Influence of Heart Rate, Age, and Gender on Heart Rate Variability in Adolescents and Young Adults.

Key autonomic functions are in continuous development during adolescence which can be assessed using the heart rate variability (HRV). However, the influence of different demographic and physiological factors on HRV indices has not been fully explored in adolescents. In this study we aimed to assess the effect of age, gender, and heart rate on HRV indices in two age groups of healthy adolescents (age ranges, 13-16 and 17-20 years) and two groups of healthy young adults (21-24 and 25-30 years). We addressed the issue using 5-min ECG recordings performed in the sitting position in 255 male and female participants. Time, frequency, and informational domains of HRV were calculated. Changes in HRV indices were assessed using a multiple linear regression model to adjust for the effects of heart rate, age, and gender. We found that heart rate produced more significant effects on HRV indices than age or gender. There was a progressive reduction in HRV with increasing age. Sympathetic influence increased with age and parasympathetic influence progressively decreased with age. The influence of gender was manifest only in younger adolescents and young adults. In conclusion, age, gender, and particularly heart rate have a substantial influence on HRV indices, which ought to be considered to avoid biases in the study of the autonomic nervous system development. The lack of the gender-related effects on HRV indices in late adolescence could be related to non-completely achieved maturity of the autonomic mechanisms, which deserves further exploration.

Very High Frequency Oscillations of Heart Rate Variability in Healthy Humans and in Patients with Cardiovascular Autonomic Neuropathy.

Literature reports on the very high frequency (VHF) range of 0.4-0.9 Hz in heart rate variability (HRV) are scanty. The VHF presence in cardiac transplant patients and other conditions associated with reduced vagal influence on the heart encouraged us to explore this spectral band in healthy subjects and in patients diagnosed with cardiac autonomic neuropathy (CAN), and to assess the potential clinical value of some VHF indices. The study included 80 healthy controls and 48 patients with spinocerebellar ataxia type 2 (SCA2) with CAN. The electrocardiographic recordings of short 5-min duration were submitted to three different spectral analysis methods, including the most generally accepted procedure, and the two novel methods using the Hilbert-Huang transform. We demonstrated the presence of VHF activity in both groups of subjects. However, VHF power spectral density, expressed in relative normalized units, was significantly greater in the SCA2 patients than that in healthy subjects, amounting to 36.1 ± 17.4% vs. 22.9 ± 14.1%, respectively, as also was the instantaneous VHF spectral frequency, 0.58 ± 0.05 vs. 0.64 ± 0.07 Hz, respectively. These findings were related to the severity of CAN. We conclude that VHF activity of HRV is integral to the cardiovascular autonomic control.

Permutation entropy analysis of heart rate variability for the assessment of cardiovascular autonomic neuropathy in type 1 diabetes mellitus.

Heart rate variability (HRV) analysis is a relevant tool for the diagnosis of cardiovascular autonomic neuropathy (CAN). To our knowledge, no previous investigation on CAN has assessed the complexity of HRV from an ordinal perspective. Therefore, the aim of this work is to explore the potential of permutation entropy (PE) analysis of HRV complexity for the assessment of CAN. For this purpose, we performed a short-term PE analysis of HRV in healthy subjects and type 1 diabetes mellitus patients, including patients with CAN. Standard HRV indicators were also calculated in the control group. A discriminant analysis was used to select the variables combination with best discriminative power between control and CAN patients groups, as well as for classifying cases. We found that for some specific temporal scales, PE indicators were significantly lower in CAN patients than those calculated for controls. In such cases, there were ordinal patterns with high probabilities of occurrence, while others were hardly found. We posit this behavior occurs due to a decrease of HRV complexity in the diseased system. Discriminant functions based on PE measures or probabilities of occurrence of ordinal patterns provided an average of 75% and 96% classification accuracy. Correlations of PE and HRV measures showed to depend only on temporal scale, regardless of pattern length. PE analysis at some specific temporal scales, seem to provide additional information to that obtained with traditional HRV methods. We concluded that PE analysis of HRV is a promising method for the assessment of CAN.

Efecto de la edad sobre la variabilidad de la frecuencia cardíaca en individuos sanos / Effect of age on heart rate variability in healthy people

Introducción: La Variabilidad de la Frecuencia Cardíaca (VFC) constituye un instrumento de cuantificación de la actividad autónoma ante diferentes situaciones patofisiológicas. Objetivos: Caracterizar el efecto de la edad sobre el control autónomo del corazón y dilucidar las posibles bondades de índices poco explotados en este campo. Métodos: El estudio se efectuó en una población de sujetos sanos de 17 a 44 años. Resultados: Se obtuvo un decremento de la variabilidad en ambos sexos con el avance de la edad, empleando índices derivados del Gráfico de Poincaré. Conclusiones: La reducción de la VFC se debe a la degeneración del sistema neurovegetativo y los métodos de análisis empleados resultaron ser menos variables que los utilizados comúnmente por otros autores.

Introduction: the heart rate variability is an instrument of quantification of the autonomous activity before different pathophysiological situations. Objectives: To characterize the effect of age on the autonomous control of the heart and elucidate the possible kindnesses of little exploited indexes in this field. Methods: the study was conducted in a population of sound subjects aged 17-44. Results: It was obtained a decrease of variability in both sexes with age, using indexes derived from Poincaré's Graphic. Conclusions: The reduction of the heart rate variability is due to the generation of the neurovegetative system and the methods of analysis used proved to be less variable than those commonly used by other authors.

Efecto de la edad sobre la variabilidad de la frecuencia cardíaca en individuos sanos / Effect of age on heart rate variability in healthy people

Introducción: La Variabilidad de la Frecuencia Cardíaca (VFC) constituye un instrumento de cuantificación de la actividad autónoma ante diferentes situaciones patofisiológicas. Objetivos: Caracterizar el efecto de la edad sobre el control autónomo del corazón y dilucidar las posibles bondades de índices poco explotados en este campo. Métodos: El estudio se efectuó en una población de sujetos sanos de 17 a 44 años. Resultados: Se obtuvo un decremento de la variabilidad en ambos sexos con el avance de la edad, empleando índices derivados del Gráfico de Poincaré. Conclusiones: La reducción de la VFC se debe a la degeneración del sistema neurovegetativo y los métodos de análisis empleados resultaron ser menos variables que los utilizados comúnmente por otros autores(AU)

Introduction: the heart rate variability is an instrument of quantification of the autonomous activity before different pathophysiological situations. Objectives: To characterize the effect of age on the autonomous control of the heart and elucidate the possible kindnesses of little exploited indexes in this field. Methods: the study was conducted in a population of sound subjects aged 17-44. Results: It was obtained a decrease of variability in both sexes with age, using indexes derived from Poincaré's Graphic. Conclusions: The reduction of the heart rate variability is due to the generation of the neurovegetative system and the methods of analysis used proved to be less variable than those commonly used by other authors(AU)