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Results 401 - 450 of 833
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Ekstrand K E - - 2001
The relative output factors of the four helmets for a model B Leksell Gamma Knife and the end effect times for each helmet have been measured. For the three helmets with the smallest-diameter collimators a technique employing Kodak XV-2 film was used. The measured output factors are in good agreement ...
Blevins, Jennifer Susanne
Obstructive sleep apnea (OSA) is estimated to affect 2 to 4 percent of the adult population (Young T 1993, Skomro and Kryger 1999). However, an estimated 80 to 90 percent of adults with moderate to severe OSA may be clinically undiagnosed. Identification of those at risk and their subsequent diagnosis ...
Wotton S B - - 2000
Cattle are normally stunned electrically by three sequential cycles, first a three-second head-only cycle, to stun the animal, secondly a 15-second cardiac cycle, to induce ventricular fibrillation (cardiac arrest), and thirdly a four-second discharge cycle, to reduce convulsions after death. An effective and immediate stun was produced when > or ...
Jin H - - 2000
This study determined the effects of exercise training on cardiac function, gene expression, and apoptosis. Rats exposed to a regimen of treadmill exercise for 13 wk had a significant increase in cardiac index and stroke volume index and a concomitant decrease in systemic vascular resistance compared with both age-matched and ...
Boone T - - 2000
The purpose of this study was to determine cardiovascular responses to laughter. The CO(2) rebreathing method was used to determine cardiac output and understand the role of the central and peripheral components of oxygen consumption and its relation to energy expended. Eight college-age subjects participated in this study. During periods ...
Sundblad P - - 2000
Seven healthy men performed steady-state dynamic leg exercise at 50 W in supine and upright postures, before (control) and repeatedly after 42 days of strict head-down tilt (HDT) (-6 degrees) bedrest. Steady-state heart rate (fc), mean arterial blood pressure, cardiac output (Qc), and stroke volume (SV) were recorded. The following ...
Auerbach I - - 2000
BACKGROUND: Relatively light isometric exercise (handgrip) in heart transplant recipients induces attenuated increments in heart rate, blood pressure, and systemic vascular resistance, but hemodynamic response to whole-body, heavy isometric exercise is unknown. The aim of our study was to investigate the influences of whole-body, heavy, isometric exercise on Doppler-derived parameters ...
Farmer C G - - 2000
Mechanical integration of the cardiac, muscular and ventilatory pumps enables mammals to vary cardiac output over a wide range to match metabolic demands. We have found this integration lacking in a lizard (Iguana iguana) that differs from mammals because blood flow from the caudal body and ventilation are maximal after, ...
Brown S C - - 2000
This study examined the development, implementation, and evaluation of a module to enhance self-esteem among patients in an outpatient cardiac clinic. Eighty percent of the subjects reported that activities such as exercise and social functions helped them feel better about themselves. This data supported the use of spirituality, interpersonal relationships, ...
Kizakevich P N - - 2000
Very little is known about the cardiovascular responses of exercising individuals when exposed to carbon monoxide (CO). Sixteen healthy nonsmoking men aged 18-29 years participated in the study. Using a combination of exposures to CO by breathing from a bag or in an environmental chamber, subjects performed a randomized sequence ...
Kallinen M - - 2000
Cardiac arrhythmias, ST segment depressions and other cardiac adverse effects are occasionally seen in relation to physical exercise in elderly people. However, the magnitude, quality, and time-dependence of these events need to be clarified. During voluntary maximal cycle ergometer exercise (CEE), immediate cardiac disturbances as a reason for exercise termination ...
Pardo Y - - 2000
BACKGROUND: A protective effect of exercise in preventing sudden cardiac death is supported by studies in healthy populations as well as in patients with cardiac disease. The mechanisms involved in this protective effect are unknown. HYPOTHESIS: We hypothesized that exercise conditioning would beneficially alter autonomic nervous system tone, measured by ...
Tagarakis C V - - 2000
BACKGROUND: Concomitant application of anabolic-androgenic steroids and physical exercise can induce cardiac hypertrophy. These experiments investigate the still unknown response of the cardiac myocytes and capillaries to the combined influence of various anabolic steroids and muscular exercise. METHODS: Female SPF-NMRI mice were divided into the following groups: a) sedentary control, ...
