The dimension of 2D and 3D Poincare plots obtained from 24 hour ECG registrations

The dimension is a basic concept in non linear dynamics. The box counting dimension (BCD) is one of the methods that is available to determine the dimension. We studied the dimension of the heartrate signal in both 2 and 3D Poincare plots in a group of twenty five post myocardial infarction (MI) patients together with an age and sex matched control group. The average BCD from the normal subjects based on a 2D first return plot was 1.46/spl plusmn/0.09, while in the infarction group this was significantly lower: 1.34/spl plusmn/0.17 (p=0.003). Excluding ectopic data from the analysis caused large changes in the resulting dimension.