Search Results
Results 701 - 750 of 1817
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Hamner J W - - 2004
We set out to fully examine the frequency domain relationship between arterial pressure and cerebral blood flow. Oscillatory lower body negative pressure (OLBNP) was used to create consistent blood pressure oscillations of varying frequency and amplitude to rigorously test for a frequency- and/or amplitude-dependent relationship between arterial pressure and cerebral ...
Iwasaki Ken-Ichi - - 2004
Adaptation to spaceflight or head-down-tilt bed rest leads to hypovolemia and an apparent abnormality of baroreflex regulation of cardiac period. In a previous study, we demonstrated that both chronic (2 wk) head-down-tilt bed rest and acute induced hypovolemia led to similar impairments in spontaneous baroreflex control of cardiac period, suggesting ...
Chapuis Bruno - - 2004
The objective of the present study was to examine whether a simple linear feedback model of arterial pressure (AP) control by the sympathetic nervous system would be able to reproduce the characteristic features of normal AP variability by using AP and renal sympathetic nerve activity (RSNA) data collected in conscious ...
Eitzen Ingrid - - 2004
OBJECTIVES: To discuss the methodologic challenges related to pressure mapping in seating and to present a new approach to the analysis and interpretation of results: the frequency analysis approach. DESIGN: Pressure mapping was performed on 3 prototypes of a newly developed foam and gel seat cushion. SETTING: Data collection was ...
Landén Mikael - - 2004
Measuring heart rate variability (HRV) is a way to assess the autonomic regulation of the heart. Decreased HRV, indicating reduced parasympathetic tone, has previously been found in depression and anxiety disorders. The objective of this study was to assess HRV in women with premenstrual dysphoric disorder (PMDD). To this end, ...
Deschamps Alain - - 2004
BACKGROUND: Epidurals are effective in relieving labor pain but result in a sympathectomy that may compromise maternal hemodynamic stability and fetal perfusion. Decreases in blood pressure and heart rate can be corrected, but markers of autonomic activity would be useful to predict and prevent such changes. The goal of this ...
Sahin I. - - 2004
Background: Many studies have shown that autonomic activation is one of the major factors in the etiology of hypertension. Furthermore, sympathovagal imbalance may be responsible for arrhythmias and sudden cardiac death. The aim of the present study was to compare and to evaluate the effects of short-term therapy with amlodipine ...
Penttilä J - - 2004
1 This double-blind, cross-over, placebo-controlled study on six healthy male volunteers was designed to evaluate the effects of alpha2-adrenoceptor antagonism on cardiac parasympathetic regulation. 2 The subjects received atipamezole intravenously as a three-step infusion, which aimed at steady-state serum concentrations of 10, 30 and 90 ng ml(-1) at 50-min intervals. ...
Westerhof Berend E - - 2004
OBJECTIVE: To test a new method (cross-correlation baroreflex sensitivity, xBRS) for the computation of time-domain baroreflex sensitivity on spontaneous blood pressure and heart interval variability using the EUROBAVAR data set. METHODS: We applied xBRS to the 42 records in the EUROBAVAR data set, obtained from 21 patients in the lying ...
Bouhaddi Malika - - 2004
Loss of autonomic cardiovascular homoeostasis is often suspected in hypertension that has developed after organ transplantation. We serially assessed autonomic cardiovascular control in eight patients in generally good condition who needed cyclosporine (CyA) treatment because of high risk of rejection in corneal transplantation. To this aim, we investigated the patients, ...
Bartels Matthew N - - 2004
Wide variations in respiratory rate and hypoxic stimulation of chemoreceptors may produce unreliable autonomic results in patients with COPD. We studied the reproducibility of two consecutive measurements of heart rate variability (HRV) and blood pressure variability (BPV) by time frequency analysis in patients with COPD while controlling respiratory rate and ...
Souza Neto Edmundo P - - 2004
This study investigated patients undergoing elective cardiac surgery to evaluate the effects of cardiopulmonary bypass (CPB) on the spontaneous variability of mean arterial pressure (MAP) and heart rate (HR). Forty-one adult patients receiving different cardiovascular system drugs were included in the study. Patients were divided into three groups: no preoperative ...
Tanaka M - - 2004
BACKGROUND: In conscious humans, men have a greater cardiovagal baroreflex gain than women. We studied gender-related differences in baroreflex function during general anaesthesia. METHODS: Sixty healthy patients (30 male and 30 female) were anaesthetized with sevoflurane 2% end-tidal in air and oxygen, and their lungs were mechanically ventilated. We recorded ...
