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Query: UMLS:C0851184 (thinning)
 11,252 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In spite of major limitation in the application of computerized transmission tomography to the cardiovascular system, it has several unique advantages. The aim of this lecture is to give the recent advance and perspective of cardiac CT examination. The advantages include excellent spatial and contrast resolution and obtaining three dimensional images of the heart and the great vessels. Although CT scanning of the heart without contrast medium provides vague differentiation of the cardiac structures, with contrast medium injection it gives more precise information. Rapid sequential scanning with table movement may be useful to give tomographic images covering the whole heart. Since temporal resolution is improved with rapid sequential scanning at the fixed position, functional analysis of the cardiovascular system in a slice, for example patency of the aorto-coronary bypass graft, can be easily examined with excellent accuracy. ECG-gated scanning provides anatomical information with good temporal resolution, as well as functional values, such as left ventricular mass, left ventricular volume, left ventricular ejection fraction and cardiac output. These values obtained from cardiac CT showed a good correlation with the values from cine left ventriculography and a dye-dilution study. Thrombi or tumors in the cardiovascular lumen could be detected with CT examination. Attenuation of left ventricular wall motion, thinning of the ventricular wall and reduced regional myocardial thickness seemed to be major landmarks for computed tomographic diagnosis in ischemic heart disease. Cardiac CT examination may give the comparable information with echocardiography in this field. In the future, ultra-fast CT scanners will be developed to give the multiple section capacity for three dimensional imaging and to improve temporal resolution for cardiac functional analysis.
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PMID:[Application of computed tomography to cardiovascular system: present status and perspective]. 667 84

Implantable devices in direct contact with flowing blood are associated with the risk of thromboembolic events. This study addresses the need to improve our understanding of the thrombosis mechanism and to identify areas on artificial surfaces susceptible to thrombus deposition. Thrombus deposits on artificial blood step transitions are quantified experimentally and compared with shear stress and shear rate distributions using computational fluid dynamics (CFD) models. Larger steps, and negative (expanding) steps result in larger thrombus deposits. Fitting CFD results to experimental deposit locations reveals a specific shear stress threshold of 0.41 Pa or a shear rate threshold of 54 s(-1) using a shear thinning blood viscosity model. Thrombosis will occur below this threshold, which is specific to solvent-polished polycarbonate surfaces under in vitro coagulation conditions with activated clotting time levels of 200-220 s. The experimental and computational models are valuable tools for thrombosis prediction and assessment that may be used before proceeding to clinical trials and to better understand existing clinical problems with thrombosis.
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PMID:In vitro and computational thrombosis on artificial surfaces with shear stress. 2096