Quadricuspid Aortic Valve Repair Facilitated by Geometric Ring Annuloplasty

Quadricuspid aortic valve (QAV) is a rare congenital anomaly often associated with aortic insufficiency. The exact anatomy of QAV is variable, and most cases have undergone aortic valve replacement. With the recognition that aortic valve repair achieves superior patient outcomes as compared to replacement, a systematic approach to autologous reconstruction of QAV is needed. This article reports 2 cases having successful repair utilizing geometric aortic annuloplasty rings, and describes a proposed scheme for repairing most QAV defects, based on relative leaflet and commissural characteristics. Using either tri-leaflet or bicuspid ring annuloplasty, the normal sub-commissural triangles can be remodeled into a 120° or 180° configuration, respectively, and then the leaflets can be sutured and plicated to fit annular geometry. With this approach, most quadricuspid valves potentially could undergo autologous reconstruction.

An Alfvenic reconnecting plasmoid thruster

A new concept for the generation of thrust for space propulsion is introduced. Energetic thrust is generated in the form of plasmoids (confined plasma in closed magnetic loops) when magnetic helicity (linked magnetic field lines) is injected into an annular channel. Using a novel configuration of static electric and magnetic fields, the concept utilizes a current-sheet instability to spontaneously and continuously create plasmoids via magnetic reconnection. The generated low-temperature plasma is simulated in a global annular geometry using the extended magnetohydrodynamic model. Because the system-size plasmoid is an Alfvenic outflow from the reconnection site, its thrust is proportional to the square of the magnetic field strength and does not ideally depend on the mass of the ion species of the plasma. Exhaust velocities in the range of 20 to $500\ \textrm {km}\ \textrm {s}^{-1}$ , controllable by the coil currents, are observed in the simulations.

3-Dimensional assessment of tricuspid annular geometry after percutaneous edge-to-edge repair in patients with severe tricuspid regurgitation

Background Transcatheter tricuspid valve repair (TTVR) using edge-to-edge leaflet therapy (E2E) has evolved as a feasible therapy to treating severe tricuspid regurgitation (TR). The TRILUMINATE trial using the new TriClip NT has shown promising clinical and functional improvements. However, the 3rd generation MitraClip XTr (Abbott Structural Heart, Santa Clara, CA, USA) has a broad off-label experience in the European Union to address tricuspid TR with wider gaps. There is insufficient data on the secondary effects of E2E on tricuspid annular geometry. The aim of this study was to address this lack of knowledge by evaluating the acute effects of E2E using the MitraClip XTr. Methods We retrospectively analyzed the imaging data of procedures using the MitraClip XTr to treat severe symptomatic TR at our Institution in 2018. Tricuspid annular geometry was assessed before and immediately after clip implantation by 3D TEE analysis of biplane and manual and automated volume data. Results During 2018, 69 patients were treated for severe TR using a transcatheter approach. In 61 patients, E2E was used, in 58 patients the MitraClip XTr was utilized (Pascal: n=3, Edwards Lifesciences, Irvine, CA, USA). Mean age was 79.0 years ± 6.4. Percutaneous TTVR using the MitraClip XTr significantly decreased the diastolic septal-lateral diameter (S/L: 4.1±0.7cm vs. 3.6±0.7cm; p<0.001), annulus area (14.9±6.7 vs. 12.8±6.2 cm2; p<0.001) and annulus perimeter (14.7±25.0 vs. 13.8±24.4 cm; p<0.001) whereas the diastolic anterior-posterior diameter was not significantly affected (A/P: 4.5±1cm vs. 4.4±0.8cm; p=0,45). Conclusions Percutaneous TTVR using MitraClip XTr showed significant changes in TV annulus geometry by focal perimeter and area reduction. This highlights a new mechanism of E2E therapy through indirectly adressing the dilated annulus in patients with severe TR. Annulus geometry by TOE, 3D- and autoMPR Funding Acknowledgement Type of funding source: None

Intermittency and Critical Scaling in Annular Couette Flow

The onset of turbulence in subcritical shear flows is one of the most puzzling manifestations of critical phenomena in fluid dynamics. The present study focuses on the Couette flow inside an infinitely long annular geometry where the inner rod moves with constant velocity and entrains fluid, by means of direct numerical simulation. Although for a radius ratio close to unity the system is similar to plane Couette flow, a qualitatively novel regime is identified for small radius ratio, featuring no oblique bands. An analysis of finite-size effects is carried out based on an artificial increase of the perimeter. Statistics of the turbulent fraction and of the laminar gap distributions are shown both with and without such confinement effects. For the wider domains, they display a cross-over from exponential to algebraic scaling. The data suggest that the onset of the original regime is consistent with the dynamics of one-dimensional directed percolation at onset, yet with additional frustration due to azimuthal confinement effects.