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Results 451 - 500 of 844
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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 ...
Green J S - - 1998
The purpose of this study was to determine whether supplemental estrogen influences cardiovascular hemodynamics at peak exercise in endurance trained and sedentary postmenopausal women. Subjects were 22 women between 3 and 10 yr past menopause who had engaged in endurance exercise at least three times per week for one or ...
Douard H - - 1997
Exercise capacity in cardiac transplanted patients has been reported to remain decreased in some studies; however, functional results after transplantation may vary, ranging from modest to spectacular improvement. The aim of the study was to quantify exercise capacity in a large series of transplanted patients and to search for factor ...
Barron B A - - 1997
Chronic exercise changes cardiac function and responsiveness to autonomic control. Catecholamines and enkephalins are neuroendocrine transmitters involved in autonomic regulation and signaling. We hypothesized that intermittent increased sympathetic stimulation caused by exercise training would decrease cardiac catecholamine and enkephalin content. Dogs and miniswine were exercise trained and hearts extracted for ...
Ohashi Y - - 1997
An electromechanical driven pusher plate type total artificial heart (TAH) has been developed in the Department of Surgery at Baylor College of Medicine. The control of this TAH is based upon Frank-Starling's law, and the output is likely to be affected by the respiration cycle. The necessity of an averaging ...
Weipert J - - 1997
OBJECTIVE: Continued follow-up of the Fontan population group is mandatory in order to evaluate the best approach for long term treatment. We studied exercise capacity and survival in patients with either right atrial to right ventricular (Fontan-Bjoerk, RA-RV) anastomosis or right atrial to pulmonary artery (RA-PA) connection. METHODS: Between January ...
Kouatli A A - - 1997
BACKGROUND: Angiotensin-converting enzyme inhibitors improve exercise capacity in adults with congestive heart failure by decreasing systemic vascular resistance and improving ventricular diastolic function. Patients who have undergone the Fontan procedure have decreased cardiac output, increased systemic vascular resistance, abnormal diastolic function, and decreased exercise capacity compared with normal people. METHODS ...
Steele I C - - 1997
1. The role of cardiac output limitation in the pathophysiology of exercise in patients with chronic failure remains undefined. During steady-state submaximal exercise, oxygen uptake is similar in patients and control subjects, but it is not known if cardiac output is also similar. We wished to determine if the reduced ...
Rowland T - - 1997
BACKGROUND: Animal studies and investigations of adult endurance athletes indicate a transient depression of myocardial function after prolonged high-intensity exercise. PURPOSE: To determine whether a similar decrease is observed in child distance runners after a 4-km competitive road race. METHODS: Anthropometric measures, resting M-mode echocardiograms, maximal cycle exercise tests with ...
DiCarlo S E - - 1997
"Central command" may initiate the sympathoexcitatory responses at the onset of exercise by shifting the operating point of the arterial baroreflex toward higher pressures. Daily exercise (DE) attenuates the sympathoexcitatory responses to submaximal exercise. This DE-induced adaptation may be due, in part, to an enhanced inhibitory influence of cardiac afferents. ...
Rowland T - - 1997
Previous investigations have indicated that children demonstrate a lower cardiac output at a given oxygen uptake during exercise compared with adults. This study compared cardiac responses with maximal upright cycle exercise in 15 boys (mean age 10.9 yr) and 16 men (mean age 30.7 yr) to determine whether this observation ...
Siscovick D S - - 1997
This article summarizes available population-based data related to the risk of sudden cardiac death during exercise and the factors that influence the risk among apparently healthy adults in the community. Recent evidence puts into perspective the cardiac risks and benefits of exercise. The data suggest that although the occurrence of ...
Weber K T - - 1997
Noninvasive cardiopulmonary exercise (CPX) testing has proven useful in the assessment of heart and lung disease, including cardiac and ventilatory reserves. CPX includes the monitoring of respiratory gas exchange, O2 uptake the CO2 production, together with minute ventilation and its components--tidal volume and respiratory rate--together with surveillance of electrocardiography and ...
Korsmeyer K E - - 1997
Cardiac performance in the yellowfin tuna (Thunnus albacares, 673-2470 g, 33-53 cm fork length, FL) was examined in unanesthetized fish swimming in a large water tunnel. Yellowfin tuna were fitted with either electrocardiogram electrodes or a transcutaneous Doppler blood-flow probe over the ventral aorta and exposed to changes in swimming ...
