美国90年代的人工心脏

本文综述了美国人工心脏研究在９０年代的发展趋势，在心室辅助方面着重介绍了ＮｏｖａｃｏｒＨｅａｒｅＭａｔｅ，Ｔｈｏｒａｔｅｘ，ＣａｒｄｉｏＷｅｓｔ等脉动型装置，简要介绍了ＢｉｏｍｅｄｉｃｕｓＳａｒｎｓＳｔ．Ｊｕｄｅ等离心型装置以及Ｈｅｍｏｐｕｍｐ轴流型装置，在全人工心脏方面较详细介绍了Ａｂｉｏｍｅｄ公司，Ｃｌｅｖｅｌａｎｄ中心，Ｐｅｎｎ大学，Ｕｔａｈ大学，Ｂａｙｌｏｒ医学院和Ｂｉｌｗａｕｋｅｅ中心等     

美国90年代的人工心脏

本文综述了美国人工心脏研究在９０年代的发展趋势，在心室辅助方面着重介绍了Ｎｏｖａｃｏｒ、ＨｅａｒｅＭａｔｅ、Ｔｈｏｒａｔｅｘ、ＣａｒｄｉｏＷｅｓｔ等脉动型装置，简要介绍了ＢｉｏｍｅｄｉｃｕｓＳａｒｎｓＳｔ．Ｊｕｄｅ等离心型装置以及Ｈｅｍｏｐｕｍｐ轴流型装置。在全人工心脏方面较详细介绍了Ａｂｉｏｍｅｄ公司、Ｃｌｅｖｅｌａｎｄ中心、Ｐｅｎｎ大学、Ｕｔａｈ大学、Ｂａｙ－ｌｏｒ医学院和Ｂｉｌｗａｕｋｅｅ中心等六个单位对血泵、驱动系统、能源系统以及控制系统的研究特色。对心室辅助和全人工心脏在临床应用现状也作了介绍。     

人工心脏及心室辅助研究的进展

近年来对心脏因重症和病务而部分或完全丧失功能，临床上不能用常规方法进行救治时，通常应用人工制造的装置部分或完全替代病损的心脏以及补偿其生理功能，而心脏辅助循环是应用机械或生物机械手段部分或全部替代心脏的泵机能，维持全身良好的血液循环状况的治疗方法，分为左心室辅助装置（ＬＶＡＤ）右心室辅助装置（ＤＶＡＤ）及双心室辅助装置（ＢＶＡＤ）本文试对人工心脏及心室辅助研究进展，前景及问题作了一综述。     

人工心脏研究进展

人工心脏在近半个世纪的研制过程中，血泵的材质，结构，制作工艺，功能和使用寿命均有显改进，出现了气动，电动，电液压等不同驱动方式，所产生的血流也更接近生理心脏。最新的微型血泵还可植入主动脉内，通过促进局部血流而达到辅助整体循环的效果。人工心脏的控制系统也达到了智能化。迄今已有各种特性和功能的血泵先后研制成功。目前全人工心脏和心室辅助装置均已进入临床应用。既可作为心脏移植的过渡又可用于心衰病人的长期     

人工心脏及心室辅助研究的进展

近年来对心脏因重症和病伤而部分或完全丧失功能，临床上不能用常规方法进行救治时，通常应用人工制造的装置部分或完全替代病损的心脏以补偿其生理功能；而心脏辅助循环是应用机械或生物机械手段部分或全部替代心脏的泵机能，维持全身良好的血液循环状况的治疗方法，分为左心室辅助装置（ＬＶＡＤ）、右心室辅助装置（ＤＶＡＤ）及双心室辅助装置（ＢＶＡＤ）。本文试对人工心脏及心室辅助研究进展、前景及问题作一综述。     

辅助循环的现状

辅助循环是应用机械或生物机械手段部分或全部替代心脏泵功能，以维持良好全身循环状态的治疗方法，目的改善循环功能不全患的循环状态。本介绍了辅助循环的分类、全人工心脏研究状况、心室辅助装置应用现状和辅助循环研究的最新发展。     

