average normal male ballistocardiogram of the HF type, and another of the ULF type.
  • The tips of the H and I waves of the HF records follow those of the ULF records by an average of 0.012 and 0.022 second, respectively, and these are significant differences.
  • In the first group are the differences in size and shape of the waves.
  • If this were true, the authors should be able to start with the record secured by one instrument and, through the use of physical principles, compute the record of the other.

It became possible only recently

  • With the development of the digital computer.
  • The authors took as a starting point a typical complex secured by the low-frequency instrument, a complex midway between the largest and smallest ones of the respiratory cycle.
  • The results (Figs. 12,D and 13,D) show clearly that the curves thus constructed from measurements made on low-frequency ballistocardiograms bear a close resemblance in shape and amplitude to the HF ballistocardiograms (Figs. 10 and 11 ) secured experimentally on the same subjects.
  • Obviously, therefore, the authors have a clear understanding of the reason for the major points of difference between the two types of records,9 the average differences of wave height and timing shown in Fig. 7,A and B .
  • Theoretical studies on the effect of loose masses within the body.

Discussion

  • (a) The HF force tracing is distorted by movement of the body on the table, although it should be noted that because of recent improvements this movement is much smaller and the distortion caused is much less than that sometimes seen on records secured by older instruments with high natural frequency.
  • It is far from certain that all the slurs and notches so commonly seen in ULF ballistocardiograms have their origin in the circulation, and, if not, a better estimate of circulatory abnormalities might be made if they were not recorded.
  • The chief argument in favor of a circulatory origin for the notches so often seen in ULF record lies in their apparent movement with respiration.
  • Chiefly because of the difference in J-wave amplitude, the over-all amplitudethe vertical distance between the tips of the I and J waves-is larger in HF than in ULF records.

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Citations
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Journal ArticleDOI
TL;DR: Preliminary results suggest that the relationship between local and central disturbances is highly dependent on both the individual and the location where the accelerometer is placed on the body and that these differences can be resolved via calibration to accurately measure changes in cardiac output and contractility from a wearable sensor.
Abstract: Recent advances have led to renewed interest in ballistocardiography (BCG), a noninvasive measure of the small movements of the body due to cardiovascular events. A broad range of platforms have been developed and verified for BCG measurement including beds, chairs, and weighing scales: while the body is coupled to such a platform, the cardiogenic movements are measured. Wearable BCG, measured with an accelerometer affixed to the body, may enable continuous, or more regular, monitoring during the day; however, the signals from such wearable BCGs represent local or distal accelerations of skin and tissue rather than the whole body. In this paper, we propose a novel method to reconstruct the BCG measured with a weighing scale (WS BCG) from a wearable sensor via a training step to remove these local effects. Preliminary validation of this method was performed with 15 subjects: the wearable sensor was placed at three locations on the surface of the body while WS BCG measurements were recorded simultaneously. A regularized system identification approach was used to reconstruct the WS BCG from the wearable BCG. Preliminary results suggest that the relationship between local and central disturbances is highly dependent on both the individual and the location where the accelerometer is placed on the body and that these differences can be resolved via calibration to accurately measure changes in cardiac output and contractility from a wearable sensor. Such measurements could be highly effective, for example, for improved monitoring of heart failure patients at home.

27 citations


Cites background from "A comparison between ultralow-frequ..."

  • ...The issue of comparing BCG displacements, velocities, and accelerations has also been raised: Starr and Noordergraaf remarked on the similarity of the HF BCG (displacement) to the second derivative (acceleration) of the ULF BCG [14]....

    [...]

Journal ArticleDOI
TL;DR: Five of the 5 men with initially abnormal ballistocardiograms had normal records at the end of the program, and significant increases occurred in mean I, J, GI, HI and IJ forces.
Abstract: Fifteen middle-aged men participated in a program of endurance exercise and running for six months. Changes in cardiovascular function were evaluated by using an air-supported ultralow-frequency ballistocardiograph. Significant increases occurred in mean I, J, GI, HI and IJ forces. Four of the 5 men with initially abnormal ballistocardiograms had normal records at the end of the program.

21 citations

Dissertation
01 Jan 1978
TL;DR: The validity of the model was tested by comparing the predicted sway based on cardiorespiratory events with actual sway behaviour, which confirmed the widely held hypothesis that sway is a direct outcome of the dynamic equilibrium that exists between gravitatiqnal forces and the myotatic reflex responses.
Abstract: In an attempt to determine the influence of cardiorespiratory events on sway behaviour. a series of four experiments were undertake.n on a total of 95 subjects, all young healthy adults. Sway tiehaviour, defined as the corrective force recorded between the soles of the feet and the surface of a biomechanical measuring platform (Kistler, 9261A), was first examined to determine the extent to which it is a function.of sex and physique. Height, weight and obesity measurements were taken from 58 subjects (29 male, 29 female) and their influence on sway behaviour analysed. The second experiment was an extended ideographic study designed to test the constancy of sway behaviour over a six-week period for ten subjects (six male, four female) in an attempt to identify the personal characteristics of postural sway. This led to the formulation of a dynamic model of postural sway behaviour based on cardiorespiratory events. In the third experiment the magnitude of the cardiac forces and stroke volume,by transcutaneous aortovelography, were measured on 18 subjects (eight male, ten female), and used to establish the direct effect of cardiac action on sway behaviour. In the final experiment the role of 18 antigravity muscles of the lower limbs and trunk in postural maintenance was examined in nine subjects (five male, four female) to test the widely held hypothesis that sway is a direct outcome of the dynamic equilibrium that exists between gravitatiqnal forces and the myotatic reflex responses. The validity of the model was tested by comparing the predicted sway based on cardiorespiratory events with actual sway behaviour.

