Finite-element-method (FEM) model generation of time-resolved 3D echocardiographic geometry data for mitral-valve volumetry

INTRODUCTION: Mitral Valve (MV) 3D structural data can be easily obtained using standard transesophageal echocardiography (TEE) devices but quantitative pre- and intraoperative volume analysis of the MV is presently not feasible in the cardiac operation room (OR). Finite element method (FEM) modelling is necessary to carry out precise and individual volume analysis and in the future will form the basis for simulation of cardiac interventions. METHOD: With the present retrospective pilot study we describe a method to transfer MV geometric data to 3D Slicer 2 software, an open-source medical visualization and analysis software package. A newly developed software program (ROIExtract) allowed selection of a region-of-interest (ROI) from the TEE data and data transformation for use in 3D Slicer. FEM models for quantitative volumetric studies were generated. RESULTS: ROI selection permitted the visualization and calculations required to create a sequence of volume rendered models of the MV allowing time-based visualization of regional deformation. Quantitation of tissue volume, especially important in myxomatous degeneration can be carried out. Rendered volumes are shown in 3D as well as in time-resolved 4D animations. CONCLUSION: The visualization of the segmented MV may significantly enhance clinical interpretation. This method provides an infrastructure for the study of image guided assessment of clinical findings and surgical planning. For complete pre- and intraoperative 3D MV FEM analysis, three input elements are necessary: 1. time-gated, reality-based structural information, 2. continuous MV pressure and 3. instantaneous tissue elastance. The present process makes the first of these elements available. Volume defect analysis is essential to fully understand functional and geometrical dysfunction of but not limited to the valve. 3D Slicer was used for semi-automatic valve border detection and volume-rendering of clinical 3D echocardiographic data. FEM based models were also calculated. METHOD: A Philips/HP Sonos 5500 ultrasound device stores volume data as time-resolved 4D volume data sets. Data sets for three subjects were used. Since 3D Slicer does not process time-resolved data sets, we employed a standard movie maker to animate the individual time-based models and visualizations. Calculation time and model size were minimized. Pressures were also easily available. We speculate that calculation of instantaneous elastance may be possible using instantaneous pressure values and tissue deformation data derived from the animated FEM

Echocardiographic guidance for HARPOON beating-heart mitral valve repair

The HARPOON mitral valve (MV) repair system has been shown to safely and effectively treat a degenerative MV prolapse with transventricular implantation of artificial cords on a beating heart. The low profile system is introduced and precisely steered under 3D TEE guidance towards the previously selected target on a prolapsing MV segment. It allows puncture and deployment of a knot on the leaflet. The procedure is repeated until desired number of knots are implanted and the cords are optimally tensioned to restore coaptation. The cords are then tied down on the epicardium over a felt pledget. State of the art echocardiographic imaging is a crucial part of the procedure. It starts from patients screening, pre-procedural analysis and planning, access selection, navigation, deployment, optimal cordal tensioning, and final MV assessment and is continued during the follow-up assessment. This article illustrates the specific echocardiographic aspects of the HARPOON procedure including 2D and advanced 3D TEE techniques. The echocardiographic protocol was developed based on initial experience in 60 procedures. Detailed training of the echocardiographer and surgical team, is mandatory to achieve excellent results of this procedure, being now introduced in the clinical practice

Edge-to-edge repair for prevention and treatment of mitral valve systolic anterior motion

The edge-to-edge technique has been proposed to prevent systolic anterior motion (SAM) of the mitral valve. There is limited clinical data available on outcomes of this technique for this indication. We reviewed the midterm results of this technique for SAM prevention and treatment

An intercellular transfer of telomeres rescues T cells from senescence and promotes long-term immunological memory

The common view is that T lymphocytes activate telomerase to delay senescence. Here we show that some T cells (primarily naïve and central memory cells) elongated telomeres by acquiring telomere vesicles from antigen-presenting cells (APCs) independently of telomerase action. Upon contact with these T cells, APCs degraded shelterin to donate telomeres, which were cleaved by the telomere trimming factor TZAP, and then transferred in extracellular vesicles at the immunological synapse. Telomere vesicles retained the Rad51 recombination factor that enabled telomere fusion with T-cell chromosome ends lengthening them by an average of ~3,000 base pairs. Thus, there are antigen-specific populations of T cells whose ageing fate decisions are based on telomere vesicle transfer upon initial contact with APCs. These telomere-acquiring T cells are protected from senescence before clonal division begins, conferring long-lasting immune protection

Safety and performance of a novel transventricular beating heart mitral valve repair system: 1-year outcomes

The objective of this study was to evaluate the safety and performance of a novel, beating heart procedure that enables echocardiographic-guided beating heart implantation of expanded polytetrafluoroethylene (ePTFE) artificial cords on the posterior mitral leaflet of patients with degenerative mitral regurgitation