Whaley M H - - 1997
PURPOSE: Recent exercise guidelines recommend a generalized rating of perceived exertion (RPE) range of 12 to 16 (15-point Borg scale) as the perceptual range associated with a physiological training effect. However, whether an individual who selects an RPE within the generalized range during an graded exercise test or exercise training, ...
Jansen J R - - 1997
A new thermodilution method for frequent (near continuous) estimation of cardiac output, without manual injection of fluid into the blood, was tested. The method utilizes a pulmonary artery catheter equipped with a fluid filled heat exchanger. The technique is based on cyclic cooling of the blood in the right atrium ...
Arnold J H - - 1997
OBJECTIVE: To examine the utility of single breath CO2 analysis as a noninvasive measure of cardiac output in a model of acute lung injury. SETTING: An animal laboratory in a university-affiliated medical center. DESIGN: A prospective, animal cohort study comparing 21 parameters derived from single breath CO2 analysis with cardiac ...
Lu J H - - 1997
This study sought to evaluate the use of tetrazolium salt XTT reduction as an indicator of valvular viability in a cryoprocessed porcine cardiac homograft model. The XTT tetrazolium assays was based on the metabolic reduction of Sodium 3'-[1-(phenylamino-carbonyl)-3,4-Tetrazolium]-bis(4-methoxy-6-nitro) benzene sulfonic acid hydrate. The relationship between XTT reduction and: (1) leaflet ...
Leung D Y - - 1997
Impaired functional capacity is common in patients with mitral regurgitation (MR), but the determinants of functional capacity in patients with normal left ventricular (LV) function are unclear. Forty patients with chronic, isolated, nonrheumatic MR with no coronary artery disease underwent exercise echocardiography with continuous expired gas analysis. Cardiac output and ...
Liu Y - - 1997
The use of the acetylene rebreathing method to estimate cardiac output (CO) during high-intensity exercise, which may be influenced by recirculation of acetylene, has not been validated. This study was designed to validate the acetylene rebreathing method to measure CO during high-intensity exercise using the direct Fick method. CO was ...
Izrailtyan I - - 1997
OBJECTIVE: Bradykinin (BK) is an endogenous peptide exerting a potent influence on the behavior of the heart. The local regulatory mechanisms responsible for BK modulation of cardiac automaticity and contractility remain poorly understood. The role of the intrinsic cardiac nervous system (ICNS) in mediating the BK-induced regulatory effect was investigated. ...
Humphrey R - - 1997
LVAD use in the heart failure population is increasing and allows severely impaired patients an opportunity for exercise rehabilitation before cardiac transplantation. Although the LVAD provides nearly all of the cardiac output at rest, the native left ventricle contributes a modest amount during exercise, with the LVAD capable of providing ...
Convertino V A - - 1997
Maximal oxygen uptake (VO2max) is reduced in healthy individuals confined to bed rest, suggesting it is independent of any disease state. The magnitude of reduction in VO2max is dependent on duration of bed rest and the initial level of aerobic fitness (VO2max), but it appears to be independent of age ...
Malpass D - - 1997
Resting cardiovascular parameters were predicted from anthropometric data, resting baseline cardiovascular data, and cardiovascular responses to three laboratory stressors completed 1 year earlier. Subjects were 106 male and female children (72 Whites, 34 Blacks) aged 6-7 years at the initial evaluation. During initial testing, blood pressure, heart rate, cardiac output, ...
Eames G M - - 1997
Sixty-three patients who had undergone a BMT at age < or = 18 years were evaluated cross-sectionally to determine cardiac function as well as the long-term prevalence, types, severity, and risk factors of cardiac abnormalities. Patients were > or = 1 year post-BMT and were evaluated by history, resting ECG, ...
Wilson J R - - 1996
BACKGROUND: We recently reported that some patients with heart failure and exercise intolerance exhibit severe hemodynamic dysfunction during exercise, whereas others have normal cardiac output responses to exercise. We postulated that patients with preserved cardiac output responses to exercise are limited by deconditioning and would respond to exercise training, whereas ...
Saito T - - 1996
The action of efonidipine hydrochloride ((+/-)-2-[benzyl(phenyl)-amino]ethyl 1,4-dihydro-2,6-dimethyl-5-(5,5-dimethyl-2-oxo-1, 3,2-dioxaphosphorinan-2-yl)-4-(3-nitrophenyl)-3-pyridinecarboxy late hydrochloride ethanol, CAS 1110011-76-8, NZ-105) a new dihydropyridine calcium antagonist, on cardiac hemodynamics at rest and during exercise as well as plasma concentration and pharmacokinetic parameters were studied in 9 patients with angina pectoris. NZ-105 was administered 40 mg once daily ...
