Ballistocardiography and Seismocardiography: A Review of Recent Advances <s>  <s> Abstract Ballistocardiograms were made 106 times on 55 patients with coronary heart disease. In the acute period after infarction the circulation may be either normal or below. If normal, it tends to diminish, and usually reaches a minimum below the normal limit between the third and fifth week. Later, recovery sets in. The left ventricular work, as calculated from the cardiac output and the blood pressure, follows a generally similar course. In chronic coronary heart disease, with angina of effort, the circulation is subnormal in the great majority of cases, and the ballistocardiogram provides objective evidence to support the diagnosis. Abnormalities of the form of the ballistocardiogram are frequently encountered in coronary heart disease, usually when the patient has greatly reduced exercise tolerance. <s> BIB001 </s> Ballistocardiography and Seismocardiography: A Review of Recent Advances <s>  <s> One hundred patients, who had survived their first episode of myocardial infarction, were studied by serial ballistocardiograms which provided a reliable index in determining myocardial functional recovery. The degree of ballistocardiographic reversion toward normal, as judged by an 18-month or longer follow-up period, has proved to be a valuable standard for prognosis. <s> BIB002 </s> Ballistocardiography and Seismocardiography: A Review of Recent Advances <s>  <s> Seismocardiography is a new noninvasive technique for recording cardiac vibrations. Changes in the recorded waves have been correlated with acute and chronic changes in left ventricular function. In this report, we describe a patient who developed ischemia induced by coronary angiography in the cardiac catheterization laboratory. The patient's seismocardiogram showed distinct changes during the ischemic episode that actually preceded the onset of symptoms and resolved after nitroglycerin therapy. The patient's seismocardiographic recordings were significantly different from the recordings from five control individuals. This observation suggests that seismocardiography may be helpful for monitoring left ventricular function during episodes of myocardial ischemia. <s> BIB003 </s> Ballistocardiography and Seismocardiography: A Review of Recent Advances <s>  <s> A multicenter study was performed to compare the diagnostic accuracy of a new technique, seismocardiography, with that of electrocardiography for physiologically and anatomically significant ischemic coronary artery disease (CAD) during exercise stress testing. Five participating centers enrolled 129 patients who had simultaneous seismocardiograms and 12-lead electrocardiograms at the time of their exercise treadmill stress tests. Two different definitions of CAD were used: anatomic and physiologically significant disease. The presence of anatomically significant CAD (> or = 50% diameter stenosis) was documented by coronary angiography. Physiologically significant CAD was defined as present in the same 129 patients when coronary arteriography (> or = 50% diameter stenosis) and thallium-201 scintigraphy (defect on initial postexercise images) were both abnormal. Seismocardiography had a significantly better sensitivity for detecting anatomic CAD than did electrocardiography (73 vs 48%; p < 0.001), without loss of specificity (78 vs 80%; p = NS). Exercise seismocardiography added significant incremental diagnostic information beyond that provided by exercise electrocardiography. Seismocardiography was more sensitive (without less specificity) in women and in patients who did not achieve maximal predicted heart rate. In patients with physiologically significant CAD, the seismocardiogram was also significantly more sensitive (78%) than was the electrocardiogram (55%) (p < 0.02), without loss of specificity (84 vs 74%). Seismocardiography significantly improved sensitivity for the detection of anatomic and physiologic CAD. It is easy to perform and may be a clinically useful adjunct in exercise stress testing. <s> BIB004 </s> Ballistocardiography and Seismocardiography: A Review of Recent Advances <s>  <s> The field of ballistocardiography seems to be enjoying a recent resurgence, most notably through the development of novel technologies and signal processing methods for measurement and analysis. After the method almost vanished in the late 80's and 90's, it is reasonable to wonder what is different this time, and if the technique has now more chances of becoming what its pioneer always wanted — a widespread clinical tool. This paper is an effort to compare and contrast this novel wave of research (notably in the context of the authors' own work). It also suggests that the new approaches have several key differences with past embodiments that place them in a good position to address some specific issues such as cardiac resynchronization therapy device optimization or congestive heart failure monitoring. This optimism is largely fed by the recent technological advances enabling the measurement of the BCG unobtrusively, frequently, at home or in a hospital, and by a re-focus on monitoring and trending applications. <s> BIB005
body in reaction to cardiac ejection of blood into the vasculature  , while the seismocardiogram (SCG) represents the local vibrations of the chest wall in response to the heartbeat  . The BCG phenomenon was first observed in 1877 by Gordon, with the finding that, as a subject would stand on a weighing scale, the needle would vibrate synchronously to the subject's heartbeat  . Nearly 60 years later, Starr and colleagues created an instrument in the form of a table with a mobile top surface to measure the BCG in a repeatable scientific manner  . The SCG was first observed by Bozhenko in 1961  , and was first applied in clinical studies 30 years later in 1991 by Salerno and Zanetti BIB003 . Throughout the 1900s, both BCG and SCG signals were heavily investigated and several publications appeared in major scientific and clinical journals (e.g., BIB003 BIB001 BIB002 BIB004 ). However, because of the advent of echocardiography and magnetic resonance imaging, and overly-cumbersome hardware, BCG and SCG were largely abandoned by the medical community BIB005 . Today, technological advancements largely simplify the measurement and assessment of these signals and open new perspectives in their clinical use. This paper reviews the instrumentation and signal processing advances which have helped to propel BCG and SCG into this revival. It also summarizes some of the key human subjects studies performed recently that support the use of BCG and SCG in extra-clinical applications.