Baroreflex Sensitivity In Patients Research Articles

Diabetic Neuropathy Is a More Important Determinant of Baroreflex Sensitivity Than Carotid Elasticity in Type 2 Diabetes

The object of this study was to evaluate the contribution of carotid distensibilty on baroreflex sensitivity in patients with type 2 diabetes mellitus with at least 2 additional cardiovascular risk factors. Carotid distensibility was measured bilaterally at the common carotid artery in 79 consecutive diabetic patients and 60 matched subjects without diabetes. Spontaneous baroreflex sensitivity assessment was obtained using time and frequency methods. Baroreflex sensitivity was lower in diabetic subjects as compared with nondiabetic control subjects (5.25+/-2.80 ms/mm Hg versus 7.55+/-3.79 ms/mm Hg; P<0.01, respectively). Contrary to nondiabetic subjects, diabetic subjects showed no significant correlation between carotid distensibility and baroreflex sensitivity (r2=0.08, P=0.04 and r2=0.04, P=0.13, respectively). In diabetic subjects, baroreflex sensitivity was significantly lower in subjects with peripheral neuropathy than in those with preserved vibration sensation (4.1+/-0.5 versus 6.1+/-0.4 ms/mm Hg, respectively; P=0.005). Age in nondiabetic subjects, diabetes duration, systolic blood pressure, peripheral or sensitive neuropathy, and carotid distensibility were introduced in a stepwise multivariate analysis to identify the determinants of baroreflex sensitivity. In diabetic patients, neuropathy is a more sensitive determinant of baroreflex sensitivity than the reduced carotid distensibility (stepwise analysis; F ratio=5.1, P=0.028 versus F ratio=1.9, P=0.16, respectively). In diabetic subjects with 2 additional cardiovascular risk factors, spontaneous baroreflex sensitivity is not related to carotid distensibility. Diabetic subjects represent a particular population within the spectrum of cardiovascular risk situations because of the marked neuropathy associated with their metabolic disorder. Therefore, neuropathy is a more significant determinant of baroreflex sensitivity than carotid artery elasticity in patients with type 2 diabetes.

Carotid Artery Elasticity and Baroreflex Sensitivity in Patients With Glaucoma

To investigate non-invasively the elasticity of common carotid artery and the arterial baroreflex function in patients with chronic open-angle glaucoma. Data were obtained from patients with chronic open-angle glaucoma (n = 16) [primary open angle- and juvenile open-angle glaucoma] and from age- and sex-matched healthy control subjects (n = 18). End diastolic diameter and pulsatile distension of the common carotid artery were measured with a high-precision, automated ultrasound wall-tracking system (WTS). Spontaneous fluctuation in cardiac interval and systolic pressure were used to determine baroreflex sensitivity. There was no difference in heart rate and pulse pressure between patients with glaucoma and the control subjects. In the glaucoma patients both distensibility coefficient of common carotid artery and baroreflex sensitivity were reduced (two-way factorial ANOVA; P < 0.002). Stiffness (characterizing the rigidity of vessel wall) was higher in the glaucoma patients than in the controls (P = 0.002). Our results suggest that in patients with chronic open-angle glaucoma the arterial rigidity is significantly increased and therefore the baroreflex function is significantly decreased. These findings may have relevance in the understanding of the autonomic dysfunction and vascular dysregulation in glaucoma.

Influence of exercise training on cardiac baroreflex sensitivity in patients with COPD.

Decreased spontaneous cardiac baroreflex sensitivity (BRS), which could lead to the onset of cardiovascular events, has been demonstrated in chronic obstructive pulmonary disease patients. This study evaluates the effects of an exercise training programme on BRS. Twenty-one chronic obstructive pulmonary disease patients (mean+/-SD age 62+/-9 yrs; forced expiratory volume in one second 43.6+/-18.1% of the predicted value) with mild hypoxaemia (arterial oxygen tension 8.96+/-1.18 kPa) were compared to 18 healthy age-matched subjects. BRS was calculated as the slope of the baroreflex sequences between spontaneous changes in systolic blood pressure and subsequent consecutive relative risk deviation length, and was measured in the supine position and following head-up tilt for sympathetic stimulation. Pulmonary function test results and blood gas levels, measured only in patients, did not change after the training programme. Exercise training increased the maximal sustained workload (16.5%) and peak oxygen consumption (20.5%). Before training, BRS was lower in patients than in controls (2.7+/-1.5 versus 7.8+/-4.9 ms x mmHg(-1)) and tilting induced a smaller reduction in BRS (13 versus 34%). After training, BRS increased to 3.4+/-2.6 ms x mmHg(-1) in patients but remained lower than in controls. The response to the tilt test remained unchanged after training. It is concluded that, in chronic obstructive pulmonary disease patients, exercise training is associated with a gain in spontaneous baroreflex sensitivity, reflecting cardiovascular benefits.

