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This Article Full Text Full Text (PDF) All Versions of this Article: 295/2/H578    most recent 00247.2008v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in ISI Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Google Scholar Articles by Bai, Y. Articles by Chon, K. H. PubMed PubMed Citation Articles by Bai, Y. Articles by Chon, K. H.

Nonlinear coupling is absent in acute myocardial patients but not healthy subjects

¹Department of Biomedical Engineering, State University of New York at Stony Brook, Stony Brook, New York; and ²Dipartimento di Fisica, Universita di Trento, Trento, Italy

Submitted 10 March 2008 ; accepted in final form 30 May 2008

We investigated whether autonomic nervous system imbalance imposed by pharmacological blockades and associated with acute myocardial infarction (AMI) is manifested as modifications of the nonlinear interactions in heart rate variability signal using a statistically based bispectrum method. The statistically based bispectrum method is an ideal approach for identifying nonlinear couplings in a system and overcomes the previous limitation of determining in an ad hoc way the presence of such interactions. Using the improved bispectrum method, we found significant nonlinear interactions in healthy young subjects, which were abolished by the administration of atropine but were still present after propranolol administration. The complete decoupling of nonlinear interactions was obtained with double pharmacological blockades. Nonlinear couplings were found to be the strongest for healthy young subjects followed by degradation with old age and a complete absence of such couplings for the old age-matched AMI subjects. Our results suggest that the presence of nonlinear couplings is largely driven by the parasympathetic nervous system regulation and that the often-reported autonomic nervous system imbalance seen in AMI subjects is manifested as the absence of nonlinear interactions between the sympathetic and parasympathetic nervous regulations.

autonomic nervous system; bispectrum; heart rate variability