Smallest ventricular assist system by use of Peltier elements with shape memory alloy

Further discussion may be necessary concerning the driving mechanisms of the totally implantable ventricular assist system (VAS). If consideration is given to the actuator with the shape memory alloys (SMAs), the system is simple enough for implantation. A simple system is, of course, desirable for the artificial heart, if durability, economy, reliability, and the implant are considered. When the actuator with the SMAs is considered, the problem of rate of reaction becomes important. With the SMAs, the reaction time is too slow for driving an artificial heart. One of the reasons for this slow reaction is the amount of time it takes to refrigerate. Heating can be done rapidly if the electric current is large enough, but because the process of refrigeration is slow, the function cycle becomes slow. The Peltier element was applied for the refrigeration process in this study. By application of the Peltier element, epoch-making improvement of the refrigeration speed is anticipated. An improvement in the rate of refrigeration will mean an improvement in the rate of reaction. An actuator driving frequency of around 1 Hz was possible with this design concept. This speed couldn't be anticipated in the previous reports of SMA. These results showed the possibility of application of the Peltier elements for use with the artificial heart system. We are now developing the artificial myocardium by using the SMA and Peltier elements. There are still problems with this system; however, it may be possible that this simple system may become the smallest VAS in future use.