Correlation of ballistocardiogram with work performance and energy cost for guidance in rehabilitation of cardiac patients.

Correlative studies of the resting ballistocardiogram and the ability to expend energy in cardiac l)a-tients indicate that the resting ballistocardiogram may be a useful tool in evaluating the functional or work capacity of a cardiac patient for rehabilitation purposes and vocational guidance, and may serve as a screening device for finding those cardiacs, other things being equal, who possess the functional capacity to perform jobs or activities whose energy requirements are known or can be estimated. However, in view of the relatively higher incidence of abnormal resting ballistocardiograms in the older age groups, for practical purposes, this usefulness of the ballistocardiogranm may be limited to the cardiac patient under the age of 50. W ITH the introduction in 1949, by Dock and Taubman,1 of a simplified electromagnetic device for recording the ballistocardiogram, great impetus was given to the study of clinical ballistocardiography and considerable experience has been accumu-lated2-7 which does not differ essentially from that derived from the use of the more complicated instruments of Starr and Nickerson.8-'1 Significant diagnostic ballistocardiographic changes have been found in patients with coronary artery disease, particularly with angina pectoris. Taymor and associates found that the resting ballistocardiogram was abnormal in 62 (83 per cent) of 75 patients with angina pectoris, normal resting electrocardiograms and positive Master two-step tests. After exercise the ballistocardiogram became abnormal in an additional eight patients, or a total of 70 (93 per cent). Rinzler and co-workers7 compared 740 the usefulness of the resting ballistocardiogram with the exercise tolerance test in the diagnosis of coronary artery disease in 24 patients with chest pain and normal resting electrocardio-grams, and found a 91 per cent correlation; that is, an abnormal resting ballistocardiogram was associated with an abnormal exercise tolerance test, or a normal resting ballistocardiogram with a normal exercise tolerance test, in 91 per cent of instances. The Mandelbaums5a reported that 200 of 224 patients with clinical angina pectoris had abnormal resting ballisto-cardiograms. These findings suggest that the resting ballistocardiogram may serve as a sensitive indicator of coronary artery disease. Since the ballistocardiogram is a reflection of the mechanical or pumping activity of the heart, it might be expected to give information about cardiac functional capacity. Evidence for this has been presented by Starr12 who found that patients in congestive heart failure demonstrated abnormal ballistocardiographic patterns, with return to normal patterns upon recovery of cardiac compensation. Starr and Wood8 also noted good correlation …