Minimizing Paravalvular Regurgitation With the Novel SAPIEN 3 Ultra TAVR Prosthesis: A Real-World Comparison Study

Objectives: We investigated performance and outcome of the latest-generation balloon-expandable SAPIEN 3 Ultra prosthesis (S3U) compared to the established SAPIEN 3 prosthesis (S3) in a real-world cohort, with focus on paravalvular regurgitation (PVR).Background: PVR is an adverse prognostic indicator of short- and long-term survival after transcatheter aortic valve replacement (TAVR). The S3U has been designed to improve sealing.Methods: We enrolled 343 consecutive patients presenting with severe native aortic valve stenosis eligible for a balloon-expandable prosthesis. The established S3 was implanted in the first 200 patients, the following 143 patients received the novel S3U after introduction in our institution. Primary endpoint was PVR after TAVR. Furthermore, we investigated procedural parameters and in-hospital and 30-day outcome.Results: PVR was significantly lower in the S3U cohort compared to the S3 cohort. They differed in their rate of mild PVR (11.2 vs. 48.0%, p < 0.001), whereas at least moderate PVR was similarly low in both cohorts (0.7 vs. 0.5%, p = 0.811). A significant reduction of post-dilatation rate, fluoroscopy time, and amount of contrast was observed in patients treated with the novel S3U (p < 0.001). The rate of adverse events in the in-hospital course and at 30 days were similarly low. At 30 days more patients receiving S3U improved in NYHA class (improvement ≥2 grades 34.6 vs. 19.9%, p = 0.003).Conclusion: The current study provides evidence that the novel S3U strongly minimizes PVR, thereby demonstrating the efficacy of improved sealing. Further studies will have to address if the observed reduction of PVR with S3U has prognostic significance.

Influence of Thermal Expansion on Fluid Dynamics of Turbulent Premixed Combustion and Its Modelling Implications

The purpose of this paper is to demonstrate the effects of thermal expansion, as a result of heat release arising from exothermic chemical reactions, on the underlying turbulent fluid dynamics and its modelling in the case of turbulent premixed combustion. The thermal expansion due to heat release gives rise to predominantly positive values of dilatation rate within turbulent premixed flames, which has been shown to have significant implications on the flow topology distributions, and turbulent kinetic energy and enstrophy evolutions. It has been demonstrated that the magnitude of predominantly positive dilatation rate provides the measure of the strength of thermal expansion. The influence of thermal expansion on fluid turbulence has been shown to strengthen with decreasing values of Karlovitz number and characteristic Lewis number, and with increasing density ratio between unburned and burned gases. This is reflected in the weakening of the contributions of flow topologies, which are obtained only for positive values of dilatation rate, with increasing Karlovitz number. The thermal expansion within premixed turbulent flames not only induces mostly positive dilatation rate but also induces a flame-induced pressure gradient due to flame normal acceleration. The correlation between the pressure and dilatation fluctuations, and the vector product between density and pressure gradients significantly affect the evolutions of turbulent kinetic energy and enstrophy within turbulent premixed flames through pressure-dilatation and baroclinic torque terms, respectively. The relative contributions of pressure-dilatation and baroclinic torque in comparison to the magnitudes of the other terms in the turbulent kinetic energy and enstrophy transport equations, respectively strengthen with decreasing values of Karlovitz and characteristic Lewis numbers. This leads to significant augmentations of turbulent kinetic energy and enstrophy within the flame brush for small values of Karlovitz and characteristic Lewis numbers, but both turbulent kinetic energy and enstrophy decay from the unburned to the burned gas side of the flame brush for large values of Karlovitz and characteristic Lewis numbers. The heat release within premixed flames also induces significant anisotropy of sub-grid stresses and affects their alignments with resolved strain rates. This anisotropy plays a key role in the modelling of sub-grid stresses and the explicit closure of the isotropic part of the sub-grid stress has been demonstrated to improve the performance of sub-grid stress and turbulent kinetic energy closures. Moreover, the usual dynamic modelling techniques, which are used for non-reacting turbulent flows, have been shown to not be suitable for turbulent premixed flames. Furthermore, the velocity increase across the flame due to flame normal acceleration may induce counter-gradient transport for turbulent kinetic energy, reactive scalars, scalar gradients and scalar variances in premixed turbulent flames under some conditions. The propensity of counter-gradient transport increases with decreasing values of root-mean-square turbulent velocity and characteristic Lewis number. It has been found that vorticity aligns predominantly with the intermediate principal strain rate eigendirection but the relative extents of alignment of vorticity with the most extensive and the most compressive principal strain rate eigendirections change in response to the strength of thermal expansion. It has been found that dilatation rate almost equates to the most extensive strain rate for small sub-unity Lewis numbers and for the combination of large Damköhler and small Karlovitz numbers, and under these conditions vorticity shows no alignment with the most extensive principal strain rate eigendirection but an increased collinear alignment with the most compressive principal strain rate eigendirection is obtained. By contrast, for the combination of high Karlovitz number and low Damköhler number in the flames with Lewis number close to unity, vorticity shows an increased collinear alignment with the most extensive principal direction in the reaction zone where the effects of heat release are strong. The strengthening of flame normal acceleration in comparison to turbulent straining with increasing values of density ratio, Damköhler number and decreasing Lewis number makes the reactive scalar gradient align preferentially with the most extensive principal strain rate eigendirection, which is in contrast to preferential collinear alignment of the passive scalar gradient with the most compressive principal strain rate eigendirection. For high Karlovitz number, the reactive scalar gradient alignment starts to resemble the behaviour observed in the case of passive scalar mixing. The influence of thermal expansion on the alignment characteristics of vorticity and reactive scalar gradient with local principal strain rate eigendirections dictates the statistics of vortex-stretching term in the enstrophy transport equation and normal strain rate contributions in the scalar dissipation rate and flame surface density transport equations, respectively. Based on the aforementioned fundamental physical information regarding the thermal expansion effects on fluid turbulence in premixed combustion, it has been argued that turbulence and combustion modelling are closely interlinked in turbulent premixed combustion. Therefore, it might be necessary to alter and adapt both turbulence and combustion modelling strategies while moving from one combustion regime to the other.