人工心脏研究进展

人工心脏在近半个世纪的研制过程中 ,血泵的材质、结构、制作工艺、功能和使用寿命均有显著改进 ,出现了气动、电动、电液压等不同驱动方式 ,所产生的血流也更接近生理心脏。最新的微型血泵还可植入主动脉内 ,通过促进局部血流而达到辅助整体循环的效果。人工心脏的控制系统也达到了智能化。迄今已有各种特性和功能的血泵先后研制成功。目前全人工心脏和心室辅助装置均已进入临床应用。既可作为心脏移植的过渡又可用于心衰病人的长期辅助以便自体心脏恢复功能。大量试验研究证实了人工心脏的安全性和有效性。总之 ,随着人工心脏的功能完善将在临床中产生重要的应用价值。     

临床用叶轮式心室辅助装置的改进与完善

0 引 言 作者研制的叶轮式心室辅助装置,在数年前曾经辅助小公牛血液循环62d[1].     

叶轮全人工心脏的双心室辅助急性动物试验研究

叶轮全人工心脏的双心室辅助急性动物试验研究＊钱坤喜郑铭茹伟民（江苏理工大学生物医学工程研究所，镇江２１２０１３）ＡＣＵＴＥＢＩＶＥＮＴＲＩＣＵＬＡＲＡＳＳＩＳＴＩＮＰＩＧＳＷＩＴＨＩＭＰＥＬＬＥＲＴＯＴＡＬＨＥＡＲＴＱｉａｎＫｕｎｘｉ，ＺｈｅｎｇＭｉ...     

辅助循环的现状

辅助循环是应用机械或生物机械手段部分或全部替代心脏泵机能，以维持良好全身循环状态的治疗方法，目的改善循环功能不全患者的循环状态。本文介绍了辅助循环的分类、全人工心脏研究状况、心室辅助装置应用现状和辅助循环研究的最新发展。     

叶轮泵式全人工心脏的结构设计及流体力学特性

目的通过模型样机研制和流体力学特性测试．探索以叶轮式血泵为结构基础的新型可完全植入的全人工心脏。方法全人工心脏模型样机分为左心泵和右心泵2个基本单位。2血泵均采用叶轮泵．共同设置在球形外壳中。2半球形外壳由高分子材料经激光快速成型制成．球形腔内设置固定左右心泵后对合为球形外壳．表面由医用聚氨酯橡胶涂层，直径55mm，总质量150g左右。在体外模拟循环台上对左心泵和右心泵的流体力学特性进行测试．主要观测指标为泵的转速、输出压力、流量、能耗和效率。模拟循环装置由模拟左右心房、血泵、阻力调节器、流量计串联组成，采用30％甘油水溶液作为循环介质。通过调节阻力测定特定泵转速下压力和流量。结果体外模拟测试表明全人工心脏模型样机可满足血液动力学基本要求，左心泵在9000-13000r／min转速条件下可以达到5-7L／min流量和13．3kPa（100mmHg）的压力输出，右心泵在约1／2左心泵转速和4．00kPa（30mmHg）后负荷下达到相似流量．可分别满足体、肺循环的要求。在该工作负荷条件下，2血泵的总效率约为14％。结论轴流泵作为人工心脏的血泵单位．流体力学特性可达到全人工心脏的基本要求．     

心力衰竭的辅助循环装置治疗的新进展

心力衰竭是世界范围内导致心血管患者死亡的主要原因之一,心脏移植是目前治疗终末期心力衰竭有效的方法,但因供体严重不足等原因,这种疗法的应用受到限制。近几年包括主动脉球囊反搏,心室辅助装置和全人工心脏在内的机械辅助循环支持(mechanical circulatory support,MCS)装置得到迅速发展。现对MCS的分类、近年发展情况,目前存在的问题及未来发展趋势等进行综述。     

