Search Results
Results 451 - 500 of 1795
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Tong Yan-Qing - - 2007
OBJECTIVE: We attempt to identify heart rate variability (HRV) components and decide whether or not such components are more sensitive to the hemodialysis (HD) process by excluding the presence of comorbid conditions known to affect HRV. METHODS: It was a prospective cohort study of factors associated with HRV. Thirty-five HD ...
Hata Tadayoshi - - 2007
BACKGROUND: We hypothesized that patients with atrial (ASD) and ventricular septal defects (VSD) have similarly reduced heart rate variability (HRV) since both defects cause similar increases in pulmonary blood flow and right ventricular filling pressure. We examined the correlation between HRV and respiratory frequency (RSA) characteristics and left-to-right shunt ratio ...
Rossi M - - 2007
The aim of the study was to investigate whether chronic cigarette smoke habit is associated with changes of laser Doppler (LD) skin blood flowmotion (SBF). We performed spectral analysis of skin forearm LD signal detected by a LD flowmetry (Periflux PF4, Perimed, Sweden) before and during forearm post-ischemic hyperaemia, in ...
Baldi Emilio - - 2007
The question whether pulsed electromagnetic field (PEMF) can affect the heart rhythm is still controversial. This study investigates the effects on the cardiocirculatory system of ELF-PEMFs. It is a follow-up to an investigation made of the possible therapeutic effect ELF-PEMFs, using a commercially available magneto therapeutic unit, had on soft ...
Hsu Chih-Chieh - - 2007
In this study, the EEG, ECG and blood-pressure-pulse recorder were employed to evaluate heart rate variability, pulse rate variability, and EEG of 10 adults after scalp (experimental test I) at Sishencong scalp acupoint and auricular (experimental test II) acupuncture at Shenmen auricular acupoint for about 10 min. Comparison of the ...
Courtar Dorette A - - 2007
Plasma volume (PV) varies with the menstrual cycle not only in healthy parous controls (CON) but also in formerly preeclamptic women with a subnormal PV (LPV). It is unknown whether formerly preeclamptic women with LPV are more susceptible to orthostatic stress than healthy controls. In this study, the authors compared ...
Woo Mary A - - 2007
Heart failure (HF) is associated with aberrant autonomic nervous system (ANS) activity, with altered responses to blood pressure and breathing challenges that appear to reflect abnormal central nervous system function. The authors used functional magnetic resonance imaging (fMRI) to determine whether the Valsalva maneuver, an ANS challenge, would show abnormal ...
Glos Martin M Center of Sleep Medicine, Charite - Universitaetsmedizin 10117 Berlin, Germany. - - 2007
In 18 patients with obstructive sleep-apnea syndrome (OSAS), time-variable spectral analysis was employed to study the course of heart-rate variability (HRV) and blood-pressure variability (BPV), before and during apnea episodes. Time intervals of 6 minutes' length were detected and analyzed from nocturnal sleep recordings. In addition, a software package was ...
Lee Jongwon J Department of Electrical Engineering, University of Minnesota, Minneapolis, 200 Union St SE, MN55455, USA. - - 2007
High frequency chest compression (HFCC) supplies a sequence of air pulses through a jacket worn by a patient to remove excessive mucus for the treatment or prevention of lung disease patients. The air pulses produced from the pulse generator propagates over the thorax delivering the vibration and compression energy. A ...
Nescolarde L - - 2007
Mono-frequency (50 kHz) and multi-frequency (3 kHz - 1 MHz) whole-body and thoracic segment bioimpedance measurement were doing before and after hemodialysis session in 20 patients. The patients were classified in hypertensive or non-hypertensive according to the mean blood pressure, BPmean. The relation between hyper-hydration in thorax segment through real ...
Abe Makoto M Graduate School of Engineering, Tohoku University, 6-6-05 Aoba, Aramaki, Aoba-ku, Sendai 980-8579, Japan. - - 2007
To quantify the effect of visually-induced motion sickness on the autonomic nervous system, the authors previously proposed a new physiological index rho max representing the maximum cross-correlation coefficient between blood pressure variability and heart rate variability whose frequency components are limited to the Mayer wave band. However, rho max requires ...
Ostlund Nils N Department of Biomedical Engineering & Informatics, University Hospital, Umeå, Sweden. - - 2007
Heart rate variability (HRV) is often used to study disturbances in the autonomic nervous system. Respiratory related HRV is seen as an indicator of a working autonomic mechanism. However, sometimes a high HRV may be caused by non-autonomic mechanisms. This study investigated if the wavelet coherence could be used to ...