Evolution of Surface Density Function in an Open Turbulent Jet Spray Flame

A three-dimensional Direct Numerical Simulation of an open turbulent jet spray flame representing a laboratory-scale burner configuration has been used to analyse the statistical behaviours of the magnitude of reaction progress variable gradient $$\left| {\nabla c} \right|$$ ∇ c [alternatively known as the Surface Density Function (SDF)] and the strain rates, which affect its evolution. The flame has been found to exhibit fuel-lean combustion close to the jet exit, but fuel-rich conditions have been obtained further downstream due to the evaporation of fuel droplets, which leads to the reduction in the mean value of the SDF in the downstream direction. This change in mixture composition in the axial direction has implications on the statistical behaviours of the SDF and the strain rates affecting its evolution. The mean value of dilatation rate remains positive, whereas the mean normal strain rate assumes positive values where the effects of heat release are strong but becomes negative towards both unburned and burned gas sides. The mean values of dilatation rate, normal strain rate and tangential strain rate decrease downstream of the jet exit. However, the mean behaviours of displacement speed and its components do not change significantly away from the jet exit. The mean values of normal strain rate arising from flame propagation remain positive and thus act to thicken the flame. The mean tangential strain rate due to flame propagation (alternatively the curvature stretch rate) remains negative throughout the flame at all axial locations investigated. The mean effective normal strain rate assumes positive values throughout the flame and it increases in the downstream direction for the present case, which is consistent with the reduction in the peak mean value of the SDF in the axial direction. The mean effective tangential strain rate (alternatively stretch rate) assumes negative values throughout the flame at all axial locations.

445Effects of losartan and beta-blockers on aortic root dilatation in patients with Marfan Syndrome - results of the extended COMPARE trial

Introduction Despite several randomized trials, beneficial effects of Losartan and β-blockers in adults with Marfan syndrome (MFS) are not entirely clear. The COMPARE trial previously showed a small but significant beneficial effect of Losartan on top of β-blocker use on aortic root dilatation rate. Yet, this effect was not reproduced by other trials, although in general a favourable effect of Losartan could be demonstrated. All trials in adults with MFS showed lower than expected aortic root dilatation rates, suggesting mildly affected study populations. Therefore we extended the follow-up period of the COMPARE trial up to 10 years and aimed to assess the clinical outcomes of the study cohort, as well as the effect of medication regimes on aortic root dilatation rates in the subgroup of patients with a native aortic root at initial randomization. Methods Patients previously enrolled in the COMPARE trial were retrospectively analyzed. Cardiovascular events (aortic dissections, ruptures and operations) and all-cause mortality were assessed. Individual aortic root dilatation rates were estimated in patients with a native aortic root at time of randomization on the basis of linear regression analysis of multiple transthoracic echocardiogram (TTE) results. Correlations between aortic root dilatation rates and cumulative Losartan or β-blocker treatment days were assessed with Spearman's rho (ρ). Results During a median follow-up of 8.0 years, two dissections and three deaths occurred in the 151 patients with a native aortic root at time of randomization. The 122 patients that were eligible for aortic root dilatation analysis, underwent a median of 6 TTEs. The median aortic root dilatation rate in these patients was 0.28 (interquartile range 0.09 - 0.59) mm/y. These patients were further classified as either patients with a stable aortic root (n=102) or with aortic root growth (n=20), based on the threshold of 0.9 mm per year. Patients with aortic root growth had significantly more aortic root replacements during follow-up (17/20 vs 18/102, P=0.001). Furthermore, aortic root dilatation rate was negatively correlated with the number of Losartan treatment days (ρ=−0.272, P=0.003), β-blocker treatment days (ρ=−0.217, P=0.017) and with the duration of follow-up (ρ=−0.437, P<0.001). Conclusions Our results support previous findings that Losartan and β-blockers appear to be equally effective on aortic root dilatation rate in Marfan Syndrome patients. The low event rate in the long term follow-up of this subgroup of the COMPARE trial represent a relatively mildly affected study population and an aggressive prophylactic surgical regime.

