Hyperthyroidism is a pathological condition characterized by an altered autonomic cardiovascular control, resulting in an increase of the sympathetic and a decrease of the parasympathetic modulation of heart rate variability. Recently, the entropy-based indices derived from short-term heart period variability have been proved to be helpful in evaluating the autonomic cardiovascular modulation. The aim of our study was to evaluate the autonomic cardiovascular modulation of hyperthyroid subjects at rest and during standing using spectral parameters and corrected conditional entropy indices derived from short-term heart period variability in 12 hyperthyroid (HYPTH) and 9 normal healthy (N) females. Mean heart period was significantly decreased by standing both in N and HYPTH and the LF power expressed in normalized units was increased. The respiratory rate was faster in the HYPTH group compared to N and complexity was significantly greater in HYPTH compared to N during standing. Results suggested an enhanced complexity of cardiovascular control in HYPTH, more evident in a condition of sympathetic activation. The increased complexity of the cardiovascular regulation is probably not completely due to autonomic control but also to other influences, such as metabolic effects of thyroid hormones impinging upon respiratory control mechanisms and, therefore, on cardiorespiratory coupling.

Increased complexity of short-term heart rate variability in hyperthyroid patients during orthostatic challenge / E. Tobaldini, A. Porta, M. Bulgheroni, M. Pecis, M. Muratori, M. Bevilacqua, N. Montano - In: Engineering in Medicine and Biology Society, 2008. EMBS 2008. 30th Annual International Conference of the IEEE[s.l] : IEEE Service Center, 2008. - ISBN 978-1-4244-1814-5. - pp. 1988-1991 (( Intervento presentato al 30. convegno IEEE EMBS : Annual International Conference tenutosi a Vancouver nel 2008 [10.1109/IEMBS.2008.4649579].

Increased complexity of short-term heart rate variability in hyperthyroid patients during orthostatic challenge

E. Tobaldini
Primo
;
A. Porta
Secondo
;
M. Bulgheroni;N. Montano
Ultimo
2008

Abstract

Hyperthyroidism is a pathological condition characterized by an altered autonomic cardiovascular control, resulting in an increase of the sympathetic and a decrease of the parasympathetic modulation of heart rate variability. Recently, the entropy-based indices derived from short-term heart period variability have been proved to be helpful in evaluating the autonomic cardiovascular modulation. The aim of our study was to evaluate the autonomic cardiovascular modulation of hyperthyroid subjects at rest and during standing using spectral parameters and corrected conditional entropy indices derived from short-term heart period variability in 12 hyperthyroid (HYPTH) and 9 normal healthy (N) females. Mean heart period was significantly decreased by standing both in N and HYPTH and the LF power expressed in normalized units was increased. The respiratory rate was faster in the HYPTH group compared to N and complexity was significantly greater in HYPTH compared to N during standing. Results suggested an enhanced complexity of cardiovascular control in HYPTH, more evident in a condition of sympathetic activation. The increased complexity of the cardiovascular regulation is probably not completely due to autonomic control but also to other influences, such as metabolic effects of thyroid hormones impinging upon respiratory control mechanisms and, therefore, on cardiorespiratory coupling.
Settore MED/09 - Medicina Interna
Settore ING-INF/06 - Bioingegneria Elettronica e Informatica
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/2434/217434
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