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Biomedical subjects

M H Picard

Publications and source records attributed to M H Picard.

81 records · Page 5Linked to original sources
PubMed1989

Cost-benefit analysis of early return to work after uncomplicated acute myocardial infarction.

The economic consequences of an Occupational Work Evaluation designed to identify low risk patients recovering from uncomplicated acute myocardial infarction (AMI) and hasten their return to work was evaluated in a randomized trial. Two hundred one employed, clinically low risk men recovering from AMI were randomized to undergo an intervention (intervention group, 99 patients) consisting of an Occupational Work Evaluation or to receive usual care (usual care group, 102 patients). The time to return to work was reduced from 75 days in usual care patients to 51 days in intervention patients (p less than 0.002). Significant differences were found between groups for medical costs and occupational income during follow-up. Total medical costs per patient were lower in the intervention patients than in the usual care patients in the 6 months after AMI ($2,970 vs $3,472). Occupational income per patient was higher in intervention patients than in the usual care group in the 6 months after AMI ($9,655 vs $7,553). The per capita benefit accounting for medical costs and occupational income was $6,685 for intervention patients and $4,081 for usual care patients. Projected to the greater than 300,000 low risk, employed survivors of AMI annually in this country, the savings generated by the Occupational Work Evaluation could yield an annual economic benefit greater than 800 million dollars.

Algorithms↗
PubMedDate not supplied

Pulsatile pressure affects the disappearance of echocardiographic contrast agents.

The purpose of this study was to determine in an in vitro model the effect of pulsatile pressure on the decay of echocardiographic contrast agents. Use of contrast agents for quantitative assessment of perfusion requires understanding of the factors controlling their rates of disappearance. Prior studies have shown that constant pressure affects the rate of disappearance of these agents. It is not known whether pulsatile pressure influences the rate of decay of contrast agents. In an in vitro chamber, three contrast agents (Albunex, hand-agitated saline solution, and hand-agitated Angiovist) were exposed to pulses of pressure at three rates (30, 60, and 120 pulsations/min), keeping pressure characteristics (peak, nadir, and mean) within a narrow range. Five injections were performed for each agent at each rate. Two-dimensional echocardiographic images of the effects of contrast material were recorded from injection until total disappearance. Videointensity was measured and time-intensity curves were generated. These curves of intensity decay were fitted to an exponential decay function (I = Ae-lambda t) and the velocity of decay (lambda) was used for comparisons. For all agents, intensity of contrast decreased over time. Saline solution and Angiovist, but not Albunex, showed pulsatile decreases in intensity of contrast with each peak pressure and partial recovery of contrast intensity with each nadir pressure. (ABSTRACT TRUNCATED AT 250 WORDS)

Albumins↗
PubMedDate not supplied

Two-dimensional and color Doppler echocardiographic diagnosis of penetrating missile wounds of the heart: chronic complications from intracardiac course of a bullet.

Two-dimensional echocardiography has gained a role in the management of the acute complications of penetrating cardiac trauma and in precisely localizing retained bullet fragments within the heart. We report the case of an 8-year-old boy with chronic symptoms after a bullet wound. In this case, traumatic mitral regurgitation caused by mitral leaflet perforation and retention of the bullet in the tricuspid annulus occurred because of an unusual intracardiac course of the projectile. The diagnosis was made by transthoracic echocardiography. The ability of two-dimensional echocardiography to delineate the true location of the foreign body within the heart and Doppler ultrasound to identify mitral valve perforation helped guide a prompt, efficient, and successful surgical procedure.

Child↗
PubMedDate not supplied

Automated assessment of ventricular volume and function by echocardiography: validation of automated border detection.

To determine the utility of a new on-line echocardiographic automated border detection (ABD) algorithm in assessing ventricular volume and ejection fraction, an optimal model was studied. This open-chest canine model allowed continuous measurement of actual left ventricular volume. In four dogs, true end-systolic and end-diastolic volume and ejection fraction were compared with those obtained by two-dimensional echocardiography with an automated method calculated from a border detection algorithm to define left ventricular endocardium and the single-plane Simpson method to calculate volume. Left ventricular volumes that used manual, off-line tracings of the left ventricle by two-dimensional echocardiograms and the single-plane Simpson method were compared. The automated echocardiographic volumes correlated with true volumes (y = 0.7x + 8.9; standard error of the estimate = 13.5 cc; r = 0.81). A significant mean underestimation of 11 +/- 15 cc was noted (p < 0.0001). Volumes obtained from the manual tracings of left ventricular endocardial contours also correlated well with true volumes (y = 0.89x + 4; standard error of the estimate = 6.7 cc; r = 0.96). However, the 3 +/- 7 underestimation was significantly lower than the error of the ABD method (p = 0.00005). Both on-line ABD and off-line ejection fractions correlated well with true ejection fractions (r = 0.94 and 0.96, respectively). There was no statistically significant difference between the mean errors of the ABD or manually derived ejection fractions. In the setting of optimal left ventricular imaging, the on-line and rapid features of this automated method make it potentially useful for quickly obtaining left ventricular volumes and ejection fraction.

