The moving-actuator type total artificial heart (human model)

In a human type electromechanical total artificial heart (TAH) developed in Seoul National University Hospital, we verified that it was very acceptable for the human implantation through several cases of successful animal experiment. Our system can be characterized by the moving-actuator type electromechanical pump, which consists of a high energy efficiency brushless DC motor inside the moving actuator, and two polyurethane blood sacs. The entire TAH system has the internal controller based on the microprocessor, the transcutaneous energy transmission (TET) system as an energy source of the motor, and the transcutaneous information transmission (TIT) system. The newly developed TAH has structural advantages of small size (600-650cc, total volume), and light weight (approximately 900 grams). At the current stage towards long-term successful implantation, the practical problems that can face the animal experiment were minimized by improving our system from the following three points. First of all, we implemented the change in the shape of blood pump housing for the solution of the anatomical problem through the Angio-Spiral CT image analysis of a human chest structure, and consequently the anatomical fitting failure was almost overcome by the development of a new model for human implantation. Secondly, for enhanced blood compatibility, the polyurethane (PU) surface was modified by immobilizing Lumbrokinase on it, employed as a major material of the TAH. Actually, it improved the thromboresistance of the commercial PU. Thirdly, the regulation mechanism of cardiac output (CO) was improved by analyzing the measured pressure of the interventricular volume space (IVP) and the motor current. It was very effective to obtain the CO regulation in response to the physiological demand as well as the prevention of atrial collapse due to the suction. As the indicators of an accurate estimation of the hemodynamic, the IVP was used to predict the preload condition, and the motor current to represent the afterload variations. The TET system has been developed to transport energy into the implantable total artificial heart by means of a skin tunnel transformer. The total efficiency is in the range of 75-78% for 30-50 watts of delivered mean power. The alternative to drive the TAH through the skin is to transmit energy across intact skin via magnetic fields. In addition, it permits simultaneous transfer of electric data through the skin, by means of a bidrectional data link for a 9600 baud rate, half duplex, RS- 232C protocol with an error rate of less than 10^-5 per character. In conclusion, it is strongly believed that the application of the newly developed implantable electromechanical artificial heart to the long-term human implantation is very promising.