1009-196 Acute arterio-venous fistula occlusion reduces sympathetic nerve traffic and increases baroreflex sensitivity in patients with kidney transplant

1009-196 Acute arterio-venous fistula occlusion reduces sympathetic nerve traffic and increases baroreflex sensitivity in patients with kidney transplant

Increased hypoxic blood pressure response in patients with amyotrophic lateral sclerosis

Objectives: There is evidence of impaired cardiovascular autonomic control and reduced baroreflex sensitivity in patients with amyotrophic lateral sclerosis (ALS). A compromised baroreflex–chemoreflex interaction might result in inadequate responses to chemoreflex activation with progressive hypercapnia and hypoxia and contribute to early fatalities. This study was performed to assess cardiovascular and ventilatory responses to hypercapnic and hypoxic stimulation in ALS patients with impaired baroreflex function. Patients and methods: In 15 ALS patients with previously demonstrated baroreflex dysfunction and in 15 age-matched controls, we compared electrocardiographic RR-interval (RRI), systolic blood pressure (SBP) and minute ventilation (VE) during normal ventilation and during selective progressive hypoxia and hypercapnia. Results: Ventilatory and RRI responses to hypoxic and hypercapnic stimulation as well as SBP responses to hypercapnia did not differ between patients and controls. In contrast, hypoxia induced a significant SBP increase in patients only. Conclusions: The normal ventilatory and RRI responses to chemoreflex activation suggest intact afferent chemoreflex function. The hypertensive response to hypoxia might be due to a compromised interaction with the baroreflex. Avoiding hypoxic episodes might reduce the risk of cardiovascular crisis in ALS patients.

SYMPATHETIC NEURAL OUTFLOW IN PATIENTS WITH CORONARY ARTERY DISEASE

PURPOSE: Baroreflex sensitivity is an important prognostic indicator in patients with coronary artery disease (CAD) and can be used for risk stratification. However, despite sizable research examining cardiovagal baroreflex sensitivity in patients with CAD, to our knowledge no data have examined baroreflex control of vascular sympathetic outflow. HYPOTHESIS: We hypothesized that patients with CAD would have higher resting sympathetic outflow but preserved baroreflex-mediated control of vascular sympathetic nerve activity. METHODS: Four normotensive patients with documented CAD (age 56 ± 3 yrs) and 5 control subjects (63 ± 3 yrs) were studied. Patients were weaned from all cardioactive medications prior to data collection. Sympathetic activity was assessed at rest and during the modified Oxford technique (sequential I.V. bolus of nitroprusside and phenylephrine) while R-R interval (ECG), beat-by-beat blood pressure (Finapres), and muscle sympathetic nerve activity from the peroneal nerve (microneurography) were recorded. RESULTS: Baseline muscle sympathetic nerve activity was 44% higher in patients compared to controls (61 vs. 42 bursts/100 heart beats, p = 0.09). Preliminary analysis indicates that sympathetic baroreflex sensitivity was similar between groups (−6.0 ± 0.73 vs. −7.4 ± 1.38 AIU per beat/mmHg, p = NS). CONCLUSION: Baseline muscle sympathetic nervous activity tends to be higher and sympathetic baroreflex sensitivity preserved in this small group of subjects with documented CAD. Supported by an ACSM Foundation Research Endowment Grant from the ACSM Foundation and F32 HL10211 (to W.B.F.), and R29 AG14376 (to J.A.T.)

