Residual mitral regurgitation after repair for posterior leaflet prolapse- Importance of preoperative anterior leaflet tethering

Background Carpentier's techniques for degenerative posterior mitral leaflet prolapse have been established with excellent long‐term results reported. However, residual mitral regurgitation ( MR ) occasionally occurs even after a straightforward repair, though the involved mechanisms are not fully understood. We sought to identify specific preoperative echocardiographic findings associated with residual MR after a posterior mitral leaflet repair. Methods and Results We retrospectively studied 117 consecutive patients who underwent a primary mitral valve repair for isolated posterior mitral leaflet prolapse including a preoperative 3‐dimensional transesophageal echocardiography examination. Twelve had residual MR after the initial repair, of whom 7 required a corrective second pump run, 4 underwent conversion to mitral valve replacement, and 1 developed moderate MR within 1 month. Their preoperative parameters were compared with those of 105 patients who had an uneventful mitral valve repair. There were no hospital deaths. Multivariate analysis identified preoperative anterior mitral leaflet tethering angle as a significant predictor for residual MR (odds ratio, 6.82; 95% confidence interval, 1.8–33.8; P =0.0049). Receiver operator characteristics curve analysis revealed a cut‐off value of 24.3° (area under the curve, 0.77), indicating that anterior mitral leaflet angle predicts residual MR . In multivariate regression analysis, smaller anteroposterior mitral annular diameter ( P &lt;0.001) and lower left ventricular ejection fraction ( P =0.002) were significantly associated with higher anterior mitral leaflet angle, whereas left ventricular and left atrial dimension had no significant correlation. Conclusions Anterior mitral leaflet tethering in cases of posterior mitral leaflet prolapse has an adverse impact on early results following mitral valve repair. The findings of preoperative 3‐dimensional transesophageal echocardiography are important for consideration of a careful surgical strategy. </jats:sec

Flow-Induced Transport via Optical Heating of a Single Gold Nanoparticle

Optothermal trapping has gained increasing popularity in manipulation such as selecting, guiding, and positioning submicron objects because of a few mW laser power much lower than that required for optical trapping. The optotothermal trapping uses thermal gradient-induced phoretic motions, but the underlying physics of driving force has not been fully understood. In this study, we performed optotothermal trapping of 500-nm-diameter colloidal silica via a continuous laser illumination of a single gold nanoparticle from the bottom in a closed chamber. Under illumination, the tracer particles were attracted to the gold nanoparticle and trapped. Notably, the direction of migrating particles was always to hot gold nanoparticle regardless of the configuration of gold nanoparticle placed at two opposite sides of the chamber, on the bottom surface of an upper substrate (ceiling) or on the top surface of a lower substrate (floor). The previous interpretation based on thermal convective flow from the bottom to the top and circulating inside the chamber was only applicable to floor configuration and failed to explain our observation for ceiling. Instead, temperature-induced Marangoni effect at the water/superheated water interface is likely to play a role. This study promoted a better understanding of the driving mechanism in optothermal trapping. Moreover, as an application of the single-particle platform, we showed the photothermal phase separation-induced microdroplet formation of thermoresponsive polymers and the coating of non-thermoresponsive polymers on nanoparticles

Mitral valve reoperation under ventricular fibrillation through right mini-thoracotomy using three-dimensional videoscope

BACKGROUND: Conventional reoperative mitral valve surgery by median sternotomy has several difficulties. We performed mitral valve replacement (MVR) under ventricular fibrillation (VF) through right mini-thoracotomy with three-dimensional videoscope for avoiding the problems. METHODS: Between 2006 and 2011, we performed 257 cases of MVR, in which 125 cases underwent isolated MVR. Ten cases of patients underwent reoperative MVR under VF through thoracotomy with three-dimensional videoscope (Group I), and 27 cases of patients underwent reoperative conventional MVR through median sternotomy (Group II). We retrospectively reviewed the outcomes and compared Group I with Group II. Preoperative left ventricular ejection fraction (LVEF) was significantly lower (50.5 ± 19.8% vs 64.4 ± 12.0%; p = 0.046), and significantly higher Euro SCORE was found in Group I (4.8 ± 2.0 vs 3.8 ± 2.4; p = 0.037). RESULTS: Although Group I required cooling and rewarming time, average operative times was significantly shorter in Group I (262 ± 46 min vs 300 ± 57 min; p = 0.044), and cardiopulmonary bypass times and average VF times in Group I and aortic cross-clamp times in Group II were equivalent. There was no significant difference in the average of postoperative maximum creatine kinase (CK)-MB. In-hospital mortality was 0/10 (0%) and 1/27 (3.7%), and postoperative paravalvular leakage occurred in 0/10 (0%) and 1/27 (3.7%), and stroke occurred in 1/10 (10%) and 1/27 (3.7%) for Groups I and II. Two patients underwent reoperation for bleeding in Group II. Intensive care unit stay in Group I was significantly shorter than in Group II (1.8 ± 0.6 days vs 3.0 ± 1.7 days; p = 0.025). CONCLUSIONS: The higher risk of preoperative background in Group I had no effect on the operation. Mitral valve surgery under VF through right mini-thoracotomy can be an alternative procedure for reoperation after conventional various cardiothoracic surgeries

