Journal Article•
How to measure baroreflex sensitivity
TL;DR: The use of vasoactive drugs and the analysis of spontaneously occurring changes in blood pressure and heart rate are described.
Abstract: In normal subjects arterial baroreflexes play a key role in short-term blood pressure adjustments to a variety of environmental stresses, thereby maintaining circulatory homeostasis. These responses are mediated by the sympathetic and parasympathetic nervous systems through their effects on heart rate, venous return, contractility and peripheral resistance. The evaluation of baroreflex sensitivity (BRS) has recently found unexpected exploitations as alterations in the baroreflex control of heart rate have been associated with an increased propensity for cardiac mortality and sudden cardiac death [1]. Among several quantitative approaches developed for evaluating BRS including the analysis of reflex responses to pharmacological or mechanical manipulations of baroreceptors, this article describes the use of vasoactive drugs and the analysis of spontaneously occurring changes in blood pressure and heart rate.
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TL;DR: This study is the first to indicate that harmful cardiovascular outcomes are related to depressive-like behaviors in susceptible rats and to suggest a mechanism by which resilient rats are protected from these changes, and suggests that enhanced HRV and vagal tone may be an important trait in resilient individuals.
16 citations
TL;DR: Results show that baroreflex gains derived from these 2 methods cannot be used interchangeably, and that cardiac barore Flex gain is frequency dependent between 0.03 Hz and 0.1 Hz, which challenges the conventional practice of summarizing barore flex gain as a single number.
Abstract: Cardiac baroreflex gain is usually quantified as the reflex alteration in heart rate during changes in blood pressure without considering the effect of the rate of change in blood pressure on the estimated gain. This study sought to (i) characterize baroreflex gain as a function of blood pressure oscillation frequencies using a repeat sit-to-stand method and (ii) compare baroreflex gain values obtained using the sit-to-stand method against the modified Oxford method. Fifteen healthy individuals underwent the repeated sit-to-stand method in which blood pressure oscillations were driven at 0.03, 0.05, 0.07, and 0.1 Hz. Sixteen healthy participants underwent the sit-to-stand and modified Oxford methods to examine their agreement. Sit-to-stand baroreflex gain was highest at 0.05 Hz (8.8 ± 3.2 ms·mm Hg(-1)) and lowest at 0.1 Hz (5.8 ± 3.0 ms·mm Hg(-1)). Baroreflex gains at 0.03 Hz (7.7 ± 3.0 ms·mm Hg(-1)) and 0.07 Hz (7.5 ± 3.3 ms·mm Hg(-1)) were not different from the baroreflex gain at 0.05 Hz. There was moderate correlation between phenylephrine gain and sit-to-stand gain (r values ranged from 0.52 to 0.75; all frequencies, p < 0.05), but no correlation between sodium nitroprusside gain and sit-to-stand gain (r values ranged from -0.07 to 0.22; all p < 0.05). Bland-Altman analysis of phenylephrine gain and sit-to-stand gain showed poor agreement and a positive proportional bias. These results show that baroreflex gains derived from these 2 methods cannot be used interchangeably. Furthermore, cardiac baroreflex gain is frequency dependent between 0.03 Hz and 0.1 Hz, which challenges the conventional practice of summarizing baroreflex gain as a single number.
13 citations
TL;DR: This review evaluated several prognostic models for acute, right, chronic, and end-stage heart failure based on multiple parameters and believes that multiparametric scores for risk assessment in heart failure are promising but their widespread use needs to be experienced.
