Applicability of recent methods used to estimate spontaneous baroreflex sensitivity to resting mice

2008 ◽  
Vol 294 (1) ◽  
pp. R142-R150 ◽  
Author(s):  
Dominique Laude ◽  
Véronique Baudrie ◽  
Jean-Luc Elghozi
Keyword(s):  
Baroreflex Sensitivity ◽  
Low Frequency ◽  
Pulse Interval ◽  
Arterial Baroreflex ◽  
Baroreflex Control ◽  
Spectral Estimates ◽  
Sequence Method ◽  
Highly Correlated ◽  
Spontaneous Baroreflex ◽  
Sequence Techniques

Short-term blood pressure (BP) variability is limited by the arterial baroreflex. Methods for measuring the spontaneous baroreflex sensitivity (BRS) aim to quantify the gain of the transfer function between BP and pulse interval (PI) or the slope of the linear relationship between parallel BP and PI changes. These frequency-domain (spectral) and time-domain (sequence) techniques were tested in conscious mice equipped with telemetric devices. The autonomic relevance of these indexes was evaluated using pharmacological blockades. The significant changes of the spectral bandwidths resulting from the autonomic blockades were used to identify the low-frequency (LF) and high-frequency (HF) zones of interest. The LF gain was 1.45 ± 0.14 ms/mmHg, with a PI delay of 0.5 s. For the HF gain, the average values were 2.0 ± 0.19 ms/mmHg, with a null phase. LF and HF bands were markedly affected by atropine. On the same 51.2-s segments used for cross-spectral analysis, an average number of 26.4 ± 2.2 slopes were detected, and the average slope in resting mice was 4.4 ± 0.5 ms/mmHg. Atropine significantly reduced the slopes of the sequence method. BRS measurements obtained using the sequence technique were highly correlated to the spectral estimates. This study demonstrates the applicability of the recent methods used to estimate spontaneous BRS in mice. There was a vagal predominance in the baroreflex control of heart rate in conscious mice in the present conditions.

Hemodynamic and autonomic correlates of postexercise hypotension in patients with mild hypertension

2002 ◽  
Vol 282 (4) ◽  
pp. R1037-R1043 ◽  
Author(s):  
Jacopo M. Legramante ◽  
Alberto Galante ◽  
Michele Massaro ◽  
Antonio Attanasio ◽  
Gianfranco Raimondi ◽  
...  
Keyword(s):  
Baroreflex Sensitivity ◽  
Autonomic Function ◽  
Peripheral Resistance ◽  
Low Frequency ◽  
Arterial Baroreflex ◽  
Aged Patients ◽  
Before And After ◽  
Cardiac Component ◽  
Postexercise Hypotension ◽  
Spontaneous Baroreflex

We investigated the interplay of neural and hemodynamic mechanisms in postexercise hypotension (PEH) in hypertension. In 15 middle-aged patients with mild essential hypertension, we evaluated blood pressure (BP), cardiac output (CO), total peripheral resistance (TPR), forearm (FVR) and calf vascular resistance (CVR), and autonomic function [by spectral analysis of R-R interval and BP variabilities and spontaneous baroreflex sensitivity (BRS)] before and after maximal exercise. Systolic and diastolic BP, TPR, and CVR were significantly reduced from baseline 60–90 min after exercise. CO, FVR, and HR were unchanged. The low-frequency (LF) component of BP variability increased significantly after exercise, whereas the LF component of R-R interval variability was unchanged. The overall change in BRS was not significant after exercise vs. baseline, although a significant, albeit small, BRS increase occurred in response to hypotensive stimuli. These findings indicate that in hypertensive patients, PEH is mediated mainly by a peripheral vasodilation, which may involve metabolic factors linked to postexercise hyperemia in the active limbs. The vasodilator effect appears to override a concomitant, reflex sympathetic activation selectively directed to the vasculature, possibly aimed to counter excessive BP decreases. The cardiac component of arterial baroreflex is reset during PEH, although the baroreflex mechanisms controlling heart period appear to retain the potential for greater opposition to hypotensive stimuli.

