Search Results
Results 201 - 250 of 1600
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Minns Alicia B - - 2010
INTRODUCTION: Guanfacine is an alpha(2)-adrenoreceptor agonist used for the treatment of attention-deficit hyperactivity disorder and tic disorders. Few reports exist regarding overdose with guanfacine. CASE REPORT: A 16-year-old female with Tourette's syndrome presented with diaphoresis, dry mouth, and hypertension 8 h after ingesting 25 mg of guanfacine. These symptoms improved ...
Jarvis Sara S - - 2010
The volume indifferent point (VIP) is the point within the circulation where blood volume does not change with changes in posture. Because both volume and pressure are unaffected by posture at this point, its location should dictate the filling gradient to the heart. Previously we identified a contribution of the ...
MacDiarmid Scott A - - 2010
To evaluate the orthostatic effects and safety of coadministration of silodosin with the phosphodiesterase-5 inhibitors sildenafil and tadalafil. In this placebo-controlled, open-label crossover study, 22 healthy men aged 45-78 years received 8 mg silodosin for 21 days. On days 7, 14, and 21, subjects also received a single dose of ...
Dyson Kenneth S - - 2010
We compared Modelflow (MF) estimates of cardiac stroke volume (SV) from the finger pressure-pulse waveform (Finometer) with pulsed Doppler ultrasound (DU) of the ascending aorta during acute changes in total peripheral resistance (TPR) in the supine and head-up-tilt (HUT) postures. Twenty-four women were tested during intravenous infusion of 0.005 or ...
Sheriff Don D - - 2010
Tolerance to +G(z) gravitational stress is reduced when +G(z) stress is preceded by exposure to hypogravity (fractional, 0, or negative G(z)). For example, there is an exaggerated fall in eye-level arterial pressure (ELAP) early on during +G(z) stress (head-up tilt; HUT) when this stress is immediately preceded by -G(z) stress ...
Hernandez Juliane P - - 2010
This investigation attempted to determine whether heart-rate and blood pressure responses to maximal acute lower body negative pressure (LBNP) are exacerbated compared with maximal graded LBNP in active older (n = 9, 70 +/- 7 yr) and endurance-trained younger (n = 10, 23 +/- 3 yr) individuals. Heart rate increased ...
Corino V D A - - 2010
During atrial fibrillation (AF), ventricular response is highly irregular and thus the beat-to-beat variation of blood pressure is increased because of variations in filling time and in contractility. Aim of the present study is to investigate the short-term dynamics of RR and SAP series in patients with AF, during rest ...
Thomas Kate N - - 2010
There are several reports on syncope occurring following standing at high altitude (HA), yet description of the detailed physiological responses to standing at HA are lacking. We examined the hypothesis that appropriate physiological adjustments to upright posture would be compromised at HA (5050 m). Ten healthy volunteers stood up rapidly ...
Okpechi Ikechi G - - 2010
Hypertension is the most prevalent cardiovascular disease of adults and is a major risk factor for cardiovascular (CV) and cerebrovascular morbidity and mortality worldwide. Treatment of hypertension leads to reduction of CV morbidity and mortality through blood pressure reduction. The role of renin-angiotensin-aldosterone system (RAAS) in the pathophysiology of hypertension ...
Morimoto Satoshi - - 2010
Rigid control of blood pressure (BP) is essential to prevent cardiovascular disease. However, only about 40% of hypertensive patients undergoing pharmacological intervention with a single agent achieve their BP goals in contemporary clinical practice. Combined therapy using currently available agents is effective in maximizing treatment outcome, although it raises medical ...
Ladino Marco - - 2010
Chronic kidney disease (CKD) affects approximately 26 million adults in the United States and millions of others are at increased risk. Type 2 diabetes and hypertension are the two main causes of CKD. Blood pressure control is critical to slow the progression of CKD. Despite adequate control, however, patients continue ...
Formes Kevin - - 2010
This study sought to test the hypothesis that orthostasis-induced cerebral hypoperfusion would be less severe in physically active elderly humans (ACT group) than in sedentary elderly humans (SED group). The peak O(2) uptake of 10 SED (67.1 +/- 1.4 yr) and 9 ACT (68.0 +/- 1.1 yr) volunteers was determined ...
Goldstein David S - - 2010
OBJECTIVE: Chronic autonomic failure (CAF), as in Parkinson disease (PD), multiple system atrophy (MSA), and pure autonomic failure (PAF), typically entails baroreflex failure, neurogenic orthostatic hypotension (NOH), and supine hypertension. The combination might predispose to cardiac ectopy, which in turn might predispose to syncope and falls during manipulations decreasing venous ...
