It is with great pleasure that we here present Artificial Heart 4 (proceedings of the 4th international symposium on artificial heart and assist devices). The symposium was held in Tokyo, Japan, on August 7 and 8, 1992 under the patronage of Mr. Hiromitsu Yoshioka, Chairman of the Board of Trustees, Tokyo Women's Medical College. Artificial heart 4 consists of the papers presented in nine sessions: Oral Presentations A to E, Forums 1 to 10, and nine lectures by invited guest speakers from the United States and Europe. In this volume, papers from two new sessions, sessions IV and VII, entitled New Approaches, were prepared for devices and systems developed according to new ideas. Twenty-one papers in these two sessions were presented in five Forums (3, 4, 7, 8, and 9). Session VI was provided to deal with heart transplantation, which is now closely related to both ventricular assist systems (VAS) and the total artificial heart (TAH). In this session, papers by two guest speakers from major heart transplantation centers in Europe were included.

The 5th International Symposium on Artificial Heart and Assist Devices was held in Tokyo on January 26 - 27, 1995, bringing together leading researchers and specialists from all over the world. The proceedings of the symposium presents the newest ideas and approaches in the field, and will be of special interest and relevance to all who are concerned with artificial organs, cardiovascular surgery, organ transplantation, biomaterials, and related disciplines. Reflecting the content of the symposium, the major topics in this volume include biocompatible material development, clinical use of assist devices, completely implantable devices, and heart transplantation. These are presented in the two main divisions of the book: The first consists of eight lectures by leading researchers, world-renowned in the field of the artificial heart. The second comprises more than 50 papers on such subjects as biomaterials, research and development of ventricular assist systems and the total artificial heart, and their use as a bridge to heart transplantation. An additional, special feature of the book is the inclusion of descriptions of exhibitions at the symposium, with photographs of all artificial heart devices and systems displayed by major laboratories and companies from around the world.

The International Symposium on Artificial Heart and Assist Devices has been held three times, first in 1985, then in 1987 and 1990. It is my great pleasure to present Artificial Heart 3 (Proceedings of the 3rd International Symposium on Artificial Heart and Assist Devices). The third symposium was held in Tokyo on February 16 and 17, 1990. Our original intention was to invite all the principal investigators from the major artificial heart research laboratories in the world, in the first three symposia. The numbers of investigators in the fields of the artificial heart, ventricular assist systems, and biomaterials, invited for the symposia, totalled 7 in 1985, 8 in 1987, and 13 in 1990. The program of the third symposium consisted of 41 papers; 13 invited lectures, 8 papers contributed upon request, with 2 from the United States, and 20 regular selected papers including 2 from the United States, ana 1 each from Australia, Germany, and South Korea. During the last three years, the state of clinical application of artificial hearts and assist devices has changed. In the case of pneumatically driven blood pumps, we have now stepped into the age of practical use in patients. Accordingly, in this symposium we gave a special emphasis to topics of clinical application, particularly the use of an artificial heart as a bridge to heart transplantation. Sessions on implantable artificial hearts, biomaterials for the artificial heart, and heart transplantation were also included.

The 6th International Symposium on Artificial Heart and Assist Devices met in Tokyo in July 1996, bringing together researchers and specialists from around the world. The symposiums proceedings in this volume comprise papers from nine sessions, each opening with contributions by leading scientists: TAH, heart transplantation, biomaterials, VAS, clinical application, pathophysiology, engineering, new approaches, and special sessions. Of special note is the inclusion, for the first time, of pathophysiology related to clinical use of assist devices. The clinical application section includes a paper by Dr. Michael DeBakey on the progress made in recent years. With descriptions of the scientific exhibition, accompanied by photographs of all artificial heart devices and systems displayed by major laboratories and manufacturers, Artificial Heart 6 presents the latest information on developments in the field of artificial heart, biomaterials, and heart transplantation.