Measuring baroreflex sensitivity from the gain function between arterial pressure and heart period

2002 ◽  
Vol 103 (1) ◽  
pp. 81-88 ◽  
Author(s):  
Gian Domenico PINNA ◽  
Roberto MAESTRI ◽  
Grzegorz RACZAK ◽  
Maria Teresa LA ROVERE
Keyword(s):  
Arterial Pressure ◽  
Frequency Band ◽  
Baroreflex Sensitivity ◽  
Low Frequency ◽  
Systolic Arterial Pressure ◽  
Normal Subjects ◽  
Heart Period ◽  
Gain Function ◽  
Limits Of Agreement ◽  
Spectral Technique

We tested an innovative approach for estimating baroreflex sensitivity (BRS) from the gain function between spontaneous oscillations of systolic arterial pressure (SAP) and heart period (HP). The major goal was to assess the practical implications of abandoning the classical coherence criterion (⩾0.5) as regards measurability of BRS, and agreement with values of BRS obtained using the phenylephrine test (Phe-BRS). We studied 19 normal subjects, 44 patients with a history of previous myocardial infarction (MI) and 45 patients with chronic heart failure (CHF). The experimental protocol included recording of SAP and HP for 10min of supine rest, and evaluation of Phe-BRS. From resting SAP and HP, the gain and coherence functions were computed. The new BRS index was obtained in all subjects by averaging the gain function over the whole low-frequency band (0.04-0.15Hz) (whole-band average BRS, WBA-BRS). WBA-BRS was 7.4 (5.8-10.8)ms/mmHg [median (25th-75th percentile)] in normal controls, 3.1 (1.4-5.4)ms/mmHg in MI patients (P<0.001 compared with normals) and 5.0 (3.2-6.9)ms/mmHg in CHF patients (P<0.01 compared with normals). Using the coherence criterion, BRS could be measured in only 43% and 49% of MI and CHF patients respectively, and the proportion of the low-frequency band contributing to the measurement was 21% (14-47%) and 29% (16-35%) respectively. The correlation between WBA-BRS and Phe-BRS was 0.47, 0.63 and 0.36 in the normal, MI and CHF groups respectively (all P<0.001). The relative bias of WBA-BRS was -5.2ms/mmHg (P<0.001) in normals, -1.4ms/mmHg (P = 0.004) in MI patients and -1.0ms/mmHg (P = 0.11) in CHF patients. The limits of agreement were -13 to 2.6, -7.4 to 4.6 and -9.3 to 7.3ms/mmHg in the normal, MI and CHF groups respectively. Thus the WBA-BRS method standardizes the computation of BRS among subjects, and dramatically increases its measurability in subjects with pathology compared with the classical spectral technique based on the coherence criterion. Compared with Phe-BRS, WBA-BRS tends to give negatively biased results. The correlation and the magnitude of the limits of agreement between the two methods are similar to those observed previously using coherence-based spectral methods.

Comparison of phenylephrine bolus and infusion methods in baroreflex measurements

1990 ◽  
Vol 69 (3) ◽  
pp. 962-967 ◽  
Author(s):  
J. T. Sullebarger ◽  
C. S. Liang ◽  
P. D. Woolf ◽  
A. E. Willick ◽  
J. F. Richeson
Keyword(s):  
Heart Rate ◽  
Arterial Pressure ◽  
Baroreflex Sensitivity ◽  
Heart Rate Response ◽  
Pressor Response ◽  
Plasma Catecholamines ◽  
Systolic Arterial Pressure ◽  
Normal Subjects ◽  
Vagus Nerves ◽  
Baroreflex Control