Comparison of various techniques used to estimate spontaneous baroreflex sensitivity (the EuroBaVar study)

2004 ◽  
Vol 286 (1) ◽  
pp. R226-R231 ◽  
Author(s):  
Dominique Laude ◽  
Jean-Luc Elghozi ◽  
Arlette Girard ◽  
Elisabeth Bellard ◽  
Malika Bouhaddi ◽  
...  
Keyword(s):  
Spectral Analysis ◽  
Frequency Band ◽  
Baroreflex Sensitivity ◽  
Low Frequency ◽  
The Other ◽  
Data Sets ◽  
Noninvasive Blood Pressure ◽  
Sequence Method ◽  
Baroreflex Failure ◽  
Spontaneous Baroreflex

This study compared spontaneous baroreflex sensitivity (BRS) estimates obtained from an identical set of data by 11 European centers using different methods and procedures. Noninvasive blood pressure (BP) and ECG recordings were obtained in 21 subjects, including 2 subjects with established baroreflex failure. Twenty-one estimates of BRS were obtained by methods including the two main techniques of BRS estimates, i.e., the spectral analysis (11 procedures) and the sequence method (7 procedures) but also one trigonometric regressive spectral analysis method (TRS), one exogenous model with autoregressive input method (X-AR), and one Z method. With subjects in a supine position, BRS estimates obtained with calculations of α-coefficient or gain of the transfer function in both the low-frequency band or high-frequency band, TRS, and sequence methods gave strongly related results. Conversely, weighted gain, X-AR, and Z exhibited lower agreement with all the other techniques. In addition, the use of mean BP instead of systolic BP in the sequence method decreased the relationships with the other estimates. Some procedures were unable to provide results when BRS estimates were expected to be very low in data sets (in patients with established baroreflex failure). The failure to provide BRS values was due to setting of algorithmic parameters too strictly. The discrepancies between procedures show that the choice of parameters and data handling should be considered before BRS estimation. These data are available on the web site ( http://www.cbi.polimi.it/glossary/eurobavar.html ) to allow the comparison of new techniques with this set of results.

scholarly journals Artifacts in dependency structures of Portapres® signals

2019 ◽  
Vol 2 (1) ◽  
Author(s):  
Marko Mozetić ◽  
Tamara Škorić ◽  
Jelena Antelj ◽  
Katarina Otašević ◽  
Branislav Milovanović ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Baroreflex Sensitivity ◽  
Pulse Interval ◽  
Signal Acquisition ◽  
Non Invasive ◽  
Complex Procedure ◽  
Sequence Method ◽  
Copula Density ◽  
Spontaneous Baroreflex ◽  
Dependency Structures

Portapres® is a unique device that reliably accomplishes a challenging task of continuous and non-invasive recording ofblood pressure (BP) waveforms in moving subjects. The complex procedure of Portapres® signal acquisition includes periodic changesof cuffed fingers to avoid pain and stress, as well as the blood pressure correction due to the increasing and decreasing elevation of armposture. Due to these procedures, the recorded waveforms are corrupted. The aim of this paper is to analyze the influence of inevitableartifacts on parameters obtained from the blood pressure waveforms. The analyzed waveforms are obtained from healthy volunteers atBezanija Kosa Hospital, Belgrade. The parameters include systolic blood pressure (SBP) and pulse interval (PI) extracted byBeatscope® software. The interrelationship of SBP and PI signals forms a major cardiovascular feedback – baroreflex. It can beanalyzed using the sequence method for spontaneous baroreflex sensitivity, but the tools that reveal more profound dependencystructures include cross-approximate and cross-sample entropy, as well as the copula structures. The influence of artifacts, inevitable inPortapres® signals, is the main goal of this study. The analyses revealed that automatic artifact correction induced no significantchanges considering the statistical moments and the baroreflex sensitivity; the same applies to the copula density and rank tests. Theentropy analysis, however, turned out to be extremely sensitive so its implementation in Portapres® signal analysis is not recommended.

Change in spontaneous baroreflex control of pulse interval during heat stress in humans

2003 ◽  
Vol 95 (5) ◽  
pp. 1789-1798 ◽  
Author(s):  
Kichang Lee ◽  
Dwayne N. Jackson ◽  
Douglas L. Cordero ◽  
Takeshi Nishiyasu ◽  
Jochen K. Peters ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Heat Stress ◽  
Stroke Volume ◽  
Linear Relationship ◽  
Baroreflex Sensitivity ◽  
Pulse Interval ◽  
Baroreflex Control ◽  
Arterial Blood ◽  
Transfer Function Analysis ◽  
Spontaneous Baroreflex

