Assessment of baroreflex sensitivity by the closed-loop blood pressure to interbeat interval transfer function

2002 ◽  
Author(s):  
H. VanDeVooren ◽  
C.A. Swenne ◽  
B.J. TenVoorde ◽  
E.E. VanDerWall
Keyword(s):  
Blood Pressure ◽  
Transfer Function ◽  
Baroreflex Sensitivity ◽  
Closed Loop ◽  
Interbeat Interval

Fundamental relationships between arterial baroreflex sensitivity and dynamic cerebral autoregulation in humans

2010 ◽  
Vol 108 (5) ◽  
pp. 1162-1168 ◽  
Author(s):  
Yu-Chieh Tzeng ◽  
Samuel J. E. Lucas ◽  
Greg Atkinson ◽  
Chris K. Willie ◽  
Philip N. Ainslie
Keyword(s):  
Blood Pressure ◽  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Transfer Function ◽  
Blood Flow Velocity ◽  
Cerebral Autoregulation ◽  
Baroreflex Sensitivity ◽  
Cerebral Blood Flow Velocity ◽  
Arterial Baroreflex ◽  
Dynamic Cerebral Autoregulation

The functional relationship between dynamic cerebral autoregulation (CA) and arterial baroreflex sensitivity (BRS) in humans is unknown. Given that adequate cerebral perfusion during normal physiological challenges requires the integrated control of CA and the arterial baroreflex, we hypothesized that between-individual variability in dynamic CA would be related to BRS in humans. We measured R-R interval, blood pressure, and cerebral blood flow velocity (transcranial Doppler) in 19 volunteers. BRS was estimated with the modified Oxford method (nitroprusside-phenylephrine injections) and spontaneous low-frequency (0.04–0.15) α-index. Dynamic CA was quantified using the rate of regulation (RoR) and autoregulatory index (ARI) derived from the thigh-cuff release technique and transfer function analysis of spontaneous oscillations in blood pressure and mean cerebral blood flow velocity. Results show that RoR and ARI were inversely related to nitroprusside BRS [ R = −0.72, confidence interval (CI) −0.89 to −0.40, P = 0.0005 vs. RoR; R = −0.69, CI −0.88 to −0.35, P = 0.001 vs. ARI], phenylephrine BRS ( R = −0.66, CI −0.86 to −0.29, P = 0.0002 vs. RoR; R = −0.71, CI −0.89 to −0.38, P = 0.0001 vs. ARI), and α-index ( R = −0.70, CI −0.89 to −0.40, P = 0.0008 vs. RoR; R = −0.62, CI −0.84 to −0.24, P = 0.005 vs. ARI). Transfer function gain was positively related to nitroprusside BRS ( R = 0.62, CI 0.24–0.84, P = 0.0042), phenylephrine BRS ( R = 0.52, CI 0.10–0.79, P = 0.021), and α-index ( R = 0.69, CI 0.35–0.88, P = 0.001). These findings indicate that individuals with an attenuated dynamic CA have greater BRS (and vice versa), suggesting the presence of possible compensatory interactions between blood pressure and mechanisms of cerebral blood flow control in humans. Such compensatory adjustments may account for the divergent changes in dynamic CA and BRS seen, for example, in chronic hypotension and spontaneous hypertension.

Enhanced open-loop but not closed-loop cardiac baroreflex sensitivity during orthostatic stress in humans

2011 ◽  
Vol 301 (5) ◽  
pp. R1591-R1598 ◽  
Author(s):  
Toshinari Akimoto ◽  
Jun Sugawara ◽  
Daisuke Ichikawa ◽  
Nobuyuki Terada ◽  
Paul J. Fadel ◽  
...  
Keyword(s):  
Heart Rate ◽  
Transfer Function ◽  
White Noise ◽  
Baroreflex Sensitivity ◽  
Closed Loop ◽  
Low Frequency ◽  
Open Loop ◽  
Orthostatic Stress ◽  
Arterial Baroreflex ◽  
Transfer Function Gain