Kim S J - - 1996
This study was performed to examine whether an alpha 1-constrictor tone, which limits coronary functional hyperemia during exercise, imposes a significant limitation on global cardiac performance as determined by cardiac output (CO). Seven dogs were chronically instrumented to measure left ventricular pressure (LVP), maximum rate of rise of LVP (dP/dtmax), ...
Wright L B - - 1996
John Henryism, a coping style characterized by a strong predisposition to confront daily psychosocial stressors in an active and effortful manner, has been associated with cardiovascular (CV) disease risk in adults. This study examined the relationship of John Henryism to CV functioning at rest and during laboratory stressors (i.e. forehead ...
Vonk Noordegraaf A - - 1996
Until now, electrical impedance tomography (EIT) has been used for cardiac imaging with the electrodes attached transversally at the level of the fourth intercostal space at the anterior side. However, the results obtained with this electrode configuration have been disappointing. The aim of the present study was to improve the ...
Buckey J C JC - - 1996
Orthostatic intolerance occurs commonly after spaceflight, and important aspects of the underlying mechanisms remain unclear. We studied 14 individuals supine and standing before and after three space shuttle missions of 9-14 days. After spaceflight, 9 of the 14 (64%) crew members could not complete a 10-min stand test that all ...
Notarius C F - - 1996
Central venous pressure (CVP) gives the integral result of changes in cardiac and peripheral factors. Thus, the sudden increase in CVP observed at the onset of dynamic exercise has been attributed to the action of the muscle pump but is also affected by reflex changes in cardiac response. To determine ...
Paterson D J - - 1996
Exercise disturbs cardiac sympathovagal and ionic balance. In arterial blood, vigorous exercise can double plasma K(+), decrease pH by 0.4 unit, and raise catecholamines 15-fold. If any of these changes are experienced at rest, there is an increased risk of arrhythmia and cardiac arrest, yet in exercise they are usually ...
Barton C - - 1996
STUDY OBJECTIVE: To determine whether the computer-derived measures of median frequency or peak amplitude of ventricular fibrillation (VF), obtained by fast Fourier transform of the VF waveform, change during selective aortic arch perfusion in a canine model of cardiac arrest. METHODS: Eight mongrel dogs (including 4 control animals) were sedated, ...
Pianosi P - - 1996
Electric bioimpedance has been used to measure cardiac output for decades. Improvements in modeling and microprocessor technology have spawned newer generations of such devices. This method would be especially useful in children, in whom the use of invasive methods is limited. We tested a device (ICG-M401, ASK Ltd.) in 30 ...
Pianosi P - - 1996
Previous studies comparing cardiac output (Q) and stroke volume (SV) between cystic fibrosis (CF) patients and control subjects have shown conflicting results: some found lower SV in CF patients with severe airflow limitation, and others showed no difference between CF and control subjects. Methodologic problems could explain these discrepant findings. ...
Halliwill J R - - 1996
The occurrence of a sustained vasodilation and hypotension after acute, dynamic exercise suggests that exercise may alter arterial baroreflex mechanisms. Therefore, we assessed systemic hemodynamics, baroreflex regulation of heart rate, and cardiac vagal tone after 60 min of cycling at 60% peak oxygen consumption in 12 healthy, untrained men and ...
Reisner C - - 1996
BACKGROUND: Continuous nebulization is a safe and practical method of administration of beta 2-adrenergic agonists during acute asthma. There are essentially two types of continuous nebulizer systems; one utilizes a large volume nebulizer and the other a small volume nebulizer attached to a constant volume infusion pump. OBJECTIVES: We compared ...
Rådström M - - 1995
Bolus doses of ephedrine are often used by anaesthesiologists for intraoperative hypotension. This randomized single-blind cross-over study was designed to simultaneously evaluate circulatory, respiratory and metabolic effects of intravenously given ephedrine in 12 healthy male volunteers. Oxygen uptake and carbon dioxide excretion were measured with indirect calorimetry and non-invasive transthoracic ...
Thrush D - - 1995
OBJECTIVE: Cardiac outputs were determined with continuous thermodilution, bolus thermodilution, and the Fick method during pharmacologically varied hemodynamics. DESIGN: Prospective comparison of techniques. SETTING: University animal laboratory. PARTICIPANTS: Swine. INTERVENTIONS: Swine were anesthetized, tracheally intubated, and instrumented to measure continuous (QTDC) and bolus (QTDB) thermodilution cardiac outputs and sample arterial ...
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