Determination of vagal baroreflex sensitivity in normal subjects

Abstract

Introduction The Valsalva maneuver (VM) is used widely to quantify the sensitivity of the vagal baroreflex loop (vagal baroreflex sensitivity, BRS_v), but most studies have focused on the heart rate (HR) response to blood pressure (BP) decrement (BRS_v↓), even though the subsequent response to an increment in BP following the VM (BRS_v↑) is important and different. Methods We evaluated recordings of HR and BP in 187 normal subjects during the VM and determined both BRS_v↑ determined by relating HR to the BP increase following phase III and BRS_v↓. Results BRS_v↑ was related inversely to age. In addition, BRS_v↓, age, and magnitude of phase IV were independent predictors of BRS_v↑ in a multivariate model, accounting for 47% of the variance of BRS_v↑. Discussion The results indicate that both BRS_v↑ and BRS_v↓ become blunted with increasing age and that these indices relate to each other.

Influence of age and gender on the phase and strength of the relation between heart period and systolic blood pressure spontaneous fluctuations

“…Briefly, we evaluated 110 apparently healthy humans (55 males and 55 females) aged from 21 and 70 yr. The overall range of age was divided into five decades: from 21 to 30 yr (21)(22)(23)(24)(25)(26)(27)(28)(29)(30), from 31 to 40 yr (31)(32)(33)(34)(35)(36)(37)(38)(39)(40), from 41 to 50 yr (41)(42)(43)(44)(45)(46)(47)(48)(49)(50), from 51 to 60 yr (51)(52)(53)(54)(55)(56)(57)(58)(59)(60), and from 61 to 70 yr (61-70). Twenty-two subjects (11 men and 11 women) fell in each decade.…”

“…This position is particularly evident in protocols assessing the effect of aging on cardiac baroreflex control. Indeed, while it is well-known that BRS progressively decreases with age (1,14,16,24,26,32,52), as a likely result of the progressive sympathetic activation and vagal withdrawal observed during senescence (1,6,12,14,18,24,34,47,51), the effects of age on K 2 HP-SAP and Ph HP-SAP are not explored from spontaneous HP and SAP variabilities. The sole data on BL modification with age are based on carotid baroreceptor stimulation via neck suction or pressure (17).…”

“…The sole data on BL modification with age are based on carotid baroreceptor stimulation via neck suction or pressure (17). Similarly, while the influence of gender on the decline of BRS with age has been evaluated (1,52), it is unclear whether K 2 HP-SAP and Ph HP-SAP might show differences in relation to gender. Since the sympathetic drive increases with age and sympathetic activation is known to affect BL (7,25,41) and the degree of the SAP-HP coupling (36,44), it can be hypothesized that Ph HP-SAP and K 2 HP-SAP could vary with age.…”

Maximal expiratory pressure and Valsalva manoeuvre do not produce similar cardiovascular responses in healthy men

“…In contrast, the MAG tended to increase PVR and HR to adjust CO and MAP during the VM. Nevertheless, PVR is the key to maintaining these variables because the increase in HR observed in the MAG was smaller than in the YG as a result of decreased cardiac vagal withdrawal response and/or baroreflex response caused by decreased vascular compliance (Laitinen et al 2004;Huang et al 2007;Wada et al 2014).…”

“…The cardiovascular responses to the VM are mediated by the autonomic nervous system and vary according to sympathetic and parasympathetic activation and/or inhibition, which makes this manoeuvre a useful tool to evaluate the function of this system (Freeman, 2006;Low et al 2013). This dynamic pattern of cardiovascular autonomic activity is determined by different stimuli, such as breathing, muscle contraction, stimulation of arterial baroreceptors (Huang et al 2007;Wada et al 2014), postural changes (Singer et al 2001;Minatel et al 2012) and ageing (Laitinen et al 2004;Huang et al 2007;Milic et al 2009;Takahashi et al 2012;Catai et al 2014).…”