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Results 351 - 400 of 1786
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Liu David S - - 2008
This study attempted to use the eyesight range to quantify presyncope symptoms (PS), assess the relation between angle of head-up tilt, severity of injury on the American Spinal Injury Association (ASIA) scale, and PS on physiological signals, and determine the notable signals that represent PS in spinal cord injury (SCI) ...
Renaud Guillaume - - 2008
To study "non-classical" acoustical nonlinearities in cracked materials, we developed a nonlinear (NL) wave coupling technique. Propagation velocity and amplitude of short high-frequency (HF, 600 kHz) bursts are modulated as result of nonlinear interaction with a low-frequency (LF, 3 kHz) wave. Time Of Flight Modulation (TOFM) is indeed related to ...
Fazan Rubens R - - 2008
Sildenafil induces vasodilation and is used for treating erectile dysfunction. Although its influence on resting heart function appears to be minimal, recent studies suggest that sildenafil can increase sympathetic activity. We therefore tested whether sildenafil injected into the central nervous system alters the autonomic control of the cardiovascular system in ...
Xavier Rita - - 2008
The Valsalva maneuver is an autonomic test that evokes short sharp cardiovascular fluctuations mediated by the autonomic nervous system. Numerous spectral analysis methods have been proposed to analyze biological signals. When applied to heart rate (HR) variability, two major bands related to autonomic influence have been defined: LF (mainly sympathetic) ...
Madsen Line B - - 2008
OBJECTIVES: The objective of this study was to compare heart rate variability (HRV) in patients with essential hypertension, in patients with white-coat hypertension and in normotensive control individuals, and to investigate a possible relation between HRV and vasoactive hormones. METHODS: Patients with essential hypertension (n=19, 61 years, median and interquartile ...
Laude Dominique - - 2008
1. Indices quantifying blood pressure (BP) and heart rate (HR) variability have been recently developed and may be used to assess the contribution of the autonomic nervous system to cardiovascular fluctuations. 2. Cardiovascular variables were measured in eight conscious mice equipped with a BP telemetric device. Each recording session was ...
La Rovere Maria Teresa - - 2008
Alterations of the baroreceptor-heart rate reflex (baroreflex sensitivity, BRS) contribute to the reciprocal reduction of parasympathetic activity and increase of sympathetic activity that accompany the development and progression of cardiovascular diseases. Therefore, the measurement of the baroreflex is a source of valuable information in the clinical management of cardiac disease ...
Yamada Jiko - - 2008
BACKGROUND: The present study was conducted to clarify whether azelnidipine might have beneficial effects on autonomic functions, and whether such beneficial effects might affect the vascular functions (i.e., arterial stiffness and endothelial function). METHODS AND RESULTS: This study with a cross-over design was conducted in 21 hypertensive patients (65 +/- ...
Makai Attila - - 2008
Premature ventricular contractions (PVC-s) induce baroreflex mediated arterial pressure and heart rate fluctuations. PVC-related RR interval fluctuations detected on Holter ECG recordings could be characterized by the heart rate turbulence (HRT) parameters, including early post-extrasystolic acceleration, described by turbulence onset, and late deceleration, described by turbulence slope (TS). We have ...
Vanapalli S - - 2008
Microminiature pulse tube cryocoolers should operate at a frequency of an order higher than the conventional macro ones because the pulse tube cryocooler operating frequency scales inversely with the square of the pulse tube diameter. In this paper, the design and experiments of a high frequency pressure oscillator is presented ...
Genovesi Simonetta - - 2008
In adults, initial stages of hypertension are associated with elevated sympathetic drive and significant alterations in indirect autonomic markers. There is growing evidence that children in the highest-pressure percentiles will be more likely to develop hypertension in adulthood, although mechanisms are not understood. We assessed whether computer analysis of RR ...
Liu Weiwei - - 2008
The mechanism of human thermal comfort is important for building a comfortable and healthy indoor environment. This paper analyzes human heart rate variability (HRV) at different thermal comfort levels and discusses the mechanism of human thermal comfort. A total of 33 subjects were divided in 3 groups. Under air temperatures ...
Sykora Marek - - 2008
Autonomic nervous system impairment plays an important role in the clinical course of tetanus and is thought to be responsible for life-threatening complications. It is believed to be associated with predominance of sympathetic activity. Direct baroreflex involvement has not yet been reported. We hypothesized that impaired baroreflex may contribute to ...
