用于心室辅助装置血流动力学性能评价的体外模拟循环系统技术进展

体外模拟循环系统(mock circulatory systems,MCS)是一个模拟人体循环系统血流动力学状态的试验平台,被广泛用于心室辅助装置和人工瓣膜等心血管人工器官的体外性能评价和生机电系统中的血流动力学响应研究。通过调整模拟心脏的驱动元件和模拟血管系统的集中参数元件,MCS可以模拟人体健康、运动、心力衰竭等不同生理状态的血流动力学特性。自1960年代至今,MCS研发目标从满足最基本的心室辅助装置或机械瓣膜的系统性能评价要求,已发展到能够复现局部重要器官的血流动力学状态。总结MCS目前的设计原则、系统搭建以及研究进展和未来展望。     

Left Ventricular Assist Devices: Challenges Toward Sustaining Long-Term Patient Care

Over the last few decades, the left ventricular assist device (LVAD) technology has been tremendously improved transitioning from large and noisy paracorporeal volume displacement pumps to small implantable turbodynamic devices with only a single transcutaneous element, the driveline. Nevertheless, there remains a great demand for further improvements to meet the challenge of having a robust and safe device for long-term therapy. Here, we review the state of the art and highlight four key areas of needed improvement targeting long-term, sustainable LVAD function: (1) LVADs available today still have a high risk of thromboembolic and bleeding events that could be addressed by the rational fabrication of novel surface structures and endothelialization approaches aiming at improving the device hemocompatibility. (2) Novel, fluid dynamically optimized pump designs will further reduce blood damage. (3) Infection due to the paracorporeal driveline can be avoided with a transcutaneous energy transmission system that additionally allows for increased freedom of movement. (4) Finally, the lack of pump flow adaptation needs to be encountered with physiological control systems, working collaboratively with biocompatible sensor devices, targeting the adaptation of the LVAD flow to the perfusion requirements of the patient. The interdisciplinary Zurich Heart project investigates these technology gaps paving the way toward LVADs for long-term, sustainable therapy.     

A Novel Multi-objective Physiological Control System for Rotary Left Ventricular Assist Devices

Various control and monitoring algorithms have been proposed to improve the left-ventricular assist device (LVAD) therapy by reducing the still-occurring adverse events. We developed a novel multi-objective physiological control system that relies on the pump inlet pressure (PIP). Signal-processing algorithms have been implemented to extract the required features from the PIP. These features then serve for meeting various objectives: pump flow adaptation to the perfusion requirements, aortic valve opening for a predefined time, augmentation of the aortic pulse pressure, and monitoring of the LV pre- and afterload conditions as well as the cardiac rhythm. Controllers were also implemented to ensure a safe operation and prevent LV suction, overload, and pump backflow. The performance of the control system was evaluated in vitro, under preload, afterload and contractility variations. The pump flow adapted in a physiological manner, following the preload changes, while the aortic pulse pressure yielded a threefold increase compared to a constant-speed operation. The status of the aortic valve was detected with an overall accuracy of 86% and was controlled as desired. The proposed system showed its potential for a safe physiological response to varying perfusion requirements that reduces the risk of myocardial atrophy and offers important hemodynamic indices for patient monitoring during LVAD therapy.     

人工心脏电动叶轮血泵动物试验及临床试用

研制的叶轮血泵在动物小公牛身上做左心室辅助存活试验，其中三头牛存活约２个月，血液生化检测表明，动物血液成分及器官功能均未有显著改变。     

Technical Review: In Situ Hybridization

In situ hybridization is a technique that is used to detect nucleotide sequences in cells, tissue sections, and even whole tissue. This method is based on the complementary binding of a nucleotide probe to a specific target sequence of DNA or RNA. These probes can be labeled with either radio‐, fluorescent‐, or antigen‐labeled bases. Depending on the probe used, autoradiography, fluorescence microscopy, or immunohistochemistry, respectively, are used for visualization. In situ hybridization is extensively used in research, as well as clinical applications, especially for diagnostic purposes. This review discusses the basic technique of in situ hybridization. The standard in situ hybridization process is reviewed, and different types of in situ hybridization, their applications, and advantages and disadvantages are discussed. Anat Rec, 297:1349–1353, 2014. © 2014 Wiley Periodicals, Inc.     

