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Radtke Andrea A Virchow Klinikum der Charité, Augustenburger Platz 1, 13353 Berlin, FRG, Germany. - - 2003
We examined the hypothesis that vestibular signals may exert a rapid control on the heart adjusting cardiovascular function to maintain homoestasis during changes in body posture. Short- and long-latency effects of vestibular stimulation on heart rate (HR), systolic blood pressure (SP), diastolic pressure (DP) and digital blood flow (BF) were ...
Stewart Julian M - - 2002
BACKGROUND: Adrenergic agents are commonly used in the treatment of chronic orthostatic intolerance with postural tachycardia syndrome (POTS). POTS may be associated with increased limb blood flow ("high flow") and defective orthostatic vasoconstriction or decreased limb blood flow ("low flow") and potentially with small blood volume. METHODS AND RESULTS: We ...
Garland Emily M - - 2002
Orthostatic intolerance, seen predominantly in young women, is characterized by symptoms of lightheadedness, fatigue and palpitations in the upright posture. With standing, plasma norepinephrine levels rise dramatically and heart rate often increases by more than 30 beats per minute, although blood pressure does not usually fall. A theory recently popularized ...
Cooke William H - - 2002
Recent studies suggest that an underlying mechanism for susceptibility of patients and astronauts to presyncope includes hypoadrenergic responses to orthostatic stress. However, data used to reach this conclusion are open to various interpretations. In this report, maintenance of sympathetic neural activity (MSNA; peroneal nerve microneurography) during -60 mmHg lower body ...
Faghri Pouran D - - 2002
OBJECTIVE: To evaluate the central haemodynamic responses during position changes from supine to sitting and during 30 min of standing between able-bodied and spinal cord-injured subjects. Also to assess the effects of the physiologic muscle pump in both groups during 30 min of standing. DESIGN: A repeated measure design. Both ...
Hakeman Amy L - - 2002
Brief exposure to -G(z) ("push") reduces eye-level blood pressure (elbp) during subsequent exposure to +G(z) ("pull"). This is called the "push-pull effect." To evaluate the influence of gender and the axis of rotation (pitch vs. roll) on the push-pull effect, 10 isoflurane-anesthetized male and 10 female Sprague-Dawley rats were restrained ...
Schroeder Christoph - - 2002
BACKGROUND: Orthostatic symptoms and syncope are common, even in apparently healthy subjects. In patients with severe autonomic dysfunction, water drinking elicits an acute pressor response and improves orthostatic hypotension. We tested the hypothesis that water drinking also improves orthostatic tolerance in healthy subjects. METHODS AND RESULTS: In a randomized, controlled, ...
Weiss Avraham - - 2002
BACKGROUND: Orthostatic hypotension (OH) is a common finding among older patients. We designed a study to examine the prevalence and consistency of OH during the day. METHODS: A total of 502 inpatients (241 men and 261 women) with a mean age of 81.6 years were included in the study. Orthostatic ...
Jones Reese T - - 2002
Marijuana and delta9-tetrahydrocannabinol (THC) increase heart rate, slightly increase supine blood pressure, and on occasion produce marked orthostatic hypotension. Cardiovascular effects in animals are different, with bradycardia and hypotension the most typical response. Cardiac output increases, and peripheral vascular resistance and maximum exercise performance decrease. Tolerance to most of the ...
Monahan Kevin D - - 2002
Aging attenuates the increase in muscle sympathetic nerve activity (MSNA) and elicits hypotension during otolith organ engagement in humans. The purpose of the present study was to determine the neural and cardiovascular responses to otolithic engagement during orthostatic stress in older adults. We hypothesized that age-related impairments in the vestibulosympathetic ...
Romano Salvatore M - - 2002
BACKGROUND: The aim of this study was to assess whether a non-invasive automatic evaluation of the pulse wave characteristics could provide clinical clues when monitoring the hemodynamic adjustments to head-up tilting. METHODS: A continuous assessment of the peripheral pulse wave characteristics (systolic, diastolic, dicrotic and pulse pressures) in 8 control ...
Sarasin Francois P - - 2002
We sought to determine the prevalence of orthostatic hypotension as a cause of syncope in the emergency setting, and describe the characteristics of patients diagnosed with this condition. Blood pressure orthostatic changes were measured prospectively in a standardized fashion up to 10 minutes, or until symptoms occurred, in all consecutive ...
