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Highlights • We numerically investigated the physiological relationship between the severity of regurgitation and the effect of a left ventricular assist device (LVAD) on cardiovascular system responses. • Under conditions of mitral regurgitation, the effects of both pulsatile and continuous LVAD treatment on ventricular unloading were significant. • Under conditions of aortic regurgitation (AR), the effects of the LVADs on ventricular unloading were not significant. The effects of LVAD treatment decreased according to the severity of AR., Background A left ventricular assist device (LVAD) is normally contraindicated in significant aortic regurgitation (AR) and requires intraoperative valve repair or exclusion. Nevertheless, AR can coexist with an LVAD, so a valid question when asked might still be of clinical significance. The purpose of this study is to analyze the effects of valve regurgitation on the pumping efficacy of continuous and pulsatile LVADs with a computational method. Methods A cardiovascular model was developed based on the Windkessel model, which reflects the hemodynamic flow resistance and the blood wall elasticity. Using the Windkessel model, important cardiovascular components, such as the right atrium, right ventricle, pulmonary artery, pulmonary vein, left atrium (LA), left ventricle (LV), aorta, and branching blood vessels, were expressed. Results In the case of AR, continuous and pulsatile LVADs improved cardiac output and reduced mechanical load slightly. In the case of mitral regurgitation, the LVADs improved cardiac output (cardiac outputs were about 5 L/min regardless of the severity of regurgitation) and reduced afterload significantly. Conclusion AR reduced both continuous and pulsatile LVAD function significantly while mitral regurgitation did not affect their pumping efficacy.

Nanocrystalline diamond (NCD) film surfaces were modified with fluorine or oxygen by plasma treatment in an O 2 or C 3 F 8 gas environment in order to induce wettability. The oxygenated-NCD (O-NCD) film surface was hydrophilic and the fluorinated-NCD (F-NCD) surface was hydrophobic. The efficiency of early cell adhesion, which is dependent on the wettability of the cell culture plate and necessary for the growth and proliferation of cells, was 89.62 ± 3.92% on the O-NCD film and 7.78 ± 0.77% on the F-NCD film surface after 3 h of cell culture. The wettability of the NCD film surface was artificially modified using a metal mask and plasma treatment to fabricate a micro-pattern. Four types of micro-patterns were fabricated (line, circle, mesh, and word) on the NCD film surface. We precisely arrayed the neuroblastoma cells on the micro-patterned NCD film surfaces by controlling the surface wettability and cell seeding density. The neuroblastoma cells adhered and proliferated along the O-NCD film surface.

To fabricate micro-patterns for bioengineering applications, we used graphene sheet, metal mask, and plasma treatment rather than the commonly used photolithography process. Two types of micro-patterns were fabricated (line, and circle) on SiO 2 /Si (100, p-typed) substrate. In the line and circle micro-patterns, graphene etched areas were 100 and 150 μm, respectively, with fluorinated graphene spacing. The efficiencies of early cell adhesion, which is necessary for the growth and proliferation of cells, were 62, 17, and 65% on the pristine, fluorinated, and etched graphene surface, respectively, for 6 h of cell culture. After seeding the neuron cells on the patterned substrate, neuron cells proliferated and differentiated along the graphene etched regions. The graphene sheet was used as a passivation layer for micro-array of the neuron cell on SiO 2 /Si.

Genetic factors play an important role in the pathogenesis of atrial flutter (AF). Although mutation in KCNQ1 has been widely correlated with AF, the mechanism by which mutation promotes AF remains poorly understood. The purpose of this study was to investigate the proarrhythmic effect of V241F KCNQ1 mutation in human atrium using the electrophysiological model of human atrium. Using 2D and 3D cardiac electrophysiological models that incorporate the Courtemanche human atrial model, we simulated electrical conduction through atrial tissue and compared spiral wave dynamics under the wild-type and V241F KCNQ1 conditions. In 2D and 3D simulation, V241F KCNQ1 showed a stable and persistent wave without spiral break-up, whereas the wild-type wave was less stable, resulting in early self-termination. According to the results, we concluded that compared to the wild type, the electrical activity of the V241F KCNQ1 mutation is more likely to sustain spiral wave.