Higher Frequency Phenomena in the Normal Ballistocardiogram

Physiologic higher frequency phenomena may be demonstrated in ballistocardiograms from normal subjects. These phenomena consist of notches or multiple oscillations on the H-I and K-L segments of the tracings. They may be demonstrated by recording the unfiltered output of an electromagnetic direct-body ballistocardiograph. They become more prominent as the transducer is applied closer to the source of cardiovascular forces, or by passing the output of the transducer through a band pass filter. The time relationship of these oscillations to simultaneously recorded heart sounds suggests their association with the ballistics of the closing heart valves.