Spontaneous baroreflex control of pulse interval (PI) was assessed in healthy volunteers under thermoneutral and heat stress conditions. Subjects rested in the supine position with their lower legs in a water bath at 34°C. Heat stress was imposed by increasing the bath temperature to 44°C. Arterial blood pressure (Finapres), PI (ECG), esophageal and skin temperature, and stroke volume were continuously collected during each 5-min experimental stage. Spontaneous baroreflex function was evaluated by multiple techniques, including 1) the mean slope of the linear relationship between PI and systolic blood pressure (SBP) with three or more simultaneous increasing or decreasing sequences, 2) the linear relationship between changes in PI and SBP (ΔPI/ΔSBP) derived by using the first differential equation, 3) the linear relationship between changes in PI and SBP with simultaneously increasing or decreasing sequences (+ΔPI/+ΔSBP or -ΔPI/-ΔSBP), and 4) transfer function analysis. Heat stress increased esophageal temperature by 0.6 ± 0.1°C, decreased PI from 1,007 ± 43 to 776 ± 37 ms and stroke volume by 16 ± 5 ml/beat. Heat stress reduced baroreflex sensitivity but increased the incidence of baroreflex slopes from 5.2 ± 0.8 to 8.6 ± 0.9 sequences per 100 heartbeats. Baroreflex sensitivity was significantly correlated with PI or vagal power ( r2 = 0.45, r2 = 0.71, respectively; P < 0.05). However, the attenuation in baroreflex sensitivity during heat stress appeared related to a shift in autonomic balance (shift in resting PI) rather than heat stress per se.

Baroreflex effectiveness index: an additional measure of baroreflex control of heart rate in daily life

2001 ◽  
Vol 280 (3) ◽  
pp. R744-R751 ◽  
Author(s):  
Marco Di Rienzo ◽  
Gianfranco Parati ◽  
Paolo Castiglioni ◽  
Roberto Tordi ◽  
Giuseppe Mancia ◽  
...  
Keyword(s):  
Baroreflex Sensitivity ◽  
Time Window ◽  
Sinus Node ◽  
Normal Subjects ◽  
Pulse Interval ◽  
Arterial Baroreflex ◽  
Additional Measure ◽  
Baroreflex Control ◽  
Healthy Humans ◽  
Effectiveness Index

In healthy subjects, progressive beat-to-beat increases or decreases in systolic blood pressure (SBP) ramps are not always accompanied by baroreflex-driven lengthening or shortening in pulse interval (PI) ramps, respectively. This phenomenon has been quantified by a new index, the baroreflex effectiveness index (BEI), defined as the ratio between the number of SBP ramps followed by the respective reflex PI ramps and the total number of SBP ramps observed in a given time window. Specificity of BEI was shown in eight cats by a −89% reduction of BEI after sinoaortic denervation. In 14 healthy humans, the 24-h average BEI value was 0.21, with a marked day-night modulation (≈0.25 day, ≈0.15 night) in counterphase with modulation of baroreflex sensitivity (BRS). Our analysis indicates that 1) in normal subjects, arterial baroreflex can induce beat-by-beat PI changes in response to only 21% of all SBP ramps, possibly because of central inhibitory influences or of interferences at sinus node level by nonbaroreflex mechanisms and 2) BEI provides information on the baroreflex function that is complementary to BRS.

Abstract 268: Toll-like Receptor 9 (TLR9) Plays a Key Role in the Autonomic Cardiac and Baroreflex Control of Arterial Pressure

Hypertension ◽  
2013 ◽  
Vol 62 (suppl_1) ◽  
Author(s):  
Fernanda L Rodrigues ◽  
Gisele F Bomfim ◽  
Carlos A Silva ◽  
Rubens Fazan ◽  
Rita C Tostes ◽  
...  
Keyword(s):  
Arterial Pressure ◽  
Immune Responses ◽  
Peripheral Nerves ◽  
Linear Method ◽  
Symbolic Analysis ◽  
Pulse Interval ◽  
Toll Like Receptor ◽  
Baroreflex Control ◽  
Receptor Blockers ◽  
Spontaneous Baroreflex