Advanced analysis of spontaneous baroreflex sensitivity, blood pressure and heart rate variability in patients with dilated cardiomyopathy

Baroreflex sensitivity (BRS) is an important parameter in the classification of patients with reduced left ventricular function. This study aimed at investigating BRS in patients with dilated cardiomyopathy (DCM) and in healthy subjects (controls), as well as comparing the values of BRS parameters with parameters of heart rate variability (HRV) and blood pressure variability (BPV). ECG, continuous blood pressure and respiration curves were recorded for 30 min in 27 DCM patients and 27 control subjects. The Dual Sequence Method (DSM) includes the analysis of spontaneous fluctuations in systolic blood pressure and the corresponding beat-to-beat intervals of heart rate to estimate bradycardic, opposite tachycardic and delayed baroreflex fluctuations. The number of systolic blood pressure/beat-to-beat interval fluctuations in DCM patients was reduced in comparison with controls (DCM patients: male, 154.4+/-93.9 ms/mmHg; female, 93.7+/-40.5 ms/mmHg; controls: male, 245.5+/-112.9 ms/mmHg; female, 150.6+/-55.8 ms/mmHg, P<0.05). The average slope in DCM patients was lower than in controls (DCM, 5.3+/-1.9 ms/mmHg; controls, 8.0+/-5.4 ms/mmHg; P<0.05). Discriminant function analysis showed that, in the synchronous range of the standard sequence method, the DCM and control groups could be discriminated to only 76% accuracy, whereas the DSM gave an improved accuracy of 84%. The combination of six parameters of HRV, BPV and DSM gives an accuracy of classification of 96%, whereas six parameters of HRV and BPV could separate the two groups to only 88% accuracy. Thus the DSM leads to an improved characterization of autonomous regulation in order to differentiate between DCM patients and healthy subjects. BRS in DCM patients is significantly reduced and apparently less effective.

Percutaneous transluminal mitral valvuloplasty improves cardiopulmonary baroreflex sensitivity in patients with mitral stenosis

Patients with heart failure frequently have increased sympathetic tone, which could result in part from impairment of the inhibitory influence of cardiopulmonary baroreflexes. Percutaneous transluminal mitral valvuloplasty (PTMV) provides a unique model for evaluating functional changes in cardiopulmonary baroreflexes without open-heart surgical manipulation. We examined the effects of PTMV on cardiopulmonary baroreflexes and sympathetic nerve activity in 10 patients with mitral stenosis. We measured muscle sympathetic nerve activity using microneurography. Cardiopulmonary baroreflex provocation was performed by applying a lower body negative pressure of −10 mm Hg, and its sensitivity was determined by dividing the percent change in muscle sympathetic nerve activity by the change in central venous pressure. Response to isometric exercise was assessed by handgrip at 30% of maximal voluntary contraction for 3 min. PTMV significantly increased mitral valve area and cardiac index and decreased mean left atrial pressure. PTMV significantly decreased burst rate from 25.1±2.5 to 15.6±2.6 bursts/min ( p<0.01) and burst incidence from 37.1±3.7 to 23.6±3.3 bursts/100 heart beats ( p<0.01). After PTMV, cardiopulmonary baroreflex sensitivities measured using burst rate and burst incidence were −39.9±4.9%/mm Hg and −38.7±6.2%/mm Hg, respectively, which were significantly steeper than those before PTMV (−9.2±1.1%/mm Hg and −8.4±1.1%/mm Hg; p<0.01). There were significant correlations between muscle sympathetic nerve activity at rest and cardiopulmonary baroreflex sensitivity. PTMV did not affect muscle sympathetic responses to handgrip exercise. These results suggest that patients with mitral stenosis have baseline sympathetic nerve activation, which could result in part from impaired cardiopulmonary baroreflexes.

Depressed baroreflex sensitivity in patients with Alzheimer's and Parkinson's disease.

Parkinson's disease (PD) and Alzheimer's dementia (AD) are often associated with an autonomic neuropathy. The extent of autonomic involvement, however is poorly defined and unpredictable. In order to assess the autonomic cardiovascular regulation baroreflex sensitivity (BRS) was determined non-invasively in 23 patients (age: 65 +/- 9.3 years) with PD and 24 patients with AD (age: 72.3 +/- 7.2 years). The results were compared with those on 22 healthy age- and sex-matched volunteers. Patients with PD and AD exhibited marked abnormalities in cardiovascular autonomic reflex regulation showed by markedly depressed BRS. The possible predictive value of centrally based depression of baroreflex sensitivity necessitates further studies.

