Convolutional Neural Networks for Mechanistic Driver Detection in Atrial Fibrillation

The maintaining and initiating mechanisms of atrial fibrillation (AF) remain controversial. Deep learning is emerging as a powerful tool to better understand AF and improve its treatment, which remains suboptimal. This paper aims to provide a solution to automatically identify rotational activity drivers in endocardial electrograms (EGMs) with convolutional recurrent neural networks (CRNNs). The CRNN model was compared with two other state-of-the-art methods (SimpleCNN and attention-based time-incremental convolutional neural network (ATI-CNN)) for different input signals (unipolar EGMs, bipolar EGMs, and unipolar local activation times), sampling frequencies, and signal lengths. The proposed CRNN obtained a detection score based on the Matthews correlation coefficient of 0.680, an ATI-CNN score of 0.401, and a SimpleCNN score of 0.118, with bipolar EGMs as input signals exhibiting better overall performance. In terms of signal length and sampling frequency, no significant differences were found. The proposed architecture opens the way for new ablation strategies and driver detection methods to better understand the AF problem and its treatment.     

Cyp1 Inhibition Prevents Doxorubicin-Induced Cardiomyopathy in a Zebrafish Heart-Failure Model

Doxorubicin is a highly effective chemotherapy agent used to treat many common malignancies. However, its use is limited by cardiotoxicity, and cumulative doses exponentially increase the risk of heart failure. To identify novel heart failure treatment targets, a zebrafish model of doxorubicin-induced cardiomyopathy was previously established for small-molecule screening. Using this model, several small molecules that prevent doxorubicin-induced cardiotoxicity both in zebrafish and in mouse models have previously been identified. In this study, exploration of doxorubicin cardiotoxicity is expanded by screening 2271 small molecules from a proprietary, target-annotated tool compound collection. It is found that 120 small molecules can prevent doxorubicin-induced cardiotoxicity, including 7 highly effective compounds. Of these, all seven exhibited inhibitory activity towards cytochrome P450 family 1 (CYP1). These results are consistent with previous findings, in which visnagin, a CYP1 inhibitor, also prevents doxorubicin-induced cardiotoxicity. Importantly, genetic mutation of cyp1a protected zebrafish against doxorubicin-induced cardiotoxicity phenotypes. Together, these results provide strong evidence that CYP1 is an important contributor to doxorubicin-induced cardiotoxicity and highlight the CYP1 pathway as a candidate therapeutic target for clinical cardioprotection.     

基于运动对象局部场景截取的碰撞检测算法

为了解决虚拟心脏介入手术系统中的碰撞检测问题,提出了一种基于运动对象局部场景截取的碰撞检测算法.通过实时构建运动对象的局部场景截取体,可以获取该对象周围的局部场景数据,有效地降低了碰撞检测复杂性.并且它对虚拟场景中埘象的形变属性没有特殊要求,可适用于虚拟环境中包含可形变对象的情形.通过虚拟心脏介入手术中的碰撞检测实验表明,碰撞检测频率达到500Hz以上,并能精确给出碰撞点和发生碰撞的基本几何元素等碰撞信息,可以满足虚拟心脏介入手术对碰撞检测的实时性与精确性要求.     

面向短 QT 综合征的电生理建模与仿真研究进展

近年来,多物理尺度建模仿真心电动力学研究已经取得了显著进展。本文介绍当前心脏建模仿真领域中心肌细胞钾离子通道基因突变引起短QT综合征的研究情况。首先从Denis Noble多物理尺度划分的角度介绍了亚细胞与细胞级模型、心肌纤维与组织级模型、心脏器官级模型以及仿真心电图等数学模型,并从量化的角度来分析短QT综合征基因变异在细胞、组织、器官等多层面上对心电功能的影响;然后重点列出了三种短QT综合征亚型近期的研究成果;最后进一步探讨了面向短QT综合征的电生理建模与仿真的研究方向和应用前景。     

Biomass fuel smoke exposure was associated with adverse cardiac remodeling and left ventricular dysfunction in Peru