Fathizadeh Payman - - 2004
OBJECTIVE: To evaluate the effects of sympathetic and parasympathetic nervous system activity on the heart rate and other hemodynamic variables in acute emergency patients with mild to moderately severe trauma. DESIGN: Clinical study. SETTING: Level 1 university-run trauma service. PATIENTS: Fourteen trauma patients studied immediately after admission to the emergency ...
Penttilä Jani - - 2004
We evaluated the cardiovascular effects of intravenously (i.v.) and buccally administered dexmedetomidine, a selective alpha2-adrenoceptor agonist. Six healthy male subjects were studied unmedicated and after 2 micro g/kg i.v. or buccal doses of dexmedetomidine, using repeated recordings of ECG and blood pressure. Cardiac parasympathetic activity was estimated by measurements of ...
Allan Louise - - 2004
Defaecation syncope is defined as blacking out at, or around, the time of defaecation. It is associated with increased mortality; however, patients rarely voluntarily report symptoms. We have examined autonomic function in a cohort of patients with defaecation syncope. METHODS: We prospectively identified all subjects referred to our unit with ...
Altieri Paolo - - 2004
BACKGROUND: The objective of the study was to compare the convective treatment modes, on-line hemofiltration (HF) and on-line hemodiafiltration (HDF), regarding cardiovascular tolerance and effects on blood pressure, when applied under similar conditions in stable dialysis patients. METHODS: 39 clinically stable dialysis patients were treated with HD for 6 months ...
Minami Junichi - - 2004
We assessed ambulatory blood pressure and heart rate variability in two female patients with pheochromocytoma. The ambulatory blood pressure and ECG R-R intervals were measured during a 24-h period with a portable recorder before and 3 weeks after surgery. A power-spectral analysis of R-R intervals was performed to obtain the ...
Alijani A - - 2004
BACKGROUND: This study hypothesized that patients in whom bradycardia and hypotension develop with induction of positive-pressure capnoperitoneum have an underlying autonomic cardiovascular dysfunction. METHODS: A case-control study was conducted to examine the baseline autonomic function of patients in whom bradycardia and hypotension develop with induction of positive-pressure capnoperitoneum. The control ...
Fletcher Janine - - 2004
OBJECTIVES: We have examined the acute effects (<45 min) of aldosterone antagonism on heart rate variability and baroreflex sensitivity, markers of cardiac vagal control, in 13 healthy subjects. BACKGROUND: Evidence for the beneficial effects of aldosterone antagonists comes from studies showing increased survival rates following their addition to standard heart ...
Moran Andrew - - 2004
OBJECTIVE: Cardiovascular autonomic neuropathy is associated with microalbuminuria in young and middle-aged patients with type 2 diabetes. We examined this relationship and the potential mediating role of blood pressure in older patients. RESEARCH DESIGN AND METHODS: At least two of three components of cardiovascular autonomic testing were completed by 132 ...
Virtanen R - - 2004
Although pulse pressure (PP), heart rate variability (HRV) and baroreflex sensitivity (BRS) have been shown to predict cardiovascular events and mortality in various populations, their relationships have not been clarified. We examined these associations in two separate population-based samples of healthy middle-aged subjects. In population 1, data were obtained from ...
González Julián J - - 2004
The short-term cardiovascular control system is reviewed from the analysis of the heart rate, respiration and blood pressure beat-to-beat variability signals. The present state of the art concerning fractal and non-linear techniques as applied to the cardiovascular system and the differences between both approaches are highlighted. We present results obtained ...
Bravo Guadalupe - - 2004
The recent developments in the management of spinal cord injury (SCI) have led to a reduction in mortality and in the consequences, resulting from incomplete spinal cord damage in those who survive. In this respect, it is noteworthy that SCI not only results in paraplegia or tetraplegia, but also in ...
Larsen Jakob R - - 2004
OBJECTIVE: To study the association between 18 years of mean HbA(1c) and cardiac autonomic function in type 1 diabetic patients having used intensive insulin treatment. RESEARCH DESIGN AND METHODS: A total of 39 patients with type 1 diabetes were followed during 18 years, and HbA(1c) was measured yearly. At 18 ...