EFFECTS OF A RESIDENTIAL EXERCISE TRAINING ON BAROREFLEX SENSITIVITY AND HEART RATE VARIABILITY IN PATIENTS WITH CORONARY ARTERY DISEASE: A RANDOMIZED, CONTROLLED STUDY

Background—Myocardial ischemia and infarction impair baroreflex sensitivity (BRS), which when depressed is predictive of future cardiac events after myocardial infarction (MI). The main objective of this study was to determine whether exercise training improves BRS in patients with coronary artery disease. Methods and Results—Ninety-seven male patients with and without a previous MI were recruited after myocardial revascularization surgery and randomized into trained (TR) or untrained (UTR) groups. TR patients underwent a residential exercise program at 85% of maximum heart rate (HRmax) consisting of 2 daily sessions 6 times a week for 2 weeks. Eighty-six patients (45 TR and 41 UTR) completed the study. BRS was assessed at baseline and at the end of the protocol by the spontaneous baroreflex method. The standard deviation of mean R-R interval (RRSD) was also assessed as a measure of heart rate variability. At baseline, there were no significant differences between TR and UTR patients in any variable. In T...

Effects of noradrenaline on human vagal baroreflexes

BACKGROUND. Baroreflex sensitivity (BRS) is depressed in conditions associated with high sympathetic nerve activity in proportion to circulating noradrenaline (NA) levels. Despite the prognostic importance of measurements of BRS in patients, there is little information on how high NA levels affect arterial baroreflex function.AIM. To understand better the role of NA in cardiovascular homeostasis.METHODS. We gave incremental intravenous NA infusions (at 50 and 100 ng/kg/min) to 12 healthy young men. We measured RR intervals and photoplethysmographic arterial pressures and estimated BRS with cross-spectral and sequence methods during metronome-guided respiration at 0.25 Hz.RESULTS. The high NA infusion rate significantly increased respiratory-frequency (0.15-0.40 Hz) RR interval spectral power and decreased low-frequency (0.04-0.15 Hz) systolic pressure spectral power compared with baseline levels (P < 0.05 for both). Cross-spectral BRS increased from an average (± SD) baseline level of 17.3 ± 6.6 to 34.1 ± 20.8 msJmmHg at the high NA infusion rate (P < 0.05). Sequence BRS values did not increase significantly during NA infusions. The percentage of sequences with parallel changes in systolic pressures and RR intervals decreased progressively from a baseline level of 16.0 ± 12.9 to 10.1 ± 7.4 during the low NA infusion rate and to 6.2 ± 6.2% during the high rate (P < 0.05 and 0.01, respectively).CONCLUSIONS. Increases in circulating NA to high physiological levels do not depress BRS but interfere with the close baroreflex-mediated coupling that is usually present between arterial pressure and heart rate.

Assessment of baroreflex sensitivity in patients with preserved and impaired left ventricular function by means of the Valsalva manoeuvre and the phenylephrine test

