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Filling Patterns (filling + pattern)

Distribution by Scientific Domains

Medical Sciences	60%

Selected Abstracts

An Echocardiographic Analysis of the Long-Term Effects of Carvedilol on Left Ventricular Remodeling, Systolic Performance, and Ventricular Filling Patterns in Dilated Cardiomyopathy

ECHOCARDIOGRAPHY, Issue 7 2005
Peter S. Rahko M.D.
Background: The long-term clinical benefit of beta blockade is well recognized, but data quantifying long-term effects of beta blockade on remodeling of the left ventricle (LV) is limited. Methods: This consecutive series evaluates the long-term response of the LV to the addition of carvedilol to conventional therapy for dilated cardiomyopathy. There were 33 patients who had a LV ejection fraction <45%, LV enlargement and symptomatic heart failure. Quantitative Doppler echocardiography was performed at baseline 6, 12, 24, and 36 months after initiation of carvedilol to evaluate LV ejection fraction, LV volume, wall stress, mass, regional function, and diastolic performance. Results: Compared to baseline there was a significant and sustained reduction in end-systolic volume and end-systolic wall stress with a corresponding improvement in LV ejection fraction. The LV mass did not decline but relative wall thickness increased toward normal. An analysis of regional wall motion responses showed an improvement in all areas, particularly the apical, septal, and lateral walls that was significantly more frequent in patients with a nonischemic etiology. Filling patterns of the LV remained abnormal throughout the study but changed with therapy suggesting a decline in filling pressures. These changes were sustained for 3 years. Conclusion: (1) The addition of carvedilol to conventional therapy for a dilated cardiomyopathy significantly improves LV ejection fraction and reduces LV end-systolic volume and wall stress for at least 3 years, (2) the response to 6 months of treatment predicts the long-term response, (3) the typical response is partial improvement of the LV, complete return to normal size, and function is uncommon, and (4) abnormalities of LV filling persist in virtually all patients throughout the course of treatment. [source]

Cardiac amyloidosis: MR imaging findings and T1 quantification, comparison with control subjects

JOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 6 2007
Gabriele A. Krombach MD
Abstract In cardiac amyloidosis an interstitial deposition of amyloid fibrils causes concentric thickening of the atrial and ventricular walls. We describe the results of tissue characterization of the myocardium by T1 quantification and MRI findings in a patient with cardiac amyloidosis. The T1 time of the myocardium was elevated compared to that in individuals without amyloidosis. The T1 time of the myocardium was 1387 ± 63 msec (mean value obtained from four measurements ± standard deviation [SD]) in the patient with cardiac amyloidosis, while the reference value obtained from the myocardium of 10 individuals without known myocardial disease was 1083 ± 33 msec (mean value ± SD). In combination with other MR findings suggestive of amyloidosis, such as homogeneous thickening of the ventricular and atrial walls, thickening of the valve leaflets, restrictive filling pattern, and reduction of systolic function, T1 quantification may increase diagnostic confidence. J. Magn. Reson. Imaging 2007;25:1283,1287. © 2007 Wiley-Liss, Inc. [source]

Random discontinuous carbon fiber preforms: Experimental permeability characterization and local modeling

POLYMER COMPOSITES, Issue 4 2010
A. Endruweit
Injection experiments indicate that for random discontinuous carbon fiber preforms, increasingly uneven flow fronts develop with increasing fiber bundle length and filament count. While at high propensity for fiber bundle splitting, the preform permeability increases continuously with increasing fiber length, no trend can be identified at low propensity. No clear influence of the virgin bundle filament count on the preform permeability was observed. Types of sizing used on the fibers and bundle cross-sectional shapes may vary and affect the intrinsic filamentization behavior, thus dominating the preform permeability. In a model for local preform permeability, interbundle voids, distributed randomly across the preform thickness, are approximated via a regular void structure. Simulated filling patterns are qualitatively similar to those observed experimentally, showing more pronounced features than those derived from a model based on local through-thickness homogenization of the filament distribution. A model based on an alternating arrangement of fiber bundles and voids allows prediction of global preform permeability values from series of injection simulations, showing quantitatively better agreement with corresponding experimental results than the homogenization model. For global permeability, agreement between simulated and experimental mean values improves with increasing fiber volume fraction, whereas calculated coefficients of variation show no strong dependence on the fiber volume fraction. POLYM. COMPOS., 2010. © 2009 Society of Plastics Engineers [source]

Effects of conductive fibers and processing conditions on the electromagnetic shielding effectiveness of injection molded composites

POLYMER COMPOSITES, Issue 6 2002
S. Y. Yang
This paper investigates the electromagnetic interference shielding effectiveness (EMI SE) of injection molded ABS disks filled with stainless steel fibers (SSF) and nickel-coated graphite fibers (NGF). The effects of fiber type, fiber length and weight percentage on SE were studied. Optical microscope (OM) and scanning electron microscopy (SEM) observations of the fiber distribution and dispersion were used to aid interpretation of the deviation on SE. The effects of processing conditions such as ring gate angles and injection speed on SE and fiber dispersions were also investigated. It is found that the SE of SSF filled disks is better than that of NGF with the same fiber length and weight percentage. The SEM shows that the SSF with severe twists connect with each other to form a three-dimensional network. Nevertheless, the NGF break into straight fragments, which make it difficult to form networks. With the same type of fiber (SSF), the critical concentration of 6mm was similar to that of 4mm. But the SE of 6mm is a little higher than that of 4mm. Minor improvements of SE values were obtained with expanded ring gate angles. Gate design and injection speed both change filling patterns. [source]