Khurana Ramesh K - - 2002
The role of trigeminal afferents in a patient with eye examination - induced syncope was investigated. A head-up tilt test precipitated presyncope with a reduced blood pressure. On a separate day, the application of Schirmer's lacrimation test strips in each conjunctival sac caused vasodepression and cardioinhibition. Topical administration of 0.5 ...
Belz G G - - 2002
In order to test the efficacy of a combination of natural D-camphor and an extract of fresh crataegus berries (Korodin Herz-Kreislauf-Tropfen) on orthostatic hypotension, two similar, controlled, randomized studies were carried out in a balanced crossover design in 24 patients each with orthostatic dysregulation. The camphor-crataegus berry combination (CCC) was ...
Youde J - - 2002
INTRODUCTION: Abnormalities of cardiac baroreceptor sensitivity (BRS) may contribute towards the high prevalence of orthostatic hypotension and falls in the elderly. Most mathematical analyses used to determine BRS in the time or frequency domains assume a stationary physiological state and cannot be performed under dynamic change and therefore are not ...
Akiyama Katsuyoshi - - 2002
KMD-3213 ((-)-1-(3-hydroxypropyl)-5-((2R)-2-[[2-([2-[(2,2,2-trifluoroethyl)oxy]phenyl]oxy)ethyl]amino]propyl)-2,3-dihydro-1H-indole-7-carboxamide), an alpha(1A)-adrenoceptor antagonist with potency similar to that of tamsulosin, is under development for the treatment of bladder outlet obstruction in patients with benign prostatic hypertrophy. In the present study, we investigated the effects of KMD-3213 on the tilt-induced blood pressure response in anesthetized normotensive rats. Male normotensive ...
Watenpaugh Donald E - - 2002
We hypothesized that vestibular otolith organ stimulation contributes to human orthostatic responses. Twelve subjects underwent three 60 degrees upright tilts: (1) with the neck flexed from 0 degrees to 30 degrees relative to the body during 60 degrees tilt, such that the head moved from horizontal to 90 degrees above ...
Krediet C T Paul - - 2002
BACKGROUND: Posture-related vasovagal syncope is by far the most frequent cause of transient loss of consciousness, and present pharmacological and cardiac pacing treatment remains unsatisfactory. A simple maneuver to prevent or diminish vasovagal reactions would be beneficial. METHODS AND RESULTS: Twenty-one patients with recurrent syncope (age 17 to 74 years, ...
Takata Theodore S - - 2002
BACKGROUND: The purpose of this study was to assess the effect of the serotonin reuptake inhibitor paroxetine hydrochloride (Paxil, SmithKline Beecham) on cardiovascular reflexes. We hypothesized that Paxil prevents neurally mediated syncope (NMS) by attenuating the sympathoinhibition and vagotonia associated with a vasovagal reaction. METHODS AND RESULTS: In a double-blind ...
Cooper V L - - 2002
During orthostatic stress, an increase in peripheral vascular resistance normally results in arterial blood pressure being well maintained, despite a decrease in cardiac output. The present study was undertaken to determine whether the sensitivity of the carotid baroreceptor reflex was increased during orthostatic stress and whether failure to develop this ...
Braune S - - 2002
The potential health risks of radiofrequency electromagnetic fields (EMFs) emitted by mobile phones are of considerable public interest. The present study investigated the hypothesis, based on the results of our previous study, that exposure to EMFs can increase sympathetic vasoconstrictor activity. Forty healthy young males and females underwent a single-blind, ...
Flevari Panagiota P - - 2002
Heart rate changes to hypotensive stimuli (baroreceptor sensitivity [BRS]) and forearm blood flow (FBF) reduction during head-up tilt are mediated by arterial and cardiopulmonary baroreceptors. Regarding baroreflexes in neurocardiogenic syncope (NCS), an apparent variation exists in findings reported in the literature. This may be due to the existence of different ...
Kaufmann Horacio - - 2002
Neurally mediated syncope is the most frequent cause of syncope in patients without structural heart disease. Its most common trigger is a reduction in venous return to the heart due to excessive venous pooling in the legs. We conducted a double-blind, randomized, crossover trial to investigate the efficacy of midodrine, ...
Timmers H J L M - - 2002
BACKGROUND: Data on the prevalence of orthostatic intolerance (OI) in patients with chronic fatigue syndrome (CFS) are limited and controversial. We tested the hypothesis that a majority of CFS patients exhibit OI during head-up tilt. METHODS: Hemodynamic and neurohumoral responses to 40 minutes of head-up tilt were studied in 36 ...
