First percutaneous transcatheter aortic valve‐in‐valve implant with three year follow‐up
Catheterization and Cardiovascular Interventions (Impact Factor: 2.11). 08/2008; 72(2):143 - 148. DOI: 10.1002/ccd.21597
Objectives: This study was conducted to report the clinical, hemodynamic, and iconographic outcomes of the longest survivor of the global CoreValve experience. Background: Early results of percutaneous heart valve (PHV) implantation for severe symptomatic aortic stenosis (AS) have been encouraging, with mid term survival up to 2 years; however longer durability term is unknown. Although a PHV has been implanted in a degenerated surgical bioprosthesis, the feasibility of a PHV-in-PHV has not been demonstrated. Methods: A patient with severe refractory heart failure due to severe aortic regurgitation (AR) and moderate AS, underwent CoreValve prosthesis implantation. The PHV was deployed too proximal into the left ventricular outflow tract, resulting in severe AR through the frame struts. Using the first PHV as a landmark, a second CoreValve was then deployed slightly distal to the first, with trivial residual paravalvular leak. Results: The second CoreValve expanded well with proper function. Transvalvular gradient was 8 mmHg. Both coronary ostia were patent. New mild to moderate mitral regurgitation occurred due to impingement of the anterior mitral leaflet by the first PHV. NYHA functional class improved from IV to II, maintained over the past 3 years. Echocardiography at 3 years showed normal functioning CoreValve-in-CoreValve prostheses, without AR or paravalvular leaks. Transvalvular gradient was 10 mmHg. Cardiac CT showed stable valve-in-valve protheses with no migration. Conclusion: The CoreValve prosthesis has maintained proper function up to 3 years, with no structural deterioration or migration. Treating mixed aortic valve disease with predominant AR is feasible. The concept as well as durability of the first PHV-in-PHV has also been demonstrated. © 2008 Wiley-Liss, Inc.
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ABSTRACT: It has been recently shown that adaptive observers may achieve an arbitrarily-fast rate of convergence if the dynamic order of the observer is sufficiently large. This paper investigates the behavior of an adaptive observer with regard to the choice of design parameters and to the magnitude of parameter, ignorance for the case where arbitrarily-fast convergence is guaranteed and the lower-order cases for which assurance of arbitrarily-fast convergence has not been given. A controller for the arbitrarily-fast placement of plant poles of stable systems is presented, also with evaluationDecision and Control including the 16th Symposium on Adaptive Processes and A Special Symposium on Fuzzy Set Theory and Applications, 1977 IEEE Conference on; 01/1978
Conference Paper: Another look at the single wheel derailment criteria[Show abstract] [Hide abstract]
ABSTRACT: The friction force in the plane of contact, between the wheel flange of a rail vehicle and the rail, reaches its Coulomb's limit only when the direction of sliding coincides with the net resultant tangential force in this plane. Therefore, for derivation of any derailment criterion, it becomes necessary to embed the inequality that relates the friction force to the normal contact force and coefficient of friction into the equations of action and reaction equilibrium between the two contacting surfaces at the point of contact. Assuming a quasi static state, it is natural to ignore all the detailed and microscopic considerations such as whether the lateral creep is due to spin or lateral velocity or both etc.. However, by ignoring the spin moment, the method remains general and it recognizes that there are lateral and longitudinal creep forces which are due to longitudinal, lateral, and spin creepages. The main consideration is based upon balancing the action and reaction between the two contacting surfaces at the point of flange contact. It is further assumed that the effect of wheel yaw in the contact angle is negligible. This can be proved by geometrical considerations. The mathematical solutions show why Nadal's limit (Nadal, 1896) is the most conservative derailment criterion. They also provide the ranges of L/V for which the wheel has potential to climb or slide up the rail. The solutions also reveal why, at times, the wheel withstands a much higher L/V ratio than Nadal's limit without derailingRailroad Conference, 1996., Proceedings of the 1996 ASME/IEEE Joint; 01/1996
Conference Paper: Optimal real time DSP implementation of ITU G.729 speech codec[Show abstract] [Hide abstract]
ABSTRACT: Spectral efficiency is the most important aspect in wireless communication systems and cellular mobile radio. As speech transmissions are the most used form of communications in the personal communication systems, the low bit speech codecs play an important role in determining the system's spectral efficiency. A toll quality low bit rate speech codec that was proposed to meet the personal communication system's requirement is the CS-ACELP speech codec. The speech codec has high robustness to withstand high-bit error rates and performs well in tandeming conditions, hence leading to efficient bandwidth utilization and increased channel capacity. In this paper several optimization techniques are presented for efficient implementation of ITU G.729 standard (CS-ACELP, conjugate structure algebraic code excited linear prediction) of 8 Kbit/s bit rate on a real time digital signal processor (DSP), with the aim of overcoming the limitation of computational burden and also scaling this application for enhanced speed to process more channels. These techniques are in general applicable to any speech codec and DSP processor platform.Vehicular Technology Conference, 2004. VTC2004-Fall. 2004 IEEE 60th; 10/2004
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