Phenylephrine (PE) bolus and infusion methods have both been used to measure baroreflex sensitivity in humans. To determine whether the two methods produce the same values of baroreceptor sensitivity, we administered intravenous PE by both bolus injection and graded infusion methods to 17 normal subjects. Baroreflex sensitivity was determined from the slope of the linear relationship between the cardiac cycle length (R-R interval) and systolic arterial pressure. Both methods produced similar peak increases in arterial pressure and reproducible results of baroreflex sensitivity in the same subjects, but baroreflex slopes measured by the infusion method (9.9 +/- 0.7 ms/mmHg) were significantly lower than those measured by the bolus method (22.5 +/- 1.8 ms/mmHg, P less than 0.0001). Pretreatment with atropine abolished the heart rate response to PE given by both methods, whereas plasma catecholamines were affected by neither method of PE administration. Naloxone pretreatment exaggerated the pressor response to PE and increased plasma beta-endorphin response to PE infusion but had no effect on baroreflex sensitivity. Thus our results indicate that 1) activation of the baroreflex by the PE bolus and infusion methods, although reproducible, is not equivalent, 2) baroreflex-induced heart rate response to a gradual increase in pressure is less than that seen with a rapid rise, 3) in both methods, heart rate response is mediated by the vagus nerves, and 4) neither the sympathetic nervous system nor the endogenous opiate system has a significant role in mediating the baroreflex control of heart rate to a hypertensive stimulus in normal subjects.

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

2018 ◽  
Vol 124 (3) ◽  
pp. 791-804 ◽  
Author(s):  
Juliana C. Milan-Mattos ◽  
Alberto Porta ◽  
Natália M. Perseguini ◽  
Vinicius Minatel ◽  
Patricia Rehder-Santos ◽  
...  
Keyword(s):  
Arterial Pressure ◽  
Coherence Function ◽  
Low Frequency ◽  
Systolic Arterial Pressure ◽  
Progressive Increase ◽  
Heart Period ◽  
Baroreflex Control ◽  
And Gender ◽  
Spontaneous Fluctuations ◽  
Cardiovascular Variables

Aging affects baroreflex regulation. The effect of senescence on baroreflex control was assessed from spontaneous fluctuations of heart period (HP) and systolic arterial pressure (SAP) through the HP-SAP gain, while the HP-SAP phase and strength are usually disregarded. This study checks whether the HP-SAP phase and strength, as estimated, respectively, via the phase of the HP-SAP cross spectrum (PhHP-SAP) and squared coherence function (K2HP-SAP), vary with age in healthy individuals and trends are gender-dependent. We evaluated 110 healthy volunteers (55 males) divided into five age subgroups (21–30, 31–40, 41–50, 51–60, and 61–70 yr). Each subgroup was formed by 22 subjects (11 males). HP series was extracted from electrocardiogram and SAP from finger arterial pressure at supine resting (REST) and during active standing (STAND). PhHP-SAP and K2HP-SAP functions were sampled in low-frequency (LF, from 0.04 to 0.15 Hz) and in high-frequency (HF, above 0.15 Hz) bands. Both at REST and during STAND PhHP-SAP(LF) showed a negative correlation with age regardless of gender even though values were more negative in women. This trend was shown to be compatible with a progressive increase of the baroreflex latency with age. At REST K2HP-SAP(LF) decreased with age regardless of gender, but during STAND the high values of K2HP-SAP(LF) were more preserved in men than women. At REST and during STAND the association of PhHP-SAP(HF) and K2HP-SAP(HF) with age was absent. The findings points to a greater instability of baroreflex control with age that seems to affect to a greater extent women than men. NEW & NOTEWORTHY Aging increases cardiac baroreflex latency and decreases the degree of cardiac baroreflex involvement in regulating cardiovascular variables. These trends are gender independent but lead to longer delays and asmaller degree of cardiac baroreflex involvement in women than in men, especially during active standing, with important implications on the tolerance to an orthostatic stressor.