Jordan Jens - - 2002
Water drinking elicits a large, acute, pressor response in patients with autonomic failure who experience severe orthostatic hypotension. This essentially cost-free intervention has been successfully employed therapeutically in these patients to attenuate orthostatic and postprandial hypotension. In orthostatic intolerance patients, water drinking blunts the orthostatic tachycardia but has only a ...
Freeman Roy - - 2002
Venous denervation and increased venous pooling may contribute to symptoms of orthostatic intolerance. We examined venous compliance in the calf and forearm in 11 orthostatic-intolerant patients and 15 age-matched controls over a range of pressures, during basal conditions and sympathetic excitation. Occlusion cuffs placed around the upper arm and thigh ...
Shoemaker J K - - 2002
Sympathetic outflow increases during head-up tilt (HUT) to stabilize blood pressure in the presence of decreases in venous return and stroke volume (SV). Otherwise, orthostatic hypotension would develop. Gender differences in orthostatic tolerance have been noted but the mechanisms are still uncertain. More recently, Waters et al. reported in a ...
Hinghofer-Szalkay H - - 2002
This study was undertaken to identify combinations ('neutral points', NP) of orthostatic (tilt: head-down = HDT, head-up = HUT) and pseudo-orthostatic (lower body pressure: positive = LBPP, negative = LBNP) stimuli able to compensate one another in their effect on hemodynamic variables, electrical thoracic impedance (TI), hematocrit and plasma mass ...
Krishnan Anita - - 2002
Perfimttion of the tympanic membrane is nature's may of maintaining the middle far vntilation under the pressure of inflammatory process in the tempanomastoid cleft. An attempt at reconstruction with the possibility of infection lurking in and around the mastoid air cells may seem futile. Vow the quntinn arises as to ...
Baisch Friedhelm J - - 2002
In 1951 Gauer, Henry and Sieker proposed that "central hyper-volemia" might produce a diuresis that serves to reduce blood volume, a postulated negative-feedback system for the control of blood volume. Recent surprising results from human spaceflight indicate that although a central hyper-volemia takes place in weightlessness, an increase in salt ...
Convertino Victor A - - 2002
Head-up tilt table experiments conducted in astronauts prior to and immediately after the NASA Neurolab Space Mission (STS-90) revealed that a reduction in stroke volume induced by moving from the supine to upright posture was associated with increased muscle sympathetic nerve activity (MSNA). Although this finding was not unexpected, lower ...
Holmes M J - - 2002
The vestibular system is known to participate in cardiovascular regulation during movement and postural alterations. The present study considered whether lesions of two regions of the posterior cerebellar vermis (the nodulus and uvula) that provide inputs to vestibular nucleus regions that affect control of blood pressure would alter cardiovascular responses ...
Hisdal Jonny - - 2002
Mild (0 to -20 mmHg) lower body negative pressure (LBNP) has traditionally been considered to elicit reflex responses mediated by cardiopulmonary baroreceptors only, without any arterial baroreflex involvement. Mild LBNP has therefore frequently been used to study the influence of cardiopulmonary baroreceptors on the human circulatory system. In a previous ...
Stewart Julian M - - 2002
BACKGROUND: Orthostatic intolerance is characterized by postural tachycardia syndrome (POTS) with exaggerated tachycardia, orthostatic symptoms, and "pooling" (which comprises acrocyanosis and dependent edema when upright). My colleagues and I tested the hypothesis that pooling results from increased venous compliance in POTS patients. METHODS AND RESULTS: Fifteen patients aged 13 to ...
Harada Chizuru - - 2002
OBJECTIVE: This pilot study was undertaken to determine the effects of a 10-degree leg elevation for 30-degree head-up position on body displacement and sacral interface pressure for 2 hours. DESIGN: The study used a comparative, quasi-experimental design with repeated measures. Settings and Subjects: A convenience sample of 10 healthy Japanese ...
Mukai Seiji - - 2002
A common problem among elderly people, orthostatic hypotension is associated with significant morbidity and mortality, which may be caused by medications, the cumulative effects of age- and hypertension-related alterations in blood pressure regulation, or age-associated diseases that impair autonomic function. Evaluation requires multiple blood pressure measurements taken at different times ...
Hilz M J - - 2002
OBJECTIVE: Cerebral autoregulation was assessed by transcranial Doppler sonography in 10 patients with familial dysautonomia and 10 age matched controls. METHODS: Blood pressure, heart rate, and middle cerebral artery blood flow velocity (CBFV) were simultaneously recorded when supine and during 180 seconds of head up tilt. Cerebrovascular resistance (CVR) was ...
