Search Results
Results 401 - 450 of 1594
< 4 5 6 7 8 9 10 11 12 13 14 >
Dalla Pozza R - - 2005
Syncope represents a diagnostic challenge in patients affected by long-QT syndrome (LQTS). It is crucial for the therapeutic decision to distinguish between potentially life-threatening ventricular tachycardias (Torsadede-pointes) and-especially during adolescence-neurocardiogenic syncopes. This case report presents a patient with LQTS2 (mutation in the HERG gene) on medication with beta-blocker, in whom ...
Chang Angela T - - 2005
Passive tilting increases ventilation in healthy subjects; however, controversy surrounds the proposed mechanism. This study is aimed to evaluate the possible mechanism for changes to ventilation following passive head-up tilt (HUT) and active standing by comparison of a range of ventilatory, metabolic and mechanical parameters. Ventilatory parameters (V (T), V ...
Gibbons Christopher H - - 2005
The authors report a 46-year-old woman with antibodies to the nicotinic acetylcholine receptor (NiAchR) of the autonomic ganglia. She presented with severe orthostatic intolerance refractory to treatment with midodrine, fludrocortisone, erythropoietin, vasopressin, salt, and fluid loading. Addition of L-threo-3,4-dihidroxyphenylserine (L-DOPS) substantially improved blood pressure and orthostatic tolerance. L-DOPS may benefit ...
Goldstein David S - - 2005
Patients with Parkinson disease often have orthostatic hypotension. Neurocirculatory abnormalities underlying orthostatic hypotension might reflect levodopa treatment. Sixty-six Parkinson disease patients (36 with orthostatic hypotension, 15 off and 21 on levodopa; 30 without orthostatic hypotension) had tests of reflexive cardiovagal gain (decrease in interbeat interval per unit decrease in systolic ...
van Lieshout J J - - 2005
BACKGROUND: The stroke volume (SV) of the heart depends on the diastolic volume but, for the intact organism, central pressures are applied widely to express the filling of the heart. METHODS: This study evaluates the interdependence of SV and thoracic electrical admittance of thoracic fluid content (TA) vs. the central ...
Laperrière E - - 2006
North American workers usually stand while working, and prolonged standing is associated with discomfort and cardiovascular problems. Since prolonged sitting is also associated with health problems, and standing postures differ as to mobility and access to seating, it is desirable to identify an optimal mix of postures. As a step ...
Kimmerly Derek S - - 2005
The purpose of the present study was to determine the cortical structures involved with integrated baroreceptor-mediated modulation of autonomic cardiovascular function in conscious humans independent of changes in arterial blood pressure. We assessed the brain regions associated with lower body negative pressure (LBNP)-induced baroreflex control using functional magnetic resonance imaging ...
Fortrat Jacques-Olivier - - 2005
BACKGROUND: Sophisticated atrio-ventricular pacing models are designed to integrate the pacemaker into cardiovascular autonomic control to react appropriately to the cardiovascular demands. Such an approach might be beneficial for patients with vasovagal responses to counterbalance the upright fall in arterial blood pressure by a pacing rate increase. We hypothesized that ...
Diehl Rolf R - - 2005
BACKGROUND: The clinical diagnosis of the postural tachycardia syndrome (POTS) includes the demonstration of an upright heart rate (HR) of at least 30 beats per minute (bpm) above supine HR. The dynamic behavior of HR during the course of standing has not yet been studied systematically in POTS. METHODS: HR ...
Kim Kye Hun - - 2005
BACKGROUND: It is known that approximately two-thirds of patients with vasovagal syncope have prodromal symptoms and when these start, physical maneuvers that can increase venous return may abort the syncopal attack. The aims of this study were to evaluate the effects of 3 physical maneuvers, squatting, leg-crossing with muscle tensing, ...
Carvalho D C L - - 2005
Blood pressure pattern was analyzed in 12 complete quadriplegics with chronic lesions after three months of treadmill gait training. Before training, blood pressure values were obtained at rest, during treadmill walking and during the recovery phase. Gait training was performed for 20 min twice a week for three months. Treadmill ...
Tanaka Kunihiko - - 2005
To examine a hypothesis that change in regional blood flow due to decreased hydrostatic pressure gradient and redistribution of blood during reduced gravity (rG) is different between organs, changes in cerebrocortical blood flow (CBF) and blood flow in the temporal muscle (MBF) with exposure to rG were measured in anesthetized ...