Comparison between spectral analysis and the phenylephrine method for the assessment of baroreflex sensitivity in chronic heart failure

1999 ◽  
Vol 97 (4) ◽  
pp. 503-513 ◽  
Author(s):  
Roberto COLOMBO ◽  
Giorgio MAZZUERO ◽  
Gianluca SPINATONDA ◽  
Paola LANFRANCHI ◽  
Pantaleo GIANNUZZI ◽  
...  
Keyword(s):  
Heart Failure ◽  
Spectral Analysis ◽  
Arterial Pressure ◽  
Baroreflex Sensitivity ◽  
Coherence Function ◽  
Systolic Arterial Pressure ◽  
Multivariate Regression Analysis ◽  
Chronic Congestive Heart Failure ◽  
Limits Of Agreement ◽  
Controlled Breathing

Baroreflex sensitivity assessed by means of the phenylephrine test plays a prognostic role in patients with previous myocardial infarction, but the need for drug injection limits the use of this technique. Recently, several non-invasive methods based on spectral analysis of systolic arterial pressure and heart period have been proposed, but their agreement with the phenylephrine test has not been investigated in patients with heart failure. The two methods (phenylephrine test and spectral analysis) were compared in a group of 49 patients with chronic congestive heart failure both at rest and during controlled breathing. The linear correlation and the limits of agreement between the phenylephrine test slope and the α-index [αc; corrected by the coherence function between the interbeat interval (RR interval) and systolic arterial pressure] were evaluated. Only 16 patients had a measurable α-index at rest in both the low-frequency (LF) and high-frequency (HF) bands; the αc-index allowed measurements in all patients. It correlated moderately with the phenylephrine test slope at rest (r = 0.71 and P< 0.001 in LF; r = 0.57 and P< 0.001 in HF) and during controlled breathing (r = 0.51 and P< 0.001 in LF; r = 0.63 and P< 0.001 in HF). Multivariate regression analysis showed that only αcLF during rest and αcHF during controlled breathing contributed significantly to baroreflex gain estimation. However, the agreement between methods was weak; the normalized limits of agreement and bias were -162 to 243% (0.46 ms/mmHg) for αcLF and -185 to 151% (-0.99 ms/mmHg) for αcHF. Thus the comparison between baroreflex sensitivity measurements obtained by the phenylephrine test and spectral analysis showed a moderate correlation between the two methods; however, despite the linear association, a consistent lack of agreement between the two techniques was found. Because both systematic and random factors contribute to the difference, these two techniques cannot be considered as alternatives for the assessment of heart failure.

Abstract 607: Combined Intracerebroventricular Angiotensin-(1-7) and Candesartan Normalizes Blood Pressure and Improves Baroreflex Function in Transgenic (mRen2)27 Hypertensive Rats

Hypertension ◽  
2013 ◽  
Vol 62 (suppl_1) ◽  
Author(s):  
Manisha Nautiyal ◽  
Hossam A Shaltout ◽  
Mark C Chappell ◽  
Debra I Diz
Keyword(s):  
Blood Pressure ◽  
Arterial Pressure ◽  
Baroreflex Sensitivity ◽  
Low Frequency ◽  
Systolic Arterial Pressure ◽  
Therapeutic Benefit ◽  
Receptor Blockade ◽  
Artificial Cerebrospinal Fluid ◽  
Cardiovascular Pathologies ◽  
Sympathovagal Imbalance