The neural interaction between the cardiopulmonary and arterial baroreflex may be critical for the regulation of blood pressure during orthostatic stress. However, studies have reported conflicting results: some indicate increases and others decreases in cardiac baroreflex sensitivity (i.e., gain) with cardiopulmonary unloading. Thus the effect of orthostatic stress-induced central hypovolemia on regulation of heart rate via the arterial baroreflex remains unclear. We sought to comprehensively assess baroreflex function during orthostatic stress by identifying and comparing open- and closed-loop dynamic cardiac baroreflex gains at supine rest and during 60° head-up tilt (HUT) in 10 healthy men. Closed-loop dynamic “spontaneous” cardiac baroreflex sensitivities were calculated by the sequence technique and transfer function and compared with two open-loop carotid-cardiac baroreflex measures using the neck chamber system: 1) a binary white-noise method and 2) a rapid-pulse neck pressure-neck suction technique. The gain from the sequence technique was decreased from −1.19 ± 0.14 beats·min−1·mmHg−1 at rest to −0.78 ± 0.10 beats·min−1·mmHg−1 during HUT ( P = 0.005). Similarly, closed-loop low-frequency baroreflex transfer function gain was reduced during HUT ( P = 0.033). In contrast, open-loop low-frequency transfer function gain between estimated carotid sinus pressure and heart rate during white-noise stimulation was augmented during HUT ( P = 0.01). This result was consistent with the maximal gain of the carotid-cardiac baroreflex stimulus-response curve (from 0.47 ± 0.15 beats·min−1·mmHg−1 at rest to 0.60 ± 0.20 beats·min−1·mmHg−1 at HUT, P = 0.037). These findings suggest that open-loop cardiac baroreflex gain was enhanced during HUT. Moreover, under closed-loop conditions, spontaneous baroreflex analyses without external stimulation may not represent open-loop cardiac baroreflex characteristics during orthostatic stress.

scholarly journals Development of Causal Interactions Between Systolic Blood Pressure and Inter-Beat Intervals in Adolescents

2015 ◽  
pp. 821-829 ◽  
Author(s):  
J. SVAČINOVÁ ◽  
M. JAVORKA ◽  
Z. NOVÁKOVÁ ◽  
E. ZÁVODNÁ ◽  
B. CZIPPELOVÁ ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Systolic Blood Pressure ◽  
Healthy Subjects ◽  
Baroreflex Sensitivity ◽  
Closed Loop ◽  
Loop Model ◽  
Bivariate Model ◽  
Causal Pathways ◽  
Linear Approach ◽  
Age Related

Systolic blood pressure (SBP) changes control the cardiac inter-beat intervals (IBI) duration via baroreflex. Conversely, SBP is influenced by IBI via non-baroreflex mechanisms. Both causal pathways (feedback – baroreflex and feedforward – non-baroreflex) form a closed loop of the SBP – IBI interaction. The aim of this study was to assess the age-related changes in the IBI – SBP interaction. We have non-invasively recorded resting beat-to-beat SBP and IBI in 335 healthy subjects of different age, ranging from 11 to 23 years. Using a linear autoregressive bivariate model we obtained gain (GainSBP,IBI, used traditionally as baroreflex sensitivity) and coherence (CohSBP,IBI) of the SBP–IBI interaction and causal gain and coherence in baroreflex (GainSBPIBI, CohSBPIBI) and coherence in non-baroreflex (CohIBISBP) directions separately. A non-linear approach was used for causal coupling indices evaluation (CSBPIBI, CIBISBP) quantifying the amount of information transferred between signals. We performed a correlation to age analysis of all measures. CohIBISBP and CIBISBP were higher than CohSBPIBI and CSBPIBI, respectively. GainSBP,IBI increased and CohSBPIBI decreased with age. The coupling indices did not correlate with age. We conclude that the feedforward influence dominated at rest. The increase of GainSBP,IBI with age was not found in the closed loop model. A decrease of CohSBPIBI could be related to a change in the cardiovascular control system complexity during maturation.

