Impulse response analysis of baroreceptor sensitivity

Panerai, R.B.; James, Martin; Potter, JF

doi:10.1152/ajpheart.1997.272.4.h1866

Cited by 20 publications

(24 citation statements)

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“…A coherence value Ͼ0.40 was considered significant. 22 Recordings with an ectopy rate Ͼ2% were rejected. Spikes on the resampled tracings of the PI and SBP recordings were manually removed, and a straight line was interpolated by the computer, although resampled tracings with Ͼ4 spikes were excluded from subsequent analysis to avoid bias.…”

Section: Discussionmentioning

confidence: 99%

Cardiac Baroreceptor Sensitivity Predicts Long-Term Outcome After Acute Ischemic Stroke

Robinson¹,

Dawson²,

Eames³

et al. 2003

Stroke

204

173

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Background and Purpose-The baroreceptor reflex arc is important in the short-term regulation of the cardiovascular system, and small studies have reported impaired cardiac baroreceptor sensitivity (BRS) after acute stroke. However, the prognostic significance of impaired BRS is uncertain. Methods-One hundred twenty-four patients underwent simultaneous ECG and noninvasive beat-to-beat blood pressure (BP) monitoring within 72 hours of neuroradiologically confirmed acute ischemic stroke. Cardiac BRS was assessed from the combined ␣-index by means of power spectral analysis techniques. Baseline data for acute stroke patients were compared with those of a control group matched for age, sex, and casual BP. Patients were followed up for a median of 1508 days (range, 9 to 2656 days), and outcome was compared between patients with and without impaired BRS. Results-Median

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Section: Discussionmentioning

confidence: 99%

Cardiac Baroreceptor Sensitivity Predicts Long-Term Outcome After Acute Ischemic Stroke

Robinson¹,

Dawson²,

Eames³

et al. 2003

Stroke

204

173

View full text Add to dashboard Cite

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“…The peak value of the inverse Fourier transform of the cross-spectral transfer function between R-R interval and systolic pressure was derived for this index. 29,30 Also calculated from the 15 minutes of resting R-R interval data was respiratory sinus arrhythmia. Although cardiac vagal outflow is crucial for nearly all frequencies of heart rate variability, 31 phasic vagal modulation with respiration produces an oscillation proportional to the mean level of cardiac vagal outflow.…”

Section: Discussionmentioning

confidence: 99%

“…It is surprising, considering their broad use, that others before us have reported poor agreement of these purported indices with classic measures of baroreflex gain. 30,45,62,65,66 Moreover, it appears that the agreement progressively worsens from healthy individuals to those with mild and more severe cardiovascular disease, 63,67 the very population for whom baroreflex assessment is most clinically relevant.…”

