Improving Matching Accuracy of Underwater Gravity Matching Navigation Based on Iterative Optimal Annulus Point Method with a Novel Grid Topology

In this study, we improve the matching accuracy of underwater gravity matching navigation. Firstly, the Iterative Optimal Annulus Point (IOAP) method with a novel grid topology is proposed for breaking through the inherent grid structure limit of the canonical gravity matching algorithm and enhancing its underwater gravity matching accuracy. The theory of IOAP is as follows: (1) small-annulus matching and positioning mechanism on the tracking starting point is developed by employing the starting point and drift error of the INS (Inertial Navigation System), the fixed rotation angle, etc. The optimal matching location of the starting point is obtained by matching and comparing the matched points in this small-annulus grid, which contributes to heightening the initial-position error insensitivity of the algorithms. (2) Variable-angle three-layer annulus matching and positioning mechanisms on the tracking ending point were constructed by using the optimal matching location of the starting point and combining the tracking direction-and-distance information of the INS and the cumulative drift error, etc. It is used to generate the annulus matching points with the ring-type grid topology. (3) The optimal matching position of the ending point in this annulus is obtained by iteratively calculating the evaluation index value of the matching points and following the evaluation index optimal rule. Secondly, we comprehensively consider the main performance evaluation indexes of the underwater gravity matching algorithms, such as the statistical indicators of the matching accuracy, the average matching time and the matching success rate, and take them as a basis of the pros and cons of the matching analysis. Furthermore, under conditions that include different scale searching regions or different reference-angle ring radii, the statistical results verify that the IOAP had a different matching ability and better robustness. Finally, several trajectories with the starting points from different areas and the ending points in different gravity ranges are tested and compared to carry out the numerical simulations. These results indicate that the IOAP has many advantages, such as a high matching accuracy and strong positioning applicability in different gravity regions. Compared with the TERCOM (terrain contour matching algorithm), its average matching accuracy was the highest, increased by 40.39%.

Predictors of haemodynamic performance in patients with aortic stenosis and small annulus undergoing TAVI with self-expandable valves

Background Small aortic annular size is one of the most important predictor of poor hemodynamic and clinical outcomes in patients treated for aortic stenosis. Post-hoc analyses of pivotal trials showed that transcatheter aortic valve intervention (TAVI) offer better outcomes then surgery in patients with small aortic annulus, especially with self-expandable valves (SEV). However, data about SEVs comparison in this population are limited. Purpose Our aim is to assess how valve design and oversizing, with anatomical and echographic features, impact on the hemodynamic performance of SEVs in TAVI patients with small aortic annulus. Methods The TAVI SMALL registry enrolled 859 patients with small aortic annulus (CT-scan annular perimeter≤72 mm or area ≤400 mm2) treated for aortic stenosis with currently available SEVs (Evolut R=397; Evolut PRO =84; Acurate Neo=140; Acurate TA= 61; Portico=177) at 9 European centers between 2011 and 2018. We performed multivariable backward logistic regression analyses to identify predictors of high postprocedural mean gradient, moderate-to-severe PPM, and moderate-to-severe para-valvular leak (PVL). Results After adjustment for LVEF, we identified annular perimeter and percentage of oversizing as independent predictors of lower post-procedural mean gradient. Implantation of intra-annular rather than supra-annular bioprosthesis was the only independent predictor of moderate-to-severe PPM. Predictors of moderate-to-severe PVL are reported in the Table. Conclusions Among patients with aortic stenosis and small aortic annulus treated with transcatheter SEVs, use of supra-annular bioproshtesis and oversizing were associated with improved valve performance. Funding Acknowledgement Type of funding source: None

P1788The outcome of TAVI in patients with small annulus and the comparison between intra-annular and supra-annular devices in small anulus: From the analysis of the Japanese nationwide registry