Asteroid Flyby Cycler Trajectory Design Using Deep Neural Networks

Asteroid exploration has been attracting more attention in recent years. Nevertheless, we have just visited tens of asteroids while we have discovered more than one million bodies. As our current observation and knowledge should be biased, it is essential to explore multiple asteroids directly to better understand the remains of planetary building materials. One of the mission design solutions is utilizing asteroid flyby cycler trajectories with multiple Earth gravity assists. An asteroid flyby cycler trajectory design problem is a subclass of global trajectory optimization problems with multiple flybys, involving a trajectory optimization problem for a given flyby sequence and a combinatorial optimization problem to decide the sequence of the flybys. As the number of flyby bodies grows, the computation time of this optimization problem expands maliciously. This paper presents a new method to design asteroid flyby cycler trajectories utilizing a surrogate model constructed by deep neural networks approximating trajectory optimization results. Since one of the bottlenecks of machine learning approaches is the computation time to generate massive trajectory databases, we propose an efficient database generation strategy by introducing pseudo-asteroids satisfying the Karush-Kuhn-Tucker conditions. The numerical result applied to JAXA's DESTINY+ mission shows that the proposed method is practically applicable to space mission design and can significantly reduce the computational time for searching asteroid flyby sequences

Delayed diagnosis of single compartment muscle contusion after radical hysterectomy in the lithotomy position: A case report

AbstractIntroductionMuscle contusions usually occur as a result of blunt trauma, which damages the muscle fibers and connective tissue without breaking the skin. Rapid bleeding can cause an increase in pressure that requires surgical intervention, commonly referred to as compartment syndrome. Here, we report a case with delayed diagnosis of single compartment muscle contusion in which compartment syndrome did not develop.Presentation of caseA 50-year-old woman underwent radical hysterectomy. She complained of edema and tenderness in the lower left leg on postoperative day 6. The serum creatine phosphokinase level was slightly elevated at 177 IU/L (normal range: 6–142 IU/L). T2-weighted magnetic resonance imaging revealed swelling of the muscle in the deep posterior compartment of the lower left leg, edematous fascia, and subcutaneous adipose tissue. She recovered naturally without other complications.DiscussionIn the lithotomy position during surgery, muscle contusion might occur, without general symptoms.ConclusionMagnetic resonance imaging is useful for diagnosis. For patients who complain of edema and tenderness in the lower leg after surgery in the lithotomy position, muscle contusions should be considered

Probing a ferromagnetic critical regime using nonlinear susceptibility

The second order para-ferromagnetic phase transition in a series of amorphous alloys (Fe{_5}Co{_{50}}Ni{_{17-x}}Cr{_x}B{_{16}}Si{_{12}}) is investigated using nonlinear susceptibility. A simple molecular field treatment for the critical region shows that the third order suceptibility (chi{_3}) diverges on both sides of the transition temperature, and changes sign at T{_C}. This critical behaviour is observed experimentally in this series of amorphous ferromagnets, and the related assymptotic critical exponents are calculated. It is shown that using the proper scaling equations, all the exponents necessary for a complete characterization of the phase transition can be determined using linear and nonlinear susceptiblity measurements alone. Using meticulous nonlinear susceptibility measurements, it is shown that at times chi{_3} can be more sensitive than the linear susceptibility (chi{_1}) in unravelling the magnetism of ferromagnetic spin systems. A new technique for accurately determining T{_C} is discussed, which makes use of the functional form of chi{_3} in the critical region.Comment: 11 Figures, Submitted to Physical Review