Abstract: AIMS Heart failure is a widespread syndrome involving several organs, still characterized by high mortality and morbidity, and whose clinical course is heterogeneous and hardly predictable.In this scenario, the assessment of heart failure prognosis represents a fundamental step in clinical practice. A single parameter is always unable to provide a very precise prognosis. Therefore, risk scores based on multiple parameters have been introduced, but their clinical utility is still modest. METHODS In this review, we evaluated several prognostic models for acute, right, chronic, and end-stage heart failure based on multiple parameters. In particular, for chronic heart failure we considered risk scores essentially based on clinical evaluation, comorbidities analysis, baroreflex sensitivity, heart rate variability, sleep disorders, laboratory tests, echocardiographic imaging, and cardiopulmonary exercise test parameters. RESULTS What is at present established is that a single parameter is not sufficient for an accurate prediction of prognosis in heart failure because of the complex nature of the disease. However, none of the scoring systems available is widely used, being in some cases complex, not user-friendly, or based on expensive or not easily available parameters. CONCLUSION We believe that multiparametric scores for risk assessment in heart failure are promising but their widespread use needs to be experienced.
10 citations
TL;DR: Baroreceptor sensitivity (BRS) was more robustly responsive than other cardiovascular measures commonly used to assess the psychophysiological response to stress, suggesting BRS is a useful marker for evaluating operator functional state during psychological and physical tasks.
Abstract: Presently, adaptive systems use various cognitive and cardiovascular measures to evaluate the functional state of the operator One marker that has been largely ignored as an assessment tool is bar
7 citations
TL;DR: Routine measurement of resting HR in the clinical setting has become an accepted component of the cardiovascular risk profile assessment, and routine measurement of this variable has been recently included in screening strategies for the prevention of cardiovascular diseases.
Abstract: Clinical value of heart rate measured in and outside a clinic setting A large number of epidemiologic studies have shown that elevated resting heart rate (HR) is associated with a higher risk of developing hypertension and atherosclerosis and is a potent predictor of cardiovascular morbidity and mortality [1–6]. In some of these studies, the predictive power of HR for mortality was equal to or even greater than that of total cholesterol, smoking or systolic blood pressure (BP) [2,5]. The predictive power of HR for cardiovascular mortality was evident not only in general populations but also among individuals affected by myocardial infarction (MI), chronic coronary heart disease, diabetes, arterial hypertension or heart failure [7]. On the background of this data, resting HR obtained in the clinical setting has become an accepted component of the cardiovascular risk profile assessment, and routine measurement of this variable has been recently included in screening strategies for the prevention of cardiovascular diseases [8]. In most epidemiologic studies, resting HR was assessed by one or a few measurements taken in the medical environment. However, it is known that HR is a highly variable physiologic parameter, which is subjected to the influence of many environmental stimuli, including those typical of a clinic setting [9]. Several studies have shown that the medical environment elicits a rise in BP, leading office measurements to overestimate the usual BP of patients because of a ‘white-coat’ effect [10,11]. To overcome this problem, strategies for assessing BP out of the office have been devised, including both home and ambulatory BP monitoring. A rise during the medical visit has also been observed for resting HR, the patients’ reactions varying as a result of whether the measurement was carried out by a doctor or a nurse [10,11]. Thus, a few readings taken in a clinic
5 citations
References
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TL;DR: An alternative approach, based on graphical techniques and simple calculations, is described, together with the relation between this analysis and the assessment of repeatability.
43,884 citations
TL;DR: The ATRAMI study as discussed by the authors provides clinical evidence that after myocardial infarction the analysis of vagal reflexes has significant prognostic value independently of LVEF and ventricular arrhythmias and that it significantly adds to the prognosis value of heartrate variability.
2,950 citations
TL;DR: It is concluded that the baroreceptor reflex are can be rapidly reset, particularly during sleep, and the lower arterial pressures during sleep may be actively maintained in some subjects by increased baroreflex sensitivity.
Abstract: The control of arterial pressure during sleep was studied in 13 untreated, unsedated subjects aged 20 to 46, including 7 with hypertension. Arterial pressure was measured directly. A transient rise of arterial pressure up to 30 mm Hg was produced by the sudden intravenous injection of 0.25 to 2 µg of angiotensin. Linear plots were obtained in 10 of 13 subjects when the systolic pressures of successive pulses during the pressure rise were plotted against the pulse intervals which began the next beat. The relationship was disturbed by movement or arousal, and was better when pulse intervals falling in inspiration were discarded. The slope of the line (milliseconds of cardiac slowing per millimeter rise in systolic pressure) in the awake subject ranged from 2 to 15.5 msec/mm Hg, and from 4.5 to 28.9 during sleep. Reflex sensitivity was highest in dreaming sleep. In 7 of 10 subjects, baroreflex sensitivity increased significantly during sleep; in 6, the prevailing arterial pressure was inversely correlated wi...