Background Transcatheter aortic valve implantation (TAVI) has been widely accepted strategy of the treatment for aortic stenosis in patients at intermediate to high or prohibitive surgical risk. The Asian people are of smaller body size compared to Western people. As the result, Asian people have smaller aortic annulus size, which accommodate only smaller transcatheter heart valves (THVs), however, the details and consequences of small aortic annulus size in TAVI is uncertain. Purpose The purposes of this study were to clarify the short-term outcomes of TAVI in patients with small annulus and the differences of intra-annular and supra-annular THVs in small annulus using Japanese national TAVI registry. Methods Multi-detector computed tomography (MDCT) was performed before TAVI and the annulus area was registered. We compared the 30-day clinical outcomes between patients with and without small annulus (annulus area 3.14cm2). Further investigation to compare intra-annular and supra-annular THVs in patients with small annulus was conducted. Results The total of 5,870 patients (103 sites in Japan) who underwent TAVI between August 2013 to December 2017 were enrolled in this study. Out of 5,870 patients, 647 had small annulus. Thirty-day mortality, new pacemaker implantation and stroke rate were comparable between patients with and without small annulus. Echocardiography within 30 days after TAVI revealed that patients with small annulus had significantly smaller indexed effective orifice area (iEOA, 1.10.cm2/m2 [0.92–1.35] vs. 1.16 cm2/m2 [0.96–1.39], p<0.001), higher mean pressure gradient (10.0 mmHg [6.9–14.2] vs. 8.5 mmHg [6.0–11.5], p<0.001) and lower frequency of paravalvular leakage moderate (17.3% vs. 24.4%, p<0.001). Patient-prosthesis mismatch (PPM) were more frequent in patients with small annulus (p=0.002). Logistic regression analysis revealed that small annulus (OR: 1.82; 95% CI: 1.45–2.30, p<0.001), female gender (OR: 0.54; 95% CI: 0.42–0.70, p<0.001), weight (OR: 1.03; 95% CI: 1.02–1.04, p<0.001), height (OR: 1.04; 95% CI: 1.02–1.05, p<0.001), hyperlipidemia (OR: 1.25; 95% CI: 1.07–1.47, p=0.006), femoral access (OR: 0.80; 95% CI: 0.66–0.97, p=0.026) were significantly associated with the PPM after TAVI. The use of SAPIEN 3 20mm THV in patients with small annulus was associated with the smaller iEOA (0.94 cm2/m2 [0.78–1.06] vs. 1.07 cm2/m2 [0.84–1.24], p=0.001) and higher mean pressure gradient (14.0 mmHg [10.0–18.5] vs. 11.0 [7.0–14.0], p<0.001) compared to the usage of Evolut R 23 mm THV. The rate of paravalvular leakage more than moderate was similar in both THVs (14.4% vs. 16.5%, p=0.69). Conclusions Small annulus did not affect clinical 30-day outcomes, however, small annulus was associated with smaller iEOA and higher mean pressure gradient. Supra-annular device might contribute the better hemodynamical improvement in patients with small annulus without increase of paravalvular leakage. Acknowledgement/Funding None

Lobocriconema iranense (Van den Berg, Eskandari, Tiedt & Karegar, 2010) n. comb. and description of L. nokandense n. sp. (Nematoda: Criconematidae) from Iran

Summary Two populations of Lobocriconema were recovered from the rhizosphere of Parrotia persica in Rango forest, Gorgan, and Nargesi forest, Nokandeh, Golestan province, northern Iran. Both of the recovered populations were characterised using morphological (light and scanning electron microscopy), morphometric and molecular data based upon small, partial large and internal transcribed spacer 1 ribosomal RNA (SSU, LSU D2-D3, ITS1 rDNA) and the mitochondrial cytochrome c subunit oxidase I (COI mtDNA) gene sequences. The first examined population, recovered from Gorgan, was mainly characterised by having 34-39 retrorse body annuli 11-16 μm thick at mid-body with crenate, dentate and lobulate margins, longitudinal cuticular scratches on entire body on both lateral regions, sometimes one or two anastomoses along the body, a single labial annulus with smooth margin and smaller than the first body annulus, four distinct submedian lobes, simple open vulva with no overhang, and a terminal anus. This population was almost identical to Neolobocriconema iranense, a close examination of a topotype population recovered in this study confirming that they were conspecific. The second population, L. nokandense n. sp., was recovered from the Nokandeh and looked similar to the first population but was morphologically separated from it by a slightly crenate labial annulus under SEM (vs smooth), longer tail (13-21 vs 6-10 μm) and smaller ratio c (23.6-32.4 vs 44.7-86.0). In molecular phylogenetic analyses, the two populations formed a clade in both SSU and LSU phylogenies. In ITS1 and COI phylogenies, the Nokandeh population (the new species) formed a separate sister clade to the N. iranense clade. Detailed observations using SEM data revealed a small annulus between the submedian lobes and the single labial annulus, an open vulva and a slightly ornamented cuticle in all three studied populations (the newly recovered populations from Golestan and the topotype population of N. iranense from Mazandaran province and the new species), corroborating their placement under Lobocriconema. As a result, N. iranense was transferred to Lobocriconema as L. iranense n. comb. (= N. iranense). The new species was morphologically compared with its close relatives L. iranense n. comb., L. pauperum, L. incrassatum, and L. nasuense, all of which having the aforementioned small annulus between the submedian lobes and the first labial annulus. The phylogeny of the genus is discussed.

How to Control Subannular Hemorrhage during Aortic Root Enlarging Procedures

We describe an effective suture technique to control the persistent subannular bleeding at the aortoventricular curtain in four patients with aortic stenosis and small annulus who underwent aortic root enlargement and patch reconstruction. This technique approximates the left atrial roof to the aortic root without the need for re-replacement of the aortic prosthesis or revision of the patch. Reintervention for aortic root, valve, or the residual aorta was not required.