Experiences with surgical treatment of ventricle septal defect as a post infarction complication

<p>Abstract</p> <p>Background</p> <p>Complications of acute myocardial infarction (AMI) with mechanical defects are associated with poor prognosis. Surgical intervention is indicated for a majority of these patients. The goal of surgical intervention is to improve the systolic cardiac function and to achieve a hemodynamic stability. In this present study we reviewed the outcome of patients with post infarction ventricular septal defect (PVSD) who underwent cardiac surgery.</p> <p>Methods</p> <p>We analysed retrospectively the hospital records of 41 patients, whose ages range from 48 to 81, and underwent a surgical treatment between 1990 and 2005 because of PVSD.</p> <p>Results</p> <p>In 22 patients concomitant coronary artery bypass grafting (CAGB) was performed. In 15 patients a residual shunt was found, this required re-op in seven of them. The time interval from infarct to rupture was 8.7 days and from rupture to surgery was 23.1 days. Hospital mortality in PVSD group was 32%. The mortality of urgent repair within 3 days of intractable cardiogenic shock was 100%. The mortality of patients with an anterior VSD and a posterior VSD was 29.6% vs 42.8%, respectively. All patients who underwent the surgical repair later than day 36 survived.</p> <p>Conclusion</p> <p>Surgical intervention is indicated for a majority of patients with mechanical complications. Cardiogenic shock remains the most important factor that affects the early results. The surgical repair of PVSD should be performed 4–5 weeks after AMI. To improve surgical outcome and hemodynamics the choice of surgical technique and surgical timing as well as preoperative management should be tailored for each patient individually.</p

Real-time scanning tunneling microscopy observation of the evolution of Ge quantum dots on nanopatterned Si(001) surfaces

To investigate the effect of surface patterning on island growth, a real-time study by scanning tunneling microscopy (STM) of Ge deposition on nanostructured Si(001) surfaces is presented. The substrate is nanopatterned by the STM tip and the subsequent evolution of a Ge layer deposited at 500 degreesC is recorded. The formation of the wetting layer, a transition stage and the growth of three-dimensional (3D) Ge huts are examined dynamically. The 2D-3D transition is described in terms of the nucleation and evolution of pre-pyramids consisting of (001) oriented terraces, which eventually transform into pyramids by successive introduction of {105} facets. Substrate patterning strongly affects the positioning of 3D islands, and represents a route toward ordering of Ge islands

STM study of Si(111)7x7 reconstructed surface carbonization induced by acetylene

The morphology of the first stages of acetylene reaction with Si(1 1 1)7 x 7 reconstructed surface has been investigated by scanning tunneling microscopy (STM). We studied the surface modification for two substrate temperatures during reaction (650 and 700 degreesC) and as a function of acetylene doses. Both these parameters have been observed to play a crucial role in the carbonization reaction, the formation of nanostructures and their development. For low acetylene exposure, almost the entire surface appears root3 x root3-R30degrees reconstructed but islands, mainly decorating the step edges, are generally surrounded by 7 x 7 reconstructed areas, located deeper with respect to the plane of root3 x root3-R30degrees reconstruction. For highest acetylene dose, the surface is characterized by nanostructures and large holes (as deep as 3-5 nm) that occupy one or more terraces between the original silicon surface step edges with their inner side constituted of islands itself. For intermediate acetylene exposure, the small increase (from 650 to 700 degreesC) of substrate temperature during the reaction is sufficient to make the resulting carbonization mechanism switch towards the highest exposure behaviour. (C) 2004 Elsevier B.V. All rights reserved

Role of patterning in islands nucleation on semiconductor surfaces

Quantum dots (QDs) grown on semiconductors surfaces are actually the main researchers' interest for applications in the forthcoming nanotechnology era. New frontiers in nanodevice technology rely on the precise positioning of the nucleation site and on controlling the shape and size of the dots. In this article we will review some recent studies regarding the control of the nucleation process on semiconductor surfaces. A few approaches to form ordered patterns on surfaces are described: natural patterning induced by surface instabilities (as step bunching or step meandering), in situ substrate patterning by Scanning Tunneling Microscopy (STM), high resolution patterning by Focused Ion Beam (FIB). Growth of epitaxial layers of semiconductors (Ge/Si(100) and InAs/GaAs(100)) on patterned surfaces has been studied by STM or Atomic Force Microscopy (AFM) unveiling the way in which the first atoms start to aggregate and identifying their exact nucleation site. Control of the dot size to match the patterning typical wavelength has been achieved by using surfactants on misoriented substrates. STM images acquired in real time allows one to identify the mechanism of Ge cluster formation on patterned Si(100), and to follow the island transition from pre-pyramid to pyramid. Nucleation of ordered Ge dots on SiO2 substrates has been obtained thanks to FIB tight patterning, achieving island densities of 3.5 × 1010 / cm2. To cite this article: N. Motta et al., C. R. Physique 7 (2006). © 2006 Académie des sciences

Self-assembly of InAs and Si/Ge quantum dots on structured surfaces

We discuss the self-aggregation process of InAs and Si-Ge quantum dots (QDs) on natural and patterned GaAs(00l) and Si(00l) and Si(l 11) surfaces, with reference to our recent studies with scanning tunnelling and atomic force microscopy and current experimental and theoretical works. Various methods for obtaining naturally structured surfaces are briefly surveyed, as the patterning formed by the surface instability and by the strain in mismatched heteroepitaxy, and the latest methods of pre-patterning and growth at selected sites are discussed. Basic topics are also addressed that determine the final morphology of QDs, such as the wetting layer formation, the elastic strain field and the two-dimensional to three-dimensional phase transition

Composition of Ge(Si) islands in the growth of Ge on Si(111)

X-ray photoemission electron microscopy (XPEEM) is used to investigate the chemical composition of Ge/Si individual islands obtained by depositing Ge on Si(111) substrates in the temperature range 460-560 degreesC. We are able to correlate specific island shapes with a definite chemical contrast in XPEEM images, at each given temperature. In particular, strained triangular islands exhibit a Si surface content of 5%-20%, whereas it grows up to 30%-40% for "atoll-like" structures. The island's stage of evolution is shown to be correlated with its surface composition. Finally, by plotting intensity contour maps, we find that island centers are rich in Si. (C) 2004 American Institute of Physics

Proximal Probe Induced Chemical Processing for Nanodevice Elaboration

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