Low dimensional chaos in cardiac tissue

Article Abstract:

The study of chaos is a new enterprise of applied mathematics; chaotic interpretations have been applied to data from many fields of research. Chaos refers to the evolution in time of a system which seems to be random, but is actually the result of very simple underlying dynamics. A typical feature of chaotic systems is that they are very sensitive to small changes in parameters. In other words, a slight alteration in the conditions at the beginning will drastically affect changes in the system over time. Usually chaotic systems are nicely periodic with some parameters and become wildly unpredictable at others. Although the methods of chaos have been applied to the study of cardiac physiology, most researchers have concentrated on the pacemaker activity of the atria. Investigators have now shown that the Purkinje fibers, which carry a wave of excitation along the heart muscle, also have chaotic properties. Experiments on the electrophysiology of sheep heart Purkinje fibers revealed what the applied mathematicians call period-doubling bifurcations; when the interval between impulses became short enough, the periodicity broke down into chaos. The mathematical model developed to characterize this behavior indicates some conditions which are more stable, and some which are less so. The identification of conditions which contribute to stability in the model may guide the choice of drugs which will reduce cardiac arrhythmias, or abnormal heart rhythms, in clinical cases. (Consumer Summary produced by Reliance Medical Information, Inc.)

Health aspects, Models, Heart, Chaos theory, Chaotic systems, Heart conduction system

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Decrease of cardiac chaos in congestive heart failure

Article Abstract:

Information obtained using electrocardiogram tests on healthy people and people with severe congestive heart failure (CHF) indicates that cardiac chaos exists in the healthy heart. Indeed, a decline in cardiac chaos may be an indication of CHF. People with CHF tend to show intermittent heartbeat oscillations, indicating that they may be at the brink of intermittency, a common way in which the heart enters and leaves chaos. It was not possible to identify the mechanisms of cardiac chaos and its recession in heart failure.

Diagnosis, Congestive heart failure, Heart beat, Heart rate

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Finding chaos in abyssal hills

Article Abstract:

Geophysicists have attempted to describe the process of mid-ocean-ridge faulting which creates abyssal hills on the sea bed. Numerical analysis methods are being used to investigate the physical process that creates chaos and turbulence on the ocean floor.

Abyssal zone, Ocean bottom

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