Benditt David G - - 2005
BACKGROUND: "Cough syncope" is uncommon, and its mechanism remains controversial. OBJECTIVES: This study evaluated susceptibility to cough-triggered neural reflex hypotension-bradycardia among cough syncope patients. We hypothesized that individuals with cough syncope would manifest not only more profound cough-triggered hypotension than do other fainters but also an inappropriate chronotropic response accompanying ...
Cooke William H - - 2005
Cardiovascular adaptations driven by exposure to weightlessness cause some astronauts to experience orthostatic intolerance upon return to Earth. Maladaptations of spaceflight that lead to hemodynamic instability are temporary, and therefore astronauts provide for researchers a powerful model to study cardiovascular dysfunction in terrestrial patients. Orthostatic intolerance in astronauts is linked ...
Shewchenko N - - 2005
OBJECTIVES: Head impacts from footballs are an essential part of the game but have been implicated in mild and acute neuropsychological impairment. Ball characteristics have been noted in literature to affect the impact response of the head; however, the biomechanics are not well understood. The present study determined whether ball ...
Sagawa Sueko - - 2005
INTRODUCTION: Accumulated evidence indicates attenuated vasopressin (AVP) release associated with hyperbaria in humans. The present study was designed to test the hypothesis that plasma AVP response to central hypovolemia was attenuated in a hyperbaric environment. METHODS: Response of AVP to central hypovolemic stress, in the form of lower-body negative pressure ...
Cui Jian - - 2005
Orthostatic stress leads to a reduction in central venous pressure (CVP), which is an index of cardiac preload. Skin surface cooling has been shown to improve orthostatic tolerance, although the mechanism resulting in this outcome is unclear. One possible mechanism may be that skin surface cooling attenuates the drop in ...
Chao Clare Y - - 2005
OBJECTIVE: To determine whether application of functional electric stimulation (FES) to lower-limb muscles during postural tilting improves orthostatic tolerance in people with tetraplegia. DESIGN: A crossover design. SETTING: A rehabilitation hospital. PARTICIPANTS: Sixteen acute and chronic subjects with tetraplegia (15 men, 1 woman) with complete motor function loss at the ...
Pennock Andrew T - - 2005
The purpose of this study was to evaluate and quantify the effects of forearm rotation on radial inclination, radial height and palmar tilt. Seventeen arms, nine cadaveric and eight volunteer, were examined using a radiolucent device that allowed for the controlled rotation of each arm. Lateral and posterior-anterior X-rays were ...
Convertino Victor A - - 2005
There is little evidence obtained from space flight to support the notion that occurrence of cardiac dysrhythmias, impaired cardiac and vascular function, and manifestation of asymptomatic cardiovascular disease represent serious risks during space flight. Therefore, the development of orthostatic hypotension and instability immediately after return from spaceflight probably reflect the ...
Eiken Ola - - 2005
BACKGROUND: Motion sickness is a common aeromedical problem that may occur in pilots exposed to increased gravitoinertial load in the head-to-foot direction (+Gz). Since motion sickness may affect autonomic nervous functions including cardiovascular control, it was hypothesized that it might interfere with cardiovascular responses to high +Gz, thereby decreasing G ...
Hernandez Juliane P - - 2005
BACKGROUND: The purpose of this investigation was to determine the effects of age and fitness on tolerance to maximal lower body negative pressure (LBNP). METHODS: Ten older fit (OF) [73.9 +/- 2 years; 39.0 +/- 2 ml.kg(-1).min(-1) (age and estimated VO(2)peak, respectively)], 10 older unfit (OU) (70.9 +/- 1 years; ...
Kamiya Atsunori - - 2005
Since humans are under ceaseless orthostatic stress, the mechanism to maintain arterial pressure (AP) under orthostatic stress against gravitational fluid shift is of great importance. We hypothesized that (1) orthostatic stress resets the arterial baroreflex control of sympathetic nerve activity (SNA) to a higher SNA, and (2) resetting of the ...
Convertino Victor A - - 2005
Recent studies in our laboratory demonstrated that spontaneous breathing through an inspiratory impedance threshold device (ITD) increased heart rate (HR), stroke volume (SV), cardiac output (Q), and mean arterial blood pressure (MAP) in supine human subjects. In this study, we tested the effectiveness of an ITD as a countermeasure against ...
Ito Tomoyuki - - 2005
The aim of this study was to elucidate the interactive effect of central hypovolemia and plasma hyperosmolality on regulation of peripheral vascular response and AVP secretion during heat stress. Seven male subjects were infused with either isotonic (0.9%; NOSM) or hypertonic (3.0%; HOSM) NaCl solution and then heated by perfusing ...
