Development of the next generation implantable pneumatic ventricular assist device for permanent use.

这项工作的目的是开发下一代植入式气动心室辅助装置（P-VAD）永久使用。研制了一种用于植入式P-VAD的隔膜式血泵。进、出口安装角度的大小影响着血泵的流动行为和血栓的形成。采用粒子图像测速（PIV）可视化方法研究了进出口阀口方向（ODIV， ODOV，其中膜片-壳体连接处方向（DHJ）定义为0度）的影响。采用单片式机械阀（美敦力霍尔阀，ρ23mm）。观察到的流速分布在进出口根部之间相对较低，在90°ODIV处最低（0.05m/s）。另一方面，在135°ODIV时，该区域的流速分布最高，为1.9m/s。此外，在135°ODOV时，靠近DHJ边缘区域的流速相对较高，在45°ODOV时相对较低。在脉动周期的任何时刻，135度ODOV（0.05m/s-0.65m/s）时进气道近端流速始终高于45度ODOV（0.05m/s-0.22m/s）时的流速。血泵内部的流动行为受到ODIV和ODOV的显著影响，表现为流动停滞和血栓形成。随着阀门的开启和关闭而产生的空化会导致阀门表面的侵蚀和血液的溶血。研究了瓣膜定位角对双小管机械心脏瓣膜空化的影响。采用A23mm Edwards MIRA双小环阀，在倾斜水平面上旋转0 ~ 90度。利用CCD激光位移传感器测量阀的关闭运动。利用高速摄像机记录MHV空化气泡的图像。接触延迟时间范围为0.88+/-0.41 ~ 0.50+/-0.27ms， 0°和30°的阀瓣取向角比45°、60°和90°的阀瓣取向角的阀瓣接触延迟时间更长。空化气泡主要由第一次阀门关闭、阀门回弹和第二次阀门关闭引起，并沿小叶尖端集中。左侧小叶的空化泡仅在45度、60度和90度的方向角上由第一次阀门关闭引起。第一次阀门关闭45度、60度和90度处产生的空化气泡观察时间长于阀门回弹产生的空化气泡观察时间。MHV空化发生的机制不同于阀门关闭运动。研究发现，气门方向影响两叶的非同步闭合运动和气蚀机理。对于植入式VAD患者来说，传动系统感染是一个严重的主要问题。开发了一种连接经皮传动系统外表面与皮下组织的新型经皮系统。该系统主要由多孔分段聚氨酯组成，具有三维网状结构，具有组织样柔韧性和足够的机械强度。研究了将硅胶管植入成年山羊皮下组织的试验材料及其组织相容性。植入30天后，颗粒组织浸润到试管中。浸润组织包括成熟结缔组织，不包括试管内的炎症或坏死灶。新开发的材料有足够的能力连接经皮传动系统和皮下组织在目标治疗与植入式VAD。研制了一种用于心室辅助装置的紧凑型可穿戴气动驱动装置。驱动单元由无刷直流电动机、曲轴、气缸活塞、非圆齿轮和气压调节阀组成。驱动气压由气缸活塞产生。非圆齿轮产生收缩比，空气压力调节阀限制最大和最小压力。驱动单元的重量约为1.8公斤。在溢流型模拟循环中，当负荷为120mmHg时，收缩率为44%的驱动单元使用70mL冲程容积的血泵，以100bpm的速度实现7L/min以上的泵输出。随着转速和后负荷的变化，平均电耗在8.6 ~ 17.7W之间。慢性动物试验选用2头体重分别为62kg和74kg的荷斯坦犊牛，驱动装置收缩率分别为45%和53%，于第30天和第39天无故障终止。在第一次动物实验中，平均主动脉压、旁路流量和电力消耗分别维持在90+/-13mm Hg、3.9+/-0.9L/min和12+/-1W。在第二次动物实验中，这些值保持在88+/-13mmHg， 5.0+/-0.5L/min和16+/-2W。这些结果表明，新开发的驱动单元具有成为可穿戴驱动单元的潜力。少

The purpose of this work is to develop a next generation implantable pneumatic ventricular asist device(P-VAD) for permanent use. A diaphragm type blood pump for the implantable P-VAD has been developed. The mount angle of the inlet and outlet value affects the flow bahavior the blood pump and thrombus formation. The effect of the orifice direction of the inlet and outlet valve(ODIV, ODOV ; where direction toward the diaphragm-housing junction(DHJ) was defined as 0 degrees) was investigated by means of particle image velocimetry(PIV) visualization method. Monoleaflet mechanical valves(Medtronic-Hall Valve, (ρ23mm) was used. The observed flow velocity distribution was relatively low in the area between the inlet and outlet port roots, it was lowest(0.05m/s) at the 90 degrees ODIV. On the other hand, the flow velocity distribution in this area was highest(1.9m/s) at 135 degrees ODIV. Furthermore, the flow velocity of marginal area near the DHJ was relatively high at 135 degrees ODOV, and … More relatively low at 45 degree ODOV. The flow velocity in the proximal to the inlet port at 135 degrees ODOV(0.05m/s-0.65m/s) was always higher then that at 45 degrees ODOV(0.05m/s-0.22m/s) at any time of the beat cycle.The flow behavior inside the blood pump is significantly affected by the ODIV and ODOV, in terms of flow stagnation and thrombus formation.The cavitation which was generated with opening and closing of a valve causes erosion of the valve surface and hemolyzed blood. The effect of the valve orientation angle on a bileaflet mechanical heart valve(MHV) cavitations was investigated. A23mm Edwards MIRA bileaflet valve was used and the valve was rotated from o to 90 degrees on an inclined horizontal plane. The