Comparing spectral and invasive estimates of baroreflex gain

Head, Geoffrey A.; Лукошкова, Е. В.; Burke, Sandra L.; Malpas, Simon C.; Lambert, Elisabeth; Janssen, Ben J. A.

doi:10.1109/51.917723

Cited by 34 publications

(38 citation statements)

References 46 publications

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“…It is assumed that LF fluctuations of the R-R interval and SBP are attributed to the BR and mediated by sympathetic as well as parasympathetic nerve activity. HF fluctuations of the R-R interval and SBP are associated with respiratory activity, and HF R-R interval fluctuations are mainly mediated through the (fast-acting) parasympathetic system (1,2,7,15,22,23,25). The R-R interval is expressed in ms and spectral power values in ms 2 .…”

Section: Discussionmentioning

confidence: 99%

“…Transfer function analysis. In addition to the spectral density power, the transfer function analysis (coherence, transfer gain, and phase) was calculated, as previously described in detail (6,21,22). Briefly, transfer gain reflects the degree to which the input signal (SBP) amplitude becomes manifest in the output signal (R-R interval) amplitude at a discrete frequency.…”

mentioning

confidence: 99%

“…Briefly, transfer gain reflects the degree to which the input signal (SBP) amplitude becomes manifest in the output signal (R-R interval) amplitude at a discrete frequency. At LF, transfer gain is an estimate for BR gain/ sensitivity (22,23). The phase difference (degrees or seconds) indicates the lead or lag of one signal with respect to the other at a discrete frequency.…”

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confidence: 99%

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Cardiovascular Autonomic Regulation in Preterm Infants: The Effect of Atropine

et al. 2004

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To study cardiovascular autonomic control, we assessed the effect of atropine on heart rate (HR) and blood pressure (BP) variability in 12 preterm infants (range 26 -32 wk) before intubation for respiratory insufficiency. Spectral power analysis of R-R interval and systolic BP (SBP) series were estimated in a low-frequency (LF; 0.04 -0.15 Hz) and high-frequency (HF; 0.4 -1.5 Hz) band and evaluated for a 10-min period before and a 10-min period after atropine sulfate (0.01 mg/kg). Baroreceptor reflex (BR) functioning was estimated using transfer function analysis at LF (coherence, gain, and phase). Atropine resulted in a significant 12% increase in steady-state HR (p Ͻ 0.01) and unchanged SBP. For R-R interval series, the total spectral power decreased 6-fold (p Ͻ 0.01), which was predominantly due to a reduction in the LF band (16-fold; p Ͻ 0.01). In contrast, we observed a significant increase (25%; p Ͻ 0.05) in total spectral power of SBP series partly as a result of an increase in HF power. The LF power of SBP series was not altered. The median LF transfer gain (BR sensitivity) between SBP and R-R interval decreased from 4.2 to 1.4 ms/mm Hg (p Ͻ 0.01) after atropine. The LF phase relationship (BP leads R-R interval fluctuations bỹ 4 s) was not changed after atropine. In conclusion, even in preterm infants in distress, atropine modulates HR and BP variability, suggesting that BR-mediated parasympathetic control of heart rate is of significance for cardiovascular control at that age. The baroreceptor reflex (BR) is the most important regulatory mechanism in the short-term control of heart rate (HR) and blood pressure (BP). The BR buffers sudden changes in systemic BP by adapting HR and peripheral vascular resistance. These responses of HR and vascular resistance are mediated by the efferent parasympathetic and sympathetic limb of the BR. As both systems are involved, studies on the BR give information on autonomic cardiovascular regulation (1,2).Data about the ontogeny of the BR and functional maturation in the human infant are limited. This is partly caused by the limited experimental (pharmacologic or mechanical) possibilities to challenge the BR in neonates. Passive head-up tilt test has been applied to neonates to measure responses in BP, HR, and limb blood flow to body tilting. In preterm infants (26 -38 wk gestation), passive head-up tilt resulted in significant vasoconstriction of the lower limb with a slight fall in aortic BP and unchanged HR (3). The inadequate ability to maintain BP and the lack of tachycardia suggest that preterm infants lack the full integrated BR response as seen in adults. In term infants, however, a fall in systolic BP (SBP) was observed in conjunction with tachycardia and a fall in limb blood flow, suggesting the presence of active reflex vasoconstriction (4). In a recent study, BR maturation was studied longitudinally in preterm infants, using a beat-to-beat analysis of R-R interval series and noninvasively measured SBP (5). BR sensitivity (the R-R interval change in millisecon...