Joyner Michael J - - 2008
New ideas about the relative importance of the autonomic nervous system (and especially its sympathetic arm) in long-term blood pressure regulation are emerging. It is well known that mean arterial blood pressure is normally regulated in a fairly narrow range at rest and that blood pressure is also able to ...
Eckberg Dwain L - - 2008
Many cardiovascular models involve prediction of changes that occur when a subject is perturbed in some way, to move from one state to another. A successful, predictive model should involve at least two elements: First, the model should include some index of the intensity of the perturbation that elicits the ...
Madden Kenneth M - - 2008
Although postprandial decreases in blood pressure are a common cause of syncope in the older adult population, the postprandial effects of the oral glucose tolerance test on blood pressure and the arterial baroreflex remain poorly characterized in older adults. Therefore, arterial blood pressure and the arterial baroreflex were studied in ...
Visontai Zsuzsanna - - 2008
PURPOSE: To investigate the parasympathetic cardiovascular regulation, baroreflex sensitivity (BRS), and pulse wave velocity (PWV) in exfoliation syndrome (XFS). METHODS: Heart rate variability indices [standard deviation of all RR intervals (SDNN); the mean of absolute successive differences (RMSSD); the percentage of intervals differing by >50 ms from the preceding interval ...
Guzik Przemyslaw - - 2008
This study was designed to determine whether or not the addition of a single nighttime dose of doxazosin in extended-release form (GITS; gastrointestinal therapeutic system) would affect the autonomic modulation of the cardiovascular system in patients with uncontrolled hypertension treated with a multi-drug regimen. Resting 5-min noninvasive finger blood pressure ...
Kim Y K - - 2008
We tested the effect of 100% oxygen on heart rate (HR), arterial blood pressure (ABP), cardiac output (CO), stroke volume (SV), total peripheral resistance (TPR), HR variability (HRV), systolic blood pressure variability (SBPV) and baroreflex sensitivity (BRS) in 20 healthy volunteers during simulated haemorrhage induced by -40 mmHg lower body ...
Stubhan Miriam - - 2008
INTRODUCTION: The objective of this study was to evaluate the normal cardiovascular and ECG parameters in freely moving minipigs and to use these data as the basis of pharmacological drug safety evaluation. METHODS: 7 Göttingen Minipigs were equipped with radiotelemetry transmitters (ITS). Aortic pressure (AP), left ventricular pressure (LVP), lead ...
Kajiura Mitsugu - - 2008
The present investigation is about cardiovascular responses and relevant autonomic function in Swedish and Japanese pubertal children on active standing using non-invasive continuous beat-to-beat finger arterial pressure (FAP) monitoring and power spectral analysis. Examined were 54 Swedish and 57 Japanese children (13-15 years). FAP and heart rate (HR) was continuously ...
Tsurugi Takuo - - 2008
OBJECTIVES: We compared, in patients with sick sinus syndrome, the effects of various pacing modes on baroreceptor (BR)-stroke volume (SV) reflex sensitivity, a method we have closely correlated with BR-heart rate (HR) reflex sensitivity. BACKGROUND: Impaired autonomic nervous function, such as decreased BR-HR reflex sensitivity, predicts sudden cardiac death. However, ...
Souza Hugo C D - - 2008
This study was conducted in one kidney, one clip (1K1C) Goldblatt hypertensive rats to evaluate vascular and cardiac autonomic control using different approaches: 1) evaluation of the autonomic modulation of heart rate (HR) and systolic arterial pressure (SAP) by means of autoregressive power spectral analysis 2) assessment of the cardiac ...
Berntson Gary G - - 2008
The concept of autonomic balance views autonomic states along a bipolar continuum from sympathetic (S) to parasympathetic (P) dominance, whereas regulatory capacity models emphasize overall autonomic flexibility as a marker of the capacity for regulation. These two concepts were evaluated for their utility in characterizing patterns of autonomic control. Measures ...
Sato Shinichi - - 2008
A reliable basal heart rate (HR) measurement in freely moving newborn mice was accomplished for the first time by using a novel noninvasive piezoelectric transducer (PZT) sensor. The basal HR was approximately 320 beats/min at postnatal day (P)0 and increased with age to approximately 690 beats/min at P14. Contribution of ...
Karas Maria - - 2008
The effect of age on autonomic nervous system was assessed at rest and while standing using systolic blood pressure (SBP) and diastolic blood pressure (DBP), heart rate, and power spectral analysis of the time duration between 2 consecutive R waves of an electrocardiogram (RR) interval variability, as well as on ...