Groothuis Jan T - - 2005
Despite loss of centrally mediated sympathetic vasoconstriction to the legs, spinal cord-injured individuals cope surprisingly well with an orthostatic challenge. This study assessed changes in leg vascular resistance following head-up tilt in healthy (C) and in paraplegic (P) individuals. After 10 min of supine rest, subjects were tilted 30 degrees ...
Fernhall Bo - - 2005
OBJECTIVES: To determine whether heart rate and blood pressure responses to upright tilt would be lower in subjects with Down syndrome (DS) than in control subjects with no disabilities. DESIGN: Comparative study. SETTING: University research laboratory. PARTICIPANTS: Nineteen people with DS (mean age, 25.1+/-7.3 y) and 17 control subjects without ...
Groothuis Jan T - - 2005
Despite the loss of centrally mediated sympathetic vasoconstriction, spinal cord-injured (SCI) individuals cope surprisingly well with orthostatic challenges. In the pathophysiology of this intriguing observation spinal sympathetic-, veno-arteriolar-(VAR), and myogenic reflexes seem to play a role. The purpose of this study was to assess whether central (stroke volume, heart rate, ...
Raffai Gábor - - 2005
Incidence of orthostatic hypertension is estimated at 5% but is even more prevalent in borderline hypertension and autonomic neuropathies. The aim of this study was to develop a potential model to investigate orthostatic hypertension. We used normotensive and hypertensive Wistar rats to analyze responses and diurnal variations of arterial blood ...
Wolinsky Fredric D - - 2005
We evaluate the test-retest stability of physical performance and physiologic assessments used in epidemiologic research. METHOD: Eighty subjects aged 50 to 65 were randomly selected from a probability sample of African Americans for test-retest assessments 5 to 45 days after baseline. Physical performance assessments included grip strength, chair stands, gait ...
Nette R W - - 2005
AIMS: Hypotensive episodes are a major complication of hemodialysis. Hypotension during dialysis could be directly related to a reduction in blood volume or to a decrease in cardiovascular activation as a response to decreased cardiac filling. A decreased cardiovascular activation could be due to patient-related or to dialysis-related factors. In ...
Petrofsky Jerrold Scott - - 2005
BACKGROUND: Diabetes is often associated with orthostatic hypotension and temperature intolerance. Studies have examined either one stress or the other and not both to see if the stresses are additive. MATERIAL/METHODS: Eight subjects with Type 1 and 12 subjects with Type 2 diabetes and 15 controls were tested for orthostatic ...
Meendering Jessica R - - 2005
Women have decreased orthostatic tolerance compared with men, and anecdotal evidence suggests women are more susceptible to orthostatic intolerance in warm environments. Because estrogen and progesterone affect numerous physiological variables that may alter orthostatic tolerance, the purpose of our study was to compare orthostatic tolerance across the menstrual cycle phases ...
Kitano Asami - - 2005
To investigate local blood-flow regulation during orthostatic maneuvers, 10 healthy subjects were exposed to -20 and -40 mmHg lower body negative pressure (LBNP; each for 3 min) and to 60 degrees head-up tilt (HUT; for 5 min). Measurements were made of blood flow in the brachial (BF(brachial)) and femoral arteries ...
Prakash E S - - 2005
In vasovagal syncope, occurrence of bradycardia/asystole in the wake of hypotension has often been considered paradoxical. The major objective of this teaching module is to critically examine the pathophysiological mechanism and significance of the hypotension-bradycardia paradox unique to this condition. We narrate here how we discussed the pathophysiology of vasovagal ...
Shibao Cyndya - - 2005
Postural tachycardia syndrome (POTS) is a disabling condition that commonly affects otherwise normal young females. Because these patients can present with a flushing disorder, we hypothesized that mast cell activation (MCA) can contribute to its pathogenesis. Here we describe POTS patients with MCA (MCA+POTS), diagnosed by episodes of flushing and ...
Uchiyama T - - 2005
BACKGROUND: Patients with multiple system atrophy (MSA) occasionally have episodes of syncope or pre-syncope after micturition. OBJECTIVE: To clarify the mechanism of these episodes by investigating the haemodynamic changes associated with micturition. METHODS: 25 patients with probable MSA and 16 age matched normal controls were studied. Continuous records of blood ...
