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BACKGROUND: This study aims to investigate whether small balloon aortic valvuloplasty (BAV) reduces the need for permanent pacemaker implantation (PPMI) after transcatheter aortic valve implantation (TAVI). METHODS: This was a retrospective analysis using data from our local TAVI database. Small BAV was defined as a small balloon size (=18 mm) pre-dilatation. Normal BAV was defined as a balloon size >18 mm. The primary endpoint was the incidence of new PPMI. RESULTS: Of 99 consecutive TAVI patients, five patients were excluded due to pre-existing permanent pacemaker. Patients in the small BAV group (n=57) had a significantly lower PPMI rate compared with the normal BAV group (n=37) (3.5% vs. 18.9%, P=0.026). Moderate or severe aortic valve regurgitation post-procedure was similar between the small BAV and normal BAV groups (5.3% vs. 8.1%, P=0.480); likewise, the mean aortic gradient post-procedure did not differ significantly (11.5±5.2 mmHg vs. 12.2±7.3 mmHg, 1 mmHg=0.133 kPa, P=0.580) between the groups. Device success rates were also similar (94.7% vs. 91.8%, P=0.680). In multivariable analysis, small BAV (P=0.027), the ratio of prosthesis diameter to annulus diameter (P=0.048), and mean aortic gradient by echo in the basement (P=0.021) were independent predictors of PPMI. CONCLUSIONS: The small BAV strategy is associated with a low rate of permanent pacemaker implantation after transcatheter self-expanding valve implantation in this single-center observational study.
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The interaction of electromagnetic waves with condensed matter and the resultant force is fundamental in the physical sciences. The maximum pressure on a planar surface is understood to be twice the incident wave power density normalized by the background velocity. We demonstrate for the first time that this pressure can be exceeded by a substantial factor by structuring a surface. Experimental results for direct optomechanical deflection of a nanostructured gold film on a silicon nitride membrane illuminated by a laser beam are shown to significantly exceed those for the planar surface. This enhanced pressure can be understood as being associated with an asymmetric optical cavity array realized in the membrane film. The possible enhancement depends on the material properties and the geometrical parameters of the structured material. Such control and increase of optical pressure with nanostructured material should impact applications across the physical sciences.
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An octave-spanning coherent supercontinuum is generated by non-collinear Raman-assisted four-wave mixing in single-crystal diamond using 7.7 fs laser pulses that have been chirped to about 420 fs in duration. The use of ultrabroad bandwidth pulses as input results in substantial overlap of the generated spectrum of the anti-Stokes sidebands, creating a phase-locked supercontinuum when all the sidebands are combined to overlap in time and space. The overall bandwidth of the generated supercontinuum is sufficient to support its compression to isolated few-to-single cycle attosecond transients. The significant spectral overlap of adjacent anti-Stokes sidebands allows the utilization of straight-forward spectral interferometry to test the relative phase coherence of the anti-Stokes outputs and is demonstrated here for two adjacent pairs of sidebands. The method can subsequently be employed to set the relative phase of the sidebands for pulse compression and for the synthesis of arbitrary field transients.
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We experimentally demonstrate that an interferometric spectrogram (i.e., fringe- and frequency-resolved autocorrelation trace) with high signal-to-noise ratio can be processed by three different procedures to accurately retrieve the spectral phase profile. We also show that the data redundancy built in the interferometric spectrogram permits simultaneous retrieval of multiple spectral phase solutions, and their weighted average may give a highly robust result against the measurement noise.