Skyba P - - 2007
Sympathetic activation and parasympathetic withdrawal are commonly observed during acute exacerbations of chronic obstructive pulmonary disease (COPD). We have demonstrated previously that noninvasive positive-pressure ventilation (NPPV) improves parasympathetic neural control of heart rate in patients with obstructive sleep apnea. We hypothesized that NPPV may exert such beneficial effects in COPD ...
Rowley A B - - 2007
Wavelet cross-correlation (WCC) is used to analyse the relationship between low-frequency oscillations in near-infrared spectroscopy (NIRS) measured cerebral oxyhaemoglobin (O(2)Hb) and mean arterial blood pressure (MAP) in patients suffering from autonomic failure and age-matched controls. Statistically significant differences are found in the wavelet scale of maximum cross-correlation upon posture change ...
Wilkins Brad W - - 2007
The ganglionic blocking agent trimethaphan (TMP) is no longer produced. Therefore, a need exists for alternative pharmacological approaches to investigate baroreflex control of the circulation. The aim of the present study was to examine baroreflex-mediated cardiovascular responses during the administration of a muscarinic receptor antagonist (glycopyrrolate; GLY: ) and a ...
Fu Chin-Hua - - 2006
OBJECTIVES: This study was designed to evaluate the correlations between cerebral hemodynamics and cardiac autonomic functions in aging process using transfer function techniques. METHODS: Arterial blood pressure (ABP), middle cerebral artery flow velocity (MCAFV) detected by transcranial Doppler sonography and electrocardiogram were recorded simultaneously in 20 young (27.5 +/- 0.9 ...
Takagi Takashi - - 2006
To evaluate morning autonomic nervous activity and blood pressure profiles in hypertensive patients by analyzing heart rate variability and ambulatory blood pressure. Data from 82 patients with untreated essential hypertension were analyzed. We evaluated the 24-h profile of blood pressure and that of indices of autonomic nervous activity, i.e., the ...
Castiglioni Paolo - - 2007
It is still unclear whether the low-frequency oscillation in heart rate is generated by an endogenous neural oscillator or by a baroreflex resonance. Our aim was to investigate this issue by analyzing blood pressure and heart rate variability and the baroreflex function in paraplegic subjects with spinal cord injury below ...
Oréa Valérie - - 2007
This study examined the possible influence of changes in heart rate (HR) on the gain of the transfer function relating renal sympathetic nerve activity (RSNA) to arterial pressure (AP) at HR frequency in rats. In seven urethane-anesthetized rats, AP and RSNA were recorded under baseline conditions (spontaneous HR = 338 ...
Cottin François - - 2007
This study investigated the relationships between walking speed and heart rate (HR) variability (HRV) in eleven subjects during a 24-h race. It was hypothesized that the nycthemeral rhythm on HR is preserved during the race. RR intervals and walking speed were measured. Fast Fourier transform was applied to samples of ...
Beuchée Alain - - 2007
BACKGROUND: Exaggerated laryngeal chemoreflexes (LCR) have been implicated in the occurrence and prolongation of apnea in premature and term neonates. OBJECTIVES: To test the hypothesis that the cardiovascular component of the LCR can occur and be prolonged in the absence of apnea. METHODS: Bolus injections of 0.5 ml of citric ...
Barbic Franca - - 2007
Cardiac autonomic abnormalities have been described in Parkinson's disease. Little is known about possible alterations of vascular sympathetic regulatory activity in patients without orthostatic hypotension or symptoms of orthostatic intolerance. Nineteen patients with Parkinson's disease without orthostatic hypotension (PD), 21 with orthostatic hypotension (PDOH), and 20 healthy controls underwent ECG, ...
Guasti L - - 2007
BACKGROUND: The effects of thyroid deprivation on the autonomic modulation to the heart remain controversial. METHODS: In this study in patients followed for thyroid carcinoma, we investigated (1) heart rate variability parameters and the baroreflex gain and (2) intracellular catecholamine levels in circulating lymphocytes during short-term hypothyroidism (phase 1) and ...
Hou R H - - 2007
Arousal is regulated by the interplay between wakefulness- and sleep-promoting nuclei. Major wakefulness-promoting nuclei are the histaminergic tuberomamillary nucleus (TMN) of the hypothalamus and the noradrenergic locus coeruleus (LC) of the pons, which also play a role in autonomic regulation. First generation antihistamines, such as diphenhydramine, are likely to cause ...
