Assessment of cardiac vagal activity in patients with hyperthyroidism

Pitzalis, Maria Vittoria; Mastropasqua, Filippo; Massari, Francesco; Ciampolillo, Anna; Passantino, Andrea; Ognissanti, Matteo; Mannarini, Antonella; Zanna, Del; Giorgino, R; Rizzon, Paolo

doi:10.1016/s0167-5273(98)00024-2

Cited by 14 publications

(23 citation statements)

References 29 publications

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“…However, evaluating the autonomic profile, we observed a significant increase of total variability in Euthyr compared to Hyperthyr both during wake and sleep, with no changes in terms of sympathetic and parasympathetic components, as shown by the LF and HF components. Interestingly, although some papers reported an altered autonomic cardiovascular modulation in hyperthyroidism [1][2][3], no HRV data during sleep in Hyperthyr have been reported. Therefore, our data seem to suggest that Hyperthyr condition is characterized by an altered autonomic cardiovascular control with respect to Euthyr, namely, a reduced total variability, that is considered an index of the ability of the ANS to react and respond to external and internal stressors stimuli [11,12], without affecting the sympathetic and parasympathetic regulation of sleep stages.…”

Section: Discussionmentioning

confidence: 97%

“…In Hyperthyr, an alteration of ANS regulation has been described: in fact, previous studies showed an increased sympathetic and a decreased parasympathetic modulation during Hyperthyr [1][2][3][4]. Interestingly, hyperthyroid subjects anecdotally reported reduced sleep quality.…”

Section: Discussionmentioning

confidence: 99%

“…It has been reported that Hyperthyr is associated with an alteration of cardiac autonomic nervous system (ANS) control, namely, a predominant sympathetic modulation associated with a reduced parasympathetic modulation [1][2][3][4]; however, conclusive results are still lacking.…”

Section: Introductionmentioning

confidence: 99%

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Autonomic Cardiovascular Control in Hyperthyroid Women during Sleep

Tobaldini

Pecis

Bulgheroni

et al. 2013

Journal of Hormones

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Hyperthyroidism is characterized by hyperadrenergic symptoms (i.e., tachycardia, anxiety, and increased metabolic state). Although hyperthyroid patients often complain about an impairment of sleep, no data are available on sleep characteristics and autonomic cardiovascular control during sleep in these patients. We aimed to assess sleep qualitative indices and autonomic cardiovascular regulation during sleep in hyperthyroidism (Hyperthyr) and after treatment. Six subjects with a first diagnosis of Graves' disease or hyperfunctioning nodule underwent a complete polysomnographic study (PSG) at the time of diagnosis and after the treatment, when they became euthyroid (Euthyr). ECG and respiratory signals were extracted and samples of consecutive 250-300 beats were analyzed using linear spectral and nonlinear entropy analysis of heart rate variability (HRV), during the different sleep stages. Heart rate was decreased and total power increased in Euthyr compared to Hyperthyr, both during wake and sleep; no changes of the sympathovagal balance were observed. Entropy analysis showed that regularity index was reduced in Euthyr compared to Hyperthyr, suggesting changes in the complexity of the cardiovascular control. Periodic leg movements (PLM) were reduced in Euthyr compared to Hyperthyr. In conclusion, hyperthyroidism seems to be associated with an increased sleep fragmentation, due to PLM and an altered cardiac autonomic control.

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Section: Discussionmentioning

confidence: 97%

Section: Discussionmentioning

confidence: 99%

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Autonomic Cardiovascular Control in Hyperthyroid Women during Sleep

Tobaldini

Pecis

Bulgheroni

et al. 2013

Journal of Hormones

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“…Spectral analysis studies showed that thyrotoxic patients have a reduced parasympathetic stimulation to the heart [27,28,29,30], and a delayed gastric emptying ascribed to decreased vagal influences to the gastric myoelectrical activity [27]. However, a study aimed to investigate the spectral components of heart rate variability in HF band during both spontaneous and controlled breathing failed to find an impaired cardiac vagal activity in hyperthyroidism [31]. Although a higher spontaneous respiratory rate has been observed in the hyperthyroid patients, no difference was observed in HF power expressed in normalized units [31].…”