Exercise and pyridostigmine prevents gastric emptying delay and increase blood pressure and cisplatin-induced baroreflex sensitivity in rats

Life Sciences ◽  
2021 ◽  
Vol 267 ◽  
pp. 118972
Author(s):  
Mariana Sousa Silva ◽  
Yasmim de Andrade Gomes ◽  
Mickael Laudrup de Sousa Cavalcante ◽  
Pedro Victor Nogueira Telles ◽  
Alda Cássia Alves da Silva ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Gastric Emptying ◽  
Baroreflex Sensitivity ◽  
Increase Blood Pressure

Heart rate and blood pressure variability and baroreflex sensitivity in patients with acute brain injury

2005 ◽  
Vol 20 (4) ◽  
pp. 394 ◽  
Author(s):  
V. Papaioannou ◽  
M. Giannakou ◽  
N. Maglaveras ◽  
E. Sofianos ◽  
M. Giala
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Brain Injury ◽  
Blood Pressure Variability ◽  
Baroreflex Sensitivity ◽  
Acute Brain Injury

Closed loop blood pressure control for cerebral perfusion studies

1991 ◽  
Vol 12 (2) ◽  
pp. 171-176 ◽  
Author(s):  
I R Chambers ◽  
R D Strachan ◽  
P J Kane ◽  
A Clark ◽  
A D Mendelow
Keyword(s):  
Blood Pressure ◽  
Blood Pressure Control ◽  
Cerebral Perfusion ◽  
Closed Loop ◽  
Pressure Control ◽  
Perfusion Studies

scholarly journals Blood pressure reduction after gastric bypass surgery is explained by a decrease in cardiac output

2017 ◽  
Vol 122 (2) ◽  
pp. 223-229 ◽  
Author(s):  
Peter M. van Brussel ◽  
Bas van den Bogaard ◽  
Barbara A. de Weijer ◽  
Jasper Truijen ◽  
C.T. Paul Krediet ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Gastric Bypass ◽  
Body Weight ◽  
Cardiac Output ◽  
Baroreflex Sensitivity ◽  
Bypass Surgery ◽  
Gastric Bypass Surgery ◽  
Left Ventricular ◽  
Ventricular Contractility ◽  
Left Ventricular Contractility

Blood pressure (BP) decreases in the first weeks after Roux-and-Y gastric bypass surgery. Yet the pathophysiology of the BP-lowering effects observed after gastric bypass surgery is incompletely understood. We evaluated BP, systemic hemodynamics, and baroreflex sensitivity in 15 obese women[mean age 42 ± 7 standard deviation (SD) yr, body mass index 45 ± 6 kg/m2] 2 wk before and 6 wk following Roux-and-Y gastric bypass surgery. Six weeks after gastric bypass surgery, mean body weight decreased by 13 ± 5 kg (10%, P < 0.001). Office BP decreased from 137 ± 10/86 ± 6 to 128 ± 12/81 ± 9 mmHg ( P < 0.001, P < 0.01), while daytime ambulatory BP decreased from 128 ± 14/80 ± 9 to 114 ± 10/73 ± 6 mmHg ( P = 0.01, P = 0.05), whereas nighttime BP decreased from 111 ± 13/66 ± 7 to 102 ± 9/62 ± 7 mmHg ( P = 0.04, P < 0.01). The decrease in BP was associated with a 1.6 ± 1.2 l/min (20%, P < 0.01) decrease in cardiac output (CO), while systemic vascular resistance increased (153 ± 189 dyn·s·cm−5, 15%, P < 0.01). The maximal ascending slope in systolic blood pressure decreased (192 mmHg/s, 19%, P = 0.01), suggesting a reduction in left ventricular contractility. Baroreflex sensitivity increased from 9.0 [6.4–14.3] to 13.8 [8.5–19.0] ms/mmHg (median [interquartile range]; P < 0.01) and was inversely correlated with the reductions in heart rate ( R = −0.64, P = 0.02) and CO ( R = −0.61, P = 0.03). In contrast, changes in body weight were not correlated with changes in either BP or CO. The BP reduction following Roux-and-Y gastric bypass surgery is correlated with a decrease in CO independent of changes in body weight. The contribution of heart rate to the reduction in CO together with enhanced baroreflex sensitivity suggests a shift toward increased parasympathetic cardiovascular control. NEW & NOTEWORTHY The reason for the decrease in blood pressure (BP) in the first weeks after gastric bypass surgery remains to be elucidated. We show that the reduction in BP following surgery is caused by a decrease in cardiac output. In addition, the maximal ascending slope in systolic blood pressure decreased suggesting a reduction in left ventricular contractility and cardiac workload. These findings help to understand the physiological changes following gastric bypass surgery and are relevant in light of the increased risk of heart failure in these patients.

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