Allison M J - - 2000
Clinicians who work with elderly people after acute cardiac events need strategies to facilitate the continuance of physical activity learned in cardiac rehabilitation programs. This exploratory study examined three factors related to this maintenance in 31 men and women: self-efficacy, stages of change, and social support for exercise. Self-efficacy was ...
Charloux A - - 2000
The objectives of this study were to evaluate the reliability and accuracy of a new impedance cardiograph device, the Physio Flow, at rest and during a steady-state dynamic leg exercise (work intensity ranging from 10 to 50 W) performed in the supine position. We compared cardiac output determined simultaneously by ...
Matsumoto A - - 2000
OBJECTIVES: We measured end-tidal CO2 pressure (PETCO2) during exercise and investigated the relationship between PETCO2 and exercise capacity, ventilatory parameters and cardiac output to determine the mechanism(s) of changes in this parameter. BACKGROUND: It is unclear whether PETCO2 is abnormal at rest and during exercise in cardiac patients. METHODS: Cardiac ...
McCole S D - - 2000
PURPOSE: We sought to determine whether older women athletes who had habitually performed vigorous endurance exercise training had higher stroke volumes and cardiac outputs than sedentary postmenopausal women during maximal exercise. METHODS: Seventeen endurance-trained, postmenopausal women athletes (age 65 +/- 4 yr; VO2max 2.11 +/- 0.31 L x min(-1), 38.3 ...
Vanhees L - - 2000
PURPOSE: The aim of the present study was to investigate the reproducibility of the exponential method of CO2 rebreathing with the use of automated curve fitting and to determine whether this method is superior to the equilibrium method in terms of reproducibility and clinical practicability. METHODS: Repeated measurements of cardiac ...
Watanabe T - - 2000
BACKGROUND: We have previously shown that QT-interval changes are more useful than ST-T changes in evaluating the severity of exercise-induced myocardial ischemia in patients with right bundle-branch block (RBBB). HYPOTHESIS: The purpose of this study was to evaluate whether the improvement in regional myocardial blood flow (RMBF) in ischemic areas ...
Tanabe Y - - 2000
OBJECTIVES: The aim of this study was to characterize the kinetics of cardiac output during recovery from maximal exercise in patients with chronic heart failure (CHF). BACKGROUND: Recent studies have shown that oxygen uptake kinetics during recovery from exercise are delayed in patients with CHF. However, the kinetics of cardiac ...
Christensen T B - - 2000
In the lower range of cardiac output (CO, up to 15 l min-1), we found an excellent agreement between CO measured by bioimpedance and carbon dioxide rebreathing techniques. CO estimated by bioimpedance was generally lower. The bioimpedance method had better reproducibility. Both methods seem valuable for non-invasive studies in healthy ...
Cohn W E - - 1999
BACKGROUND: Decreasing the ICU length of stay (LOS) after cardiac operations may increase ICU recidivism, obviating the benefit of early discharge. METHODS: From January 1, 1994 to January 1, 1998, there were 2,388 consecutive cardiac operations, from which 2,228 patients were discharged alive from the ICU and had sufficient information ...
Schoerkhuber W - - 1999
BACKGROUND AND PURPOSE: The prediction of neurological outcome in comatose cardiac arrest survivors has enormous ethical and socioeconomic implications. The purpose of the present study was to investigate the prognostic relevance of the time course of serum neuron-specific enolase (NSE) as a biochemical marker of hypoxic brain damage. METHODS: Serial ...
Ide K - - 1999
Atrial fibrillation limits the ability to increase cardiac output during exercise and may, in turn, affect the exercise-associated elevation in cerebral perfusion. In nine patients with atrial fibrillation (AF) and in five age-matched healthy subjects, middle cerebral artery blood velocity (MCA Vmean) was measured during incremental exercise using the transcranial ...
Santos B M - - 1999
Evidence shows that cardiac hypertrophy (CH) is a risk factor for many cardiovascular diseases. Several stimuli may cause CH-like manifestations and promote volume or pressure overload. Exercise-induced cardiac hypertrophy is an expected adaptation to regular exercise training. Salt intake has been shown to be the most important determinant of blood ...
