A ballisttcardiographic study using Dock´s electromagnetic ballistocardiograph was made on 250 persons who were apparently normal, having no evidence of cardiopulmonary disease. This group consisted of132 men and 118 women ranging in 69 years. The ballistocardiographicage-decade group in both sexes were comparea.
The incidences of abnormal ballistocardiograms cording to Dock´s classification were 8.8% in third age-decade; 12.5% in the fourth decade: 34.in the fifth decade: 67.7% in the sixth and seventh decade; and for the entire group 22.0%.
The frequency of abnormal ballistocardiograms in individuals under the age of 40 was not only significantly different for each age-decade group but also definitely lower than that in individuals above the age of 40. In the successive age-decades the occurrence of abnormal ballistocardiograms rose precipitousty from the fifth through the seventh decade. Furthermore, only one grade 3 abnormal ballistocardiogram was seen in 170 persons under the age of 40,whereas eight grade 3 to grade 4 abnormal ballistocardiogranls were obtained in 80 persons above the age of 40. Incidences of abnormal. ballistocardiograms in each age-decade group showed no significant difference between male and female.
The amplitudes of IJ, Hl and JK segments revealed a trend of progressive decreases with advancing age in both sexes and were markedly smaller in women than in men in all age-decade groups.
The percentage of expiratory IJ amplitude to inspiratory IJ amplitude (IJE/IJ,, %) showed a tendency to dwindle with advancing age in both sexes. The percentage of mean Hl amplitude to mean IJ amplitude (HlM/IJm, % ) also manifested the trend of progressive decrease with advancing age in men but no such trend was noted in women.
When comparing the various age-decade groups the percentage of mean JK amplitude to mean IJ amplitude (JKm,/IJu, %) was not notably different in eachage-decade group in both sexes, however, it wasdefinitely larger in men than in women in eachindividual age-decade group.
R-H, R-1, R-J and R-K intervals manifested no close relationship to age in either sex and R-Iand R-J intervals in the sixth and seventh decades and R-K interval in the fifth, sixth and seventh decades of life were markedly longer in men than in women.
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