左心室辅助装置技术现状及未来展望

介绍了临床应用的左心室辅助装置的类型和结构特点,分析了基于生理机制的血泵电机参数的血泵控制策略;提出基于多生理信号约束的控制策略控制血泵输出,易满足受体的需求。结合血泵系统现状,从血泵的结构、穿皮能量传递方式和控制策略等方面探讨今后的研究目标。     

直接心室辅助致动方法的现状与发展

直接心室辅助通过在心脏外侧柔性挤压心脏,帮助虚弱的心脏恢复功能.它能够避免人工器件与血液接触引发的血栓、血感染等问题,是人工心脏辅助器件研究与开发的重要领域之一.直接心室辅助的致动器,决定了器件的结构、形状、及其性能,是整个辅助器件关键中的关键,致动器上的任何突破有可能对直接心室辅助器件产生革命性影响.因此,本文从致动原理的角度,分析、探讨了直接心室辅助的致动方法及其存在问题,这对探索与开发满足要求的下一代直接心室辅助致动器有一定的帮助作用.     

Progress in Methods for Transcutaneous Wireless Energy Supply to Implanted Ventricular Assist Devices

Scientific and technological problems in the development of transcutaneous wireless energy supply systems for ventricle assist devices are discussed. These problems include the stability and the effectiveness of the energy transfer and the thermal safety of the implanted components of the system.     

Optimization of the Parameters of Ventricular Assist Devices Using Computerized Mathematical Modeling of the Cardiovascular System

Biomedical Engineering - The construction of secondary mathematical models for optimizing the parameters of nonpulsatile flow pumps (NPFP) for ventricular assistance is described. The model...     

Technical Review: Types of Imaging—Direct STORM

In the 1990s, new concepts of microscopy revolutionized the imaging field by breaking the lateral resolution diffraction limit for the first time, even with propagating light and regular lenses (i.e., far‐field). In 2006, several research groups independently showed super‐resolution microscopy using high‐precision localization of single fluorophores. These new developments in single‐molecule spectroscopy enabled a different approach to achieving nanometer‐scale optical microscopy. Direct stochastic optical reconstruction microscopy (dSTORM) is a technique of single‐molecule super‐resolution imaging that does not require an activator fluorophore. This technique is used to visualize cellular structures with a resolution of approximately 20 nm. dSTORM is compatible with many conventionally used fluorophores. This article provides an overview of the principles and uses of dSTORM. Advantages and disadvantages of dSTORM are also discussed. Anat Rec, 297:2227–2231, 2014. © 2014 Wiley Periodicals, Inc.     

A New Concept of Ventricular Assist Device

In principle, the heart tube of a zebrafish embryo is an impedance pump that drives blood flow forward by compressing the tube periodically and asymmetrically.In this article, we proposed a hypothesis that the blood pumping mechanism of the zebrafish embryo heart tube can be applied to the design of pulsatile ventricular assist devices, which may overcome the shortcomings of current ventricular assist devices such as hemolysis caused by the mechanical injure of blood.     

Effects of the Purkinje System and Cardiac Geometry on Biventricular Pacing: A Model Study

Heart failure leads to gross cardiac structural changes. While cardiac resynchronization therapy (CRT) is a recognized treatment for restoring synchronous activation, it is not clear how changes in cardiac shape and size affect the electrical pacing therapy. This study used a human heart computer model which incorporated anatomical structures such as myofiber orientation and a Purkinje system (PS) to study how pacing affected failing hearts. The PS was modeled as a tree structure that reproduced its retrograde activation feature. In addition to a normal geometry, two cardiomyopathies were modeled: dilatation and hypertrophy. A biventricular pacing protocol was tested in the context of atrio-ventricular block. The contribution of the PS was examined by removing it, as well as by increasing endocardial conductivity. Results showed that retrograde conduction into the PS was a determining factor for achieving intraventricular synchrony. Omission of the PS led to an overestimate of the degree of electrical dyssynchrony while assessing CRT. The activation patterns for the three geometries showed local changes in the order of activation of the lateral wall in response to the same pacing strategy. These factors should be carefully considered when determining lead placement and optimizing device parameters in clinical practice.     

3D Microfabricated Scaffolds and Microfluidic Devices for Ocular Surface Replacement: a Review

In recent years, there has been increased research interest in generating corneal substitutes, either for use in the clinic or as in vitro corneal models. The advancement of 3D microfabrication technologies has allowed the reconstruction of the native microarchitecture that controls epithelial cell adhesion, migration and differentiation. In addition, such technology has allowed the inclusion of a dynamic fluid flow that better mimics the physiology of the native cornea. We review the latest innovative products in development in this field, from 3D microfabricated hydrogels to microfluidic devices.