Transgenic (mRen2)27 rats that over express the murine Ren2 gene are hypertensive and have impaired baroreflex sensitivity (BRS) for control of heart rate (HR). We previously showed that infusion of central angiotensin-(1-7) [Ang-(1-7)] improved the vagal components of the BRS independent of altering mean arterial pressure (MAP) but that, AT 1 receptor blockade normalized MAP and blood pressure variability (BPV) without correcting the BRS. To determine if the overall sympathovagal imbalance and the BRS function can be corrected by supplementing Ang-(1-7) in combination with AT 1 receptor blockade, we compared intracerebroventricular (ICV) infusions of the AT 1 receptor antagonist candesartan (CV: 4 ug/5uL/hr) and Ang-(1-7) [0.1 ug/5uL/hr; n = 4] or artificial cerebrospinal fluid (aCSF; 5 uL/hr; n = 8) for 4 weeks in 18 week old male (mRen2)27 rats. MAP was significantly reduced in CV/ Ang-(1-7) treated rats [71 ± 13 vs. aCSF: 132 ± 12 mm Hg; p = 0.01] with no changes in HR. Lowering of MAP was associated with a reduction in low frequency systolic arterial pressure, an index of BPV, [LF-SAP%: 32 ± 8 vs. aCSF: 73 ± 10, p = 0.02] in these animals. Both vagal [high frequency alpha: 1.1 ± 0.3 vs. aCSF: 0.6 ± 0.1, p= 0.05 and Sequence UP: 1.7 ± 0.4 vs. aCSF: 0.7 ± 0.1, p= 0.03] and sympathetic [low frequency alpha: 0.65 ± 0.14 vs. aCSF: 0.34 ± 0.03, p= 0.02 and Sequence DOWN: 1.4 ± 0.3 vs. aCSF: 0.76 ± 0.1, p= 0.01] components of the BRS were significantly increased resulting in improvements in the overall BRS [Sequence ALL: 1.6 ± 0.3 vs. aCSF: 0.75 ± 0.1, p= 0.01] as well as the sympathovagal imbalance [LF RRI /HF RRI : 0.2 ± 0.1 vs. aCSF: 2.3 ± 0.6, p= 0.004] in treated animals. Thus, combination ICV therapy normalized MAP and corrected the sympathovagal imbalance leading to improved BRS function. Since impaired BRS significantly associates with cardiovascular pathologies independently from hypertension, specifically targeting an increase in central Ang-(1-7) with reduced Ang II actions to provide improved BRS and lower MAP may achieve a more optimal therapeutic benefit.

Measuring baroreflex sensitivity from the gain function between arterial pressure and heart period

2002 ◽  
Vol 103 (1) ◽  
pp. 81 ◽  
Author(s):  
Gian Domenico PINNA ◽  
Roberto MAESTRI ◽  
Grzegorz RACZAK ◽  
Maria Teresa LA ROVERE
Keyword(s):  
Arterial Pressure ◽  
Baroreflex Sensitivity ◽  
Heart Period ◽  
Gain Function

scholarly journals Physiological Sympathetic Activation Reduces Systemic Inflammation: Role of Baroreflex and Chemoreflex

2021 ◽  
Vol 12 ◽  
Author(s):  
Fernanda Brognara ◽  
Jaci Airton Castania ◽  
Alexandre Kanashiro ◽  
Daniel Penteado Martins Dias ◽  
Helio Cesar Salgado
Keyword(s):  
Nervous System ◽  
Arterial Pressure ◽  
Systemic Inflammation ◽  
Inflammatory Responses ◽  
Low Frequency ◽  
Systolic Arterial Pressure ◽  
Sympathetic Activation ◽  
Bilateral Carotid Occlusion ◽  
Bilateral Carotid ◽  
Reflex Activation

Baroreflex and chemoreflex act through the autonomic nervous system, which is involved with the neural regulation of inflammation. The present study reports the effects of reflex physiological sympathetic activation in endotoxemic rats using bilateral carotid occlusion (BCO), a physiological approach involving the baroreflex and chemoreflex mechanisms and the influence of the baroreceptors and peripheral chemoreceptors in the cardiovascular and systemic inflammatory responses. After lipopolysaccharide (LPS) administration, the arterial pressure was recorded during 360 min in unanesthetized rats, and serial blood samples were collected to analyze the plasma cytokine levels. BCO elicited the reflex activation of the sympathetic nervous system, providing the following outcomes: (I) increased the power of the low-frequency band in the spectrum of the systolic arterial pressure during the BCO period; (II) reduced the levels of pro-inflammatory cytokines in plasma, including the tumor necrosis factor (TNF) and the interleukin (IL)-1β; (III) increased the plasma levels of anti-inflammatory cytokine IL-10, 90 min after LPS administration. Moreover, selective baroreceptor or chemoreceptor denervation deactivated mechanosensitive and chemical sensors, respectively, and decreased the release of the LPS-induced cytokine but did not alter the BCO modulatory effects. These results show, for the first time, that physiological reflex activation of the sympathetic circuit decreases the inflammatory response in endotoxemic rats and suggest a novel function for the baroreceptors as immunosensors during the systemic inflammation.

