The Nonlinear Dynamics of Pacemaker Dependency

A person is considered pacemaker dependent when most of his or her heartbeats are supplied by a pacemaker. The purpose of this study was to determine whether there are significant differences between the heart dynamics of pacemaker‐dependent patients and those of normal patients. Nonlinear dynamics techniques and statistical methods were used to analyze the ECGs of normal patients and pacemaker‐dependent patients. Standard embedding of the ECG data yielded inconclusive results, but embedding the beat intervals proved to be much more useful. Lyapunov exponent calculations, recurrence plot analyses, and standard statistical analyses of these data showed significant differences in heart behavior between the two groups of patients. In particular, the beat intervals appear to exhibit chaotic behavior for the normal patients and fixed‐point dynamics for pacemaker‐dependent patients.