Section: Lipman Et Al Spontaneous Baroreflex Indices 485mentioning

confidence: 99%

Spontaneous Indices Are Inconsistent With Arterial Baroreflex Gain

2003

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Abstract-Spontaneously occurring, parallel fluctuations in arterial pressure and heart period are frequently used as indices of baroreflex function. Despite the convenience of spontaneous indices, their relation to the arterial baroreflex remains unclear. Therefore, in 97 volunteers, we derived 5 proposed indices (sequence method, ␣-index, transfer function, low-frequency transfer function, and impulse response function), compared them with arterial baroreflex gain (by the modified Oxford pharmacologic technique), and examined their relation to carotid distensibility and respiratory sinus arrhythmia. The subjects comprised men and women (nϭ41) aged 25 to 86 years, 30% of whom had established coronary artery disease. Generally, the indices were correlated with each other (except ␣-index and low-frequency transfer function) and with baroreflex gain. However, the Bland-Altman method demonstrated that the spontaneous indices had limits of agreement as large as the baroreflex gain itself. Even in individuals within the lowest tertile of baroreflex gain for whom baroreflex gain appears to be the most clinically relevant, spontaneous indices failed to relate to baroreflex gain. In fact, for these individuals, there was no correlation between any index and baroreflex gain. Forward stepwise linear regression showed that all spontaneous indices and baroreflex gain were related to respiratory sinus arrhythmia, but only baroreflex gain was related to carotid distensibility. Therefore, these data suggest that spontaneous indices are inadequate estimates of gain and are inconsistent with arterial baroreflex function. Key Words: baroreceptors Ⅲ carotid sinus Ⅲ elasticity Ⅲ arrhythmia Ⅲ baroreflex T he arterial baroreflex is a key mechanism for blood pressure homeostasis, is clinically relevant as a predictor of cardiovascular mortality, 1 and is physiologically relevant as an indicator of autonomic control. 2 The sensitivity, or gain, of the arterial baroreflex is calculated routinely from the relation of bradycardic and/or tachycardic responses to increases and/or decreases in systemic arterial pressure. 3 These responses encompass both mechanical and neural aspects of the system. Changes in pressure result in stretch of the aortic arch and the carotid sinus, wherein stretch-sensitive receptors reside. These afferent baroreceptive neurons terminate in the dorsomedial medulla, which in turn signals the neurons composing the efferent autonomic limb of the baroreflex. The resultant cardiac vagal adjustments appropriately regulate heart period to buffer against pressure rises and falls. 2 Arterial baroreflex physiology dictates that both barosensory vessel distensibility and cardiac vagal function critically determine reflex sensitivity. Indeed, a relation between baroreflex gain and carotid stiffness has been shown in healthy young and middle-aged subjects, 4 as well as in hypertensive individuals. 5 Additionally, in patients with coronary disease 6,7 and diabetes, 8,9 both gain and carotid distensibility are prognostically rele...

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“…It is similar to the correlation coefficient, with a range of 0 (no relation) to 1.0 (very strongly correlated). A value for squared coherence that is significantly <0.5 reflects too much signal noise or an output that is more dependent on variables other than blood pressure input [13,14]. If there were to be a difference in phase with age and good coherence, this would give important information on baroreceptor activity with age.…”

Section: Introductionmentioning

confidence: 99%

“…Our aims were to assess individual and combined influences of age, blood pressure and other factors on the cardiac BRS measurements derived from spectral analysis, phase IV of the Valsalva manoeuvre and the newer impulse response function (IRF) technique [14]. IRF is similar to spectral analysis but examines data in the time domain.…”

Section: Introductionmentioning

confidence: 99%

Older subjects show no age-related decrease in cardiac baroreceptor sensitivity

Dawson

Robinson²,

Youde³

et al. 1999

Age and Ageing

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Objective: to examine the relationship between age, blood pressure and cardiac baroreceptor sensitivity derived from spectral analysis, the Valsalva manoeuvre and impulse response function. Methods: we studied 70 healthy normotensive volunteers who were free from disease and not taking medication with cardiovascular or autonomic effects. We measured beat-to-beat arterial blood pressure and used standard surface electrocardiography to record pulse interval under standardized conditions with subjects resting supine as well as during three Valsalva manoeuvres. We performed single, multiple and stepwise regression of patient characteristics against cardiac baroreceptor sensitivity results. Results: there is a non-linear decline in cardiac baroreceptor sensitivity with advancing age, increasing systolic blood pressure and heart rate values (except for the Valsalva-derived result), but little further decline after the fourth decade. Only age significantly influenced values derived using the Valsalva manoeuvre and impulse response analysis. Using spectral analysis, age, systolic and diastolic blood pressure and heart rate influenced cardiac baroreceptor sensitivity, age contributing to 50% of the variability. Age also influenced the relationship between pulse interval and blood pressure, possibly indicating more non-baroreceptor-mediated changes with advancing age. Conclusions: although age is the dominant factor influencing cardiac baroreceptor sensitivity in this normotensive population, there is little change in mean values after 40 years of age. The differences in the relationship between pulse interval and blood pressure with advancing age have implications for the calculation of cardiac baroreceptor sensitivity using spectral analysis.

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Impulse response analysis of baroreceptor sensitivity

Cited by 20 publications

References 0 publications

Cardiac Baroreceptor Sensitivity Predicts Long-Term Outcome After Acute Ischemic Stroke

Cardiac Baroreceptor Sensitivity Predicts Long-Term Outcome After Acute Ischemic Stroke

Spontaneous Indices Are Inconsistent With Arterial Baroreflex Gain

Older subjects show no age-related decrease in cardiac baroreceptor sensitivity

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