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This Article Full Text Full Text (PDF) Buy All Versions of this Article: 297/2/H674    most recent 00236.2009v1 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 PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Baumert, M. Articles by Nalivaiko, E. Search for Related Content PubMed PubMed Citation Articles by Baumert, M. Articles by Nalivaiko, E.

Short-term heart rate variability and cardiac norepinephrine spillover in patients with depression and panic disorder

¹Cardiovascular Research Centre, School of Medicine, University of Adelaide, Adelaide; ²Human Neurotransmitters Laboratory, Baker 101 Heart and Diabetes Institute, Melbourne; and ³School of Biological Sciences, University of Newcastle, Newcastle, Australia

Submitted 9 March 2009 ; accepted in final form 27 May 2009

Changes in measures of heart rate variability (HRV) have been associated with an increased risk for sudden cardiac death. The mechanisms underlying this association are not known. The objective of this study was to assess the relationship between the amount of norepinephrine (NE) released from the cardiac sympathetic terminals and short-term HRV. The study comprised 8 healthy subjects, 12 patients with major depression, and 7 patients with panic disorder. Cardiac NE spillover was determined using direct coronary sinus blood sampling coupled with an NE isotope dilution methodology. Short-term HRV was quantified using detrended fluctuation analysis, symbolic dynamics, sample entropy, and standard time and frequency domain measures. Neither HRV nor cardiac NE spillover was significantly different between the analyzed groups. None of the standard HRV metrics was significantly correlated with cardiac NE spillover, but there was a moderate correlation between two complexity measures of HRV (symbolic dynamics) and cardiac NE spillover (patterns with 2 like variations, r = –0.37 and P = 0.05; and patterns with no variations: r = 0.34 and P = 0.06). In conclusion, there is no correlation between standard HRV measures and cardiac NE spillover in humans. Short-term complexity of heart rate is only moderately affected by sympathetic neural outflow. Therefore, the predictive value of most HRV measures for sudden cardiac death may predominantly result from their capacity to capture vagally mediated heart rate modulations.

complexity; sympathetic