Cardiac rehabilitation and artificial heart devices

Recently, cardiac rehabilitation has gained popularity in Japan because beneficial effects on patients’ prognosis have been reported. Another reason is that cardiac rehabilitation has been covered by health insurance since 1988 in Japan. Currently, cardiac rehabilitation is covered for the diseases of angina pectoris, acute myocardial infarction, chronic heart failure (CHF), peripheral arterial disease, and diseases of the aorta and after open-heart surgery. Left ventricular assist devices (LVADs) are sometimes used in patients with progressive CHF symptoms to provide circulatory support, because in most of these patients heart failure does not improve with application of medical therapy, intra-aortic balloon pumping, or a percutaneous cardiopulmonary system. Modern VAD control systems are compact, allowing patients to carry them around without difficulty. Since patient management at the outpatient clinic has become possible, patients are able to expand the scope of their activities. Early active rehabilitation in patients implanted with a LVAD improves their condition, favorably impacts the clinical course while they await heart transplantation, and also improves posttransplant recovery. Exercise therapy is one of the important components in comprehensive cardiac rehabilitation. Exercise therapy is important to improve the quality of life of patients with LVADs. Appropriate exercise therapy is effective for patients with various cardiac conditions who undergo diverse treatments and is practiced actively by many patients. In order to facilitate cardiac rehabilitation safely and effectively for patients with serious conditions, education for health care professionals is essential. In this review, we describe the concept of rehabilitation followed by cardiac rehabilitation for patients with heart failure, patients after open-heart surgery, and patients with implanted LVADs.     

Characteristics of cavitation intensity in a mechanical heart valve using a pulsatile device: synchronized analysis between visual images and pressure signals

To investigate the characteristics of cavitation intensity, we performed a synchronized analysis of the visual images of cavitation and the pressure signals using a pulsatile device. The pulsatile device employed was a pneumatic ventricular assist device (PVAD) that is currently being developed by our group. A 23-mm Medtronic Hall valve (M-H valve) and a 23-mm Sorin Bicarbon bileaflet valve (S-B valve) were mounted in the inlet port of the PVAD after the sewing ring had been removed. A function generator provided a square signal, which was used as the trigger signal, via Electrocardiogram R wave (ECG-R) mode, of the control - drive console for circulatory support. The square signal was also used, after a suitable delay, to synchronize operation of a pressure sensor and a high-speed video camera. The data were stored using a digital oscilloscope at a 1-MHz sampling rate, and then the pressure signal was band-pass filtered between 35 and 200 kHz using a digital filter. The valve-closing velocity, visual cavitation time, and root mean square (RMS) pressure of the M-H valve were greater than those of the S-B valve. Both the visual cavitation time and RMS pressure represent the cavitation intensity, and this is a very important factor when estimating mechanical heart valve cavitation intensity in an artificial heart.     

Surgical Treatment for Severe Heart Failure: Recent Progress in Treatment Strategy and its Present Status in Japan

Chronic intractable heart failure that is unresponsive to maximum medical therapy can have a wide variety of causes; these include advanced valvular diseases and severe myocardial ischemia, ischemic cardiomyopathy (ICM) in heart failure following extensive myocardial infarction, chronic heart failure due to dilated cardiomyopathy (DCM) in which the myocardium itself is progressively damaged or the acute aggravation of the latter. Heart transplantation has long been considered the only useful treatment for patients with heart failure due to ICM- and DCM-induced severe left ventricular hypofunction. However, because of the extremely limited number of heart transplant donors, other surgical treatments have also been attempted. In this communication, we provide an overview of the current situation with regard to left ventriculoplasty and heart transplantations, as well as of the treatment of severe heart failure using ventricular assist devices, which have recently shown remarkable progress.     

Fuzzy logic automatic control of the Phoenix-7 total artificial heart

Automatic physiological control of the pneumatic Phoenix-7 total artificial heart (TAH) occupies a pivotal position for clinical application of the device. We developed a fuzzy logic automatic control algorithm for the Phoenix-7. The object of the automatic control system is to regulate the cardiac output at a level desirable for the given preload. The system uses cardiac output-type fuzzy pressure control combined with expert knowledge, most of which is of the form If condition, then action. As a demonstration of the utility of the control algorithm, the effects of inlet air pressures, aortic pressure, pulmonary artery pressure, and heart rate on the cardiac output were analyzed. In addition, an in vitro experiment was carried out that verified good performance of the control algorithm. This fuzzy logic control algorithm possesses the potential for totally automatic operation, eliminating any need for manual intervention under variable hemodynamic conditions.     