Jaja S I - - 2008
Autonomic function following change in posture with or without vitamin C supplementation was studied in ten (10) sickle cell anemia (SCA) and twelve (12) non-sickle cell anemia (NSCA) subjects. Arterial blood pressure and electrocardiographic measurements were taken in the supine position on a couch 80cm high and immediately on assumption ...
Sala-Mercado Javier A - - 2008
Dynamic cardiac baroreflex responses are frequently investigated by analyzing the spontaneous reciprocal changes in arterial pressure and heart rate (HR). However, whether the spontaneous baroreflex-induced changes in HR translate into changes in cardiac output (CO) is unknown. In addition, this linkage between changes in HR and changes in CO may ...
Jan Yih-Kuen - - 2008
OBJECTIVES: To provide insight into the physiologic mechanisms associated with alternating pressure, using wavelet analysis of skin blood flow (SBF) oscillations, and to determine whether the application of alternating pressure induces myogenic responses, thereby enhancing SBF as compared with constant loading. DESIGN: Repeated-measures design. SETTING: University research laboratory. PARTICIPANTS: Healthy, ...
Smith Stephen Matthew - - 2008
OBJECTIVE: To compare estimates of cardiac baroreceptor sensitivity (BRS) obtained by the Finapres device and from the direct measurement of arterial blood pressure (ABP) values from the ascending aorta, using both spectral analysis and sequence analysis. DESIGN: A cohort study of 45 coronary artery disease patients undergoing routine percutaneous coronary ...
Haegele-Link S - - 2008
Different components of the autonomic nervous system may be affected by different disorders to varying degrees. The aim of this study is to report first experiences with a new device (FAN(R), Schwarzer, Germany) which measures heart rate variability (HRV), sympathetic skin responses (SSR) and the pulse wave transit time (PTT). ...
Cai Fin Z J - - 2008
INTRODUCTION: The aim of this study was to compare cardiovascular autonomic nervous system function in patients with primary Sjögren's syndrome (pSS) with that in control individuals, and to correlate the findings with autonomic symptoms and the presence of exocrine secretory dysfunction. METHODS: Twenty-seven female patients with pSS and 25 control ...
Sesay Musa - - 2008
BACKGROUND: We studied sympathovagal activity using real-time heart rate variability (HRV) and determined its relationship with plasma catecholamines to characterize short-term cardioregulatory mechanisms during laparoscopic adrenal pheochromocytoma surgery. METHODS: We recruited 20 patients with pheochromocytoma (Group P) and 20 with incidentaloma (Group I). HRV, systolic blood pressure and heart rate ...
Wyller Vegard Bruun - - 2008
BACKGROUND: Hemodynamic abnormalities have been documented in the chronic fatigue syndrome (CFS), indicating functional disturbances of the autonomic nervous system responsible for cardiovascular regulation. The aim of this study was to investigate autonomic heart rate control during mild orthostatic stress in adolescents with CFS. METHODS: A total of 14 CFS ...
Mourot Laurent - - 2008
BACKGROUND: Moderately cold head-out water immersion stimulates both baro- and cold-receptors, and triggers complex and contradictory effects on the cardiovascular system and its autonomic nervous control. OBJECTIVES: To assess the effects of water immersion and cold on cardiovascular status and related autonomic nervous activity. METHODS: Hemodynamic variables and indexes of ...
Abe Makoto - - 2008
A human watching a swaying image displayed on a wide-field display or screen sometimes suffers from visually-induced motion sickness (VIMS) that causes symptoms related to the autonomic nervous system such as nausea, vomiting, and dizziness. Previous studies indicated that the maximum cross-correlation coefficient (rho(max)) between blood pressure and heart rate, ...
Theofilogiannakos Efstratios K - - 2008
OBJECTIVE: Fatal arrhythmias are a common cause of death in chronic obstructive pulmonary disease (COPD). Two major hypotheses for arrhythmogenesis in COPD have been proposed: arrhythmias are a consequence of hypoxaemia, hypercapnia or (tissue localised) acid-base disturbances, or arrhythmias are the result of the autonomic neuropathy that characterises COPD. Our ...
Lavinio Andrea A Institute of Anaesthesiology and Intensive Care Medicine, Ospedale Civile, Pzz.le Spedali Civili, 1, 25100 Brescia, Italy. - - 2008
The autonomic nervous system exerts tonic control on cerebral vessels, which in turn determine the autoregulation of cerebral blood flow. We hypothesize that the impairment of cerebral autoregulation following traumatic brain injury might be related to the acute failure of the autonomic system. This prospective, observational study included patients with ...