Newton Julia L - - 2009
BACKGROUND: Fatigue is a significant symptom in nonalcoholic fatty liver disease (NAFLD) that impacts upon quality of life and is unrelated to liver disease severity. We examined the relationship between parameters of blood pressure regulation with perception of fatigue in NAFLD. METHODS: Thirty-four non-diabetic subjects with histologically proven, non-cirrhotic NAFLD ...
Schroeder Christoph - - 2009
BACKGROUND: In animals, the endocannabinoid system is activated during hemodynamic insults and restrains blood pressure in part through sympathetic inhibition. MATERIALS AND METHODS: We tested the hypothesis that hemodynamic stress elicited by head-up tilt testing increases systemic endocannabinoid concentrations in humans and that excessive endocannabinoid availability predisposes to presyncope. RESULTS: ...
Lalande Sophie - - 2009
INTRODUCTION: Fighter aircraft pilots are exposed to repetitive headward acceleration (+Gz) during air combat maneuvering. The objective of this study was to compare physiologic responses and the calculated +Gz tolerances of multiple successive +Gz exposures with the responses of the first +Gz exposure. METHODS: There were 13 subjects who performed ...
T??llez Maria J - - 2009
OBJECTIVE: To determine whether the heart rate changes during tilt table testing could be used in the differential diagnosis between vasovagal syncope and chronic autonomic failure. METHODS: We compared the relationship between electrocardiographic R-R intervals and beat-to-beat blood pressure in 43 patients with typical vasovagal responses and 30 patients with ...
Batzel Jerry Joseph - - 2009
To investigate patterns of cardiovascular control, a protocol of head up tilt (HUT) followed by lower body negative pressure (LBNP), which represents a significant cardiovascular control challenge, was employed. Linear regression of beat-to-beat heart rate (HR) and mean blood pressure (MBP) data collected over repeated tests was used to analyze ...
Lucas Rebekah A I - - 2010
Skin surface cooling has been shown to improve orthostatic tolerance; however, the influence of severe heat stress on cardiovascular and cerebrovascular responses to skin cooling remains unknown. Nine healthy males, resting supine in a water-perfusion suit, were heated to +1.0 and +2.0 degrees C elevation in body core temperature (T ...
Hausenloy Derek John - - 2009
AIMS: During head-up tilt (HUT) testing, a period of haemodynamic instability, marked by oscillations in blood pressure, often precedes vasovagal syncope. We hypothesized that the presence of oscillations in blood pressure during HUT testing predicts a positive diagnosis for vasovagal syncope. METHODS AND RESULTS: The haemodynamic profiles of 42 consecutive ...
Ogata Hisayoshi - - 2010
We report a case of an individual with cervical spinal cord injury who showed a unique blood pressure response during passive standing and passive walking-like leg movement, i.e., hypertension with standing and hypotension with leg movement.
Thijs Roland D - - 2010
In autonomic failure (AF), blood pressure (BP) falls upon standing which is commonly ascribed to defective vasoconstriction and excessive pooling. Observations on the amount of pooling in AF are contradictory. We evaluated pooling using strain-gauge plethysmography (SGP) during head-up tilt (HUT) with a parachute harness fixed to the tilt table ...
Kai Tatsuya - - 2009
The current study was conducted to examine the effects of cilnidipine, a dual L/N-type calcium channel blocker, on blood pressure, pulse rate, and autonomic functions in patients with mild-to-moderate hypertension. Sixteen patients with mild-to-moderate hypertension (8 males and 8 females; 44-72 years of age) were treated with cilnidipine (10 mg/day) ...
Kiviniemi Antti M - - 2010
Altered frequency of slow (0.04-0.15Hz) arterial pressure and R-R interval oscillations has been observed in various diseases but the mechanisms for this frequency shift are unclear. The median (Med) frequencies of slow R-R interval and blood pressure (BP) oscillations were recorded in 11 healthy subjects with paced breathing (0.25Hz) during ...
Ziemssen Tjalf - - 2010
Symptoms of cardiovascular dysautonomia are a common occurrence in Parkinson's disease (PD). In addition to this dysautonomia as part of PD itself, dysfunction of the autonomic nervous system (ANS) can be triggered as a side-effect of drug treatment interacting with the ANS or - if prominent and early - an ...