Gulli Giosuè - - 2005
In addition to the gain, the time delay in the input-output response in a feedback system is crucial for the maintenance of its stability. Patients with posturally related (vasovagal) syncope have inadequate control of blood pressure and one possible explanation for this could be prolonged latency of the baroreflex. We ...
Gisolf J - - 2005
Reduction in plasma volume is a major contributor to orthostatic tachycardia and hypotension after spaceflight. We set out to determine time- and frequency-domain baroreflex (BRS) function during preflight baseline and venous occlusion and postflight orthostatic stress, testing the hypothesis that a reduction in central blood volume could mimic the postflight ...
Ouchi Yasuomi - - 2005
To investigate whether a physiological change in the orthostatic condition is associated with a deterioration of cerebrovascular and metabolic homeostasis in patients with neurocardiovascular compromises, we examined 10 patients with unilateral carotid artery occlusive disease (CVD), 6 CVD patients with coronary artery disease (CVDC), and 10 healthy subjects scanned twice ...
Sahni Manish - - 2005
Orthostatic hypotension is very common in the elderly. It increases morbidity and is an independant predictor of all cause mortality. It is defined as a fall in systolic blood pressure greater than 20 mm Hg or a fall in diastolic blood pressure greater than 10 mm Hg within 3 minutes ...
Hoshide Satoshi - - 2005
To investigate the impact of arterial properties on orthostatic blood pressure (BP) dysregulation in older hypertensives, orthostatic BP dysregulation, a common phenomenon in elderly hypertensives, is associated with target organ damage and falls. However, the mechanism of orthostatic BP dysregulation remains unclear. The pulse wave velocity (PWV), related arterial stiffness, ...
Asahina Masato - - 2005
On head down tilt to the supine horizontal position (tilt reversal) after head up tilt (HUT), patients with orthostatic hypotension may show an increase in blood pressure (BP) relative to baseline readings. We assessed this BP overshoot in 8 patients with pure autonomic failure (PAF, 64+/-13 years) and 8 patients ...
van Dijk Nynke - - 2005
A 33-year old male patient, with Marfan's syndrome, reported symptoms of orthostatic intolerance and fatigue as a longstanding problem. Orthostatic cardiovascular examination showed poor orthostatic tolerance, with a rise in heart rate and a fall in arterial blood pressure and cerebral blood flow velocity. Self-discovered physical counterpressure manoeuvers improved symptoms, ...
Stage Kurt Bjerregaard Bjerregaard - - 2005
From a clinical point of view, orthostatic hypotension is a significant side effect during antidepressant treatment, particularly in the case of tricyclic antidepressants (TCAs). This prospective, randomized clinical trial evaluated the effects of clomipramine and moclobemide on orthostatic blood pressure during treatment for depression. One hundred and fifteen depressed inpatients, ...
Gorelik Oleg - - 2005
Information about orthostatic hypotension (OH) among elderly patients hospitalized for acute conditions in short-term facilities is scarce. Many older inpatients carry various predisposing factors for OH. However, its existence goes frequently unrecognized. In this context, first morning standing up following admission for an acute disease may be dangerous. The aim ...
Russomano T - - 2005
A headward fluid shift occurs during microgravity exposure, which causes the cardiovascular adaptive syndrome. Different countermeasures have been proposed to decrease its symptomatology, like the application of lower body negative pressure (LBNP). A LBNP box with an environment control system was developed, aiming to improve features of LBNP boxes used ...
Naylor Justine M - - 2005
BACKGROUND AND PURPOSE: Isolated head-down postural drainage is assumed to acutely load the cardiovascular system. Consequently, it is considered a relative contraindication in the presence of severe cardiovascular disease. Evidence demonstrating that the head-down manoeuvre as used by physiotherapists does significantly load the cardiovascular system is lacking. The present study ...
Lu Hongbing - - 2005
The aim of this study is to investigate the upper limit of protection afforded by various protective equipment and techniques that used in combination and used individually. A multi-element, nonlinear mathematical model, which was previously used to produce cardiovascular response to +Gz stress and protection afforded by anti-G suits, was ...
Tachtsidis Ilias - - 2005
The cardiovascular and cerebrovascular responses to head-up postural change are compromised in pure autonomic failure (PAF) patients because of sympathetic denervation. The aim of this study was to characterize the rate of change of systemic mean blood pressure (MBP) and cerebral haemodynamics in response to passive posture changes. Nine PAF ...
< 4 5 6 7 8 9 10 11 12 13 14 >