Aging reduces complexity of heart rate variability assessed by conditional entropy and symbolic analysis

Abstract

Increasing age is associated with a reduction in overall heart rate variability as well as changes in complexity of physiologic dynamics. The aim of this study was to verify if the alterations in autonomic modulation of heart rate caused by the aging process could be detected by Shannon entropy (SE), conditional entropy (CE) and symbolic analysis (SA). Complexity analysis was carried out in 44 healthy subjects divided into two groups: old (n = 23, 63 ± 3 years) and young group (n = 21, 23 ± 2). It was analyzed SE, CE [complexity index (CI) and normalized CI (NCI)] and SA (0V, 1V, 2LV and 2ULV patterns) during short heart period series (200 cardiac beats) derived from ECG recordings during 15 min of rest in a supine position. The sequences characterized by three heart periods with no significant variations (0V), and that with two significant unlike variations (2ULV) reflect changes in sympathetic and vagal modulation, respectively. The unpaired t test (or Mann-Whitney rank sum test when appropriate) was used in the statistical analysis. In the aging process, the distributions of patterns (SE) remain similar to young subjects. However, the regularity is significantly different; the patterns are more repetitive in the old group (a decrease of CI and NCI). The amounts of pattern types are different: 0V is increased and 2LV and 2ULV are reduced in the old group. These differences indicate marked change of autonomic regulation. The CE and SA are feasible techniques to detect alteration in autonomic control of heart rate in the old group.

Effect of the Postural Challenge on the Dependence of the Cardiovascular Control Complexity on Age

“…These findings suggest that the magnitude of the HP changes became smaller and HP dynamics turned out to be more regular and predictable as a function of age. These results are in agreement with previous studies regardless of whether they are based on entropy rates [14,15,17,18,22,23,28,34] or on different metrics [2,13,15,16,19,22,23,29,34].…”

“…These changes are mirrored by a reduction in heart period (HP) variability [2][3][4][5][6][7][8][9], by an increase of systolic blood pressure (SAP) variability [10][11][12], and by a reduction in complexity of physiological dynamics [2][3][4][13][14][15][16][17][18][19][20][21][22][23]. Although the abovementioned studies indicate that aging reduces the complexity of the cardiovascular control and prove the gender dependence, it is still unclear whether the complexity reduction and the gender relation are similarly observable from HP and SAP variabilities and if it persists during a cardiovascular control challenge.…”

“…Although the abovementioned studies indicate that aging reduces the complexity of the cardiovascular control and prove the gender dependence, it is still unclear whether the complexity reduction and the gender relation are similarly observable from HP and SAP variabilities and if it persists during a cardiovascular control challenge. Indeed, protocols assessing the effect of aging on the complexity of the cardiovascular control are mainly limited to the evaluation of the complexity of the HP variability [13][14][15][19][20][21][22][23] and mostly do not deliberately challenge the cardiovascular control according to an experimental maneuver or pharmacological intervention [13][14][15][16][17][18][19]22,23]. In addition, those studies challenging autonomic nervous system regulation have a limited power because age ranges are inadequate [20] or they are mainly based on biased indexes of complexity such as approximate entropy [21].…”

Reprodutibilidade do teste de caminhada de 6 minutos e marcadores autonômicos cardíacos em idosas ativas e sedentárias

“…All these standards are grouped according to the number and type of variations 23 . Studies with pharmacological blockers and autonomic tests have shown that the index with no variation (0V) and two unlike variations (2ULV) indicate sympathetic and parasympathetic modulation, respectively 24 . Unstable segments were avoided, since data stability is a prerequisite for symbolic analyses 25 .…”

Differences of Heart Rate Variability during Sevoflurane Anesthesia in Children by Age

“…HRV changes with aging, [4] anesthesia [5][6][7] and exercise [8,9]. Indices of various nonlinear dynamic analyses such as approximate entropy (ApEn) or Hurst exponent (H) for HRV are useful for diagnosis or predictors of prognosis in some clinical situations [10][11][12][13].…”