Section: Discussionmentioning

confidence: 99%

“…However, a study aimed to investigate the spectral components of heart rate variability in HF band during both spontaneous and controlled breathing failed to find an impaired cardiac vagal activity in hyperthyroidism [31]. Although a higher spontaneous respiratory rate has been observed in the hyperthyroid patients, no difference was observed in HF power expressed in normalized units [31]. …”

Section: Discussionmentioning

confidence: 99%

Changes in Autonomic Modulation to the Heart and Intracellular Catecholamines

et al. 2006

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Background: The effects of thyroid deprivation on the autonomic modulation to the heart remain controversial. Methods: In this study in patients followed for thyroid carcinoma, we investigated (1) heart rate variability parameters and the baroreflex gain and (2) intracellular catecholamine levels in circulating lymphocytes during short-term hypothyroidism (phase 1) and after reinstitution of TSH-suppressive thyroid hormone replacement (phase 2). Results: The RR interval value (p < 0.01) and systolic blood pressure (p < 0.05) were higher in phase 1 than in phase 2. The low-frequency/high-frequency (LF/HF) ratio was significantly lower in the hypothyroid state (p < 0.05), with a higher HF component (p < 0.05). After adjusting for mean RR interval in the regression model, the difference between the power of RR interval oscillations calculated in the two states was greater for the LF band (p = 0.005) and it was borderline significant for the HF band (p = 0.052). The baroreflex gain α_LF index was similar in the two phases. The stimulus-induced cellular production of norepinephrine and epinephrine in peripheral blood mononuclear cells was significantly higher in phase 2. Conclusion: The neurally-mediated influences on the sinus node and the study of intracellular catecholamine production suggest a reduced sympathoexcitation in hypothyroidism compared with the treatment phase. The early increase in blood pressure observed after thyroid hormone withdrawal is not due to impaired sensitivity of the baroreflex arc.

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Reversible autonomic dysfunction in hyperthyroid patients affects gastric myoelectrical activity and emptying

Barczyński

Thor

2001

Clinical Autonomic Research

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The autonomic nervous system (ANS) function in hyperthyroidism has been so far investigated mainly from the cardiovascular point of view. The aim of this study is to show that the ANS dysfunction in hyperthyroidism is also expressed in gastric myoelectrical activity disturbances and gastric emptying disorders and to search for a correlation between the severity of clinical manifestation and free thyroid hormone levels and the degree of the ANS dysfunction. The analyzed group included 50 recently diagnosed patients with hyperthyroidism who were examined twice: before and after 3 months of thyrostatic treatment. Results were compared with those of a sex-, age- and BMI-matched control group of 50 healthy volunteers. The study included: heart rate variability analysis in time and frequency domain, at rest and during a deep-breathing test, surface electrogastrography in preprandial and postprandial periods measured simultaneously with the ultrasound assessment of gastric emptying time by Bolondi method. In patients with hyperthyroidism in comparison with the control group, the following significant differences were observed: a sharp reduction of the high-frequency component and a decrease of heart rate variability, a high incidence of dysrhythmia with dominant bradyarrhythmia, and a delay of gastric emptying. The degree of disorders related to the degree of clinical manifestation of hyperthyroidism's symptoms and free triiodothyronine serum concentration both. All the disorders were functional and disappeared in a stable euthyroidism. To conclude, the ANS dysfunction in hyperthyroidism results not only in withdrawal of vagal inhibitory effect on sinoatrial node, but in impaired mutual neuro-hormonal regulation (decrease of vagal influence) of gastric myoelectrical activity followed by delay of gastric emptying.

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Assessment of cardiac vagal activity in patients with hyperthyroidism

Cited by 14 publications

References 29 publications

Autonomic Cardiovascular Control in Hyperthyroid Women during Sleep

Autonomic Cardiovascular Control in Hyperthyroid Women during Sleep

Changes in Autonomic Modulation to the Heart and Intracellular Catecholamines

Reversible autonomic dysfunction in hyperthyroid patients affects gastric myoelectrical activity and emptying

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