RESUMO CONTEXTO E OBJETIVO: Função autonômica cardíaca prejudicada é consequência importante da apneia obstrutiva do sono (AOS). Este prejuízo deve-se principalmente a episódios de hipóxia intermitente após apneias. No entanto, o impacto da gravidade da apneia na função cardíaca autonômica permanece obscuro. O objetivo deste estudo foi avaliar a relação entre gravidade da apneia do sono com turbulência da frequência cardíaca (TFC) e variabilidade da frequência cardíaca (VFC) em pacientes com AOS. DESENHO E LOCAL: Estudo observacional transversal conduzido nos Departamentos de Cardiologia e Doenças Pulmonares, Afyon Kocatepe University, Turkey. MÉTODOS: 106 pacientes com AOS e 27 voluntários saudáveis foram recrutados. Com base nos valores do índice de apneia-hypopneia (IAH), a gravidade da apneia obstrutiva do sono foi classificada assim: AOS leve (IAH ≥ 5 e < 15), AOS moderada (IAH ≥ 15 e ≤ 30) e AOS grave (IAH > 30). Parâmetros da VFC e TFC foram avaliados por meio de gravações de eletrocardiograma digital Holter de 24 horas para todos os sujeitos. RESULTADOS: Os resultados da VFC e TFC foram significativamente menores nos pacientes com OSA, em comparação com indivíduos controle (P < 0,05). No entanto, não houve diferenças significativas em VFC e TFC, entre os três subgrupos de pacientes. Correlações surgiram entre IAH e o parâmetro do intervalo-NN, RMSSD, e entre dessaturação de oxigênio e declive da turbulência (respectivamente; r = -0,22, P = 0,037; e r = -0,28, P = 0,025). CONCLUSÃO: Os resultados da VFC e TFC deterioram em AOS. Parece haver relação entre a gravidade da apneia e tais parâmetros.

ABSTRACT CONTEXT AND OBJECTIVE: Impaired autonomic cardiac function is an important consequence of obstructive sleep apnea (OSA). This impairment is mainly due to intermittent hypoxia episodes following apneas. However, the impact of apnea severity on autonomic cardiac function remains unclear. The aim of this study was to evaluate the relationship between the severity of sleep apnea and heart rate turbulence (HRT) and heart rate variability (HRV) in OSA. DESIGN AND SETTING: Observational cross-sectional study conducted in the Departments of Cardiology and Pulmonary Diseases, Afyon Kocatepe University, Turkey. METHODS: 106 patients with OSA and 27 healthy volunteers were enrolled. Based on apnea hypopnea index (AHI) values, obstructive sleep apnea severity was classified as follows: mild OSA (AHI ≥ 5 and < 15), moderate OSA (AHI ≥ 15 and ≤ 30) and severe OSA (AHI > 30). HRV and HRT parameters were assessed via 24-hour digital Holter electrocardiogram recordings for all subjects. RESULTS: HRV and HRT results were significantly lower among OSA patients than among control subjects (P < 0.05). However, there were no significant differences in HRT and HRV between the three patient subgroups. Correlations did emerge between AHI and the NN-interval parameter RMSSD and between oxygen desaturation and turbulence slope (respectively: r = -0.22, P = 0.037; and r = -0.28, P = 0.025). CONCLUSION: HRT and HRV results deteriorate in OSA. Correlations between apnea severity and these parameters seem to be present.

OBJECTIVE: Fibromyalgia is characterized by diffuse musculoskeletal pain and discomfort. There are several reports regarding autonomic nervous system dysfunction in patients with fibromyalgia. Heart rate turbulence is expressed as ventriculophasic sinus arrhythmia and has been considered to reflect cardiac autonomic activity. Heart rate turbulence has been shown to be an independent and powerful predictor of sudden cardiac death in various cardiac abnormalities. The aim of this study is to determine whether heart rate turbulence is changed in female patients with fibromyalgia compared with healthy controls. METHODS: Thirty-seven female patients (mean age, 40±11 years) with fibromyalgia, and 35 age- and sex-matched healthy female control subjects (mean age, 42±9 years) were included. Twenty-four hours of ambulatory electrocardiography recordings were collected for all subjects, and turbulence onset and turbulence slope values were automatically calculated. RESULTS: The baseline clinical characteristics of the two groups were similar. There were no significant differences in turbulence onset and turbulence slope measures between patients and control subjects (turbulence onset: −1.648±1.568% vs. −1.582±1.436%, p ϝ 0.853; turbulence slope: 12.933±5.693 ms/RR vs. 13.639±2.505 ms/RR, p ϝ 0.508). Although body mass index was negatively correlated with turbulence slope (r ϝ −0.258, p ϝ 0.046), no significant correlation was found between body mass index and turbulence onset (r ϝ 0.228, p ϝ 0.054). CONCLUSION: To the best of our knowledge, this is the first study to evaluate heart rate turbulence in patients with fibromyalgia. It appears that heart rate turbulence parameters reflecting cardiac autonomic activity are not changed in female patients with fibromyalgia.