Norton K H - - 1999
The present investigation was designed to uncouple the hemodynamic physiological effects of thermoregulation from the effects of a progressively increasing central command activation during prolonged exercise. Subjects performed two 1-h bouts of leg cycling exercise with 1) no intervention and 2) continuous infusion of a dextran solution to maintain central ...
Matsumoto A - - 1999
Patients with chronic heart failure performed exercise tests to evaluate the relation of kinetics of oxygen uptake to cardiac output and arteriovenous oxygen difference at the onset of exercise. The kinetics of oxygen uptake are primarily determined by cardiac output; these kinetics are useful in evaluating exercise intolerance and cardiac ...
Houtman S - - 1999
The arterial pulse contour method called Modelflow 2.1 calculates stroke volume continuously, beat to beat, from the non-invasive blood pressure signal measured by Finapres or Portapres. Portapres is the portable version of Finapres. The purpose of this study was to compare cardiac output (CO) calculated using Modelflow 2.1 (COmf) with ...
Wiebe C G - - 1999
PURPOSE: To clarify the physiological reasons for the decline in aerobic power of endurance trained (ET) women with aging. METHODS: Blood volume, VO2max, and exercise cardiac function were examined in 23 ET women; six age 20-29 yr, six age 40-45 yr, six age 49-54 yr, and five age 58-63 yr. ...
Lehmann K G - - 1999
OBJECTIVES: To assess whether thermodilution cardiac output determination based on measurement of injectate temperature in vivo leads to more accurate and precise estimates and to study the influence of chilled injectate on test performance. BACKGROUND: Cardiac output measurement via right heart catheterization is used extensively for hemodynamic evaluation in a ...
Wilde A A - - 1999
OBJECTIVE: This study was performed to identify a possible relationship between genotype and phenotype in the congenital familial long QT syndrome (cLQTS). BACKGROUND: The cLQTS, which occurs as an autosomal dominant or recessive trait, is characterized by QT-interval prolongation on the electrocardiogram and torsade de pointes arrhythmias, which may give ...
Haryadi D G - - 1999
OBJECTIVE: This study is an evaluation of a new thoracic bioimpedance cardiac output monitoring system which incorporates a modified form of the Kubicek equation and a method of estimating the left ventricular ejection time from the time derivative bioimpedance signals. METHODS: The performance of the new system was compared with ...
Kobashigawa J A - - 1999
BACKGROUND: In patients who have received a cardiac transplant, the denervated donor heart responds abnormally to exercise and exercise tolerance is reduced. The role of physical exercise in the treatment of patients who have undergone cardiac transplantation has not been determined. We assessed the effects of training on the capacity ...
Harms C A - - 1999
In summary, evidence shows that the respiratory muscles demand a significant portion of the cardiac output during maximal exercise. Estimates of both animal and human blood flow and VO2 to the respiratory muscles during maximal exercise approximate 14-16% of the total cardiac output and VO2. During heavy exercise, this metabolic ...
Auerbach I - - 1999
The aim of this study was to characterize Doppler-derived hemodynamic parameters in heart transplant recipients at rest and during symptom-limited supine bicycle exercise. Eighteen sedentary patients aged 54.0 +/- 2 years, 1.6 +/- 1.0 years following cardiac transplantation, and 18 sedentary healthy volunteers aged 51.8 +/- 4 years were investigated. ...
Warburton D E - - 1999
The assessment of cardiac function, particularly cardiac output (Q) during heavy exercise is essential for the evaluation of cardiovascular factors that might limit oxygen transport. A series of invasive and noninvasive techniques has been developed for the assessment and monitoring of Q during resting and submaximal exercise conditions. However, very ...
Rhéaume C - - 1998
OBJECTIVE: Evaluate the effects of 2 weeks of treatment with tasosartan (1) on cardiac function at rest and during submaximal exercise, (2) on exercise peak oxygen uptake, and (3) on regional haemodynamics at rest in a control condition and during the recovery period of submaximal exercise in patients with essential ...
Hattori T - - 1998
BACKGROUND: Distribution of skeletal muscle perfusion during exercise is an important factor in determining exercise capacity and is markedly impaired in patients with cardiac disease. This study examined the importance of intrinsic calf vasodilator capacity in determining distribution of skeletal muscle perfusion during supine bicycle exercise in patients with left ...