The purpose of the present study was to assess the agreement between measurements of baroreflex sensitivity (BRS) obtained by the Valsalva manoeuvre and by the phenylephrine test in patients with previous myocardial infarction and different degrees of left ventricular dysfunction. Patients with a previous myocardial infarction were enrolled consecutively into two groups according to their left ventricular ejection fraction (LVEF): <or=40% (n=52) or >40% (n=52). All patients underwent BRS assessment by the phenylephrine technique (Phe-BRS) and by the Valsalva manoeuvre, with the latter using both the overshoot part of phase IV (Ov-VM-BRS) and the whole of phase IV (IV-VM-BRS). The linear association between methods was assessed by correlation analysis and the agreement was evaluated by computing the bias and the limits of agreement. IV-VM-BRS and Ov-VM-BRS could not be computed in 26% and 39% of patients respectively. For both indices a much higher percentage of non-computable Valsalva manoeuvre slopes was found in the group of patients with LVEF <or=40%. Phe-BRS was significantly lower in patients with non-computable Valsalva manoeuvre slopes; 55% and 59% of patients with non-computable Ov-VM-BRS and IV-VM-BRS respectively had a markedly depressed Phe-BRS (i.e. <3 ms/mmHg, as defined by the ATRAMI study). On comparing Phe-BRS and Ov-VM-BRS in patients with LVEF <or=40%, we obtained the following results: r=0.75 (P<0.001), bias=0.5 ms/mmHg (P=0.5) and limits of agreement from -6.7 to 7.8 ms/mmHg. In patients with LVEF >40% the results were: r=0.91 (P<0.001), bias=0.1 ms/mmHg (P=0.84) and limits of agreement from -4.8 to 5 ms/mmHg. When comparing Phe-BRS and IV-VM-BRS, we found r=0.67 (P=0.001), bias=-1.5 ms/mmHg (P=0.06) and limits of agreement from -8.8 to 5.7 ms/mmHg in the group of patients with LVEF <or=40%; and r=0.66 (P<0.001), bias=-3.1 ms/mmHg (P<0.001) and limits of agreement from -12.1 to 5.9 ms/mmHg in the group of patients with LVEF >40%. Dichotomizing Ov-VM-BRS, the best cut-off value to identify patients with a Phe-BRS of <3 ms/mmHg was found to be 7 ms/mmHg, giving 100% sensitivity and 69% specificity. In conclusion, estimation of BRS by the Valsalva manoeuvre in post-myocardial infarction patients is limited by a large number of non-measurable results. When computable, measurements are well correlated with those obtained by Phe-BRS, but, because of large limits of agreement, the two methods cannot be used interchangeably. If used as a screening test for risk stratification, the Valsalva manoeuvre could reduce by about one-third the need for phenylephrine injection.

Assessment of baroreflex sensitivity in patients with preserved and impaired left ventricular function by means of the Valsalva manoeuvre and the phenylephrine test

The purpose of the present study was to assess the agreement between measurements of baroreflex sensitivity (BRS) obtained by the Valsalva manoeuvre and by the phenylephrine test in patients with previous myocardial infarction and different degrees of left ventricular dysfunction. Patients with a previous myocardial infarction were enrolled consecutively into two groups according to their left ventricular ejection fraction (LVEF): <or=40% (n=52) or >40% (n=52). All patients underwent BRS assessment by the phenylephrine technique (Phe-BRS) and by the Valsalva manoeuvre, with the latter using both the overshoot part of phase IV (Ov-VM-BRS) and the whole of phase IV (IV-VM-BRS). The linear association between methods was assessed by correlation analysis and the agreement was evaluated by computing the bias and the limits of agreement. IV-VM-BRS and Ov-VM-BRS could not be computed in 26% and 39% of patients respectively. For both indices a much higher percentage of non-computable Valsalva manoeuvre slopes was found in the group of patients with LVEF <or=40%. Phe-BRS was significantly lower in patients with non-computable Valsalva manoeuvre slopes; 55% and 59% of patients with non-computable Ov-VM-BRS and IV-VM-BRS respectively had a markedly depressed Phe-BRS (i.e. <3 ms/mmHg, as defined by the ATRAMI study). On comparing Phe-BRS and Ov-VM-BRS in patients with LVEF <or=40%, we obtained the following results: r=0.75 (P<0.001), bias=0.5 ms/mmHg (P=0.5) and limits of agreement from -6.7 to 7.8 ms/mmHg. In patients with LVEF >40% the results were: r=0.91 (P<0.001), bias=0.1 ms/mmHg (P=0.84) and limits of agreement from -4.8 to 5 ms/mmHg. When comparing Phe-BRS and IV-VM-BRS, we found r=0.67 (P=0.001), bias=-1.5 ms/mmHg (P=0.06) and limits of agreement from -8.8 to 5.7 ms/mmHg in the group of patients with LVEF <or=40%; and r=0.66 (P<0.001), bias=-3.1 ms/mmHg (P<0.001) and limits of agreement from -12.1 to 5.9 ms/mmHg in the group of patients with LVEF >40%. Dichotomizing Ov-VM-BRS, the best cut-off value to identify patients with a Phe-BRS of <3 ms/mmHg was found to be 7 ms/mmHg, giving 100% sensitivity and 69% specificity. In conclusion, estimation of BRS by the Valsalva manoeuvre in post-myocardial infarction patients is limited by a large number of non-measurable results. When computable, measurements are well correlated with those obtained by Phe-BRS, but, because of large limits of agreement, the two methods cannot be used interchangeably. If used as a screening test for risk stratification, the Valsalva manoeuvre could reduce by about one-third the need for phenylephrine injection.

