PROBLEM TO BE SOLVED: To make it possible to confirm the state of odd heartbeats and even heartbeats and also to ensure the reliability of TWA measurement.SOLUTION: A T wave feature quantity measurement part 162 measures a T wave feature quantity of electrocardiographic waveforms obtained from a subject. The T wave feature quantity is any of the width, amplitude, area, and frequency values of the T wave of the electrocardiographic waveforms, or a value obtained by performing arithmetic operations on any combination of the T wave values. A classification part 164 classifies the T wave feature quantify of each electrocardiographic waveform into a group of odd electrocardiographic waveforms or a group of even electrocardiographic waveforms. A reliability index calculation part 166 calculates a representative value of T wave feature quantities and a dispersion value for each group and calculates the difference of representative values of T wave feature quantities between the groups to determine a TWA feature quantity, the reliability index calculation part 166 also calculates the difference between the representative value of T wave feature quantities and the dispersion value in a group with a large T wave feature quantity and the sum of the representative value of T wave feature quantities and the dispersion value in a group with a small T wave feature quantity, to determine a reliability index. A reliability recognition part 168 recognizes that the reliability of the TWA feature quantity is high if the reliability index is above a threshold value and that the reliability of the TWA feature quantity is low if the reliability index is not above the threshold value.COPYRIGHT: (C)2014,JPO&INPIT
