Background. The Edwards Prima stentless valve (EPSV) is a porcine aortic root cylinder with resected coronary ostia, fixed in glutaraldehyde at low pressure. The purpose of this study was to evaluate ...the hemodynamic performance of the EPSV 1 year after aortic valve replacement.
Methods. From December 1994 to February 1996, 29 patients underwent aortic valve replacement with EPSV used in the subcoronary position (group 1, n = 23) or as a root replacement (group 2, n = 6). Hemodynamic performance of EPSV was assessed by two-dimensional Doppler echocardiography at 1 week, 6 months, and 1 year by calculating peak transprosthetic velocity, peak and mean gradients, effective orifice area, degree of aortic regurgitation, and regression of left ventricular hypertrophy.
Results. There were no operative deaths. One patient in group 2 died after 3 months at reoperation for endocarditis. In group 1 early mean gradient (25 ± 5 mm Hg for 23 mm and 19 ± 5 mm Hg for 25 mm) decreased at 6 months and 1 year in the 23-mm size (17 ± 7 mm Hg and 15 ± 4 mm Hg, p < 0.01) and at 1 year in the 25-mm size (14 ± 4 mm Hg, p = 0.03) without modifications of the effective orifice area in both sizes. A significant reduction in left ventricular hypertrophy occurred at 6 months and 1 year in both sizes. In group 2 lower early gradients were recorded with subsequent improvement at follow-up; reduction in left ventricular hypertrophy occurred as well.
Conclusions. The EPSV used in the subcoronary position has shown high early gradients, which partially regressed at 6 months, with further improvement at 1 year. Gradients are attributed to inward folding of the Dacron cloth at the right coronary ostium, being more evident in patients with aortic stenosis without dilatation of the aortic root and coronary ostia close to the annulus. In such patients a better early hemodynamic result can be obtained by using the EPSV as a root replacement.
We report a novel low-cost in-home broadcasting system using a 1-mm core graded-index plastic optical fibre split network reaching up to 35 meters. We demonstrated broadcasting 2.5Gbit/s data to four ...end-users employing discrete multi-tone modulation.
An iterative method to analyze open anisotropic dielectric waveguides with arbitrary dielectric tensor /spl epsi/~ such as tilted channel waveguides is presented. The proposed /spl beta/ formulation ...approach reduces significantly the computational resources compared to previously proposed other choices.
Background. Aortic valve replacement in elderly patients with a small aortic annulus may pose difficult problems in terms of prosthesis selection. We have evaluated the hemodynamic performance of the ...21-mm Carpentier-Edwards Perimount bioprosthesis implanted in elderly patients.
Methods. From July 1996 to June 1998, 19 patients (17 women and 2 men, mean age 76 ± 4 years and mean body surface area 1.73 ± 0.13 m2), had aortic valve replacement with a 21-mm Carpentier-Edwards Perimount bioprosthesis. The hemodynamic performance of the valve was evaluated in 16 patients, who completed at least a 6-month follow-up interval, with transthoracic color-Doppler echocardiography with particular reference to peak and mean transprosthetic gradients, effective orifice area index, and regression of left ventricular mass index.
Results. There were no late deaths and no major postoperative complications. At a mean follow-up of 12 ± 7 months, compared to discharge, all patients showed clinical improvement with a significant reduction of peak gradient (from 23 ± 4 to 21 ± 6 mm Hg, p = 0.04) and left ventricular mass index (from 181 ± 23 to 153 ± 20 g/m2; p < 0.001), whereas mean gradient (from 13 ± 3 to 13 ± 4 mm Hg, p = not significant) and effective orifice area index (from 1.12 ± 0.34 to 1.13 ± 0.28 cm2/m2, p = not significant) remained substantially unchanged.
Conclusions. The use of a 21-mm Carpentier-Edwards Perimount bioprosthesis is associated with low transprosthetic gradients and significant reduction in left ventricular hypertrophy after aortic valve replacement. The results of our study suggest that a 21-m Carpentier-Edwards Perimount bioprosthesis should be considered a valid option in elderly patients with aortic valve disease and a small aortic annulus.
The design and development process for the Square Kilometre Array (SKA) radio telescope, the Low Frequency Aperture Array component, was progressed during the SKA pre-construction phase by an ...international consortium, with the goal of meeting requirements for a critical design review. As part of the development process a full-sized prototype SKA Low station was deployed, the Aperture Array Verification System 1 (AAVS1). We provide a system overview and describe the commissioning results of AAVS1, which is a low frequency radio telescope with 256 dual-polarisation log-periodic dipole antennas working as a phased array. A detailed system description is provided, including an in-depth overview of relevant sub-systems, ranging from hardware, firmware, software, calibration,and control sub-systems. Early commissioning results cover initial bootstrapping, array calibration, stability testing, beam-forming,and on-sky sensitivity validation. Lessons learned are presented, along with future developments.
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