Notarius Catherine F - - 2009
Many heart failure (HF) patients exhibit paradoxical forearm vasodilation when central blood volume is reduced by lower body negative pressure (LBNP). We tested the hypothesis that this response results from reflex sympathetic withdrawal. We recorded simultaneously forearm blood flow, muscle sympathetic nerve activity (MSNA), and plasma norepinephrine (PNE) during four ...
Cooke William H - - 2009
Activation of sympathetic efferent traffic is essential to maintaining adequate arterial pressures during reductions of central blood volume. Sympathetic baroreflex gain may be reduced, and muscle sympathetic firing characteristics altered with head-up tilt just before presyncope in humans. Volume redistributions with lower body negative pressure (LBNP) are similar to those ...
Fan Xiao-han XH Department of Cardiology and Hypertension Division, Ministry of Education, Cardiovascular Institute & FuWai Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100037, - - 2009
The genetic background of orthostatic blood pressure dysregulation remains poorly understood. Since the renin-angiotensin system plays an important role in blood pressure regulation and response to position change, we hypothesized that angiotensin-converting enzyme (ACE) and ACE2 genetic polymorphisms might contribute, at least partially, to orthostatic blood pressure dysregulation in hypertensive ...
Ogata Hisayoshi - - 2009
OBJECTIVE: To determine whether arterial hypotension is related to hyperventilation during standing in individuals with complete spinal cord injury (SCI). METHODS: Sixteen individuals with SCI (thoracic 1 to thoracic level 12, ASIA grade: A) and 18 able-bodied individuals participated in this study. Individuals with SCI were divided into a group ...
Hindes Mariah - - 2009
The purpose of this study was to investigate the functional relationship between subsyndromal orthostatic blood pressure regulation and motor skills in 3-5 year old children. It is known that the efficiency of orthostatic blood pressure regulation is affected by a variety of processes, most especially neurohumoral as well as sympathetic ...
Newman David G - - 2009
INTRODUCTION: Fighter pilots report G tolerance increases with regular exposure. Our previous work has shown that the cardiovascular system of +Gz-adapted fighter pilots responds differently to orthostatic challenges than that of non-pilots. A +Gz training effect in pilots after repetitive +Gz exposure has also been shown. Individual pilot factors such ...
Zaar M M Department of Anesthesia, Rigshospitalet, University of Copenhagen, Denmark. - - 2009
We considered that a moderate reduction of the central blood volume (CBV) may activate the coagulation system. Lower body negative pressure (LBNP) is a non-invasive means of reducing CBV and, thereby, simulates haemorrhage. We tested the hypothesis that coagulation markers would increase following moderate hypovolemia by exposing 10 healthy male ...
Hughson Richard L - - 2009
The cardiovascular system undergoes major changes in stress with space flight primarily related to the elimination of the head-to-foot gravitational force. A major observation has been that the central venous pressure is not elevated early in space flight yet stroke volume is increased at least early in flight. Recent observations ...
Immink Rogier V - - 2009
In the upright position, cerebral blood flow is reduced, maybe because arterial carbon dioxide partial pressure (Pa(CO(2))) decreases. We evaluated the time-dependent influence of a reduction in Pa(CO(2)), as indicated by the end-tidal Pco(2) tension (Pet(CO(2))), on cerebral perfusion during head-up tilt. Mean arterial pressure, cardiac output, middle cerebral artery ...
Sharma Pramod - - 2009
BACKGROUND: Heart rate variability is actually a misnomer for R to R variability in cardiac cycle. Variation in successive cycle length is called the heart rate variability (HRV). Head-up tilt is a model of studying cardiovascular haemodynamics, which reflects in heart rate variability (HRV). OBJECTIVES: To study the effect of ...
Tahvanainen Anna - - 2009
AIMS: To examine the effects of salbutamol and L-arginine, two compounds acting largely on the endothelium, and the endothelium-independent agent nitroglycerin on blood pressure, arterial compliance, cardiac function and vascular resistance. METHODS: Continuous radial pulse wave analysis, whole-body impedance cardiography, and plethysmographic blood pressure from fingers in the supine position ...
Goswami Nandu - - 2009
We studied individual stability of orthostatic tolerance as well as presyncopal signs and symptoms across four runs in subjects undergoing combined head-up tilt (HUT) and lower body negative pressure (LBNP). Ten healthy young males were subjected to HUT+ LBNP, to achieve a presyncopal end-point. Four test runs were separated by ...
