49 research outputs found
Characteristic Evolution and Matching
I review the development of numerical evolution codes for general relativity
based upon the characteristic initial value problem. Progress in characteristic
evolution is traced from the early stage of 1D feasibility studies to 2D
axisymmetric codes that accurately simulate the oscillations and gravitational
collapse of relativistic stars and to current 3D codes that provide pieces of a
binary black hole spacetime. Cauchy codes have now been successful at
simulating all aspects of the binary black hole problem inside an artificially
constructed outer boundary. A prime application of characteristic evolution is
to extend such simulations to null infinity where the waveform from the binary
inspiral and merger can be unambiguously computed. This has now been
accomplished by Cauchy-characteristic extraction, where data for the
characteristic evolution is supplied by Cauchy data on an extraction worldtube
inside the artificial outer boundary. The ultimate application of
characteristic evolution is to eliminate the role of this outer boundary by
constructing a global solution via Cauchy-characteristic matching. Progress in
this direction is discussed.Comment: New version to appear in Living Reviews 2012. arXiv admin note:
updated version of arXiv:gr-qc/050809
Cardiovascular magnetic resonance assessment of 1st generation CoreValve and 2nd generation Lotus valves
Objectives
We sought to compare using serial CMR, the quantity of AR and associated valve hemodynamics, following the first‐generation CoreValve (Medtronic, Minneapolis, MN) and the second‐generation Lotus valve (Boston Scientific, Natick, MA).
Background
Aortic regurgitation (AR) following Transcatheter Aortic Valve Replacement (TAVR) confers a worse prognosis and can be accurately quantified using cardiovascular magnetic resonance (CMR). Second generation valves have been specifically designed to reduce paravalvular AR and improve clinical outcomes.
Methods
Fifty‐one patients (79.0 ± 7.7 years, 57% male) were recruited and imaged at three time points: immediately pre‐ and post‐TAVR, and at 6 months.
Results
CMR‐derived AR fraction immediately post‐TAVR was greater in the CoreValve compared to Lotus group (11.7 ± 8.4 vs. 4.3 ± 3.4%, P = 0.001), as was the frequency of ≥moderate AR (9/24 (37.5%) versus 0/27, P < 0.001). However, at 6 months AR fraction had improved significantly in the CoreValve group such that the two valve designs were comparable (6.4 ± 5.0 vs 5.6 ± 5.3%, P = 0.623), with no patient in either group having ≥moderate AR. The residual peak pressure gradient immediately following TAVR was significantly lower with CoreValve compared to Lotus (14.1 ± 5.6 vs 25.4 ± 11.6 mmHg, P = 0.001), but again by 6 months the two valve designs were comparable (16.5 ± 9.4 vs 19.7 ± 10.5 mmHg, P = 0.332). There was no difference in the degree of LV reverse remodeling between the two valves at 6 months.
Conclusion
Immediately post‐TAVR, there was significantly less AR but a higher residual peak pressure gradient with the Lotus valve compared to CoreValve. However, at 6 months both devices had comparable valve hemodynamics and LV reverse remodeling
Screening of whole genome sequences identified high-impact variants for stallion fertility
Characteristic Evolution and Matching
I review the development of numerical evolution codes for general relativity
based upon the characteristic initial value problem. Progress is traced from
the early stage of 1D feasibility studies to 2D axisymmetric codes that
accurately simulate the oscillations and gravitational collapse of relativistic
stars and to current 3D codes that provide pieces of a binary black spacetime.
A prime application of characteristic evolution is to compute waveforms via
Cauchy-characteristic matching, which is also reviewed.Comment: Published version http://www.livingreviews.org/lrr-2005-1
Transcriptome profiling of lentil (Lens culinaris) through the first 24 hours of Ascochyta lentis infection reveals key defence response genes
Infective endocarditis in mitral mechanical prosthesis: The role of three-dimensional transoesophageal echocardiography
Implante percutâneo de prótese valvar aórtica – experiência com o dispositivo reposicionável Lotus™
Update on percutaneous mitral valve therapy: clinical results and real life experience
Mitral regurgitation (MR) is a common valvulopathy worldwide increasing in prevalence. Cardiac surgical intervention, preferable repair, is the standard of care, but a relevant number of patients with severe MR do not undergo surgery because of high peri-operative risk. Percutaneous mitral valve repair with the MitraClip System has evolved as a new tool for the treatment of severe MR. The procedure simulates the surgical edge-to-edge technique, developed by Alfieri in 1991, creating a double orifice valve by a permanent approximation of the two mitral valve leaflets. Several preclinical studies, registries and Food and Drug Administration approved clinical trials (EVEREST, ACCESS-EU) are currently available. The percutaneous approach has been recently studied in a randomized controlled trial, concluding that the device is less effective at reducing MR, when compared with surgery, by associated with a lower adverse event rate. The patients enrolled in this trial had a normal surgical risk and mainly degenerative MR with preserved left ventricular function. On the other hand, results derived from the clinical "real life" experience, show that patients actually treated in Europe present a higher surgical risk profile, more complex mitral valve anatomy and functional MR in the most of cases. Thus these data suggest that MitraClip procedure is feasible and safe in this subgroup of patients that should be excluded from the EVEREST trial due to rigid exclusion criteria. Despite the promising results clinical experience is still small, and no data related the durability are currently available. Therefore, MitraClip device should be reserved now to high risk or inoperable patients
Reduction of mitral valve regurgitation with Mitraclip® percutaneous system
Mitral regurgitation (MR) is the second most common heart valve disease worldwide and the current gold-standard treatment is surgical repair or replacement. Nevertheless, many patients do not undergo surgical intervention due to several comorbidities. Percutaneous "edge-to-edge" mitral valve repair using the MitraClip System is an emerging and effective option to this subset of patients. This device has been used to treat both functional and degenerative mitral valve regurgitation and has been compared to surgery in the Endovascular Valve Edge-to-Edge Repair Study II (EVEREST II) randomized trial. Although the field of percutaneous management of MR is at an early stage, it has been demonstrated that percutaneous approaches can reduce MR, suggesting there is a great deal of potential for clinical benefit to patients with MR