Toward vortex identification based on local pressure-minimum criterion in compressible and variable density flows

We propose a dynamical vortex definition (the ‘$\unicode[STIX]{x1D706}_{\unicode[STIX]{x1D70C}}$definition’) for flows dominated by density variation, such as compressible and multi-phase flows. Based on the search of the pressure minimum in a plane,$\unicode[STIX]{x1D706}_{\unicode[STIX]{x1D70C}}$defines a vortex to be a connected region with two negative eigenvalues of the tensor$\unicode[STIX]{x1D64E}^{M}+\unicode[STIX]{x1D64E}^{\unicode[STIX]{x1D717}}$. Here,$\unicode[STIX]{x1D64E}^{M}$is the symmetric part of the tensor product of the momentum gradient tensor$\unicode[STIX]{x1D735}(\unicode[STIX]{x1D70C}\unicode[STIX]{x1D66A})$and the velocity gradient tensor$\unicode[STIX]{x1D735}\unicode[STIX]{x1D66A}$, with$\unicode[STIX]{x1D64E}^{\unicode[STIX]{x1D717}}$denoting the symmetric part of momentum-dilatation gradient tensor$\unicode[STIX]{x1D735}(\unicode[STIX]{x1D717}\unicode[STIX]{x1D70C}\unicode[STIX]{x1D66A})$, and$\unicode[STIX]{x1D717}\equiv \unicode[STIX]{x1D735}\boldsymbol{\cdot }\unicode[STIX]{x1D66A}$, the dilatation rate scalar. The$\unicode[STIX]{x1D706}_{\unicode[STIX]{x1D70C}}$definition is examined and compared with the$\unicode[STIX]{x1D706}_{2}$definition using the analytical isentropic Euler vortex and several other flows obtained by direct numerical simulation (DNS) – e.g. liquid jet breakup in a gas, a compressible wake, a compressible turbulent channel and a hypersonic turbulent boundary layer. For low Mach number ($M\lesssim 5$) compressible flows, the$\unicode[STIX]{x1D706}_{2}$and$\unicode[STIX]{x1D706}_{\unicode[STIX]{x1D70C}}$structures are nearly identical, so that the$\unicode[STIX]{x1D706}_{2}$method is still valid for low$M$compressible flows. But, the$\unicode[STIX]{x1D706}_{\unicode[STIX]{x1D70C}}$definition is needed for studying vortex dynamics in highly compressible and strongly varying density flows.

Morphological analysis using geometric parameters for splenic aneurysms

Background Considering the unique characteristics of splenic artery aneurysms, we hypothesized that hemodynamic forces could play an important role in splenic artery aneurysm formation and that splenic artery geometry should be correlated with aneurysm development. Methods Tortuosity of the splenic artery was evaluated three-dimensionally by calculating the curvature using software and the original modeling system. We selected 54 splenic artery aneurysm patients who had undergone thin-slice computed tomography imaging with contrast. We compared the splenic artery aneurysm group to non-vascular patients via propensity-score matching (35 patients in each group). The splenic artery length index, average curvature, and maximum curvature were analyzed. Results Splenic artery aneurysm patients tended to have a longer splenic artery and the curvature was more severe compared to the non-vascular control patients. The average curvature of splenic artery aneurysm patients was associated with the dilatation rate in female patients. Conclusion Females with a tortuous splenic artery may have an increased risk of aneurysm formation.

Abstract W P17: Spontaneous Dilatation of Stents at Three Months After Carotid Artery Stenting Without Post-Carotid Artery Stenting Balloon Dilatation

Objective: The aim of our retrospective study was to investigate how wide stents were spontaneously dilated at three months after carotid artery stenting (CAS) without post-CAS balloon dilatation (BT). Methods: We included in our analysis patients 1) who underwent elective CAS without post-CAS BT from January 2012 to March 2014, 2) who underwent follow-up conventional angiography at 3 months after CAS, Patients’ baseline characteristics, stent types (open cell: OP or closed cell: CL), stent diameter (SD) at the site with minimum width on the lateral projection immediately and at 3 month after CAS were evaluated. Results: Sixty-two lesions in fifty-nine patients were analyzed. Their average age was 74.9 years old, median SD immediately after CAS was 3.27mm(3.08_3.64:interquartile range), median SD at 3 months was 3.99mm(3.58-4.27), and thus SD was spontaneously dilated (p<0.0001). In OP types (18 cases), median SD changed from 3.59 to 4.05 mm and in CL types (44 cases) from 3.22 to 3.85 mm. Median SD after deployment was wider in OP type anytime (p<0.05), whereas dilatation rate seemed to be bigger in CL type. Conclusion: Stents were spontaneously dilated about 10 to 20% without post-CAS balloon dilatation. SD at 3 months was wider in OP type, whereas dilatation rate at 3 months was bigger in CL type.