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Section: Discussionmentioning

confidence: 99%

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confidence: 99%

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confidence: 99%

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Cardiovascular Autonomic Regulation in Preterm Infants: The Effect of Atropine

et al. 2004

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“…The beat to beat data were analyzed for spectral analysis using a program written in Labview (19). The auto-and cross-power spectra were calculated for each segment using Fast Fourier transform (19).…”

Section: Methodsmentioning

confidence: 99%

“…The auto-and cross-power spectra were calculated for each segment using Fast Fourier transform (19). The average value of the transfer gain in the frequency band between 0.3 and 0.5 Hz was used as the estimate of the baroreflex sensitivity ( Fig.…”

Section: Methodsmentioning

confidence: 99%

Aromatase-Deficient (ArKO) Mice Have Reduced Blood Pressure and Baroreflex Sensitivity

Head

Obeyesekere

Jones³

et al. 2004

Endocrinology

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Aromatase-deficient (ArKO) mice are deficient in estrogens due to deletion of the aromatase gene. We hypothesized that there may be changes in the cardiovascular system of ArKO mice because of evidence linking estrogens with improved cardiovascular outcomes and the induction of the glucocorticoid-metabolizing enzyme, 11␤-hydroxysteroid dehydrogenase type 2 (11␤HSD2), gene in the kidney, which is important for the regulation of blood pressure (BP). BP and baroreflex sensitivity (BRS) in female conscious ArKO mice were compared with those in age-and weight-matched wild-type (WT) mice. Power spectral analysis was used to determine cardiovascular variability and BRS. Although systolic BP was similar in the two groups, diastolic and mean BPs were lower in the ArKO mice (؊6.3 ؎ 1.9 and ؊4.6 ؎ 2.1 mm Hg, respectively).Heart rate (HR) was greater in the ArKO mice (؉36 ؎ 6 beats/ min). The mean BP in WT mice was 105 mm Hg, and the HR was 481 beats/min. In the autonomic frequency range, BP variability was 74% greater, and HR variability was only 26% that in WT mice. The BRS of ArKO mice was 46% of the value observed in WT mice. 11␤HSD2 levels were unaltered in ArKO mice, except in the kidney, where they were only 10% of WT levels. Estradiol administration to ArKO mice restored renal 11␤HSD2 to WT levels. The results show that ArKO mice have lower diastolic BP, but increased BP variability, perhaps due to an impaired BRS. Thus, aromatase activity is critical for normal autonomic control of the heart and, hence, for reducing the deleterious effects of high BP variability. (Endocrinology 145: 4286 -4291, 2004)

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Empagliflozin modulates renal sympathetic and heart rate baroreflexes in a rabbit model of diabetes

et al. 2020

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Aims/hypothesis We determined whether empagliflozin altered renal sympathetic nerve activity (RSNA) and baroreflexes in a diabetes model in conscious rabbits. Methods Diabetes was induced by alloxan, and RSNA, mean arterial pressure (MAP) and heart rate were measured before and after 1 week of treatment with empagliflozin, insulin, the diuretic acetazolamide or the ACE inhibitor perindopril, or no treatment, in conscious rabbits. Results Four weeks after alloxan administration, blood glucose was threefold and MAP 9% higher than non-diabetic controls (p < 0.05). One week of treatment with empagliflozin produced a stable fall in blood glucose (−43%) and increased water intake (+49%) but did not change RSNA, MAP or heart rate compared with untreated diabetic rabbits. The maximum RSNA to hypotension was augmented by 75% (p < 0.01) in diabetic rabbits but the heart rate baroreflex was unaltered. Empagliflozin and acetazolamide reduced the augmentation of the RSNA baroreflex (p < 0.05) to be similar to the non-diabetic group. Noradrenaline (norepinephrine) spillover was similar in untreated diabetic and non-diabetic rabbits but twofold greater in empagliflozin-and acetazolamide-treated rabbits (p < 0.05). Conclusions/interpretation As empagliflozin can restore diabetes-induced augmented sympathetic reflexes, this may be beneficial in diabetic patients. A similar action of the diuretic acetazolamide suggests that the mechanism may involve increased sodium and water excretion.

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Comparing spectral and invasive estimates of baroreflex gain

Cited by 34 publications

References 46 publications

Cardiovascular Autonomic Regulation in Preterm Infants: The Effect of Atropine

Cardiovascular Autonomic Regulation in Preterm Infants: The Effect of Atropine

Aromatase-Deficient (ArKO) Mice Have Reduced Blood Pressure and Baroreflex Sensitivity

Empagliflozin modulates renal sympathetic and heart rate baroreflexes in a rabbit model of diabetes

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