Coherence analysis overestimates the role of baroreflex in governing the interactions between heart period and systolic arterial pressure variabilities during general anesthesia

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.

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

Clinical Rheumatology ◽

10.1007/s10067-016-3284-z ◽

2016 ◽

Vol 35 (9) ◽

pp. 2347-2352 ◽

Cited By ~ 2

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

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Information Transfer through the Spontaneous Baroreflex in Healthy Humans

Methods of Information in Medicine ◽

10.3414/me09-02-0036 ◽

2010 ◽

Vol 49 (05) ◽

pp. 506-510 ◽

Cited By ~ 7

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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Short-term complexity indexes of heart period and systolic arterial pressure variabilities provide complementary information

Journal of Applied Physiology ◽

10.1152/japplphysiol.00755.2012 ◽

2012 ◽

Vol 113 (12) ◽

pp. 1810-1820 ◽

Cited By ~ 52

Author(s):

A. Porta ◽

P. Castiglioni ◽

M. Di Rienzo ◽

V. Bari ◽

T. Bassani ◽

...

Keyword(s):

Arterial Pressure ◽

Systolic Arterial Pressure ◽

Adrenergic Blockade ◽

Sympathetic Blockade ◽

Heart Period ◽

Complementary Information ◽

Beta Adrenergic ◽

Orthostatic Challenge ◽

Vagal Blockade ◽

Head Up Tilt

It is unclear whether the complexity of the variability of the systolic arterial pressure (SAP) provides complementary information to that of the heart period (HP). The complexity of HP and SAP variabilities was assessed from short beat-to-beat recordings (i.e., 256 cardiac beats). The evaluation was made during a pharmacological protocol that induced vagal blockade with atropine or a sympathetic blockade (beta-adrenergic blockade with propranolol or central sympathetic blockade with clonidine) alone or in combination, during a graded head-up tilt, and in patients with Parkinson's disease (PD) without orthostatic hypotension undergoing orthostatic challenge. Complexity was quantified according to the mean square prediction error (MSPE) derived from univariate autoregressive (AR) and multivariate AR (MAR) models. We found that: 1) MSPEMAR did not provide additional information to that of MSPEAR; 2) SAP variability was less complex than that of HP; 3) because HP complexity was reduced by either vagal blockade or vagal withdrawal induced by head-up tilt and was unaffected by beta-adrenergic blockade, HP was under vagal control; 4) because SAP complexity was increased by central sympathetic blockade and was unmodified by either vagal blockade or vagal withdrawal induced by head-up tilt, SAP was under sympathetic control; 5) SAP complexity was increased in patients with PD; and 6) during orthostatic challenge, the complexity of both HP and SAP variabilities in patients with PD remained high, thus indicating both vagal and sympathetic impairments. Complexity indexes derived from short HP and SAP beat-to-beat series provide complementary information and are helpful in detecting early autonomic dysfunction in patients with PD well before circulatory symptoms become noticeable.

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Causal relationships between heart period and systolic arterial pressure during graded head-up tilt

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.00553.2010 ◽

2011 ◽

Vol 300 (2) ◽

pp. R378-R386 ◽

Cited By ~ 72

Author(s):

Alberto Porta ◽

Aparecida M. Catai ◽

Anielle C. M. Takahashi ◽

Valentina Magagnin ◽

Tito Bassani ◽

...

Keyword(s):

Arterial Pressure ◽

Causal Relation ◽

Systolic Arterial Pressure ◽

Causal Link ◽

Heart Period ◽

Reverse Causality ◽

Tilt Table ◽

Baroreflex Control ◽

Healthy Humans ◽

Head Up Tilt

In physiological conditions, heart period (HP) affects systolic arterial pressure (SAP) through diastolic runoff and Starling's law, but, the reverse relation also holds as a result of the continuous action of baroreflex control. The prevailing mechanism sets the dominant temporal direction in the HP-SAP interactions (i.e., causality). We exploited cross-conditional entropy to assess HP-SAP causality. A traditional approach based on phases was applied for comparison. The ability of the approach to detect the lack of causal link from SAP to HP was assessed on 8 short-term (STHT) and 11 long-term heart transplant (LTHT) recipients (i.e., less than and more than 2 yr after transplantation, respectively). In addition, spontaneous HP and SAP variabilities were extracted from 17 healthy humans (ages 21–36 yr, median age 29 yr; 9 females) at rest and during graded head-up tilt. The tilt table inclinations ranged from 15 to 75° and were changed in steps of 15°. All subjects underwent recordings at every step in random order. The approach detected the lack of causal relation from SAP to HP in STHT recipients and the gradual restoration of the causal link from SAP to HP with time after transplantation in the LTHT recipients. The head-up tilt protocol induced the progressive shift from the prevalent causal direction from HP to SAP to the reverse causality (i.e., from SAP to HP) with tilt table inclination in healthy subjects. Transformation of phases into time shifts and comparison with baroreflex latency supported this conclusion. The proposed approach is highly efficient because it does not require the knowledge of baroreflex latency. The dependence of causality on tilt table inclination suggests that “spontaneous” baroreflex sensitivity estimated using noncausal methods (e.g., spectral and cross-spectral approaches) is more reliable at the highest tilt table inclinations.

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An Empirical Mode Decomposition Approach to Assess the Strength of Heart Period-Systolic Arterial Pressure Variability Interactions

2020 42nd Annual International Conference of the IEEE Engineering in Medicine & Biology Society (EMBC) ◽

10.1109/embc44109.2020.9175647 ◽

2020 ◽

Author(s):

Vlasta Bari ◽

Beatrice Cairo ◽

Beatrice De Maria ◽

Davide Tonon ◽

Gianluca Rossato ◽

...

Keyword(s):

Arterial Pressure ◽

Empirical Mode Decomposition ◽

Systolic Arterial Pressure ◽

Heart Period ◽

Decomposition Approach ◽

Mode Decomposition ◽

Arterial Pressure Variability

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Joint symbolic dynamics for the assessment of cardiovascular and cardiorespiratory interactions

Philosophical Transactions of The Royal Society A Mathematical Physical and Engineering Sciences ◽

10.1098/rsta.2014.0097 ◽

2015 ◽

Vol 373 (2034) ◽

pp. 20140097 ◽

Cited By ~ 10

Author(s):

Mathias Baumert ◽

Michal Javorka ◽

Muammar Kabir

Keyword(s):

Arterial Pressure ◽

Symbolic Dynamics ◽

Systolic Arterial Pressure ◽

Symbolic Analysis ◽

Heart Period ◽

Short Term ◽

Cardiorespiratory Control ◽

Baroreflex Control ◽

Simple Description ◽

Cardiorespiratory Coupling

Beat-to-beat variations in heart period provide information on cardiovascular control and are closely linked to variations in arterial pressure and respiration. Joint symbolic analysis of heart period, systolic arterial pressure and respiration allows for a simple description of their shared short-term dynamics that are governed by cardiac baroreflex control and cardiorespiratory coupling. In this review, we discuss methodology and research applications. Studies suggest that analysis of joint symbolic dynamics provides a powerful tool for identifying physiological and pathophysiological changes in cardiovascular and cardiorespiratory control.

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

Journal of Applied Physiology ◽

10.1152/japplphysiol.00903.2017 ◽

2018 ◽

Vol 124 (3) ◽

pp. 791-804 ◽

Cited By ~ 10

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.

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

Clinical Science ◽

10.1042/cs1030081 ◽

2002 ◽

Vol 103 (1) ◽

pp. 81-88 ◽

Cited By ~ 32

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.

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