valve-closing motion was measured by means of a CCD laser displacement sensor. Images of MHV cavitation bubbles were recorded using a high-speed video camera. The contact delay time ranged from 0.88+/-0.41 to 0.50+/-0.27ms, and the time for the valve orientation angles of 0 and 30 degrees was longer than of the angle of 45, 60 and 90 degrees. The cavitation bubbles were caused by the first valve closure, valve rebound and the second valve closure, and were concentrated along the tip of the leaflet. The cavitation bubbles of the left side leaflet were caused by the first valve closure only at orientation angles of 45, 60, 90 degrees. The observation time of the cavitation bubbles caused by the first valve closure at 45, 60 and 90 degrees was longer that that of the bubbles caused by the valve rebound. The mechanism for the occurrence of MHV xcavitation differs from the valve closure motion. Valve orientation was found to affect the asynchronous closure motion of the two leaflet and the cavitation mechanism.Driveline infection is a serious major problem for the patients with an implantable VAD system. The novel percutaneous system to connect between an outer surface of percutaneous driveline and subcutaneous tissue was developed. This system mainly consists of porous segmented polyurethane with the three-dimensional reticulated structure which has tissue-like flexibility and sufficient mechanical strength. The test materials which inserted into the silicone tube implanted into subcutaneous tissue of an adult goat and tissue-compatibility of this material was investigated. The granulated tissue infiltrated into the test tube after 30 days implantation. Infiltrated tissue included the mature connective tissue, and did not include inflammatory or necrotic foci in the test tubes. The newly developed material has a sufficient ability to connect the percutanelus driveline and subcutaneous tissue in destination therapy with implantable VAD.A compact wearable pneumatic drive unit for ventricular assist device was developed. The drive unit consists of a brushless DC motor, a crankshaft, a cylinder piston, noncircular gears and air pressure regulation valves. Driving air pressure is generated by the cylinder piston. The noncircular gears generate the systolic ratio and the air pressure regulation valves limit the maximum and minimum pressure. The weight of the drive unit is approximately 1.8kg. The drive unit of 44% systolic ratio using a blood pump of 70mL stroke volume achieved more than 7L/min of pump output at 100bpm against after-load of 120mmHg in an overflow type mock circulation. The average electric power consumption varied from 8.6 to 17.7W with the beating rate and the after-load. The chronic animal tests using 2 Holstein calves weighing 62kg and 74kg with the drive units of 45 and 53% systolic ratio terminated on 30 and 39days without any malfunction. In the first animal test, the mean aortic pressures, bypass flows and electric power consumptions were maintained at 90+/-13mm Hg, 3.9+/-0.9L/min and 12+/-1W, respectively. In the second animal test, those values were maintained at 88+/-13mmHg, 5.0+/-0.5L/min and 16+/-2W. These results indicate that the newly developed drive unit has a potential to become a wearable drive unit. Less