Evidence for chaotic behavior in driven ventricles

Abstract

Toad ventricles were externally driven by periodic pulses while monophasic action potential (MAP) signals were recorded in seven excised and seven in situ ventricles. As the frequency was slowly increased in steps, the stimulated tissue displayed several dynamic characteristics. Hierarchies of periodic behavior, like phase-locking and period-doubling sequences leading to chaos, were observed. Results showed that subharmonic bifurcations (order one and two) and chaotic-like behavior may systematically occur in the MAP signal within a definite frequency interval in the 1:1 phase locking regime. The chaotic, or more cautiously expressed, chaotic-like behavior is characterized by the power spectrum, the autocorrelation function, the Poincaré map, and the reconstructed 2-D phase portrait. It is concluded that (a) bifurcations of order one and two and the characteristic irregular behavior are evidences of local universal chaotic dynamics in cardiac tissue; (b) there are no qualitative differences in the dynamics of the in situ and excised ventricles; and (c) fibrillation seems to be related to chaotic behavior, but whether they are similar or equivalent phenomena still remains to be seen.

Chaotic dynamics in an ionic model of the propagated cardiac action potential

“…There are also very recent reports of 4:4 rhythms in ventricular tissue during ischaemia (Dilly & Lab, 1988), hypothermia (Kaplan, 1989), and fast pacing (Savino et al, 1989). These three reports of 4:4 rhythms are the only ones of which we are aware in situations predisposing to ventricular arrhythmias.…”

“…Periodic stimulation applied at a high rate can lead to a variety of periodic and aperiodic rhythms, including alternans (a rhythm in which there is a beat-to-beat alternation in one or more action potential parameters) and ventricular fibrillation (Savino & Valentinuzzi, 1988). Within the last decade, the identification of the onset of ditterent forms of alternans with a period-doubling bifurcation has been made in several different cardiac preparations (Guevara et ai., 1981(Guevara et ai., , 1984(Guevara et ai., , 1989(Guevara et ai., , 1990Adam et al, 1982Adam et al, , 1984Goldberger et at, 1984;Guevara, 1984;Chialvo & Jalife, 1987;Smith et al, 1988;Hescheler & Speicher, 1989;Savino et al, 1989;Chialvo et al, 1990). In many of these reports, the alternans is often seen just prior to the phase of induction of irregular rhythms, including ventricular fibrillation.…”

“…In many of these reports, the alternans is often seen just prior to the phase of induction of irregular rhythms, including ventricular fibrillation. Since it is wellknown that a cascade of period-doubling bifurcations can lead to chaotic dynamics (May, 1976;Thompson & Stewart, 1986), the hypothesis has been put forth that irregular rhythms, such as fibrillation, might be manifestations of chaotic dynamics occurring as the result of a cascade of period-doubling bifurcations (Guevara et al, 1981;Guevara & Glass, 1982;Adam et al, 1982;Chialvo & Jalife, 1987;Smith et al, 1988;Savino et al, 1989). We therefore decided to carry out a systematic study of the effect of pacing at different rates in an ionic model of a strand of ventricular muscle.…”

Quasiperiodicity and chaos in cardiac fibrillation.

“…High-resolution mapping and other studies have detected local spatio-temporal correlations (3)(4)(5) and other evidence of determinism (6) during fibrillation, suggesting that the underlying process is not completely random. It is therefore tempting to speculate that fibrillation is deterministic chaos, especially since definitive evidence of chaos has been found in some simpler cardiac arrhythmias (7)(8)(9).…”

Why Cardiac Resynchronization Therapy (CRT) is Usually Prescribed along with Automatic Implantable Defibrillation (AID)? Is it a Sensible Decision? Historical Perspective

“…The human heart is inhomogeneous in its anatomical and histological structure and such fact facilitates its falling into the arrhythmia, easily lethal if not attended as a right-now-emergency. Homogeneous ventricles, instead, like the herptilian heart, rarely if ever show fibrillation, which usually is described as rapid asynchronic or uncoordinated contractions [24,25]. The latter two references give evidence of these peculiarities and also possibly relate the phenomenon to non-linear chaotic behavior.…”