Further studies on a theory of the ballistocardiogram.
TL;DR: This paper relates the movement of the body in space, when the body is free to move, with the events of the cardiac cycle, based on a well-known principle.
Abstract: IN THIS THEORY of the normal human longitudinal ballistocardiogram we shall attempt to relate the record, in quantitative terms, to the events in the circulation that we believe to be its genesis. The variables concerned here fall into three groups: those concerned with the performance of the heart as a pump; those concerned with the position and elastic properties of the vessels that contain the blood and guide its movement; those concerned with the properties of body tissues themselves that influence the transfer of forces arising within the body to its support, the ballistocardiograph. Mainly the first two groups are discussed in this paper. The fourth group, comprising the properties of the instrument, has been discussed extensively. As the simplest approach to the problem we have taken as our starting point the movement of the body in space, when the body is free to move, with the events of the cardiac cycle. It is of interest to note that the advantages of this approach were recognized by Trotter in 1872, when he commented on Gordon's paper, the first on this subject. Such an approach is based on a well-known principle. Figure 1 shows a striking example that is within the experience of everyone. If an object is free to move, when the internal position of its center of gravity is altered by forces arising within it, the object alters its position in space so that the position of its center of mass in space remains the same. This is why the fisherman has so much difficulty recovering his hat. The body, placed in position in which it is
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TL;DR: Derivation and description are presented of an electrical analog of the left ventricle and the systemic arterial tree that has fewer limitations than the mathematical model.
107 citations
01 Dec 2011
TL;DR: Results indicate that it is possible to reliably identify the time of occurrence of the first and second heart sound within the cardiac cycle, and show significant differences in the HF component of SCG between supine and standing postures.
Abstract: Seismocardiography is the body-surface recording of vibrations produced by the beating heart. A high frequency (HF) accelerometric component of the seismocardiogram (SCG) is related to the heart sounds generated by the closure of atrio-ventricular and semilunar valves. This paper evaluates the feasibility of recording the SCG component associated to cardiac sounds by means of a wearable device originally designed for monitoring ECG, respiratory movements, body accelerations and posture in freely moving subjects. The method is based on the averaging of the HF component of the acceleration vector measured by the wearable system, and on the subsequent extraction of features from its envelope. The method is applied on data recorded in healthy volunteers in different postures and during sleep. Results indicate that it is possible to reliably identify the time of occurrence of the first and second heart sound within the cardiac cycle. They also show significant differences in the HF component of SCG between supine and standing postures. Analyzing the HF SCG in a volunteer sleeping at high altitude (4554 m asl) substantial differences were also found among three body positions (lying supine or on the left or right side). These differences are likely to reflect changes in cardiac mechanics induced by different postures of the body.
37 citations
Cites methods from "Further studies on a theory of the ..."
...This low-frequency component of the seismocardiogram (SCG) has been extensively studied with the name of ballistocardiogram mainly by Starr [4] and Noordergraaff [5] in the ‘50s and ‘60s....
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TL;DR: The present and future potential benefits of using BCG to measure cardiac cycle events and its application to clinical and applied research are reviewed.
Abstract: Ballistocardiography (BCG) is a non-invasive technology that has been used to record ultra-low-frequency vibrations of the heart allowing for the measurement of cardiac cycle events including timing and amplitudes of contraction. Recent developments in BCG have made this technology simple to use, as well as time- and cost-efficient in comparison with other more complicated and invasive techniques used to evaluate cardiac performance. Recent technological advances are considerably greater since the advent of microprocessors and laptop computers. Along with the history of BCG, this paper reviews the present and future potential benefits of using BCG to measure cardiac cycle events and its application to clinical and applied research.
32 citations
Cites background from "Further studies on a theory of the ..."
...As the blood moves towards the periphery and accumulates further away from the heart in the peripheral vessels, the centre of gravity moves towards the feet (Noordergraaf, 1961; Starr, 1965)....
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TL;DR: Surgical repair has been accomplished, using a hammock-like prosthesis which interrupts the interventricular shunting and permits unobstructed flow from the left ventricle to the aorta.
24 citations
13 Nov 2009
TL;DR: A physical analysis is presented using a finite element model of thoracic aortic vasculature to quantify forces generated by the blood flow during the cardiac cycle, which generates a Central Aortic Force (CAF) which appears of similar magnitude to recorded BCG forces.
Abstract: The ballistocardiogram (BCG) signal represents the movements of the body in response to cardiac ejection of blood. The BCG signal can change considerably under various physiological states; however, little information exists in literature describing how these forces are generated. A physical analysis is presented using a finite element model of thoracic aortic vasculature to quantify forces generated by the blood flow during the cardiac cycle. The traction at the fluid-solid interface of this deformable wall model generates a Central Aortic Force (CAF) which appears of similar magnitude to recorded BCG forces. The increased pulse pressure in an exercise simulation caused a significant increase in CAF, which is consistent with recent BCG measurements in exercise recovery.
24 citations
Cites background from "Further studies on a theory of the ..."
...Noordergraaf explained that the BCG signal results from a change in the center of mass in the body, when blood moves from the ventricles into the greater vessels [8, 9]....
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337 citations
TL;DR: The amplitude of the ballistocardiogram measures the maximum force exerted by the heart in moving the blood and preliminary normal standards for this estimate of cardiac strength have been set up.
Abstract: The interpretation of ballistocardiograms has been attacked by a method entirely new; a physiologic experiment performed at necropsy. While the subject lies on the ballistocardiograph a normal diastolic pressure is created and the heart's function is simulated by injecting fluid into the aorta and pulmonary artery, the amount injected at each instant being recorded. The resulting ballistocardiograms can be directly compared with many aspects of cardiac function. The amplitude of the ballistocardiogram measures the maximum force exerted by the heart in moving the blood and preliminary normal standards for this estimate of cardiac strength have been set up.
83 citations
TL;DR: Changes in left ventricular diameter occur very rapidly, often being manifest within the duration of a single cardiac cycle, and mechanisms by which changes in ventricular size can be directly affected by neural and hormonal influences are briefly considered.
Abstract: Left ventricular dimensions have been directly measured for extended periods of time in intact unanesthetized dogs under various conditions. The diameter of the left ventricle during diastole is very large in relation to the change in diameter during each cycle. Thus, considerable quantities of blood remain within the chamber at the end of systolic ejection. The stroke output can be increased by either more complete systolic ejection during exercise or by greater diastolic filling during a startle reaction. Accelerated heart rate occurs in both cases. Changes in left ventricular diameter occur very rapidly, often being manifest within the duration of a single cardiac cycle. Mechanisms by which changes in ventricular size can be directly affected by neural and hormonal influences are briefly considered.
70 citations
TL;DR: The amount of residual blood during life, the so-called residual blood, has been calculated approximately with the help of ante- and post-mortem roentgenologic heart volume estimations, displacement estimations of heart volume, and measurement of the capacity of the cavities.
59 citations