Atrial interstitial fibrosis plays a dual role in inducing and maintaining atrial fibrillation (AF). Hypoxia-inducible factor-1α (HIF-1α) has been reported as closely associated with renal, liver and pulmonary fibrosis diseases. However, whether HIF-1α is involved in myocardial fibrosis, and the associations between HIF-1α, transforming growth factor-β1 (TGF-β1) and matrix metalloproteinase-9 (MMP-9) remain unknown. Therefore, this area warrants studying for the significance of AF diagnosis and treatment. The present study investigated the expression of HIF-1α in atrial fibrosis and its possible mechanism in isoproterenol (ISO)-induced rats. The three groups of rats; control, ISO and ISO plus sirolimus [also known as rapamycin (Rapa)], were treated for 15 days and sacrificed to remove the myocardial tissues. The expression levels of HIF-1α, TGF-β1 and MMP-9 and their associations with atrial fibrosis were examined through histomorphology and protein and mRNA levels. The protein and mRNA levels of HIF-1α, TGF-β1 and MMP-9 in the ISO group were increased markedly (P<0.01) compared with the control group, while those in the Rapa group were clearly decreased (P<0.01) compared with the ISO group. The protein and mRNA levels of HIF-1α, TGF-β1 and MMP-9 were positively correlated (P<0.01) with atrial fibrosis (collagen volume fraction index), as were the HIF-1α, TGF-β1 and MMP-9 mRNA levels (P<0.01) and the mRNA levels between MMP-9 and TGF-β1 (P<0.01). During the process of atrial fibrosis in ISO-induced rats, HIF-1α promotes the expression of TGF-β1 and MMP-9 protein, and thus is involved in in atrial fibrosis.

This paper presents the modelling and design analysis of V- and Z-shaped electrothermal microactuators. First, a comprehensive but concise closed-form multiphysical analytical model is developed to predict the output displacement and force of both V- and Z-shaped electrothermal microactuators operating either in vacuum or in air conditions. The analytical model is verified by finite element analysis and experimental testing. Then, a novel comparison benchmark is proposed for the design and analysis of the V- and Z-shaped microactuators. With the multiphysical model and comparison benchmark, comprehensive performance comparison and analysis of the V- and Z-shaped beams are performed with the aim of providing insight and guidance on selection and design of the two typical types of electrothermal microactuators. Finally, the application of the comparison model into the design analysis is demonstrated using a design example of an electrothermal microactuator, and the detailed investigation is conducted to examine the effects of the material properties and structural parameters on the microactuator outputs.

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In this trial, long-term therapeutic effects and clinical improvements in Chinese chronic heart failure patients optimized by QuickOpt or echocardiography were compared for atrioventricular (AV) and interventricular (VV) delay optimizations after cardiac resynchronization therapy (CRT) with pacing (CRT-P) or with pacing and defibrillator (CRT-D) therapy. One hundred and ninety-six subjects (50%) had dilated cardiomyopathy, 108 (27.6%) had ischemic heart disease and 112 (28.6%) were hypertensive and were randomized into QuickOpt (198) or echocardiographic optimization (control) (194) groups at ≤2-weeks post-implantation. Programmed AV/VV delay was optimized at baseline and at 3 and 6 months. Left ventricular end-systolic volume (LVESV), New York Heart Association (NYHA) class, specific activity scale (SAS), and the six-minute walk tests (6MWT) were evaluated by blinded researchers at 12 months. Of the QuickOpt group, LVESV decreased significantly by 24.7% ± 33.9% compared with baseline, while LVESV of Controls decreased by 25.1% ± 36.1% (P = 0.924). NYHA class, SAS and 6MWT also improved similarly in both groups at 12 months. Mortality in both groups was not significantly different (11.0% vs 7.6%, P = 0.289). However, there was a significant difference in the time required for optimization by QuickOpt compared with echocardiography (3.33 ± 3.11 vs 58.79 ± 27.03 minutes, P < 0.000).