Open AccessMore than 8 million people in our country suffer from heart failure. About one million of these people die each year [1]. The problem of ventricular assist device creating - a mechanical device used for partial or complete replacement of heart function - is investigated for a long time (according to [2] just in our country since the 1970s). Today plenty of encouraging results are received. There is a number of VAD models which are successfully applied to patients with heart failure. After implantation, patients conduct a way of life that is normal in many respects: they are in the family, often they have an opportunity to work in their former specialty. Some of them live with the device about 8 years [3].According to [4] for 2010 the estimated total number of long-term devices implanted in the United States per year is over 1,700 (the population of the U.S. is 305 million), compared with over 430 per year in Europe (the population of Europe is 731 million). Unfortunately, people who need a heart transplant are much more.
The principle of VAD is that being connected to the left ventricle with one cannula and to the ascending aorta with the other cannula the pump fully or partially replaces the function of the natural heart. This scheme allows the use of VAD in two ways: as a "bridge to transplantation" when the device is used temporarily until the donor heart is found, and a "bridge to recovery", when through the use of VAD the function of the heart muscle is recovered.
VAD system can be divided into three subsystems: blood pump, power supply system and control system (Fig. 1).
Each subsystem can be the subject of separate study. Special role in the development of VAD plays medical side of the issue. Successful research and development require interaction with qualified professionals in this field. The development of VAD is a multidisciplinary problem which demands fulfilment of a number of requirements.
One of the most active programs in implantation of long-term systems of artificial circulatory support is guided by German Heart Center in Berlin (DHZB) [3].
The well-known VAD commercial models were created by Berlin Heart (Germany), HeartWare Int. (USA), Thoratec (USA), Abiomed Inc. (USA) etc.
Works devoted to VAD systems can be classified in field of research, according to the above subsystems. Concerning the blood pump - a large number of works is devoted to the study of blood behavior in the pump chamber: to modeling questions [6-24], with an emphasis on red blood cells damage - hemolysis [10, 20, 23, 27-32]. Much less works are devoted to the research of rotor (impeller) dynamics of the blood pump [33-36]. Application of magnetic bearings in VAD and magnetic levitation control tasks of are addressed in [33-39]. Biomedical part of design, associated with the selection and development of biocompatible materials is considered in [26, 32, 40-43]. Features of power supply systems and control of VAD mode work are given in works [26, 44-50].
The integrated approach to VAD development with an emphasis on design phases is presented in the works [7, 51]. In [2] the problem of artificial heart creation in Russia on 2006 is clearly reflected. The most comprehensive systematic review of existing VAD systems with description of specifications is given in the work [54], as well as in [24, 26, 55-57]. Brief review of existing methodologies and approaches to the design of artificial heart (AH) and circulatory support system (CSS) are presented in the works [58, 59]. The problem of creation of mechatronic modules of AH and CSS systems is studied in [60, 61].
With the purpose of further research in the development of VAD system, this work is the study of up to date problem state. The main part of the work consists of three sections. The first section is devoted to the study of blood pump. The second and the third sections are devoted to power supply system and control system respectively. Based on this analysis, the requirements to VAD development are generalized, main issues are underlined and new solutions are proposed in conclusion.
Purpose of investigation.The work is devoted to studying the features of VAD design with the purpose of further research on their optimization and improvement.