Shiraishi Y, Sugai T K, Tanaka A, Yoshizawa M, Yambe T, Yamada A, Omran M H, Shiga T, Kitano T, Kamiya K, Mochizuki S, Miura H, Homma D, Yamagishi M
Institute of Development, Aging and Cancer, Tohoku University, Sendai 980-8575, Japan.
Annu Int Conf IEEE Eng Med Biol Soc. 2011;2011:8353-5. doi: 10.1109/IEMBS.2011.6092060.
Total cavopulmonary connection (TCPC) is commonly applied for the surgical treatment of congenital heart disease such as single ventricle in pediatric patients. Patients with no ventricle in pulmonary circulation are treated along with Fontan algorithm, in which the systemic venous return is diverted directly to the pulmonary artery without passing through subpulmonary ventricle. In order to promote the pulmonary circulation after Fontan procedure, we developed a newly designed pulmonary circulatory assist device by using shape memory alloy fibers. We developed a pulmonary circulatory assist device as a non-blood contacting mechanical support system in pediatric patients with TCPC. The device has been designed to be installed like a cuff around the ePTFE TCPC conduit, which can contract from outside. We employed a covalent type functional anisotropic shape memory alloy fiber (Biometal, Toki Corporation, Tokyo Japan) as a servo actuator of the pulmonary circulatory assist device. The diameter of this fiber was 100 microns, and its contractile frequency was 2-3 Hz. Heat generation with electric current contracts these fibers and the conduit. The maximum contraction ratio of this fiber is about 7% in length. In order to extend its contractile ratio, we fabricated and installed mechanical structural units to control the length of fibers. In this study, we examined basic contractile functions of the device in the mock system. As a result, the internal pressure of the conduit increased to 63 mmHg by the mechanical contraction under the condition of 400 msec-current supply in the mock examination with the overflow tank of 10 mmHg loading.
全腔静脉肺动脉连接术（TCPC）常用于小儿先天性心脏病如单心室的外科治疗。肺循环中无心室的患者采用Fontan术式进行治疗，该术式将体循环静脉回流直接引流至肺动脉，而不经过肺下心室。为了促进Fontan术后的肺循环，我们利用形状记忆合金纤维开发了一种新设计的肺循环辅助装置。我们开发了一种肺循环辅助装置，作为TCPC小儿患者的非血接触式机械支持系统。该装置设计为像袖口一样安装在ePTFE TCPC导管周围，可从外部收缩。我们采用共价型功能性各向异性形状记忆合金纤维（Biometal，日本东京Toki公司）作为肺循环辅助装置的伺服致动器。这种纤维的直径为100微米，收缩频率为2 - 3赫兹。电流产生的热量使这些纤维和导管收缩。这种纤维的最大收缩长度比约为7%。为了扩大其收缩率，我们制作并安装了机械结构单元来控制纤维的长度。在本研究中，我们在模拟系统中检测了该装置的基本收缩功能。结果，在10 mmHg负荷的溢流罐模拟试验中，在400毫秒电流供应的条件下，通过机械收缩导管内压力增加到63 mmHg。