Wecht Jill M - - 2006
Cardiovascular autonomic mechanisms control heart rate (HR) and determination of heart rate variability (HRV) permits the quantitative assessment of relative shifts in autonomic cardiac control during head-up tilt (HUT). The study herein used HRV techniques to determine the vagal and sympathetic contribution to the change in HR during HUT in ...
Langager Amanda M - - 2007
The mechanisms generating high- frequency (HF) and low-frequency (LF) blood pressure variability (BPV) are reasonably well understood. However, little is known about the origin of very low-frequency (VLF) BPV. We tested the hypothesis that VLF BPV is generated by L-type Ca(2+) channel-dependent mechanisms. In conscious rats, arterial blood pressure was ...
Baudrie Véronique - - 2007
The analysis of blood pressure (BP) and heart rate (HR) variability by spectral methods has proven a useful tool in many animal species for the assessment of the vagal and sympathetic contributions to oscillations of BP and HR. Continuous BP measurements obtained in mice by telemetry were used to characterize ...
Boettger Silke - - 2006
OBJECTIVE: This study aimed to further investigate autonomic function in schizophrenic patients using long-term electrocardiographic (ECG) recordings. METHODS: Twenty unmedicated patients suffering from an acute episode of paranoid schizophrenia and 20 matched control subjects were recruited and 24-h ambulatory electrocardiograms were recorded. In order to investigate complexity of heart rate ...
Lambrecht Rein - - 2007
OBJECTIVE: To test the validity and practicality of a simple, rapid autonomic cardiovascular evaluation (RACE). INTRODUCTION: Assessment of the autonomic nervous system is costly and time consuming. Consequently, briefer measures are often utilized as evaluations of autonomic function. We therefore set out to assess the validity and practicality of a ...
Iwasaki Ken-ichi - - 2006
INTRODUCTION: The classical view states that hypoxia beyond an oxygen concentration of about 17% induces tachycardia. However, few studies have investigated the dose-dependent effects of acute normobaric hypoxia on autonomic nervous regulation of the cardiovascular system. Therefore, we evaluated the effects of stepwise hypoxia on cardiovascular neural regulation and postulated ...
Voss Andreas - - 2006
Within 5 years of first diagnosis, nearly 60% of patients with heart failure (HF) suffer from cardiac death. Early diagnosis of HF and reliable risk prediction are still required. Therefore, the objective of this study was to develop a parameter set for enhanced risk stratification in HF patients. In 43 ...
Yildirir Aylin - - 2006
BACKGROUND: Limited data are available related to the effects of sex hormones on cardiac autonomic function. Few studies investigated the heart rate variability (HRV) parameters during regular menstrual cycle or in postmenopausal women using hormone replacement therapy, but the results were contradictory. The aim of the study was to compare ...
Beckers Frank - - 2006
BACKGROUND: Non-linear analysis of heart rate variability (HRV) can give additional information about autonomic control of the heart rate. This study applied the fractal dimension (FD) in a congestive heart failure (CHF) population. METHODS: FD and HRV were evaluated in a healthy population (n=21) and an end-stage heart failure population ...
Dütsch Mathias - - 2006
Changes of cardiovascular function are frequent in temporal lobe epilepsy (TLE). The baroreflex - the most important reflex for cardiovascular stability - has not been studied systematically in TLE. We evaluated cardiovascular variability and baroreflex function in TLE. In 22 TLE patients and 20 controls, we continuously monitored heart rate ...
Perkins G M - - 2006
Pulse wave velocity (PWV) is associated with heart rate variability (HRV) in 24-39-year-old men. This study of 40-65-year-old men ranging in moderate-to-vigorous physical activity levels investigated whether (a) PWV is related to spectral HRV, (b) using normalised units for HRV influences that relationship, and (c) HRV predicts PWV when other ...
Davydov Dmitry M - - 2007
BACKGROUND: Recent studies have shown that depressive disorder is associated with impaired baroreceptor or baroreflex sensitivity, which is proposed to be a predisposing factor for sudden death in patients with manifest cardiac disease. These studies have not evaluated the afferent and efferent components of the cardiac baroreflex loop or other ...
Brychta Robert J - - 2007
We propose a simple moving-average (MA) model that uses the low-frequency (LF) component of the peroneal muscle sympathetic nerve spike rate (LF(spike rate)) and the high-frequency (HF) component of respiration (HF(Resp)) to describe the LF neurovascular fluctuations and the HF mechanical oscillations in systolic blood pressure (SBP), respectively. This method ...
