A Method of Securing the Direct Body Ballistocardiogram by Means of a Microscope, Giving a Record Readily Calibrated
We describe a simple method of recording the direct body ballistocardiogram by means of a microscope and a powerful light source. The beam passes through a slit attached to the body, and the image of this moving slit is magnified by the microscope and focused on moving photographic paper. When a static force is applied to the body, the base line of the record is permanently displaced and so the amplitude of the ballistocardiogram can be calibrated. By superimposing a ballistocardiogram obtained by means of the electrocardiogram on the same film, accurate comparisons of the two records and a calibration of the electrical instrument can be obtained.
- © 1953 American Heart Association, Inc.