Baroreflex Sensitivity in Relation to Clinical Characteristics in Subject Aged 40 to 80 Years Louise Brinth 1,2* , Kirsten Pors 1 , Tabassam Latif 1 , Andreas Kjær 3 and Jesper Mehlsen 1,2 1 Coordinating Research Centre, Frederiksberg Hospital, Frederiksberg, Denmark 2 Department of Clinical Physiology and Nuclear Medicine, Frederiksberg Hospital, Frederiksberg, Denmark 3 Department of Clinical Physiology, Nuclear Medicine & PET and Cluster for Molecular Imaging, Rigshospitalet and University of Copenhagen, Copenhagen, Denmark * Corresponding author: Louise Brinth, Coordinating Research Centre, Frederiksberg Hospital, Frederiksberg, Denmark, Tel: 4538164770; E-mail: Louisebrinth@live.dk Rec date: April 25, 2014, Acc date: May 27, 2014, Pub date: June 07, 2014 Copyright: © 2014 Brinth L, et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Abstract Baroreflex function measured as baroreflex sensitivity (BRS) mirrors an integrated capacity of the autonomic nervous system. We aimed to assess the relationship between measures of BRS and age and relevant clinical characteristics. 80 subjects participating in the Copenhagen City Heart study (43 women) with a mean age of 59 ± 11 years (range 41-79 years) were included. Baroreceptor activity was quantified through the Valsalva manoeuvre (VM) and as a spontaneous function. BRS was tested against age, gender, smoking status, body size and predicted risk of coronary heart disease based on the Framingham score. BRS was found to decline with age, but this change disappeared when correcting for the age related increase in systolic blood pressure. We found that the VM-derived indices of sympathetic vascular control declined with age as did the vagally controlled heart rate changes in response to deep breathing and VM. We could not demonstrate any correlation between BRS, smoking status, and body size when adjusting for age and gender, whereas spontaneous BRS was reduced with increasing Framingham risk score. Principal component analysis revealed three component explaining 69% of the total variance in our population comprising one component reflecting the sympathetic activity, the parasympathetic system, and the integrated spontaneous BRS, respectively. The parasympathetic component was the only one correlating with clinical characteristics of declining age, smoking habits, systolic blood pressure and Framingham score. It is concluded that the parasympathetic and sympathetic parts of the baroreflex arch behave differently with respect to aging and cardiovascular risk factors. The most prominent changes are seen in cardiovagal control whereas the effects of age related changes in sympathetic vascular control are less noticeable. Our study supports the use of the cardiovagal part of the baroreflex arch as an indicator of cardiovascular risk. Keywords: Baroreflex sensitivity; Aging; Cardiovascular risk; Autonomic nervous system Introduction Baroreflex function measured as baroreflex sensitivity (BRS) mirrors an integrated capacity of the autonomic nervous system and is an established tool for the assessment of autonomic control of the cardiovascular system. Changes in blood pressure will lead to changes in the impulse frequency of the afferent nerves from the baroreceptors terminating in the nucleus of the solitary tract and central relaying of the signal leads to changes in the sympathetic and parasympathetic outflow. In the original study by Hering [1], it was demonstrated that stimulation of the nerves from the carotid sinus induced cardiac slowing and vasodilatation with the latter being independent on the bradycardia. This distinction between the effect on heart rate and the vascular system is reflected in the division of baroreflex sensitivity in a part that causes a change in the interbeat interval (cardiovagal BRS) and a part that changes sympathetic nerve activity or vascular tone (adrenergic BRS). Both cardiovagal and adrenergic BRS has been shown to be blunted with increasing age in a mutual independent manner [2]. Cardiovagal BRS may be quantified by the heart rate response to blood pressure changes induced by vasoactive drugs with minimal effect on the sinus node. Non-interventional alternatives are mainly represented by forced changes in cardiac filling by the Valsalva manoeuver, by direct changes in external carotid pressures through the neck chamber technique, or by analysis of spontaneous variations of blood pressure and RR interval. A linearly and invers association between cardiovagal BRS and age has been demonstrated in a number of studies [3,4] and decreased cardiovagal BRS has consistently been found in several age-related disease states such as ischemic heart disease, hypertension, heart failure, and diabetes [5-7]. Cardiovagal BRS has also been shown to be a strong, independent prognostic factor in patients with ischemic heart disease or congestive heart failure [8]. Lifestyle factors are known to influence cardiovascular health and cardiovagal BRS. Smoking increases sympathetic activity [9] and a number of studies have demonstrated that - compared to non-smokers - smokers have higher heart rates, diminished heart rate variability, Hypertension: Open Access Brinth et al., J Hypertens 2014, 3:3 http://dx.doi.org/10.4172/2167-1095.1000152 Research Article Open Access J Hypertens ISSN:2167-1095 JHOA an open access journal Volume 3 • Issue 3 • 1000152