A comparison between R-R and R-T variability signals in normal and pathological subjects

Power spectrum analysis of the RR variability (RRV) signal is compared with the spectrum obtained from the RT variability (RTV) signal. The analysis is carried out on a population of 16 normal subjects and 24 patients, 15 days after an acute episode of myocardial infarction (MI). While in normal subjects the RTV signal is satisfactorily correlated with RRV, presenting the same trend in a rest/tilt maneuver, in MI patients such a correlation strongly decreases. This finding demonstrates that the pathophysiological link between the two variability signals is complex, and local properties of the ventricular cells may be accounted for by the noticed difference in their behavior. RRV and RTV signal analysis can be used to investigate the relations between the beat-to-beat variability of ventricular depolarization and repolarization durations