Bauernschmitt R - - 2004
OBJECTIVE: Impairment of the baroreceptor reflex activity reflects an alteration of the autonomous regulation of the cardiovascular system and has proven to predict fatal outcome in patients after acute myocardial infarction. The following study was performed to analyse the baroreceptor sensitivity, heart rate variability and blood pressure variability in patients ...
Neki N S - - 2004
Mechanisms that may explain the association between brain-heart connection leading to abnormal heart rate variability (HRV) and blood pressure variability (BVP) resulting into increased morbidity and mortality due to cardiovascular diseases (CVD), are reviewed. Medline search till December, 2001 and articles published in various national and international journals were reviewed. ...
Zöllei Eva - - 2004
In order to characterize autonomic responses to acute volume loss, supine ECG, blood pressure (BP) and uncalibrated breathing signal (UBS) recordings were taken before and after blood donation in 48 healthy volunteers. Time and frequency domain parameters of RR interval (RRI), BP and UBS variability were determined. Baroreflex gain was ...
Hirayanagi Kaname - - 2004
A 14-day, 6 degrees head-down bed rest (HDBR) study was conducted with 12 healthy young men to determine whether there are transient responses of the cardiovascular autonomic regulatory system including cardiovascular, autonomic nervous, and cardiac baroreceptor reflex functions in the acute phases of HDBR and post-HDBR. Compared with the supine ...
Monahan Kevin D - - 2004
Cardiovagal baroreflex sensitivity (BRS) declines with advancing age in healthy men. We tested the hypothesis that oxidative stress contributes mechanistically to this age-associated reduction. Eight young (23 +/- 1 yrs, means +/- SE) and seven older (63 +/- 3) healthy men were studied. Cardiovagal BRS was assessed using the modified ...
Laitinen Tomi - - 2004
In elderly subjects, heart rate responses to postural change are attenuated, whereas their vascular responses are augmented. Altered strategy in maintaining blood pressure homeostasis during upright position may result from various cardiovascular changes, including age-related cardiovascular autonomic dysfunction. This exploratory study was conducted to evaluate impact of age on cardiovascular ...
Buch Ashesh N - - 2004
There is substantial animal data suggesting that nitric oxide (NO) has an important role as a modulator of cardiac autonomic control with a net vagotonic and sympatholytic role. Recent human work would support this concept. This study investigated the effects of the NO donor glyceryl trinitrate (GTN) upon measures of ...
Virtanen Irina - - 2004
OBJECTIVE: To study the effect of medroxyprogesterone acetate (MPA) on autonomic cardiac control in respiratory insufficiency in postmenopausal women. DESIGN: A prospective, single-blind study. SUBJECTS: Eighteen postmenopausal women with respiratory insufficiency and eight asymptomatic postmenopausal women with nocturnal hypoxaemia as controls. METHODS: Oral MPA treatment was given at 30 mg ...
Gmitrov Juraj - - 2004
The goal of the present research was try to explain the physiological mechanism for the influence of the geomagnetic field (GMF) disturbance, reflected by the indices of the geomagnetic activity (K, K(p), A(k), and A(p) indices), on cardiovascular regulation. One hundred forty three experimental runs (one daily) comprising 50 min ...
Grandjean Philippe - - 2004
OBJECTIVE: To determine whether heart function in childhood is affected by exposure to methylmercury (MeHg) from seafood. STUDY DESIGN: Prospective study of a Faroese birth cohort (N=1022). Examinations at ages 7 and 14 years included blood pressure, heart rate variability (HRV) and its frequency components of autonomic origin, and brainstem ...
Vongpatanasin Wanpen - - 2004
In this study, we found that cocaine decreased the high-frequency power of heart rate variability in normal volunteers, implicating a decrease in vagal tone. However, the results of our autonomic blocking studies indicated the opposite, suggesting a major influence of cardiac sympathetic drive on the high-frequency power of heart rate ...
Cooke William H - - 2004
Otolith activation increases muscle sympathetic nerve activity (MSNA), and MSNA activation may alter associations among autonomic oscillators, including those modulating cerebral hemodynamics. The purpose of this study was to determine the influence of vestibulosympathetic activation on cerebral and autonomic rhythms. We recorded the ECG, finger arterial pressure, end-tidal CO(2), respiration, ...
