Mechanocardiogram Measured at the Back of Subjects Sitting in a Chair as a Non-intrusive Pre-ejection Period Measurement

A new method for recording mechanocardiogram was presented. The presented method aims at non-intrusive measurement of pre-ejection period (PEP) in usual daily life. The presented method utilized a pressure sensor, EMFi, which was attached to the back of a chair. By the pressure sensor, the variation in pressure (mechanocardiogram) at the subject´s back was measured. As a reference, impedance-cardiogram was recorded simultaneously with the mechanocardiogram. The mechanocardiogram was recorded with healthy subjects. During the measurement, valsalva maneuver or cold pressor was carried out in order to vary PEP. We found a consistency of the mechanocardiogram in the time interval between S wave and T wave of ECG among the subjects, and found that the latency between R-peak and a peak in the mechanocardiogram followed by a maximum negative slope correlated well with the PEP acquired by impedance-cardiogram. This study shows that the mechanocardiogram measured at the back can be applied to non-intrusive PEP measurement