Modulação Autonômica e Variabilidade de Frequência Cardíaca em Adultos e Idosos Mediante Eletrocardiografia Ambulatorial

• Autor(a) principal: Santos, Marcos Antonio Almeida
• Data de Publicação: 2014
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: Repositório Institucional da UFS
• Texto Completo: https://ri.ufs.br/handle/riufs/3577
• topic: Eletrocardiografia ambulatorial; Frequência cardíaca; Sistema nervoso autônomo; Saúde do idoso; Ambulatory electrocardiography; Heart rate; Autonomic nervous system; Health of the elderly; CNPQ::CIENCIAS DA SAUDE

Background: A major obstacle in the investigation of geriatric cardiovascular diseases lies in establishing normal ranges for the senescence. On account of this, there is much debate about the standards of normality for this population group. There have been few researches on the patterns of Mean Heart Rate (MHR), Heart Rate Variability (HRV) and autonomic regulation during the aging process. Objectives: To identify distribution patterns of the MHR and HRV in time domain employing 24-hour ambulatory Holter in adults and in the elderly considered active from a functional point of view and without evidence of cognitive impairment. The VFC was interpreted as global autonomic modulation (GAM) via SDNN, SDANN and SDNNIDX, as well as parasympathetic outflow (PF) via MSSD and pNN50. Methods: We assessed the impact of age, gender, body mass index (BMI) and three comorbidities: systemic arterial hypertension (SAH), dyslipidemia and non-insulin dependent diabetes (NIDD). It is a cross-sectional study, with prospectively and consecutively collected data, and an "all comers" enrollment. Results: A sample of 1743 subjects (aged 40-100 years) was divided into 5 age groups: 40-49; 50-59; 60-69; 70-79; ≥ 80 years. Regression analysis, generalized linear model and several analyses of variance were employed in the statistical evaluation. The MHR decreased with age (p<0.001), and females MHR was higher in all age groups (p<0.001). In spite of the statistical significance, it displayed a minor relevance after the coefficients and Cohen s d (0.31) were estimated. The BMI and the comorbidities did not present association with the MHR. Regarding HRV, there was a linear decrease in SDNN, SDANN and SDNNIDX with age (p<0,001), mostly in women (p<0,001), whereas rMSSD and pNN50 presented a U shaped curve, decreasing up to the sixth decade and then going upwards with further ageing. NIDD had association with lower values of all parameters of HRV (p<0,001). Dyslipidemia and SAH did not present statistical significance. BMI was associated with a lower GAM. Conclusion: the MHR decreased with ageing, and males tended to present a lower MHR in all age groups. The difference, however, was of slight magnitude. SAH, dyslipidemia and NIDD were not associated with the patterns of MHR. The HRV findings point to a general decrease in GAM with ageing. The PF decreased with age up to the 6th decade and then started to increase (U-shape pattern). Females presented a lesser GAM and a higher PF. There was association between NIDD and lower values of GAM as well as PF. Dyslipidemia and SAH had no association with the parameters of HRV. Since the GAM decreased linearly with age (contrary to the U-shaped pattern of PF), our findings suggest that it may be due to a balance in favor of the sympathetic outflow throughout the ageing process. In women, a higher MHR on a par with a lower GAM suggest a predominance of the sympathetic outflow in this gender.