Effects of a Residential Exercise Training on Baroreflex Sensitivity and Heart Rate Variability in Patients With Coronary Artery Disease

Myocardial ischemia and infarction impair baroreflex sensitivity (BRS), which when depressed is predictive of future cardiac events after myocardial infarction (MI). The main objective of this study was to determine whether exercise training improves BRS in patients with coronary artery disease. Ninety-seven male patients with and without a previous MI were recruited after myocardial revascularization surgery and randomized into trained (TR) or untrained (UTR) groups. TR patients underwent a residential exercise program at 85% of maximum heart rate (HRmax) consisting of 2 daily sessions 6 times a week for 2 weeks. Eighty-six patients (45 TR and 41 UTR) completed the study. BRS was assessed at baseline and at the end of the protocol by the spontaneous baroreflex method. The standard deviation of mean R-R interval (RRSD) was also assessed as a measure of heart rate variability. At baseline, there were no significant differences between TR and UTR patients in any variable. In TR patients, BRS increased from 3.0+/-0.3 to 5.3+/-0.7 ms/mm Hg (P:<0.001), RRSD from 18.7+/-1.4 to 23.6+/-1.6 ms (P:<0.01), and R-R interval from 792. 0+/-15.5 to 851.3+/-20.5 ms (P:<0.001). No significant changes occurred in UTR patients. Increases in BRS and RRSD were significant in patients either with or without a previous MI. Exercise training increases BRS and heart rate variability in patients with coronary artery disease. Improved cardiac autonomic function might add to the other benefits of exercise training in secondary prevention of ischemic heart disease.

Effect of angiotensin-converting enzyme inhibitor on cardiopulmonary baroreflex sensitivity in patients with acute myocardial infarction

We evaluated the effect of angiotensin-converting enzyme inhibition (quinapril) on cardiopulmonary baroreflex sensitivity in 30 patients with uncomplicated myocardial infarction (quinapril group, 15 patients; placebo group, 15 patients) at 5 and 10 days after the onset of myocardial infarction. This study indicates that quinapril improved cardiopulmonary baroreflex and thus reduced sympathetic outflow in patients with acute myocardial infarction.

Reproducibility of methods for assessing baroreflex sensitivity in normal controls and in patients with chronic heart failure

Baroreflex sensitivity (BRS) conveys useful prognostic information in patients with heart disease, yet methods for its quantification suffer from poor reproducibility and test failure in some patients with heart failure. We set out to compare the short-term reproducibility and success rate of four different methods of assessing BRS in normal subjects and patients with chronic heart failure (CHF). A total of 31 patients with CHF and 18 normal controls underwent BRS testing using four techniques: (1) bolus phenylephrine (BRS(Phe)), (2) alpha-index in both low- and high-frequency bands (BRS(alphaLF) and BRS(alphaHF) respectively), (3) the sequence method (BRS(Seq)), and (4) a new 0.1 Hz controlled-breathing, time-domain analysis method (BRS(Cbr)). Each subject underwent two test episodes with each method on the same day. The average values for BRS in patients and controls respectively were: BRS(Phe), 4.4 (+/-4.4) ms/mmHg and 19.8 (+/-11.5) ms/mmHg; BRS(alphaLF), 5.6 (+/-4.1) ms/mmHg and 15.4 (+/-5.0) ms/mmHg; BRS(alphaHF), 7.1 (+/-7.0) ms/mmHg and 25.1 (+/-8.3) ms/mmHg; BRS(Seq), 7.7 (+/-6.3) ms/mmHg and 22.5 (+/-8.4) ms/mmHg; BRS(Cbr), 6.6 (+/-5.9) ms/mmHg and 22.8 (+/-10.8) ms/mmHg. The coefficients of variation (S.D. of the difference in repeated values divided by mean) in patients and controls respectively were: BRS(Phe), 85.6% and 52.2%; BRS(alphaLF), 65.9% and 33.7%; BRS(alphaHF), 99.7% and 52. 1%; BRS(Seq), 30.7% and 40.4%; BRS(Cbr), 30.7% and 19.6%. The numbers of test failures in patients were: BRS(Phen), 15; BRS(alphaLF), 7; BRS(alphaHF), 5; BRS(Seq), 14; BRS(Cbr), 1. Of the four techniques assessed for measuring BRS, the controlled breathing time-domain method yielded the best reproducibility and lowest failure rate in controls and in patients with CHF.