Identification algorithm for systemic arterial parameters with application to total artificial heart control

A new algorithm for estimating systemic arterial parameters from systolic pressure and flow measurements at the root of the aorta is developed and tested through a systems identification approach. The resulting procedure has direct application to a total artificial heart (TAH) control system currently under development. Identification models, representing the systemic arterial system, are developed from existing work in the area of cardiovascular modeling. The resistive and compliance components of these models are physically significant, representing overall hydraulic properties of the systemic arterial system. A unique method of parameterizing the identification models is designed which operates on the basis of aortic pressure and flow measurements taken exclusively during systole. The estimator is a modified recursive least squares algorithm which utilizes covariance modification to track time-varying parameters and a dead-zone to improve the robustness. Performance of the estimation algorithm was tested on data generated by a higher-order distributed model of the systemic arterial bed using normal canine parameters. Results from model-to-model experiments verify the consistency of the estimates and the ability of the estimator to converge quickly and track dynamically varying parameters.     

Estimation of mechanical heart valve cavitation in a pneumatic ventricular assist device

In this study, we investigated the possibility of estimating the mechanical heart valve (MHV) cavitation intensity using the slope of the driving pressure (DP) just before valve closure in a pneumatic ventricular assist device. We installed a 23-mm Medtronic Hall valve at the inlet of our pneumatic ventricular assist device (VAD). Tests were conducted under physiologic pressures at heart rates ranging from 60 to 90 beats/min and cardiac outputs ranging from 4.5 to 6.7 l/min. The valve-closing velocity was measured with a CCD laster displacement sensor, and the images of MHV cavitation were recorded using a high-speed video camera. The cavitation cycle time (equal to the observed duration of the cavitation bubbles) was used as the MHV cavitation intensity. The valve-closing velocity increased as the heart rate increased. Most of the cavitation bubbles were observed near the valve stop, and the cavitation intensity increased as the heart rate increased. The slope of the DP at 20 ms before valve closure was used as an index of the cavitation intensity. There were differences in the slope of the DP between low and high heart rates, but the slope of the DP had a tendency to linearly increase with increasing valve-closing velocity.     

A nonpulsatile total artificial heart with 1/R control

A total artificial heart (TAH) using continuous flow pumps is promising for size reduction of the device; however, the role of pulsatility in TAHs has been a subject of great debate. Additionally, it is unclear whether, in a nonpulsatile TAH, a physiological control method such as 1/R control can keep the experimental animal in good condition. To realize a nonpulsatile TAH with 1/R control, the artificial valves were removed from undulation pump total artificial hearts (UPTAHs), which can produce both pulsatile and nonpulsatile flows using a single device. The UPTAHs were implanted into 18 goats, and 4 goats survived for more than 1 month. Three weeks of long-term nonpulsatile TAH operation could be tested in the goat that survived for 72 days, and it was proved that 1/R control is possible not only with a pulsatile TAH but also with a nonpulsatile TAH. The general condition of the goat and its organ function did not change on the application of nonpulsatile mode. Cardiac output and arterial pressure changed with the condition of the goat in pulsatile and also in nonpulsatile modes, and the changes seemed almost identical. However, the sucking effect of the atria was very significant in nonpulsatile mode, resulting in hemolysis. Therefore, nonpulsatile TAHs under 1/R control are considered to be inadequate unless some pulsatility can be introduced to avoid fatal sucking effects and to ensure sufficient inflow. During nonpulsatile operation, regular fluctuations were sometimes found in the aortic pressure, and these were caused by the periodic sucking effect in the left atrium that was possibly influenced by respiratory changes.