Papaioannou Vasilios - - 2008
PURPOSE: The purpose of the study was to investigate longitudinally over time heart rate (HR) and blood pressure variability and baroreflex sensitivity in acute brain injury patients and relate them with the severity of neurologic dysfunction and outcome. METHODS: Data from 20 brain injured patients due to multiple causes and ...
Galuszka Jan - - 2007
AIMS: The purpose of the study was to demonstrate autonomic nervous system (ANS) changes associated with treatment in hypertensive patients and utilization of these measurements in practice. METHODS: Hypertensive patients were examined before the start of treatment and after blood pressure compensation. The telemetric system VarCor PF 5 was used ...
Strudwick Mark W - - 2007
INTRODUCTION: Point injection as a therapeutic technique is well documented, but its physiological effects have not been formally compared with traditional acupuncture. One aim of this study was to compare the effects of the two techniques at one acupuncture point, as a step towards understanding the mode of action of ...
Hamaad Ali - - 2007
Several beta blocking drugs (BB) reduce mortality in systolic heart failure (LVSD). We have compared the initial response to introduction of carvedilol and bisoprolol during the standard dose titration protocols for each drug. Approximately 31 unselected patients with stable LVSD were randomised to either carvedilol or bisoprolol measuring blood pressure, ...
Claydon Victoria E - - 2008
Spinal cord injury (SCI) has profound effects on cardiovascular autonomic function due to injury to descending autonomic pathways, and cardiovascular diseases are the leading causes of morbidity and mortality after SCI. Evaluation of cardiovascular autonomic dysfunction after SCI and appraisal of simple noninvasive autonomic assessments that are clinically meaningful would ...
Stemper B - - 2008
OBJECTIVE: To evaluate the impact of vagus nerve stimulation (VNS) on heart rate and blood pressure (BP) modulation in epilepsy patients. MATERIAL AND METHODS: Twenty-one epilepsy patients with VNS were tested during on (60 s) and off (5 min) phases. We monitored BP, RR intervals (RRI) and respiration. Spectral analysis ...
Chen Xiaoxiao - - 2008
Heart rate (HR) power spectral indexes are limited as measures of the cardiac autonomic nervous systems (CANS) in that they neither offer an effective marker of the beta-sympathetic nervous system (SNS) due to its overlap with the parasympathetic nervous system (PNS) in the low-frequency (LF) band nor afford specific measures ...
Laude Dominique - - 2008
Short-term blood pressure (BP) variability is limited by the arterial baroreflex. Methods for measuring the spontaneous baroreflex sensitivity (BRS) aim to quantify the gain of the transfer function between BP and pulse interval (PI) or the slope of the linear relationship between parallel BP and PI changes. These frequency-domain (spectral) ...
Chen Xiaoxiao - - 2008
We previously developed a mathematical analysis technique for estimating the static gain values of the arterial total peripheral resistance (TPR) baroreflex (G(A)) and the cardiopulmonary TPR baroreflex (G(C)) from small, spontaneous beat-to-beat fluctuations in arterial blood pressure, cardiac output, and stroke volume. Here, we extended the mathematical analysis so as ...
Huang Chih-Cheng - - 2007
The baroreflex maintains a stable blood pressure (BP) by dynamically adjusting heart rate (vagal component) and total peripheral resistance (adrenergic component). Vagal baroreflex sensitivity (BRS-v) is widely used but no methodology existed to quantitate adrenergic baroreflex sensitivity (BRS-a) until we developed the indices of BP recovery time (PRT) and BRS-a. ...
Hanss R - - 2007
BACKGROUND: To investigate if changes in low-to-high frequency ratio (LF/HF), low frequency (LF) and high frequency (HF) heart rate variability reflect autonomic regulation during spinal anaesthesia (SA) in pregnant women scheduled for elective Caesarean section. METHODS: Prospective clinical trial. Systolic blood pressure (SBP) and heart rate variability were analysed at ...
Catz A - - 2007
OBJECTIVE: Study hemodynamic responses to cold application to the foot (CAF) to explore the autonomic cardiovascular control by the spinal cord. DESIGN: Controlled experimental study. Hemodynamic variables were measured or calculated for 13 healthy subjects, 10 patients with traumatic T4-T6 paraplegia, and 11 patients with traumatic C4-C7 tetraplegia. Subjects were ...
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