Tsutsui Yuka - - 2002
BACKGROUND: It is warranted to test the hypothesis that the orthostatic tolerance does not diminish in the aging process per se in healthy individuals. OBJECTIVE: The purpose of the present study was to examine the effects of aging on cardiovascular response and baroreflex sensitivity during lower body negative pressure (LBNP) ...
Heitterachi Edward - - 2002
BACKGROUND: orthostatic hypotension may be an important risk factor for falls, though this has not yet been demonstrated in prospective studies. This may be because conventional methods of measuring blood pressure changes are too imprecise and not optimally timed. OBJECTIVES: to determine whether changes in blood pressure induced by upright ...
Vloet Lilian C M - - 2002
OBJECTIVES: orthostatic hypotension is a common and potentially dangerous condition in elderly patients, often accompanied by dizziness and falls. To diagnose orthostatic hypotension, many physicians rely on blood pressure measurements performed by nurses. DESIGN: observational and descriptive study. SETTING: departments of Internal Medicine, Geriatric Medicine, and Surgery in eight hospitals ...
Jardine D L - - 2002
The importance of cardiac output (CO) to blood pressure level during vasovagal syncope is unknown. We measured thermodilution CO, mean blood pressure (MBP), and leg muscle mean sympathetic nerve activity (MSNA) each minute during 60 degrees head-up tilt in 26 patients with recurrent syncope. Eight patients tolerated tilt (TT) for ...
Mathias Christopher J - - 2002
A fundamental human expectation is to stand upright. This exposes the cardiovascular system to gravitational forces, with a fall in pressure above heart level exposing organs such as the brain to impaired perfusion if adequate adaptive mechanisms are not activated. The autonomic nervous system plays an important role in the ...
Chandler Margaret P - - 2002
Continuous haemodynamic responses to head-up tilt (HUT) and its reversal were studied in 21 subjects with sympathetic denervation due to primary chronic autonomic failure; 10 had pure autonomic failure (PAF; peripheral failure) and 11 had multiple system atrophy (MSA; central failure); 8 healthy subjects (controls) also were studied. Supine systolic, ...
Yamasaki Masao - - 2002
To clarify the effects of the head-down tilt (HDT) posture on the postnatal development of the aortic baroreflex, we raised rabbits from 3-4 weeks of age for 34-36 d in this posture, which simulates the headward shift of body fluid in space, and examined the structural and functional characteristics of ...
Shannon John R - - 2002
PURPOSE: Water drinking increases blood pressure in a substantial proportion of patients who have severe orthostatic hypotension due to autonomic failure. We tested the hypothesis that water drinking can be used as a practical treatment for patients with orthostatic and postprandial hypotension, as well as those with orthostatic tachycardia. SUBJECTS ...
Faber J - - 2002
In hypothyroidism, lack of thyroid hormones results in reduced cardiac function (cardiac output [CO]), and an increase of systemic vascular resistance (SVR). We speculated whether hemodynamic regulation in subjects with subclinical hypothyroidism (SH) (defined as mildly elevated thyrotropin [TSH] despite free thyroxine [T(4)] and triiodothyronine [T(3)] estimates within reference range) ...
Vaitl Dieter - - 2002
This article examines the relation between the perception of one's own body position and the distribution of fluid along the subject's spinal (z-) axis. Two experiments are reported. The first one is a replication of the Vaitl et al. study [J. Psychophysiol. 27 (1997) 99] which has shown that changes ...
Toska Karin - - 2002
Mechanisms involved in the control of arterial pressure during postural changes were studied by analysis of the dynamic time course of cardiovascular changes during head-up tilt (HUT) and tilt back to supine position (TB). Beat-to-beat values of cardiovascular variables were recorded continuously before, during, and after passive HUT to 30 ...
Hofer C K - - 2002
BACKGROUND: It is still controversial whether elevated cardiac filling pressures after the onset of pneumoperitoneum are the consequence of increased intrathoracic pressure or of increased venous return. The aim of this study was to assess the effects of pneumoperitoneum and body positioning on intrathoracic blood volume (ITBV). METHODS: Thirty anesthetized ...
Jordan Jens - - 2002
Orthostatic hypotension is seen in various medical conditions. It can be secondary to medications or volume depletion. It can also be due to autonomic neuropathy secondary to other diseases, such as diabetes mellitus, or to primary degenerative processes of the autonomic nervous system. Orthostatic hypotension dominates the clinical picture of ...
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