While household air pollution from biomass fuel combustion has been linked to cardiovascular disease, the effects on cardiac structure and function have not been well described. We sought to determine the association between biomass fuel smoke exposure and cardiac structure and function by transthoracic echocardiography. We identified a random sample of urban and rural residents living in the high‐altitude region of Puno, Peru. Daily biomass fuel use was self‐reported. Participants underwent transthoracic echocardiography. Multivariable linear regression was used to examine the relationship of biomass fuel use with echocardiographic measures of cardiac structure and function, adjusting for age, sex, height, body mass index, diabetes, physical activity, and tobacco use. One hundred and eighty‐seven participants (80 biomass fuel users and 107 non‐users) were included in this analysis (mean age 59 years, 58% women). After adjustment, daily exposure to biomass fuel smoke was associated with increased left ventricular internal diastolic diameter (P=.004), left atrial diameter (P=.03), left atrial area (four‐chamber) (P=.004) and (two‐chamber) (P=.03), septal E′ (P=.006), and lateral E′ (P=.04). Exposure to biomass fuel smoke was also associated with worse global longitudinal strain in the two‐chamber view (P=.01). Daily biomass fuel use was associated with increased left ventricular size and decreased left ventricular systolic function by global longitudinal strain.     

基于复合弹簧振子模型的实时心跳模拟

本文针对心脏介入仿真系统,提出了一种实时心跳模拟方法。该方法首先根据心脏的解剖结构建立了心脏的复合弹簧振子模型,然后根据心脏跳动的基本规律,使用逆向动力学技术将心房、心室的收缩、扩张与整个模型结合起来,从而得到心脏外表面的跳动效果。在此基础上,本文还实现了冠状动脉的运动模拟。实验结果表明,本方法简单、高效,能够在视觉上提供实时逼真的心脏跳动效果。     

The extended Kalman filter as a pulmonary blood flow estiṁator

Pulmonary blood flow is represented as a time-varying parameter in a simple model of the bodily uptake of gases that are soluble in blood. The pulmonary blood flow is estimated on-line using Ljung's modification of the extended Kalman filter. The experimental technique for estimation of pulmonary blood flow is based on Zwart's soluble gas method, modified to permit time-varying ventilation and pulmonary perfusion, and also to permit binary dynamic forcing of the inhaled soluble gas. Computer simulations were performed to determine the convergence time and to choose values of algorithmic parameters. Experiments done in humans gave agreement to within the accuracy of that measured invasively by a thermal dilution technique. The method shows promise for use in many biomedical applications, including patient monitoring, physiological experimentation, and clinical heart function tests.     

Background millimeter radiation influence in cardiology on patients with metabolic and pre-metabolic syndrome

The effects of background millimeter radiations (BMR) in patients with coronary artery disease (CAD), hypertension and in subjects with Inherited real risk of CAD, were investigated through invariant statistic measures, typical of nonlinear dynamics analysis of biological systems. The experimental evidences show that BMR ameliorate the nonlinear complexity in biosystems, recognized sign of physiological behavior, by increasing both the rate of unpredictability of heart rate variability (HRV) in patients with metabolic syndrome and the fractal dimension of coronary microvessel oscillations in subjects with pre-metabolic syndrome, healing their genetic alteration and CAD Inherited real risk.     

Accelerating in Situ Endothelialisation of Cardiovascular Bypass Grafts

The patency of synthetic cardiovascular grafts in the long run is synonymous with their ability to inhibit the processes of intimal hyperplasia, thrombosis and calcification. In the human body, the endothelium of blood vessels exhibits characteristics that inhibit such processes. As such it is not surprising that research in tissue engineering is directed towards replicating the functionality of the natural endothelium in cardiovascular grafts. This can be done either by seeding the endothelium within the lumen of the grafts prior to implantation or by designing the graft such that in situ endothelialisation takes place after implantation. Due to certain difficulties identified with in vitro endothelialisation, in situ endothelialisation, which will be the focus of this article, has garnered interest in the last years. To promote in situ endothelialisation, the following aspects can be taken into account: (1) Endothelial progenital cell mobilization, adhesion and proliferation; (2) Regulating differentiation of progenitor cells to mature endothelium; (3) Preventing thrombogenesis and inflammation during endothelialisation. This article aims to review and compile recent developments to promote the in situ endothelialisation of cardiovascular grafts and subsequently improve their patency, which can also have widespread implications in the field of tissue engineering.