We sought to determine whether 10 days of training would be a sufficient stimulus for cardiac adaptations that would allow a greater compensatory stroke volume during beta-blockade. We also sought to determine whether men and women had a similar cardiac reserve capacity for increasing stroke volume with beta-blockade during submaximal exercise. Eight men (age 29 +/- 2 yr, mean +/- SE) and eight...

BACKGROUND AND PURPOSE Reduction in infarct volume is the standard measure of therapeutic success in animal stroke models. Reduction in infarct volume has been advocated as a biological surrogate or auxiliary outcome measure for human stroke clinical trials to replace or supplement deficit, disability, and global clinical scales. However, few studies have investigated correlations between infar...

BACKGROUND AND PURPOSE Aqueductal stroke volume from phase-contrast MR imaging has been proposed for predicting shunt response in normal pressure hydrocephalus. However, this biomarker has remained controversial in use and has a lack of validation with invasive intracranial monitoring. We studied how aqueductal stroke volume compares with intracranial pressure scores in the presurgical work-up ...

OBJECTIVE Manual assessment of radial arterial pulse character remains an important determinant of physiological status in military and civilian casualties. This study hypothesized that changes in radial pulse character and mental status (presyncopal symptoms) in humans occur only during the later stages of progressive reductions in central blood volume in close association with systolic blood ...

About 20% of astronauts suffer postspaceflight presyncope. We studied pre- to postflight (5- to 16-day missions) cardiovascular responses to standing in 35 astronauts to determine differences between 1) men and women and 2) presyncopal and nonpresyncopal groups. The groups were presyncopal women, presyncopal men, and nonpresyncopal men based on their ability to stand for 10 min postflight. Pref...

Cardiac performance and mitral regurgitation were measured by Doppler echocardiography and right heart catheterization in 12 patients with severe congestive heart failure who performed isometric exercise during control and intravenous administration of dobutamine and nitroglycerin. During control isometric exercise, mitral regurgitant volume increased from 18±13 to 31±17 ml (p<0.01), while forw...

Cardiac performance and mitral regurgitation were measured by Doppler echocardiography and right heart catheterization in 12 patients with severe congestive heart failure who performed isometric exercise during control and intravenous administration of dobutamine and nitroglycerin. During control isometric exercise, mitral regurgitant volume increased from 18±13 to 31±17 ml (p<0.01), while forw...

Observations on heat-acclimatized men by Asmussen (1) and Williams and colleagues (2) showed no increase in cardiac output above the normal response during exercise in a hot, humid environment. Indeed, Asmussen found decrements in cardiac output below normal responses if moderate work in the heat (32° C, 80% relative humidity) was prolonged from 30 to 60 minutes. No systematic study has been re...

Continuous monitoring of stroke volume (SV) or cardiac output (CO) has long been the subject of numerous studies. The majority of existing methods are calibration-dependent, requiring invasive measurements of CO to initialize the estimation algorithms, thus limiting their application to the clinical setting. In the present study, a new calibration-free method aimed at home-based use has been de...

BACKGROUND Although left ventricular end-systolic elastance (E(es)) has often been used as an index of contractility, technical difficulties in measuring volume and in changing loading conditions have made its clinical application somewhat limited. By approximating the time-varying elastance curve by 2 linear functions (isovolumic contraction phase and ejection phase) and estimating the slope r...