Short-term forecasting of life-threatening cardiac arrhythmias based on symbolic dynamics and finite-time growth rates.
Ventricular tachycardia or fibrillation (VT-VF) as fatal cardiac arrhythmias are the main factors triggering sudden cardiac death. The objective of this study is to find early signs of sustained VT-VF in patients with an implanted cardioverter-defibrillator (ICD). These devices are able to safeguard patients by returning their hearts to a normal rhythm via strong defibrillatory shocks; additionally, they store the 1000 beat-to-beat intervals immediately before the onset of a life-threatening arrhythmia. We study these 1000 beat-to-beat intervals of 17 chronic heart failure ICD patients before the onset of a life-threatening arrhythmia and at a control time, i.e., without a VT-VF event. To characterize these rather short data sets, we calculate heart rate variability parameters from the time and frequency domain, from symbolic dynamics as well as the finite-time growth rates. We find that neither the time nor the frequency domain parameters show significant differences between the VT-VF and the control time series. However, two parameters from symbolic dynamics as well as the finite-time growth rates discriminate significantly both groups. These findings could be of importance in algorithms for next generation ICD's to improve the diagnostics and therapy of VT-VF.
Wessel
N
N
University of Applied Sciences Jena, Tatzendpromenade 1b, 07745 Jena, Germany. wessel@fvk-berlin.de
Ziehmann
C
C
Kurths
J
J
Meyerfeldt
U
U
Schirdewan
A
A
Voss
A
A
D000465:Algorithms; D001145:Arrhythmias, Cardiac / Q000175:diagnosis* / Q000503:physiopathology / Q000628:therapy; D055592:Biophysical Phenomena; D001703:Biophysics; D017147:Defibrillators, Implantable; D006333:Heart Failure / Q000503:physiopathology / Q000628:therapy; D006339:Heart Rate; D006801:Humans; D008955:Models, Cardiovascular; D017711:Nonlinear Dynamics; D017180:Tachycardia, Ventricular / Q000175:diagnosis / Q000503:physiopathology / Q000628:therapy; D014693:Ventricular Fibrillation / Q000175:diagnosis / Q000503:physiopathology / Q000628:therapy