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Results 701 - 750 of 1783
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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 ...
Lin Z - - 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 ...
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 ...
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 ...
Mussalo Hanna - - 2003
This study was designed to examine short-term blood pressure variability (BPV) in patients with different severity and forms of chronic medically treated hypertension. Power spectral analysis of BPV was performed from continuous finger blood pressure (Finapres) recordings. Ten patients with renovascular hypertension (RVHT), 34 with severe essential hypertension (SEHT) and ...
Smith Fiona E - - 2003
Multichannel MCG noninvasively measures cardiac magnetic field strength from many sites at the body surface, potentially providing useful regional information about ventricular repolarization. Previous work on ECGs has shown that automatic techniques for repolarization measurement are better than manual measurement at discriminating patients with cardiac conditions from normal subjects. Although ...
Dayawansa Samantha - - 2003
It is well known that odors affect behaviors and autonomic functions. Previous studies reported that some compounds in cedar wood essence induced behavioral changes including sedative effects. In the present study, we analyzed cardiovascular and respiratory functions while subjects were inhaling fumes of pure compound (Cedrol) which was extracted from ...
Schroeder Emily B - - 2003
Dysregulation of the autonomic nervous system has been implicated in the development of hypertension. Heart rate variability is a noninvasive tool to quantitatively estimate cardiac autonomic activity and has been used to document decreased cardiac autonomic activity in hypertension. The ability of decreased heart rate variability to predict incident hypertension ...
Brown Clive M - - 2004
Gravity places considerable stress on the cardiovascular system but cerebral autoregulation usually protects the cerebral blood vessels from fluctuations in blood pressure. However, in conditions such as those encountered on board a high-performance aircraft, the gravitational stress is constantly changing and might compromise cerebral autoregulation. In this study we assessed ...
Tanaka Kunihiko - - 2003
Lower body positive pressure (LBPP) is used for simulation of microgravity due to central fluid shift. In the present study, we evaluate R-R interval variability, which is sometimes considered as an index of human cardiovascular autonomic nerve status. 10 healthy male subjects were set in a chamber with standing position. ...
Genovesi Simonetta - - 2003
OBJECTIVE: To analyse the duration of the QT interval and its relationship with heart rate changes in patients with uraemia, before and during haemodialysis. METHODS: QT and RR intervals were measured automatically using a dedicated algorithm with 24-h Holter recordings in 29 patients (15 women) receiving chronic haemodialysis. QT corrected ...
Taylor Julian S - - 2003
OBJECTIVE: To provide evidence concerning doses of ketamine that affect electroencephalographic (EEG) and autonomic signs of arousal during nociceptive stimulation. STUDY DESIGN: Prospective psychophysical test in people. Single injection or progressively increasing infusions of ketamine in cats. ANIMALS AND PEOPLE: Seven people (20-60 years old) and three cats (3-5 kg) ...
Kawahara Eisuke - - 2003
Electrocardiographic abnormalities, cardiac injury, and autonomic nervous function were investigated in patients with acute-phase subarachnoid hemorrhage (SAH) (42 patients with SAH related to ruptured aneurysm and 42 control subjects). Electrocardiogram and Holter electrocardiogram for spectral analysis of heart rate variability (HRV) were recorded. Concentrations of cardiogenic enzymes (ie, creatine kinase-myocardial ...
Lee Po-Tsang - - 2003
BACKGROUND: Intradialysis hypotension is a common problem among hemodialysis patients. Some studies have shown that autonomic neuropathy could be a major cause of intradialysis hypotension, whereas others have not. Furthermore, whether there are parallel changes in the autonomic nervous system and somatic nerves remains unclear. METHODS: We investigated the autonomic ...
Laitinen Tomi - - 2003
The effects of hypoglycaemia during hyperinsulinaemia, occurring under various pathophysiological conditions, on the cardiovascular regulatory system and vasculature are largely unknown. The aim of the present study was to investigate regulatory and haemodynamic responses to acute hyperinsulinaemia and consequent hypoglycaemia in 18 healthy subjects. Blood sampling and 5 min ECG ...
Maser Raelene E - - 2003
This study evaluated the effect of losartan, an angiotensin II receptor antagonist, on cardiovascular autonomic function and large sensory nerve fiber function in individuals with diabetes mellitus. In a double-blind placebo-controlled trial, individuals were randomly assigned to treatment with a daily oral dose of 50-mg losartan (n=24) or placebo (n=20) ...