Radaelli Alberto - - 2006
OBJECTIVES: The intention of this study was to test the hypothesis that, in heart failure patients, dietary supplementation of polyunsaturated fatty acids (PUFA) enhances arterial baroreceptor control of the cardiovascular system. BACKGROUND: Administration of PUFA reduces the risk of life-threatening arrhythmias in patients surviving myocardial infarction. This might result from ...
Farah Vera M A - - 2006
Studies evaluated the role of the autonomic nervous system in the cardiovascular response to stress using radiotelemetric blood pressure (BP) recording coupled with autoregressive spectral analysis. Conscious male C57/BL6 mice with carotid arterial telemetric catheters were exposed to acute episodes of shaker stress before and after administration of cholinergic, beta1-adrenergic ...
Bär Karl-Jürgen - - 2006
BACKGROUND: Many symptoms of alcohol withdrawal (AW) such as tachycardia or elevated blood pressure might be explained by increased peripheral and central adrenergic activity. In contrast to many neurochemical studies of sympathetic activation during AW, only very few studies investigated autonomic balance using neurophysiological methods. METHODS: We investigated heart rate ...
Kim Young-Kug - - 2006
Compromised cardiac autonomic modulation can produce cardiovascular disturbances. We investigated whether combined deep and superficial cervical plexus (CP) blockade for carotid endarterectomy (CEA) produces changes in autonomic cardiovascular regulation. To estimate alterations in cardiovascular autonomic control before and after combined CP blockade in 22 patients undergoing CEA, the heart rate ...
Yakhou Leïla - - 2006
Carotid artery stenting (CAS) has been introduced as an alternative to carotid endarterectomy (CEA) for the treatment of carotid artery stenosis. Both techniques seem to be associated with postoperative hemodynamic lability. Both may induce baroreceptor dysfunction, possibly leading to transient impairment of cardiovascular autonomic activity and resulting in hemodynamic instability. ...
Serra X - - 2007
This paper describes the effect of high pressure (400MPa and 600MPa) applied to frozen hams at early stages of the dry-cured ham process: green hams (GH) and hams at the end of the resting stage (ERS), on some physicochemical parameters and on antioxidant and proteolytic enzyme activities in the final ...
Tewari Hem Kumar - - 2006
PURPOSE: This case-control study was conducted to evaluate autonomic function activity and reactivity in patients with central serous chorioretinopathy (CSCR), because stress and type A personality, known risk factors, are also related to autonomic nervous system activity. METHODS: Patients with CSCR were selected from the outpatient department and medical retina ...
Moriguchi Koichi - - 2006
The relation between changes in blood pressure and changes in autonomic activity over a very short period of time has not been reported thus far. To examine this relation, we here introduced a new method of power spectrum analysis with wavelet transformation, which has very fine time resolution and is ...
Skrapari Ioanna - - 2006
Arterial baroreceptors play an important role in the short-term regulation of arterial pressure, by reflex chronotropic effect on the heart and by reflex regulation of sympathetic outflow. Baroreflex sensitivity (BRS) represents an index of arterial baroreceptors function. Several methods of measuring BRS are available nowadays. Different factors influence BRS in ...
Valance D - - 2007
This study investigated whether genetic selection on a divergent behavioural trait of fearfulness (tonic immobility duration) was related to changes in the nervous control of the heart. Quail selected for either long or short tonic immobility (LTI or STI, respectively) duration was compared with an unselected control line (CTI). The ...
Iellamo Ferdinando - - 2006
Endothelial function is impaired in first-degree relatives (FDRs) of patients with type 2 diabetes. Many states characterized by endothelial dysfunction are associated with increased cardiovascular sympathetic outflow. In this study, we investigated endothelial and autonomic nervous system (ANS) functioning in FDRs and tested the hypothesis that in basal condition, impaired ...
Westerhof Berend E - - 2006
Postural stress requires immediate autonomic nervous action to maintain blood pressure. We determined time-domain cardiac baroreflex sensitivity (BRS) and time delay (tau) between systolic blood pressure and interbeat interval variations during stepwise changes in the angle of vertical body axis (alpha). The assumption was that with increasing postural stress, BRS ...
Marc A. Rosen, Raymond ...
The effect of increasing reheat pressure on the exergy efficiency of a coal-fired steam power plant is investigated. The results show that although the irreversibility rate associated with heat transfer in the steam generator decreases as reheat pressure increases, the overall-plant exergy efficiency decreases, mainly owing to the relatively large ...
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