Abstract
BackgroundThe assessment of baroreflex sensitivity (BRS) has emerged as prognostic tool in cardiology. Although available computer-assisted methods, measuring spontaneous fluctuations of heart rate and blood pressure in the time and frequency domain are easily applicable, they do not allow for quantification of BRS during cardiovascular adaption processes. This, however, seems an essential criterion for clinical application. We evaluated a novel algorithm based on trigonometric regression regarding its ability to map dynamic changes in BRS and autonomic tone during cardiovascular provocation in relation to gender and age.Methodology/Principal FindingsWe continuously recorded systemic arterial pressure, electrocardiogram and respiration in 23 young subjects (25±2 years) and 22 middle-aged subjects (56±4 years) during cardiovascular autonomic testing (metronomic breathing, Valsalva manoeuvre, head-up tilt). Baroreflex- and spectral analysis was performed using the algorithm of trigonometric regressive spectral analysis. There was an age-related decline in spontaneous BRS and high frequency oscillations of RR intervals. Changes in autonomic tone evoked by cardiovascular provocation were observed as shifts in the ratio of low to high frequency oscillations of RR intervals and blood pressure. Respiration at 0.1 Hz elicited an increase in BRS while head-up tilt and Valsalva manoeuvre resulted in a downregulation of BRS. The extent of autonomic adaption was in general more pronounced in young individuals and declined stronger with age in women than in men.Conclusions/SignificanceThe trigonometric regressive spectral analysis reliably maps age- and gender-related differences in baroreflex- and autonomic function and is able to describe adaption processes of baroreceptor circuit during cardiovascular stimulation. Hence, this novel algorithm may be a useful screening tool to detect abnormalities in cardiovascular adaption processes even when resting values appear to be normal.
Highlights
The arterial baroreflex is the primary mechanism involved in short-term cardiovascular control [1]
baroreflex sensitivity (BRS) and RR intervals (RRI) significantly increased during controlled breathing at 0.1 Hz but remained unchanged upon controlled breathing at 0.2 Hz except in the group of middle-aged subjects
The prolongation of RRI during controlled breathing at 0.1 Hz was stronger in the middle-aged group while the decrease in high frequency power of RRI was more pronounced in the young subjects
Summary
The arterial baroreflex is the primary mechanism involved in short-term cardiovascular control [1]. The sensitivity of the baroreflex (BRS) arch is a dynamic parameter of sigmoid nature which is modulated by various intrinsic factors such as breathing, chemoreceptor reflexes, central stimuli and vessel wall elasticity [2]. A pathological reduction of BRS has been associated with chronic blood pressure elevation [4] and with other cardiovascular risk factors such as age [5,6,7], obesity [8,9], arterial stiffness [10] and gender [6,11]. The assessment of baroreflex sensitivity (BRS) has emerged as prognostic tool in cardiology. Available computer-assisted methods, measuring spontaneous fluctuations of heart rate and blood pressure in the time and frequency domain are applicable, they do not allow for quantification of BRS during cardiovascular adaption processes. We evaluated a novel algorithm based on trigonometric regression regarding its ability to map dynamic changes in BRS and autonomic tone during cardiovascular provocation in relation to gender and age
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