Yi Chung-Hwi - - 2009
The damage caused by pressure in bedridden hospitalized patients is attributable to the body tissues becoming compressed against bony prominences, which results in poor capillary perfusion. Automated inclining beds were developed in this study to assist patients in repositioning, with the aim of quantifying the effects of 3 types of ...
Koyama Yu - - 2009
To assess heart rate (HR) regulation in Machado-Joseph disease (MJD), we evaluated HR variability at rest and the initial HR response to standing suddenly in 13 MJD patients and 26 normal control subjects. A head-up tilt (HUT) test involving the monitoring of blood pressure, HR, and cerebral oxy/deoxyhemoglobin concentration was ...
Wilson T E - - 2009
The Frank-Starling 'law of the heart' is implicated in certain types of orthostatic intolerance in humans. Environmental conditions have the capacity to modulate orthostatic tolerance, where heat stress decreases and cooling increases orthostatic tolerance. The objective of this project was to test the hypothesis that heat stress augments and cooling ...
Fedorowski Artur - - 2009
OBJECTIVES: Prevalence and determinants of orthostatic hypotension remain largely unexplored in younger individuals without significant burden of chronic diseases. METHODS: We investigated frequency and main associations of impaired orthostatic response in a cohort of 469 middle-aged hypertensive patients and 453 of their normotensive first-degree relatives. RESULTS: 13.4% of hypertensive and ...
Carter Jason R - - 2009
Sympathetic baroreflex sensitivity (BRS) and muscle sympathetic nerve activity (MSNA) responses during early follicular (EF) and midluteal (ML) phases of the menstrual cycle are controversial. We hypothesize an augmented sympathetic BRS and MSNA response to orthostatic stress during the ML phase of the menstrual cycle. MSNA, mean arterial pressure (MAP), ...
Goswami Nandu - - 2009
AIMS: Combined head up tilt (HUT) and lower body negative pressure (LBNP) can be used to exploit the full spectrum of cardiovascular control mechanisms and to reveal characteristics of individual blood pressure control. We studied whether the response to combined HUT and LBNP was reproducible within subjects and whether characteristic ...
Meyer Christian - - 2010
During the development of neurocardiogenic syncope (NCS) postural dependant venous blood pooling sets off a cascade of autonomic reflexes. This causes an initial rise in sympathetic tone, which is followed by an overshoot parasympathetic activation resulting in systemic vasodilatation and/or sinus bradycardia. However, other factors like associated hyperventilation or changes ...
Keller David M DM Department of Kinesiology, University of Texas at Arlington, TX 76019, - - 2009
Whole-body heat stress reduces orthostatic tolerance via a yet to be identified mechanism(s). The reduction in central blood volume that accompanies heat stress may contribute to this phenomenon. The purpose of this study was to test the hypothesis that acute volume expansion prior to the application of an orthostatic challenge ...
MacDonald Blair - - 2009
To test the hypothesis that, in comparison with a heavier, larger and more expensive manual tilt-in-space wheelchair, a lightweight manual wheelchair equipped with new rear antitip devices provides comparable mean sitting pressures in the tilted position, each of eight able-bodied participants sat for 8 mins in each wheelchair, upright, and ...
Carew Sheila - - 2009
A 21-year-old female reports an 18-month history of light-headedness on standing. This is often associated with palpitations and a feeling of intense anxiety. She has had two black-outs in the past 12 months. She is not taking any regular medications. Her supine blood pressure was 126/84 mmHg with a heart ...
Kostopoulou Anna - - 2009
Neurocardiogenic syncope is one of the most common types of syncope, characterized by arterial vasodilatation with or without bradycardia. The regulation of blood pressure and heart rate is the result of a complex reaction between the central and peripheral nervous system with the circulatory system. Multiple therapies, pharmaceutical and interventional, ...
Madden Kenneth M - - 2009
Neurocardiogenic syncope (formerly vasovagal) accounts for large numbers of falls in older adults and the mechanisms are poorly understood. This study examined the differences in baseline arterial baroreflex function in older adults with and without a neruocardiovascular response to orthostatic stress. Subjects were divided into two groups based on the ...
Tessendorf Bernd B Wearable Computing Lab., ETH Zurich, Switzerland. - - 2009
In recent years, the monitoring of sitting postures was discovered to be a promising measure of healthy sitting behavior, comfort, physical wellness and emotions. Most state-of-the-art systems for monitoring sitting behavior are based on supervised methods that are limited to a fixed set of classes. We present a method that ...
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