Improvement of a shape memory alloy fibered aortic pulsation device

Aim: We have been developing a new aortic blood flow support device using shape memory alloy (SMA) fibers as an actuator. The special features of the device were as follows: a) totally implantable design, b) small and foldable structure with actuators. The system could represent similar function of the aortomyoplasty and the extra aortic balloon pump at the ascending or descending installation. The purpose of this study was to improve the device as a non-blood contacting pulsation system, aiming at the application for the physiologically effective assistance in the artery. Material & Methods: We have designed the prototype by using covalent-type Ni-Ti SMA fibers which is capable of contracting around the aorta circumferentially. In this study, we developed a new structural design with oblique fiber orientations. The device consisted of rubber silicone wall plates, serially connected for radial contraction by the SMA fibers. We reduced the diameter of the contraction by the device. Then we tested the new structural design in the mock system, and examined its functional changes to optimize the mechanical structural design with SMA fibers. We demonstrated the radial deformation effect by using 150 micron Ni-Ti SMA fibers in a multiple circumferential oblique patterns. The orientation and length of the fibers were evaluated by the changes in oblique angles against the longitudinal axis. The fibers were secured circumferentially by using a pair of plastic grooved chambers, where the changes and contractile function was examined for each fiber Result: We could sandwich the aortic tubing of which the diameter was smaller than 30mm, under the constant pressure condition of the aortic tubing at 100mmHg Conclusion: we successfully achieved the improvement of the contraction effects of the SMA fibered device for aortic compression for smaller diameter vessels by the circumferential alignment by oblique angle of fibers.