Search Results
Results 701 - 750 of 1808
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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 +/- ...
Lu Wan-An - - 2003
PURPOSE: This study evaluated the effect of Tai Chi Chuan (TCC) on the autonomic nervous modulation in older persons. METHODS: Twenty TCC practitioners and 20 normal controls were included in this study. The stationary state spectral heart rate variability (HRV) measures between TCC practitioners and normal controls, and the sequential ...
Wecht Jill M - - 2003
Beat-to-beat fluctuations in heart rate are partially controlled by the autonomic nervous system and may be altered by a spinal cord injury. The purpose of the present investigation was to examine the role of the autonomic nervous system in modulating the heart rate response to head-up tilt (HUT) in subjects ...
Masuda Yukitaka - - 2003
The role of the autonomic nervous system in postprandial hypotension was investigated. Sixteen elderly patients (age range from 67 to 92 years) and ten healthy controls (age range from 22 to 57 years) each ate a 600-kcal lunch. Arterial blood pressure was measured every 6 min prior to, during, and ...
Nilsson Inga-Lena - - 2003
BACKGROUND: Primary hyperparathyroidism has been associated with premature death in cardiovascular diseases, but reversibility and background mechanisms are uncertain. This study investigates autonomic nervous function in hyperparathyroidism because disturbances in this respect have been related to increased cardiovascular morbidity. METHODS: Twenty-one consecutive patients with hyperparathyroidism and 23 matched control subjects ...
Cui Jian - - 2004
Whole body heating increases muscle sympathetic nerve activity (MSNA); however, the effect of heat stress on spectral characteristics of MSNA is unknown. Such information may provide insight into mechanisms of heat stress-induced MSNA activation. The purpose of the present study was to test the hypothesis that heat stress-induced changes in ...
Srinivasan K - - 2004
We investigated the effects of treatment with the tricyclic antidepressant (TCA) imipramine in eight children in supine and standing postures. We used 256 seconds of real-time data for the analyses. Spectral analysis showed a significant decrease of high-frequency (HF) power (0.15-0.5 Hz), especially in the standing posture. Low frequency (LF) ...
Fietze Ingo - - 2004
To determine the short-term effects of noninvasive positive-pressure ventilation (PPV) on spontaneous baroreflex sensitivity, we acquired time series of R-R interval and beat-to-beat blood pressure in 55 healthy volunteers (mean age 46.5 +/- 10.5 yr) who performed breathing on four occasions at frequencies of 12 and 15 breaths/min without positive ...
Tzeng Y C - - 2003
In 48 conscious resting subjects we examined the temporal coupling of heart beat timing and the onset of inspiration (cardioventilatory coupling), and the relationship between coupling and spectral indices of autonomic function. Using the proportional Shannon entropy (SH(alpha)) of the RI(-1) interval (interval between inspiration and the preceding ECG R ...
Parati Gianfranco - - 2003
Blood pressure variability is the result of a complex interaction between external stimulation and several cardiovascular control mechanisms and is enhanced in all those conditions characterized by an impaired autonomic regulation of circulation. In particular, blood pressure variability is enhanced in hypertension over 24 h and may independently contribute to ...
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