Nonlinear dynamics of heart rate variability during experimental hemorrhage in ketamine-anesthetized rats

1  Delaware Water Gap Science Institute, Bangor, 18013; and 2  Department of Emergency Medicine, Lehigh Valley Hospital, Allentown, Pennsylvania 18103 Indexes of heart rate variability (HRV) based on linear stochastic models are independent risk factors for arrhythmic death (AD). An index based on a...

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Published in:American journal of physiology. Heart and circulatory physiology 2000-10, Vol.279 (4), p.H1669-H1678
Main Authors: Skinner, James E, Nester, Brian A, Dalsey, William C
Format: Article
Language:English
Subjects:
Anesthesia
Anesthetics, Dissociative
Animals
Arrhythmias, Cardiac - mortality
Electrocardiography
Forecasting
Heart Rate
Hemorrhage - physiopathology
Ketamine
Male
Models, Cardiovascular
Nonlinear Dynamics
Rats
Rats, Sprague-Dawley
Shock, Hemorrhagic - physiopathology
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Summary:1  Delaware Water Gap Science Institute, Bangor, 18013; and 2  Department of Emergency Medicine, Lehigh Valley Hospital, Allentown, Pennsylvania 18103 Indexes of heart rate variability (HRV) based on linear stochastic models are independent risk factors for arrhythmic death (AD). An index based on a nonlinear deterministic model, a reduction in the point correlation dimension (PD2 i ), has been shown in both animal and human studies to have a higher sensitivity and specificity for predicting AD. Dimensional reduction subsequent to transient ischemia was examined previously in a simple model system, the intrinsic nervous system of the isolated rabbit heart. The present study presents a new model system in which the higher cerebral centers are blocked chemically (ketamine inhibition of N -methyl- D -aspartate receptors) and the system is perturbed over a longer 15-min interval by continuous hemorrhage. The hypothesis tested was that dimensional reduction would again be evoked, but in association with a more complex relationship between the system variables. The hypothesis was supported, and we interpret the greater response complexity to result from the larger autonomic superstructure attached to the heart. The complexities observed in the nonlinear heartbeat dynamics constitute a new genre of autonomic response, one clearly distinct from a hardwired reflex or a cerebrally determined defensive reaction. chaos theory; self-organization; surrogate controls
ISSN:0363-6135
1522-1539
DOI:10.1152/ajpheart.2000.279.4.H1669