1,297 citations
"How to measure baroreflex sensitivi..." refers background in this paper
...An increase in systemic arterial pressure increases the firing rate of baroreceptors which causes vagal excitation and sympathetic inhibition, thus decreasing heart rate; BRS can be quantified as the measure of the reflex bradycardia which follows the blood pressure rise induced by injection of an alpha-adrenoreceptor stimulant [2]....
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TL;DR: Baroreceptor-induced slowing of heart rate in normal subjects was shown to be mediated by the parasympathetic nervous system since it could be abolished with atropine.
Abstract: To define the state of the parasympathetic nervous system in heart failure, parasympathetic blockade with atropine was induced after adrenergic blockade with propranolol in 12 normal subjects and in nine patients with heart disease. Atropine elevated heart rate by 55 ± 9 per cent in normal subjects, but by only 23 ± 8 per cent in patients with heart disease (p less than 0.05). In 23 control subjects and 22 patients, transient elevations in arterial pressure were produced by intravenous injections of phenylephrine, and successive R-R intervals were plotted as a function of systolic pressure. The slowing of heart rate per unit rise in systolic arterial pressure averaged 16.0 ±1.8 msec per millimeter of mercury in normal subjects but only 3.70 ± 0.8 msec per millimeter of mercury in the patients (p less than 0.001). Baroreceptor-induced slowing of heart rate in normal subjects was shown to be mediated by the parasympathetic nervous system since it could be abolished with atropine. These findings poi...
963 citations
"How to measure baroreflex sensitivi..." refers background in this paper
...Cardiovascular disease may alter baroreceptor function, primarily because of a decreased capability to activate vagal reflexes [6]....
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TL;DR: Beat-to-beat blood pressure recording via FINAPRES provides an accurate estimate of means and variability of radial blood pressure in groups of subjects and represents in most cases an acceptable alternative to invasive blood pressure monitoring during laboratory studies.
Abstract: The accuracy of blood pressure values obtained by continuous noninvasive finger blood pressure recording via the FINAPRES device was evaluated by comparison with simultaneous intraarterial monitoring both at rest and during performance of tests known to induce fast and often marked changes in blood pressure. The comparison was performed in 24 normotensive or essential hypertensive subjects. The average discrepancy between finger and intra-arterial blood pressure recorded over a 30-minute rest period was 6.5 +/- 2.6 mm Hg and 5.4 +/- 2.9 mm Hg for systolic and diastolic blood pressure, respectively; a close between-method correspondence was also demonstrated by linear regression analysis. The beat-to-beat changes in finger systolic and diastolic blood pressure were on average similar to those measured intra-arterially during tests that induced a pressor or depressor response (hand-grip, cold pressor test, diving test, Valsalva maneuver, intravenous injections of phenylephrine and trinitroglycerine) as well as during tests that caused vasomotor changes without major variations in blood pressure (application of lower body negative pressure, passive leg raising). The average between-method discrepancy in the evaluation of blood pressure changes was never greater than 4.3 and 2.0 mm Hg for systolic and diastolic blood pressure, respectively; the corresponding standard deviations ranged between 4.6 and 1.6 mm Hg. Beat-to-beat computer analysis of blood pressure variability over the 30-minute rest period provided standard deviations almost identical when calculated by separate consideration of intra-arterial and finger blood pressure tracings (3.7 and 3.8 mm Hg, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)
945 citations
"How to measure baroreflex sensitivi..." refers methods in this paper
...Estimates of BRS are very similar when SAP is measured directly from the radial or brachial artery or from a noninvasive pressure monitor [3, 4]....
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