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.
journal_name
Biophys Jjournal_title
Biophysical journalauthors
Savino GV,Romanelli L,González DL,Piro O,Valentinuzzi MEdoi
10.1016/S0006-3495(89)82673-6subject
Has Abstractpub_date
1989-08-01 00:00:00pages
273-80issue
2eissn
0006-3495issn
1542-0086pii
S0006-3495(89)82673-6journal_volume
56pub_type
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