Theisen D - - 1998
PURPOSE: A new ensemble-averaging (EA) approach was developed with the goal of investigating central hemodynamics by transthoracic impedance cardiography during maximal arm cranking. This EA procedure of the first time derivative of impedance changes (dZ/dt) over several cardiac cycles differs from previously reported techniques with respect to cycle selection strategy, ...
Maroni J M - - 1998
STUDY OBJECTIVE: To validate a noninvasive first-pass radionuclide ventriculographic (FPRV) measurement of maximum cardiac output (Qv) during exercise. DESIGN: Comparison of Qv to that measured by the Fick principle (Qf) at peak exercise. SETTING: Academic cardiopulmonary exercise laboratory. PATIENTS: Seventy-eight consecutive patients without a history of septal defect undergoing clinically ...
DeGroot D W - - 1998
OBJECTIVE: Because blood lactic acid (LA) levels may be important in prescribing exercise for cardiac patients, this study documented the LA response to four different circuit weight training (CWT) protocols and compared these responses to both maximal treadmill and LA threshold values. DESIGN: Intervention study following a crossover trial design. ...
Kaprielian R - - 1998
Exercise intolerance in persons with paraplegia (PARAS) is thought to be secondary to insufficient venous return and a subnormal cardiac output at a given oxygen uptake. However, these issues have not been resolved fully. This study utilized lower-body positive pressure (LBPP) as an intervention during arm crank exercise in PARAS ...
Monchi M - - 1998
PURPOSE: The aim of this study was to evaluate the reliability of a new continuous cardiac output (CCO) monitoring device (Qvue/OptiQ system; Abbott Critical Care Systems, Mountain View, CA) based on the pulsed warm thermodilution technique in critically ill medical patients. METHODS: Nineteen patients with cardiogenic or septic shock were ...
Warburton D E - - 1998
PURPOSE: The acetylene rebreathe technique is a well established method for the determination of cardiac output (Q) at rest and during exercise. We sought to demonstrate that the acetylene rebreathe technique allows for highly reproducible determinations of Q. METHODS: Nine elite male endurance cyclists (VO2max = 68.9 +/- 0.6 mL.kg-1.min-1) ...
Rowland T W - - 1998
Test-retest reproducibility of stroke volume and cardiac output using Doppler echocardiography was examined during maximum cycle exercise in 13 young men. A coefficient of variation of 8.5% and 8.1% and intraclass correlation coefficient of 0.90 and 0.91 for maximum stroke volume and cardiac output, respectively, indicate a high degree of ...
Braith R W - - 1998
The mechanisms responsible for immediate adjustments in cardiac output at onset of exercise, in the absence of neural drive, are not well defined in heart transplant (HT) recipients. Seven male HT recipients (mean +/- SD 57 +/- 6 years) and 7 age-matched sedentary normal control subjects (mean age 57 +/- ...
Gray R A - - 1998
Cardiac fibrillation (spontaneous, asynchronous contractions of cardiac muscle fibres) is the leading cause of death in the industrialized world, yet it is not clear how it occurs. It has been debated whether or not fibrillation is a random phenomenon. There is some determinism during fibrillation, perhaps resulting from rotating waves ...
Losty P D - - 1998
BACKGROUND/PURPOSE: Patients with congenital diaphragmatic hernia (CDH) frequently have associated anomalies. Experiments in the nitrofen CDH model have shown differential embryonic cell death patterns in rodents suggesting unique mechanisms in the formation of right-sided (RCDH) or left-sided (LCDH) diaphragmatic hernia. These findings provide insight into the pathogenesis of CDH and ...
Cooke G A - - 1998
OBJECTIVE: To investigate whether physiological cardiac reserve can be measured in man without invasive procedures and whether it is a major determinant of exercise capacity. DESIGN: Development of method of measurement and an observational study. SETTING: A regional cardiothoracic centre. SUBJECTS: 70 subjects with a wide range of cardiac function, ...
Notarius C F - - 1998
BACKGROUND: To determine whether the reduced exercise capacity of patients after heart transplantation is primarily a result of decreased cardiac or peripheral vascular factors, we examined the cardiac output (CO) and right atrial pressure (Pra) relation during graded cycle ergometry. METHODS AND RESULTS: We studied 12 male patients (51.2+/-15.3 years ...
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