C1. A “ Ping-Pong ” Ball Left Atrial Thrombus Mimicking Left Atrial Myxoma : A Case Report

Background Valvular heart disease has a high prevalence, especially in developing countries, even though there is actually no exact number for prevalence in Indonesia. The prevalence of left atrial thrombus is around 17% in patients with severe mitral stenosis and will increase about 2 times in patients with atrial fibrillation. Although left atrial thrombus is common in mitral stenosis, left atrial thrombus mimicking myxoma is rarely reported Case Summary 47-year-old woman came to Dr. Soetomo cardiology outpatient clinic. She complained of palpitation and shortness of breath. Her electrocardiogram was showed atrial fibrillation. Echocardiography showed severe mitral stenosis and free moving, round shape, left atrial mass. She then immediately planned for Mitral Valve Replacement (MVR) surgery and evacuation of the mass. We found a solid wall spherical mass, layered and easily separate. Microscopic examination revealed extensive fibrin, hemorrhage and mononuclear inflammatory cells with the conclusion of a thrombus Discussion Left atrial thrombus and myxoma often look the same on echocardiography, especially when the thrombus is free-moving and round shape. Echocardiography in this case showed a free-moving mass, round shape, like a "ping-pong" ball. The mass also has solid wall suggesting a myxoma. After surgery, we found tha the mass is multilayered which looks like a myxoma. However, microscopically confirmed that the mass is a thrombus. This suggests that a left atrial thrombus may mimicking a myxoma on echocardiography. Therefore, the gold standard for diagnosing intracardiac mass is by histopathology

Vitrectome with Integrated LED Illumination: Development and Testing

Background: In current vitrectomy, the surgeon guides the vitrectome and a rigid fiber light guide with one hand each. It would be desirable to have a free hand for other surgical instruments and maneuvers. Methods: In the feasibility study presented here, a 20 gauge vitrectome is equipped with a miniature white LED that could eliminate the need for the separate light guide and therefore free one hand. The functionality of the system is proved in a ping-pong ball filled with agar and an ex-vivo porcine eye. Results: The brightness of the approach appears to be sufficient without any realistic phototoxic retinal hazard while the functionality of the vitrectome, in combination with the LED, is still given. Conclusion: The combination of a 20 gauge vitrectome with a LED illumination unit was successfully tested. The approach can be transferred to small vitrectomes in the future

Application of an Inertia Dependent Flow Friction Model to Snow Avalanches: Exploration of the Model Using a Ping-Pong Ball Experiment

Snow avalanches are catastrophic phenomena because of their destructive power. Therefore, it is very important to forecast the affected area of snow avalanches using numerical simulations. In our study, we focus on applying a numerical model to snow avalanches. The inertia-dependent flow friction model, which we call the “I-dependent” model, is a promising numerical model based on granular flow experiments and includes the local inertial effect. This model was introduced in previous studies as it predicts the shape and velocity of the granular flow accurately. We numerically investigated the particle diameter effect of the I-dependent model, and found that the smaller the particle diameter is, the faster the flow front velocity becomes. The final flow shape is similar to a crescent shape when the particle diameter is small. We applied this model to the ping-pong ball flow experiment, which imitated a snow avalanche on a ski jump slope. Comparing between the experimental and simulated results, the flow shape is better reproduced when the particle diameter is small, while the numerical simulation using a real ping-pong ball diameter did not show the clear crescent shape. Moreover, the relative error analysis shows that the best fit between experimental and simulated flow front velocity occurs when the particle diameter is larger than the actual size of a ping-pong ball. We conjecture that this discrepancy is mainly caused by aerodynamic effects, which, in this case, are large due to the low density of ping-pong balls. Therefore, it is necessary to explore the granular features of ping-pong balls or snow avalanches by conducting experiments, as done in previous experimental studies. Through such efforts, it may be possible to apply this I-dependent model to snow avalanches in the future.