A study in frontal plane vectorballistocardiography.

Frontal plane ballistocardiograms obtained from 10 normal subjects were analyzed and compared with abnormal records obtained from patients with known cardiovascular disease. The normal vector loop is described, and the importance of the transverse ballistocardiogram is discussed. It is suggested that the orientation of the J loop may be related to the anatomic position of the heart. No such relationship was noted with the frontal plane H, I or K vector loops. ALTHOUGH the human body vibrates in an infinite number of ways, investigators in ballistocardiography have been concerned primarily with motion in the head-to-foot direction. A limited number of investigations have been carried out, for the most part in recent years, concerning other degrees of freedom. Starr and Friedland', using a high frequency table, rotated the supine subject about the anteroposterior axis. Nickerson and Curtis2 did a similar study, using a low frequency, critically damped table. Hamilton, Dow and Remington3 recorded motion simultaneously in three planes. Scarborough and associates4 described a method for recording ballistocardiographic vectors, and Franzblau and his group' have completed a similar study with a critically damped table. Brandt and associates6 have also studied the longitudinal, transverse, and sagittal ballistocardiogram by means of a direct body coil and magnetic pickup. Recently, Tannenbaum and his coworkers7 studied the correlation between cardiac position and the direction of the H, I, J, and K loops. The results of these studies have produced conflicting data in regards to the orientation of the H, I, and J loops. These may be explained by torsional changes, as suggested by Brandt and his associates,6 or may be the result of various phase relationships, depending upon the type of instrument employed. In this study, our purpose was to analyze the frontal plane ballistocardiogram in a series of normal subjects and to compare the results with abnormal records obtained from patients with known cardiovascular disease. The two-dimensional ballistocardiograph and cathode ray oscillograph used in this study have been described in previous publications.8' 9 In the time which has elapsed since the instrument was built, circuits have been improved and other modifications have been made for ease of operation. These are described in the Appendix. MATERIAL The first group consisted of 10 apparently normal persons. The size and configuration of the heart were normal as determined by chest x-ray films. Twelve lead electrocardiograms and ballistocardio-grams were taken on each subject and these were also normal. The …