Algorithms↗
PubMedDate not supplied

Effect of static pressure on the disappearance rate of specific echocardiographic contrast agents.

Contrast echocardiography has been applied to identify cardiac structures, shunts, and perfusion territories. Most recently, quantification of flow has been proposed based on disappearance of contrast intensity. This requires that contrast agents are stable and produce a predictable effect. To assess the possible effect of pressure on their stability, the rates of backscatter decay of four echocardiographic contrast agents (Albunex, Levovist, agitated Angiovist, and agitated saline solution) exposed to constant pressures (0, 50, 100, 150, and 200 mm Hg) were quantitated. Contrast was recorded by echocardiography and measured to construct time-intensity curves. The peak decay rate for each agent at each pressure was determined. For all four agents, contrast intensity (I) decreased over time and could be described by the sigmoid function: I = a [e-lambda(t-ts)/1 + e-lambda(t-ts)] + C. Peak decay rate was significantly affected by pressure (p < 0.005) in a proportionate fashion. At pressures of 0, 100, and 200 mm Hg, the rates increased for each agent in the following fashion: Albunex, 0.144 +/- 0.109 to 0.410 +/- 0.142 to 1.442 +/- 0.309; Levovist, 0.060 +/- 0.023 to 0.162 +/- 0.049 to 0.495 +/- 0.142; Angiovist, 0.089 +/- 0.028 to 0.166 +/- 0.057 to 0.224 +/- 0.027; and saline solution, 0.068 +/- 0.039 to 0.110 +/- 0.036 to 0.154 +/- 0.057. The effect of pressure on the peak rate of contrast disappearance (lambda) was significantly different among agents (p < 0.001). Thus attempts to quantitate blood flow with contrast agents must take into account the influence of pressure.

Albumins↗
PubMedDate not supplied

Three-dimensional echocardiography: the influence of number of component images on accuracy of left ventricular volume quantitation.

One approach to three-dimensional echocardiography is to reconstruct the surface of cardiac structures from two-dimensional images positioned in three-dimensional space. This approach has yielded accurate measures; however, the relationship between the number of nonparallel images used in three-dimensional echocardiographic reconstruction to the accuracy of the volume calculated has not been determined. With a canine model in which instantaneous left ventricular volume could be measured in vivo, images were obtained from intersecting long- and short-axis scans and stored with their spatial coordinates. The left ventricle was reconstructed and its volume calculated. The difference between three-dimensional echocardiographic and true volume was determined in 84 different cavitary volumes (4 to 85 ml). In each case, long- and short-axis images were deleted serially from the original data set (maximum of 27) until there were only three images left in the reconstruction. After each set of deletions, left ventricular volume was recalculated with the remaining images. Three-dimensional echocardiography accurately quantified ventricular volume with eight to 12 intersecting images, with a mean error of less than 1 ml and an SD of 5 ml. With a reduction of component images below eight, there were progressive increases in both absolute and mean percentage error. Accurate assessment of stroke volume and ejection fraction in this beating heart model also required eight to 12 images. Left ventricular volume and systolic function can be quantitated by three-dimensional echocardiography with as few as eight to 12 intersecting or nonparallel images.

Analysis of Variance↗
PubMedDate not supplied

Moderate-high intensity exercise training after myocardial infarction: effect on left ventricular remodeling.

BACKGROUND: Regular exercise increases exercise capacity and physical fitness, but questions remain about the effects of exercise on left ventricle (LV) remodeling after myocardial infarction. This study investigated the effects of moderate to high intensity exercise training on LV remodeling after a first myocardial infarction. METHODS: An exercise group of 68 patients in cardiac rehabilitation after a first myocardial infarction had an initial echocardiogram and exercise stress test. Thirty patients completed the 12 weeks of training and had echocardiograms suitable for quantitative analysis. Follow-up echocardiograms and exercise tests were performed. A carefully matched control group of 30 patients with echocardiograms at fixed intervals after myocardial infarction and no formal exercise training were also studied. LV size was expressed as the endocardial surface area-to-body surface area (ESAi), whereas infarct size was characterized by the percent abnormal wall motion (%AWM) by echocardiography using an endocardial surface area mapping technique. Indices of LV shape (sphericity) were also assessed. RESULTS: In the exercise group, no significant changes were seen in ESAi (57.95 +/- 13.1 vs 57.80 +/- 12.04 cm2/m2) or in %AWM (19.33 +/- 15.27 vs 20.11 +/- 15.95) from the initial to the final echo. The indices of sphericity were also unchanged. None of these parameters changed in the control group. Within each group was found heterogeneity in LV remodeling. Multivariate regression analysis revealed initial ESAi and initial %AWM to predict change in ESAi over time. CONCLUSIONS: In this study of patients with predominately small infarcts, exercise training did not adversely affect LV remodeling after myocardial infarction. Remodeling is heterogeneous and appears related to infarct and LV size.

Aged↗