Jiménez Raúl F - - 2004
The purpose of this study was to characterize time-frequency behavior using the Continuous Wavelet Transform (CWT) and Fast Fourier Transform (FFT) to analyze ventricular and arterial pressure signals from anesthetized mongrel dogs. Both ventricular and arterial pressure pulsations were recorded using catheter-tip manometers and the CWT was applied to these ...
Santini Massimo - - 2004
The aim of this study is to evaluate the heart rate adaptation obtained by a pacemaker, based on a measure of ventricular impedance in patients undergoing autonomic challenges. The evaluation procedure was based on the analysis of the mean value (MV) and heart rate variability (HRV) of RR and systolic ...
Yamashita Jyunji - - 2004
Sleep apnea syndrome (SAS) is an important cardiovascular risk factor in patients with hypertension or myocardial infarction (MI). We evaluated the influence of SAS on autonomic nervous activity and QT dispersion in patients with hypertension or coronary artery disease with old MI. A portable sleep polygraph was attached to 30 ...
Elahi Ali - - 2004
BACKGROUND: Guillain-Barré Syndrome (GBS) frequently affects autonomic nerves with subsequent fluctuations in blood pressure. Posterior reversible encephalopathy syndrome (PRES) is a descriptive radiological term for hypertensive encephalopathy. This article describes a unique case in which autonomic neuropathy led to marked elevations in blood pressure with subsequent PRES prior to the ...
Kowalewski M A - - 2004
Autonomic nervous tests and heart rate variability (HRV) have been used to assess cardiac autonomic function and to evaluate long-term prognosis. The aim of this study was to evaluate the short- and long-term reproducibility of HRV parameters and autonomic nervous tests according to body position (supine or standing). The study ...
Erdoğan Doğan - - 2004
BACKGROUND: Growth hormone deficiency (GHD) is known to cause higher rates of cardiovascular mortality. The purpose of the study was to analyze the structural and functional changes in the heart and investigate their relation to autonomic function as assessed with heart rate variability (HRV). METHODS: Eleven untreated GHD patients (mean ...
Murata T - - 2004
Meditation is a specific consciousness state in which deep relaxation and increased internalized attention coexist. There have been various neurophysiological studies on meditation. However, the personal predispositions/traits that characterize the properties of meditation have not been adequately studied. We analyzed changes in neurophysiological parameters [EEG coherence and autonomic nervous activity ...
Hamaad Ali - - 2004
Many lines of experimental evidence suggest the interplay of the autonomic nervous system and a variety of mediators of vascular atheroma and ultimately vascular occlusion. In vivo study in human volunteers and patients is hampered by the lack of a reliable and sensitive marker of prevailing autonomic tone able to ...
Jaju D S - - 2004
We hypothesized that cerebral dominance may contribute to differences in cardio-vascular responses of right-handers (RH) and left-handers (LH) to autonomic stressors. We tested this hypothesis by exposing 14 RH, and 14 LH males to category I tests in which the hand and cerebral cortex were involved in performing the test ...
Pöyhönen M - - 2004
BACKGROUND: Heart rate variability (HRV) has been used for assessment of depth of anesthesia. Alterations in respiratory rate and tidal volume modulate the sympatovagal neural drive to the heart. The changes in PaCO2 that accompany changes in breathing pattern may, through chemoreceptors in the brainstem, independently influence the autonomic control ...
Lin Z Z Department of Biomedical Engineering, University of Southern California, Los Angeles, CA, - - 2004
The goal of this study was to quantify autonomic system dysfunction, as manifested by cardiovascular and respiratory response abnormalities, in patients with congenital central hypoventilation syndrome (CCHS). During wakefulness, we continuously measured the ECG, arterial blood pressure (ABP), airflow, end-tidal CO2 partial pressure (PETCO2), and arterial oxygen saturation (SatO2) in ...
Kienbaum Peter - - 2004
Arterial muscle sympathetic baroreflexes are frequently assessed using pharmacologically evoked decrements in arterial blood pressure. Since drugs administered for baroreflex tests may themselves alter the sympathetic response to evoked pressure variations we proposed a method to determine sympathetic baroreflex gain during spontaneous fluctuations in arterial pressure at rest and tested ...
Yamada Kunihiro - - 2003
The purpose of the study was to evaluate the dynamic nature of heart rate baroreflex under closed-loop conditions. We applied pressure perturbation with a random-interval cuff inflation to parametric system identification of the baroreflex. In 10 healthy men (six young, 27 +/- 3.9 years old, and four older, 50 +/- ...
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