Shi Xiangrong - - 2003
BACKGROUND: It has been demonstrated that a decrease in vagal cardiac function compromises arterial blood pressure (ABP) stability during orthostatic challenge. Augmentations in low-frequency (LF) ABP oscillations are indicative of this change in autonomic hemodynamic control. Aging is associated with diminished arterial baroreflex sensitivity and vagal cardiac dysfunction. However, the ...
Virtanen Raine - - 2003
OBJECTIVE: The purpose of this study was to determine whether psychological factors are associated with heart rate variability (HRV), blood pressure variability (BPV), and baroreflex sensitivity (BRS) among healthy middle-aged men and women. METHODS: A population-based sample of 71 men and 79 women (35-64 years of age) was studied. Five-minute ...
Lehrer Paul M - - 2003
OBJECTIVE: We evaluated heart rate variability biofeedback as a method for increasing vagal baroreflex gain and improving pulmonary function among 54 healthy adults. METHODS: We compared 10 sessions of biofeedback training with an uninstructed control. Cognitive and physiological effects were measured in four of the sessions. RESULTS: We found acute ...
Holguín Fernando - - 2003
BACKGROUND: Suspended particles and ozone have been associated with varying degrees of cardiac autonomic dysfunction. METHODS: In Mexico City, residents from a nursing home underwent heart rate variability analysis every other day for 3 months. Indoor and outdoor PM2.5 (particulate matter less than 2.5 mm in diameter) were measured daily ...
Kovács László - - 2004
OBJECTIVE: To assess the occurrence and clinical significance of a cardiovascular autonomic nervous system dysfunction in primary Sjögren's syndrome (pSS). METHODS: Fifty-one pSS patients participated in this case-control study. Heart rate and blood pressure variability measurements, spontaneous baroreflex sensitivity examinations and cardiovascular reflex tests were performed. RESULTS: The results of ...
Akar Fadi G - - 2003
Although expression of numerous ion channels is altered in heart failure (HF), mechanisms by which dysfunction at the ionic and molecular levels lead to ventricular tachyarrhythmias in HF are unknown. Previously, we found that transmural heterogeneities of repolarization play a critical role in the genesis of polymorphic ventricular tachycardia (PVT) ...
Crossley Dane A DA - - 2003
Baroreflex regulation appears in different species at different points in embryonic development. This study was designed to understand the development of the baroreflex in embryos of the American alligator at four different points of embryonic development (60%, 70%, 80% and 90% of a total incubation period of 72 days) and ...
Parati Gianfranco - - 2003
Blood pressure (BP) is characterized by continuous fluctuations, including fast changes lasting only a few seconds as well as slower and more prolonged variations, with a time constant of minutes or hours. Assessing the relative contribution of these different components to overall blood pressure variance is now possible through a ...
Franks Paul W - - 2003
PURPOSE: To compare the cardiovascular reactivity response to mental challenge of aerobically trained and untrained preadolescent boys. METHODS: Heart rate (HR) and blood pressure, as well as stroke volume, total peripheral resistance, rate pressure product, and cardiac contractility response in 15 aerobically trained (10.3 yr) and 15 untrained (9.5 yr) ...
Kaya Dayimi - - 2003
Dopamine2 (D2)-like receptor antagonists are widely used for the treatment of gastroparesis and vomiting. Metoclopramide (MCP), a peripheral and central D2-like receptor antagonist, stimulates the sympathetic nervous system and may alter autonomic modulation, but the net effect of MCP to the heart is not known. The aim of our study ...
Lipp Axel - - 2003
Riluzole is a neuroprotective agent that is currently tested for the treatment of multiple system atrophy (MSA). Riluzole may influence afferent and efferent parts of the baroreflex due to glutamate antagonistic effects. The effect of riluzole on the efferent part may be unmasked in MSA patients with dysfunction of afferent ...
Halámek Josef - - 2003
BACKGROUND: We postulated that the variability of the phase shift between blood pressure and heart rate fluctuation near the frequency of 0.10 Hz might be useful in assessing autonomic circulatory control. METHODS AND RESULTS: We tested this hypothesis in 4 groups of subjects: 28 young, healthy individuals; 13 elderly healthy ...
Igosheva N - - 2003
AIMS: To characterise the frequency response of short-term heart rate variability to external periodic perturbations in healthy and ischemic heart disease subjects. METHODS: Eleven healthy men and 11 ischemic heart disease patients were enrolled in this study. The frequency response of heart rate variability was assessed during periodic eyes opening ...
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