Dual sequence method for analysis of spontaneous baroreceptor reflex sensitivity in patients with dilated cardiomyopathy

The analysis of heart rate variability (HRV) and blood pressure variability (BPV) improves the characterization of patients with dilated cardiomyopathy (DCM). In this study we tested the hypothesis that patients with DCM and controls show a different behavior in the baroreflex (BR) regulation. In contrast to other methods, the new dual sequence method (DSM) analyzes the baroreflex sensitivity (BRS) as a response of the heart rate (interbeat interval, IBI) on dual spontaneous fluctuations of blood pressure (BP). The DSM includes the analysis of bradycardiac fluctuations (an increase of BP causes an increase of IBI) and tachycardiac fluctuations (decrease of BP causes a decrease of IBI) to obtain enhanced information about the sympathetic-vagal regulation. DCM patients show a 40-50% lower number of correlated blood pressure-heart rate fluctuations (DCM patients: male 154 +/- 93, female 93 +/- 40 vs. control group: m 245 +/- 112, f 150 +/- 55, p < 0.05). The BRS in DCM patients is significantly lower than in controls (5.2 +/- 1.9 vs. 8.0 +/- 5.4 (ms/mm Hg), p < 0.05). Using the DSM the discriminant function analysis (6 parameters) classifies correctly 84% of DCM patients and the control group. Using the classical sequence method, only 76% were correctly classified. The DSM is a useful method for analyzing the BRS based on the spontaneous BR to obtain an increased classification of patients with DCM. BRS in patients with DCM is significantly reduced and apparently more ineffective.

Noninvasive assessment of spontaneous baroreflex sensitivity in patients with liver cirrhosis.

An impairment of baroreceptor sensitivity has been found in liver cirrhosis. Noninvasive and spontaneous estimates of baroreflex sensitivity are obtained from beat-to-beat blood pressure and heart rate recordings by means of cross-spectrum analysis and calculation of alpha-index (as a measure of baroreflex gain). The aim of the present study was to investigate the function of the spontaneous baroreflex sensitivity related to clinical Child score in liver cirrhosis. The alpha-index was evaluated in 40 cirrhotic patients (18 with and 22 without ascites) and 17 healthy subjects by analysing finger arterial pressure recorded noninvasively with the Portapres device. Baroreflex sensitivity was significantly lower in cirrhotic patients with and without ascites compared with healthy subjects (p<0.01). Furthermore, in patients with ascites the baroreflex gain was significantly related to plasma sodium (p<0.01). A significant inverse relationship was present between baroreflex gain and grade of Child score and the severity of ascites (p<0.01). There were no significant relationships between hormonal parameters (catecholamines, renin, aldosterone, arginine-vasopressin, atrial natriuretic peptide and nitric oxide) and baroreflex gain. No significant differences were found between healthy subjects and cirrhotic patients with respect to systolic and diastolic blood pressure total variability in a supine position, whilst it was lower in cirrhotic patients with ascites in a tilted position (p<0.05). Our findings showed that baroreflex sensitivity was significantly impaired in cirrhotic patients when compared with healthy subjects. In addition, there was a significant trend toward lower baroreflex sensitivity values with the grade score of Child class (p<0.01). Spectral analysis of the alpha-index provides viable alternatives to the pharmacological approach for estimation of baroreflex sensitivity and may represent a prognostic tool to identify cirrhotic patients at increased risk of adverse events.

The effect of carvedilol on the baroreflex sensitivity in patients with chronic heart failure

The effect of carvedilol on the baroreflex sensitivity in patients with chronic heart failure

Effects of angiotensin converting enzyme inhibitor on cardiopulmonary baroreflex sensitivity in patients with acute myocardial infarction

Effects of angiotensin converting enzyme inhibitor on cardiopulmonary baroreflex sensitivity in patients with acute myocardial infarction