Introduction: The crosstalk between the immune and nervous system can impact cardiovascular regulation. Toll-like receptor 9 (TLR9) is expressed in immune cells, peripheral nerves and vascular smooth muscle cells. TLR9 is involved in hypertension and cholinergic stimulation suppresses immune responses mediated by TLR9. Based on that, we hypothesized that TLR9 plays a role in cardiac autonomic and baroreflex control of arterial pressure (AP). Methods and Results: TLR9 knockout (KO) and WT mice were anesthetized with isoflurane, implanted with catheters into left carotid artery and right jugular vein and allowed to recovery for 3 days. After basal recording of AP, mice received cardiac autonomic receptor blockers methyl atropine or propranolol. AP and pulse interval (PI) variability were evaluated using the symbolic analysis (non-linear method). Spontaneous baroreflex was evaluated by sequence technique. Mean AP was slightly higher in TLR9 KO (TLR9 KO: 126±2.8 vs WT: 115±4.4 mmHg). In the symbolic analysis the 0V pattern was lower (TLR9 KO: 20±5.4 vs WT: 35±5.0 %) and 2LV pattern was higher in the TLR9 KO (TLR9 KO: 6±1.6 vs WT: 2±0.5 %), an indication of sympathetic and parasympathetic activity, respectively. AP/PI sequences were similar between groups. However, the gain of AP/PI sequences was increased in TLR9 KO (TLR9 KO: 5±1.4 vs WT: 2±0.4 ms/mmHg). Atropine-induced tachycardia was increased in TLR9 KO (TLR9 KO: 23±8.0 vs WT: 2±0.7 ms), whereas propranolol-induced bradycardia was decreased (28±11.0 vs WT: 56±7.6 ms). Conclusions: Our findings demonstrate that TLR9 negatively modulates cardiac vagal tone, and consequently the baroreflex control of AP.

scholarly journals Acute Fingolimod Effects on Baroreflex and Cardiovascular Autonomic Control in Multiple Sclerosis

2019 ◽  
Vol 11 ◽  
pp. 117957351984994 ◽  
Author(s):  
Vittorio Racca ◽  
Marco Rovaris ◽  
Rosella Cavarretta ◽  
Emanuele Vaini ◽  
Anastasia Toccafondi ◽  
...  
Keyword(s):  
Multiple Sclerosis ◽  
Baroreflex Sensitivity ◽  
Low Frequency ◽  
Acute Effect ◽  
Mean Value ◽  
Autonomic Control ◽  
Oral Drug ◽  
Pulse Interval ◽  
Dose Administration ◽  
Parasympathetic System

Background: Fingolimod, an oral drug used in multiple sclerosis (MS) treatment, exerts its action through S1P-receptor engagement. These receptors are also expressed in heart and endothelial cells. The engagement of receptors on the atrial heart myocytes may cause a slowing effect on heart rate (HR). We aimed to explore the acute effect of fingolimod on the cardiac autonomic control, a side-effect of the drug that still needs to be clarified. Methods: In 10 MS patients, we investigated the influence of the first administration of fingolimod (0.5 mg) on sympathetic and parasympathetic indexes via the analysis of the HR variability, and on the baroreflex sensitivity via sequence and alpha coefficient techniques. Results: Fingolimod produced an average HR maximal drop of 12.7 (7.8) beats/min and the minimal HR occurred after 2.73 (0.38) hours from the dose administration. The pulse interval (PI) mean value and the pNN50 and RMSSD indexes of parasympathetic drive to the heart significantly increased. Interestingly, in 6 out of 10 patients also the power in the low-frequency band (LF) increased. The baroreflex sensitivity was not modified by the first dose of the drug. Conclusions: Our findings indicate that although the first dose of fingolimod invariably activates the parasympathetic system, in several subjects, it may induce also a surge in the sympathetic cardiac drive. This suggests that not only the vagal, as usually assumed, but also the sympathetic autonomic branch should be considered in the risk profile assessment of MS patients starting treatment with fingolimod.

Critical Appraisal of Indices for the Assessment of Baroreflex Sensitivity

1997 ◽  
Vol 36 (04/05) ◽  
pp. 246-249 ◽  
Author(s):  
P. Castiglioni ◽  
G. Mancia ◽  
G. Parati ◽  
A. Pedotti ◽  
M. Di Rienzo
Keyword(s):  
Blood Pressure ◽  
Baroreflex Sensitivity ◽  
Critical Appraisal ◽  
Spectral Estimation ◽  
Respiratory Frequency ◽  
Pulse Interval ◽  
Alpha Coefficient ◽  
Before And After ◽  
Reliable Parameter ◽  
Spontaneous Baroreflex

Abstract:The sequence technique and the spectral estimation of the alpha coefficient are currently employed for the assessment of “spontaneous” baroreflex sensitivity (BRS). The comparison of performance and effectiveness of these techniques is obtained by the analysis of systolic blood pressure (SBP) and pulse interval (PI) tracings recorded in conscious cats before and after baroreceptor denervation. Results indicate that (1) the average BRS estimates obtained by the sequence technique and by the alpha coefficient at the respiratory frequency are similar, (2) the alpha coefficients computed at the respiratory frequency tend to be higher than alpha coefficients estimated at 0.1 Hz, and (3) in spite of what is traditionally claimed, the PI-SBP coherence does not seem to represent a reliable parameter to enhance the specificity of the spectral estimate, because coherence values often remain above the 0.5 threshold also after baroreceptor denervation.

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