15 citations

Journal ArticleDOI
TL;DR: In this study, ultra low frequency force ballistocardiograms were recorded throughout the course of various types of acute cardiomyopathy, suggesting that this type of recording appears to offer a useful means of diagnosing and following the Course of such disease entities.
Abstract: In this study, ultra low frequency force ballistocardiograms were recorded throughout the course of various types of acute cardiomyopathy. Conditions studied included rheumatic carditis, lupus myocarditis, sarcoid carditis, viral myocarditis, acute glomerulonephritis, idiopathic myocarditis, and familial fibrous disease of the myocardium. The instrument used was characterized by an unusually light platform and a very high performance accelerometer. In 14 of the 15 cases studied, tracings were abnormal initially; the recorded force pattern subsequently manifested progressive change which appeared to parallel the clinical course of the disease. Changes included appearance of abnormal forces in early ventricular systole, progressive change in amplitude of acceleration and deceleration forces, appearance of abnormal high frequency components in various portions of the complex, and appearance of abnormal footward forces in late systole. The alterations thus recorded appear to offer a useful means of diagnosing and following the course of such disease entities. In some cases, this type of recording appears to provide information not available through any other conventional means.

12 citations

References
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Journal ArticleDOI
TL;DR: A ballistocardiograph is described which is designed to give a record of the force acting upon the "total body mass" and typical and calibrated records are shown and discussed.

48 citations

Journal ArticleDOI
TL;DR: It is hopeful that the time has come when doctors will no longer be content to regard heart diseases from the purely anatomic viewpoint, and when a statement of the strength and coordination of the heart's contraction will be considered an essential part of the record of every cardiac case.
Abstract: From the foregoing account one can see that determined efforts have been made to identify sources of error in the force ballistocardiogram as a record of the resultant of the forces generated by the heart. In few other clinical methods has there been such an extensive hunt. Certainly nothing of much moment has turned up, although we found reason to believe that differences in vessel elasticity and in size of subject would have some effect on the relation between the record and the forces which originate it. An effect of the position of the heart and of arteriosclerosis would manifest itself only if the deviation from the normal was extreme. While various other uncertainties certainly exist, it seems unlikely that they are important. Clinicians are often forced to use methods which are not perfect and much trouble can be avoided by proper care in the preparation and use of normal standards. In the case of the ballistocardiogram the scatter of the normal population will be due not only to differences in the forcefulness of the hearts of healthy persons, but also to all the other factors which might have some effect on the proper recording of such forces, such as: differences in body size, body habitus, blood pressure, arteriosclerosis and the usual technical errors. But if we identify as abnormal only those outside the statistical limits of normality of such a healthy group, the odds are strongly in favor of a valid identification of abnormality of the cardiac forces. Using the data from the cadaver experiments as a test, one finds we can identify the magnitude of the acceleration of the blood with an accuracy about equal to that of the common clinical method of taking blood pressure. It is true that the Riva-Rocci method has greater errors inherent in it than most doctors realize; the point I wish to make is that despite such errors, much important clinical information has been secured by means of it, and its introduction into clinical medicine was responsible for a great advance. I am hopeful, therefore, that the time has come when doctors will no longer be content to regard heart diseases from the purely anatomic viewpoint, and when a statement of the strength and coordination of the heart's contraction will be considered an essential part of the record of every cardiac case. The ballistocardiogram provides a method of readily securing information on this point without causing the least discomfort to the patient.

43 citations

Journal ArticleDOI
TL;DR: Two methods for calculating the amplitude characteristic of the high-frequency BCG, the difference in movement of subject and BCG taken into account, are compared and discussed.

40 citations

Journal ArticleDOI
TL;DR: The ballistocardiograms of young normal subjects as recorded with a wide frequency range technic are described and an analysis of these components in terms of known cardiovascular events strongly suggests that they have definite dynamic significance.
Abstract: The ballistocardiograms of young normal subjects as recorded with a wide frequency range technic are described. These records contain high frequency forces not previously described. An analysis of these components in terms of known cardiovascular events strongly suggests that they have definite dynamic significance. In addition, these correlations offer evidence as to the genesis of some forces in the ballistocardiogram.

38 citations

Frequently Asked Questions (1)
Q1. What are the contributions in this paper?

With this experience before us the instrument used in this study was constructed by Mr. George Peirce. The authors expected that a study of the differences between the two force records would provide important information, because each instrument approached the problem from a different direction, and neither method seemed altogether free of error.