Influences of neural mechanisms on heart period and arterial pressure variabilities in quadriplegic patients

1994 ◽  
Vol 266 (3) ◽  
pp. H1112-H1120 ◽  
Author(s):  
S. Guzzetti ◽  
C. Cogliati ◽  
C. Broggi ◽  
C. Carozzi ◽  
D. Caldiroli ◽  
...  
Keyword(s):  
Arterial Pressure ◽  
Spectral Component ◽  
Systolic Arterial Pressure ◽  
Neural Mechanisms ◽  
Heart Period ◽  
Recording Session ◽  
Sympathetic Modulation ◽  
Arterial Pressure Variability ◽  
Head Up Tilt ◽  
Vasomotor Activity

The heart period (R-R) variability power spectrum presents two components, at low (LF; approximately 0.10 Hz) and high (approximately 0.25 Hz) frequencies, whose reciprocal powers appear to furnish an index of sympathovagal interaction modulating heart rate. In addition, the LF component of the systolic arterial pressure variability spectrum furnishes a marker of sympathetic modulation of vasomotor activity. The contribution of spinal and supraspinal neural circuits to the genesis of these rhythmic oscillatory components remains largely unsettled. Therefore we performed spectral analysis of R-R and systolic arterial pressure variabilities in 15 chronic neurologically complete quadriplegic patients (QP) and in 15 control subjects during resting conditions, controlled respiration, and head-up tilt. At rest, in seven QP the LF component was undetectable in both cardiovascular variability spectra; in two QP this component was present only in R-R variability spectrum, whereas the remaining six showed a significantly reduced LF in both signals. In QP, the LF component, when present, underwent paradoxical changes with respect to controls, decreasing during tilt and increasing during controlled respiration. In five QP in whom the recording session was repeated after 6 mo, a significant increase in LF was observed in both variability spectra. These data confirm the finding that a disconnection of sympathetic outflow from supraspinal centers can cause the disappearance of the LF spectral component. However, LF presence in some QP supports the hypothesis of a spinal rhythmicity likely to be modulated by the afferent sympathetic activity.

Reliability of heart period and systolic arterial pressure variabilities in women with fibromyalgia syndrome

2016 ◽  
Vol 35 (9) ◽  
pp. 2347-2352 ◽  
Author(s):  
Carolina Pieroni Andrade ◽  
Antonio Roberto Zamunér ◽  
Meire Forti ◽  
Thalita Fonseca de França ◽  
Ester da Silva
Keyword(s):  
Arterial Pressure ◽  
Fibromyalgia Syndrome ◽  
Systolic Arterial Pressure ◽  
Heart Period

Information Transfer through the Spontaneous Baroreflex in Healthy Humans

2010 ◽  
Vol 49 (05) ◽  
pp. 506-510 ◽  
Author(s):  
A. M. Catai ◽  
A. C. M. Takahashi ◽  
V. Magagnin ◽  
T. Bassani ◽  
E. Tobaldini ◽  
...  
Keyword(s):  
Arterial Pressure ◽  
Information Transfer ◽  
Function Analysis ◽  
Systolic Arterial Pressure ◽  
Heart Period ◽  
Uniform Quantization ◽  
Transfer Function Analysis ◽  
Head Up Tilt ◽  
Spontaneous Baroreflex

Summary Objectives: This study assesses the information transfer through the spontaneous baroreflex (i.e. through the pathway linking systolic arterial pressure to heart period) during an experimental condition soliciting baroreflex (i.e. head-up tilt). Methods: The information transfer was calculated as the conditional entropy of heart period given systolic arterial pressure using a mutual neighbor approach and uniform quantization. The information transfer was monitored as a function of the forecasting time k. Results: We found that during head-up tilt the information transfer at k = 0 decreased but the rate of rise of information transfer as a function of k was faster. Conclusions: We suggest that the characterization of the information transfer from systolic arterial pressure to heart period might complement the traditional characterization of the spontaneous baroreflex based on transfer function analysis.

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