Artificial Anal Sphincter using Shape Memory Alloys

本项目取得了以下成果：1)在项目第一财年，我们建立了仔猪结肠造口动物实验方案，在造口下植入人工括约肌原型，并在设备的基本功能：闭合和打开功能方面进行了短期动物实验。2)项目第二年致力于经皮能量传输系统和防过热设备的开发，实现设备的完全植入。使用这些设备进行为期4周的动物实验。实验动物（仔猪）的健康状况得到确认。人工括约肌在开放状态下激活时，几乎每次都能观察到正常的排空。3)对人工括约肌的尺寸和形状进行了优化设计。将改进的原型植入动物体内，通过将压力传感器插入封闭的肠道中来监测内部压力。结果表明，在50 ~ 60mmHg的闭塞压力范围内，该装置具有足够的闭合功能，无缺血损伤。4)由于在材料和尺寸上对过热保护和隔热进行了精心设计，即使人工括约肌加热打开时间超过10分钟，也能将其与周围组织接触的表面温度控制在低于活组织允许的最高温度40℃。咬合压力和表面温度是评估该装置的两个最重要的标准。该项目成功解决了这两个问题，将有助于该设备在不久的将来实现商业化。

Following results and achievements have been attained in this project.1)In the first fiscal year of the project, we established the protocol of animal experiments for colostomy with piglets, implanted prototypes of the artificial sphincters under the stomas, and were successful in short-term animal experiments in the respects of basic functions : the closing and opening functions of the device.2)The second year of the project was devoted to the development of a transcutaneous energy transmission system and overheating prevention equipment in order to realize a complete implantation of the device. Animal experiments with periods of up to 4 weeks were carried out using these equipments. The healthy situation of the animal (piglet) in these experiments was confirmed. Moreover, ordinary evacuation was observed almost each time when the artificial sphincter was activated in open.3)The optimum design about the dimension and shape of the artificial sphincter was conducted. With the improved prototypes implanted into animals, the monitoring of the inner pressure was carried out with a pressure sensor inserted in the closed intestine. It was found that with the occlusion pressure ranging from 50 to 60mmHg, the device had sufficient closing function without any damage of ischemia.4)As a result of the careful design of the overheating protection and thermal insulation in materials and dimension, even when artificial sphincter was heated to open for a period longer than 10 min., it was able to control the temperature of its surface in contact with surrounding tissues to be lower than the maximum allowed temperature of living tissue,40℃.The occlusion pressure and surface temperature of the device are two most important criterions in the assessment of the device. The success in solving these two problems in this project will facilitate the commercialization of the device in near future.