The R and T waves amplitudes of the electrocardiogram recorded during the exercise test undergo strong modifications in response to stress. We analyze the time series of these amplitudes in a group of normal subjects in the framework of functional data, performing reduction of dimensionality, smoothing and principal component analysis. These methods show that the R and T amplitudes have opposite responses to stress, consisting respectively in a bump and a dip at the early recovery stage. We test these features computing a confidence band for the trend of the population mean and analyzing the zero crossing of its derivative. Our findings support the existence of a relationship between R and T wave amplitudes and respectively diastolic and systolic ventricular volumes.
@article{arxiv.1602.05907,
title = {Trend extraction in functional data of R and T waves amplitudes of exercise electrocardiogram},
author = {Camillo Cammarota and Mario Curione},
journal= {arXiv preprint arXiv:1602.05907},
year = {2016}
}