Clinical experience with the portable electromagnetic ballistocardiograph.
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The purpose of ballistocardiography is to obtain a rough objective measurement of the strength of the heart beat. Recordings have been made with a portable electromagnetic instrument on 225 persons, some normal, others with many kinds of cardiovascular disease, to determine the usefulness of the ballistocardiograph. Tracings were made at certain stages of respiration at rest and after exercise. The ballistocardiograph can in some cases be the principal diagnostic instrument in distinguishing cardiac from extracardiac disease, in the early detection of coronary artery disease, and in the diagnosis of myocarditis. It also may aid in the diagnosis of high output failure, pericardial effusion, nicotine sensitivity and coarctation or other occlusive disease of the aorta. (+info)
A simple ballistocardiographic system for a medical cardiovascular physiology course.
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Ballistocardiography is an old, noninvasive technique used to record the movements of the body synchronous with the heartbeat due to left ventricular pump activity. Despite the fact that this technique to measure cardiac output has been superseded by more advanced and precise techniques, it is useful for teaching cardiac cycle physiology in an undergraduate practical course because of its noninvasive application in humans, clear physiological and physiopathological analysis, and practical approach to considering cardiac output issues. In the present report, a simple, low cost, easy-to-build ballistocardiography system is implemented together with a theoretical and practical session that includes Newton's laws, cardiac output, cardiac pump activity, anatomy and physiology of the vessel circulation, vectorial composition, and signal transduction, which makes cardiovascular physiology easy to understand and focuses on the study of cardiac output otherwise seen only with the help of computer simulation or echocardiography. The proposed system is able to record body displacement or force as ballistocardiography traces and its changes caused by different physiological factors. The ballistocardiography session was included in our medical physiology course six years ago with very high acceptance and approval rates from the students. (+info)
Removal of BCG artifacts using a non-Kirchhoffian overcomplete representation.
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Quantitative ballistocardiography (Q-BCG) for measurement of cardiovascular dynamics.
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In the seventies of the past century ballistocardiography had been thought to be obsolete in cardiology for impossibility of objective calibration. In the present work the quantitative ballistocardiography (Q-BCG) for measurement of systolic force (F) and minute cardiac force (MF) in sitting subject was described. The new principle of piezoelectric transducer enabled to register the force caused by the heart and blood movement, which was not measured before. The calibration proved that the action of the force on the transducer was expressed quantitatively without the amplitude-, time-, and phase deformation. The close relationship of skeletal muscle force and F was proved. The F and MF changed under different physiological conditions (age, partial pressure of oxygen, body weight, skeletal muscle force). It was shown that the systolic force (F) and minute cardiac force (MF) are the physiological parameters neurohumorally regulated similarly as the heart rate or systolic volume. (+info)
Some observations on the fluttering midline echo in echoencephalography. A ballistocardiac effect and suggested cause of rupture of the septum pellucidum.
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In cases of hydrocephalus, echoes from the region of the cerebral median segittal plane may show a fluttering variation both in amplitude and range. Evidence is presented that, in the case studied, these movements arose from the falx cerebri and that they were caused by ballistocardiac forces presumably setting the CSF in the enlarged lateral ventricles into resonance within the enlarged cranium. Similar movements would be expected in the lateral ventricular walls as well as the septum pellucidum when the latter is imperforate. It is suggested that the lowering of the resonant frequency of the ventricular CSF in cases of hydrocephalus with both large ventricles and large heads allows ballistic and acceleratory forces applied to the hydrocephalic head to cause large pressure changes between the two lateral ventricles with consequent lateral movement of the midline structures separating them and possible rupture of the septum pellucidum, as is commonly found in hydrocephalus. (+info)
Respiratory challenge induces high frequency spiking on the static charge sensitive bed (SCSB).
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The static charge sensitive bed (SCSB) is a simple and noninvasive device used for the detection of sleep apnoea. In addition to episodes of apnoea or hypopnoea, heavy snorers commonly present with episodes of high frequency spiking on the SCSB. These spiking episodes have been claimed to represent partial upper airway obstruction during sleep, but the mechanism of their appearance is not known. We studied the SCSB spiking phenomenon in awake subjects during experimental respiratory challenge. One female and five male volunteers were studied whilst breathing freely, during hypoxia, hypercapnia and inspiratory and expiratory loading. Oxygen saturation, end-tidal carbon dioxide tension, minute ventilation, oesophageal pressure, electrocardiographic activity (ECG), blood pressure and the SCSB signals were monitored. During free breathing, the SCSB high frequency signal consisted of low amplitude complexes with close time relationship to the cardiac cycle. During respiratory challenge, spiking occurred. These spikes showed no time relationship to the cardiac cycle, but were time-linked to the onset of inspiration or expiration. Spike amplitude correlated with breathing frequency (r2 = 0.59; p < 0.005) and variation in oesophageal pressure (r2 = 0.57; p < 0.005). We conclude that during quiet, unobstructed breathing the static charge sensitive bed high frequency signal represents cardiac activity (ballistocardiogram), whereas during high-drive breathing high frequency spikes are produced. These spikes are respiratory in origin and are likely to represent fast components of respiratory movements. Our results support the use of static charge sensitive bed spiking as a noninvasive measure of breathing stimulation. (+info)