Search results for "Compaction"

Reduced regional systolic function evolved compacted segments in noncompaction

2010

Abstract In a recent report about noncompaction Nemes et al. reported that systolic left ventricular (LV) dysfunction assessed using the wall motion score during 2D echocardiography in noncompaction is not confined to noncompacted LV segments. These results confirmed some published reports of our group. Recently we analyzed a population of 238 patients affected by noncompaction, and demonstrated that the number of noncompacted segment is uncorrelated with the degree of systolic dysfunction. It is an attractive hypothesis that the systolic dysfunction could be depend on the fibrosis of the left ventricle, itself a consequence of microcirculatory dysfunction, which has been confirmed by repor…

Growth processes, dimensional parameters and scaling relationships of two conjugate sets of compactive shear bands in porous carbonate grainstones, F…

2012

Abstract Three main sets of deformation bands are identified in the Lower Pleistocene carbonate grainstones of Favignana Island (Italy). A bedding-parallel set is interpreted to contain compaction bands, based on the lack of evidence for shear. The other two sets are oriented at a high-angle to bedding, forming a conjugate pair comprised of compactive strike-slip shear bands. In this study, we focus on the compactive shear bands documenting their development, as well as analyzing their dimensional parameters and scaling relationships. Single compactive shear bands are thin, tabular zones with porosity less than the surrounding host rocks, and have thicknesses and displacements on the order …

Stages in the compaction of peat; examples from the Stephanian and Permian of the Massif Central, France

1987

Thick coal seams in the intramontane basins of the Massif Central allow a detailed study of peat/coal compaction. Three stages of compaction can be detected. Stage 1—occurred during the deposition of the peat. Coal beds which thicken and dip away from penecontemporaneous sandstones suggest rapid compaction. Stage 2—compaction of peat related to overburden pressure in some cases resulted in the formation of lakes over peat beds. The thickness of the lacustrine deposits may give an indication of the amount of compaction that took place. One possibility is that the early compaction was related to the progradation of siliciclastics over the peat. Stage 3—occurred after the organic sediment achi…

Microstructure Characteristics of Unsaturated Compacted Scaly Clay

2012

Microstructure characteristics of unsaturated compacted scaly clay are investigated by MIP tests on freeze dried samples and observation of SEM photomicrographs. Effects of scale microstructure and increasing compaction stresses, and microstructure changes induced by loading and unloading paths and clay saturation are analysed.

Suction controlled drying and wetting cycle effects on the volumetric behaviour of a lime-treated high plasticity clay

2016

The paper presents some experimental results collected on samples recovered from an experimental embankment obtained by compacting a lime-treated clay. Samples were collected soon after the in situ compaction and they were cured in controlled environmental conditions for at least 18 months. Mercury intrusion porosimetry tests (MIP) were carried out on freeze-dried specimens to characterize the microstructure of the material. In order to assess the durability of the improved material, laboratory tests focused on the effects of cyclic variations of the degree of saturation on the water retention properties and the volumetric behaviour of the stabilized clay. Collected results show that the li…

Left ventricular non-compaction cardiomyopathy in children: Is segmental fibrosis the cause of tissue Doppler alterations and of EF reduction?

2009

Noncompaction of the ventricular myocardium (LVNC) is a rare congenital cardiomyopathy resulting from an arrest in normal endomyocardial embryogenesis. In 2002 Jenni et al. [Jenni R, Wyss CA, Oechslin EN, Kaufmann PA. Isolated ventricular noncompaction is associated with coronary microcirculatory dysfunction. J Am Coll Cardiol 2002; 39:450-454.] reported a microvascular dysfunction in 12 patients affected by non compaction: areas of restricted myocardial perfusion have been documented by scintigraphy, suggesting a reduction of Coronary flow reserve. McMahon et al reported in a recent article a reduction of TD velocities in children with noncompaction of the left ventricle, compared with nor…

Left ventricular noncompaction presenting like a double-chambered left ventricle

2015

Diagnosis and definition of biventricular non-compaction associated to Ebstein's anomaly

2011

Abstract Background Non-compaction of ventricular myocardium is a rare congenital cardiomyopathy characterized by the presence of an extremely thickened endocardial layer with prominent trabeculations and deep recesses in communication with ventricular chamber and determining the typical spongeous aspect. The diagnosis of non-compaction of ventricular myocardium is possible through the identification of morphological alterations by echocardiographic evaluation. Ebstein's anomaly is a rare congenital cardiac disease, defined as the significant apical displacement of the part of the tricuspid valve causing significant tricuspid regurgitation and reduction of the functional right ventricle, ri…

Magnetic resonance in isolated noncompaction of the ventricular myocardium

2010

Abstract Non-compaction of the ventricular myocardium (LCVM) is a rare disorder of myocardial morphogenesis usually diagnosed in paediatric age. The diagnosis was echocardiographically made on the basis of a reported spongeous/compacted ratio >2 in one or more segments of the left ventricle during the diastolic period. We aimed to test the diagnostic accuracy of cardiovascular magnetic resonance (CMR) imaging in distinguishing pathological left ventricular non-compaction. Methods We collected a consecutive series of 8 patients, 5 males and 3 females, with a mean age of 14.9 years with non-compaction of left ventricular myocardium. All patients were admitted in our divisions of cardiology. I…

Modelling cardiac mechanics of left ventricular noncompaction

2020

Left ventricular noncompaction (LVNC) can be defined as a cardiomyopathy characterised by a pattern of prominent trabecular structure and deep intertrabecular recesses, that is thought to be caused by an arrest of normal endomyocardial morphogenesis. Using patient-specific computational modelling, we assessed the cardiac mechanics of five patients with LVNC and compared myocardial stress and pump performance to those of healthy controls. Findings shown that patients with LVNC have impaired left ventricular (LV) function, making it possible that the lack of fibre shortening of noncompacted layer can determine poor heart function. Pronounced end-systolic wall stress on left ventricular wall o…