Development of a totally implantable ventricular assist device system with improved antithrombogenicity and portability

我们一直在开发一种超紧凑、低噪音的便携式气动VAD驱动器，以提供更好的移动性和更低的噪音环境，提高患者的生活质量。该驱动器采用电液执行器而不是空气压缩机。油压通过液压/气动转换腔，产生气压，驱动气动血泵。这些技术实现了超紧凑的尺寸（35 x 30 x 45厘米），重量轻（13公斤）和低噪音（39分贝）。此外，驾驶员使用软轮轴对颠簸的地面进行安全携带，并由聚氨酯车身表面保护，防止坠落。与传统的控制台式驱动器相比，该驱动器的功耗仅为十分之一（45瓦），并且可以使用两个内部可充电镍金属氢化物电池运行2小时。该驱动器提供填空驱动模式，泵输出持续估计报警。耐久性已在超过15,000小时的台架试验中得到证实。在体外测试与丰田气动VAD显示足够的泵性能高达7升/分钟。在6只成年山羊的左心室辅助模型中进行了超过3个月的体内评估，没有任何失败。我们得出结论，该驱动器为长期气动VAD支持的患者提供了更好的生活质量。电液心室辅助装置（EHVAD）系统已经开发出来。利用EHTAH的左血泵和电液执行器开发了EHVAD系统，该系统包装有体积补偿室。系统重量为1160g。最大流量为8.8 L/min，最大效率为14.2%。该系统被植入3头小至61公斤的小牛体内。其中一只活了90天。估计心输出量为4l /min。这些结果表明，EHVAD系统具有完全植入式系统的潜力。经皮能量传递系统（TETS）、经皮光学遥测系统（TOTS）和内部电池已被开发。采用电液全人工心脏（EHTAH）系统进行动物实验，对系统性能进行了评价。系统在正常工作时由TET驱动，输入功率约为21 W。系统也每天由内部电池驱动，按照规定的协议。在放电40分钟的情况下，内部电池充满3小时。TET的直流到直流传输效率保持在85%左右。驱动参数通过皮肤传输，TOTS为9600 bps。为了实现电液人工心脏系统的最佳驱动，提出了一种新的泵隔膜位置监测方法。泵单元包括聚氨酯制造的隔膜式血泵和能量转换器，其往复并将液压硅油输送到备用血泵。两个直径为2.4 mm的超声晶体固定在泵壳两侧的最大行程轴上，长度为50mm。超声波通过血腔、隔膜和油腔传播。超声波的传播时间因隔膜位置不同而不同，因为血液的传播速度为1540 m/s，硅油的传播速度为908 m/s。溢流型模拟循环试验中，通过观测和驱动油压波形估计膜片位置，传播时间与膜片位置成正比。在全弹射和全填充状态下，传输时间最大值为0.054 ms，最小值为0.033 ms。心输出量与繁殖时间变化与心率乘积在1 ~ 9l /min范围内呈线性相关。相关系数r=0.97。这些结果表明，在没有流量计的情况下，通过传播时间来检测隔膜位置，通过传播时间的变化来计算心输出量。我们还开发了可植入人工器官解剖拟合研究的计算机模拟系统。利用人体CT扫描图像重建胸腔三维图像。移除心室后，植入泵单元并与计算机模型上的心房和血管连接，以确定合适的设计和装配。对于植入VAD或TAH系统的患者来说，口袋感染是一个严重的主要问题。为了降低这类感染的风险，一种合理的方法是在器械外表面涂上与组织相容的柔软材料，这种材料可以减轻器械的机械振动和刚性器械与周围组织之间的应力。我们开发了一种新的多孔装置涂层材料，赋予了良好的组织相容性。该材料由具有三维网状结构的分段聚氨酯组成，具有类似组织的柔韧性和足够的机械强度。试验材料被装入硅胶管，并植入成年山羊的皮下组织。植入1年后，浸润组织未见炎症或坏死灶，表明有足够的组织长入材料，形成紧密的相互连接。该材料可作为一种较理想的植入式人工心脏外表面涂层材料。少

We have been developing an ultra-compact and low-noise portable pneumatic VAD driver in order to improve patient s quality of life in terms of providing better mobility and lower noise environment. The driver utilizes an electtohydraulic actuator instead of an air compressor. Oil pressure through a hydraulic/neumatic converting chamber, generate air pressures which drive a pneumatic blood pump. These technologies realized an ultra-compact size (35 x 30 x 45 cm), a light weigh (13 kg) and low-noise (39 dB). Furthermore, the driver is carried in safety using soft wheels axis against a bumpy ground and is protected by the urethane body surface against fall-down. This driver can be actuated with only one-tenth power consumption (45 w) in comparison with conventional console type driver and can be run for 2 hours with two internal rechargeable nickel metal-hydride batteries. This driver provide fill to empty driving mode, and pump output is continuing estimated for alarm. The durability has … More been confirmed in a bench test of over 15,000 hours. In vitro testing with Toyobo pneumatic VAD demonstrated a sufficient pump performance of up to 7 L/min. In vivo evaluation for over 3 months was also carried out in a left ventricular assist model using 6 adult goats without any failure. We conclude that this driver provide better quality of life to the patients with long-term pneumatic VAD support.Electrohydraulic ventricrlar assist device(EHVAD) systems have been developed. The EHVAD system is developed by using the left blood pump and electrohydraulic actuator of EHTAH, which was packaged with a volume compensation chamber. The system weight was 1160g. The maximum flow rate was 8.8 L/min and the maximum efficiency was 14.2 %.The system was implanted in 3 calves as small as 61 kg. One of these lived for 90 days. The estimated cardiac output was 4 L/min. These results indicate that EHVAD system has the potential to be a totally implantable system.A Transcutaneous energy transfersystem(TETS), a transcutaneous optical telemetry system(TOTS), and an internal battery have been developed. The system performance was evaluated in animal experiments using Electrohydraulic total artificial heart(EHTAH) system. The system was driven by the TET during normal operation of approximately 21 W input power. The system was also driven by the internal battery everyday, as per prescribed protocol. In the case of 40 minutes of discharge, the internal battery was fully charged for 3 hours. The DC to DC transmission efficiency of the TET was maintained at nearly 85 %. Driving parameters were transmitted through the skin with the TOTS at 9600 bps.We have developed a new monitoring method of the pump diaphragm positions for optimal driving of an electrohydraulic artificial heart system. The pump unit comprises polyurethane-made diaphragm-type blood pumps and an energy converter that reciprocates and delivers hydraulic silicone oil to the alternate blood pumps. Two ultrasound crystals of 2.4 mm diameter are fixed to both sides of the pump housing on a maximum stroke axis with 50 mm length. The ultrasound propagates through the blood chamber, the diaphragm, and the oil chamber. Propagation time of the ultrasound varies according to the diaphragm position because propagation speed of blood 1540 m/s is different from that of silicone oil 908 m/s. The propagation time varied in proportion to the diaphragm position estimated from observation and driving oil pressure wave forms in an overflow type mock circulation test. The propagation time reached to the maximum value of 0.054 ms and the minimum value of 0.033 ms at full-eject and full-fill states, respectively. Linear correlation was observed between the cardiac output and product of the change of propagation time multiplied by heart rate in the range of 1 to 9 L/min. The correlation coefficient was r=0.97. These results indicate that the diaphragm position is detected by the propagation time and the cardiac output is computed by the change of propagation time without a flowmeter.We also have developed computer simulation system for anatomical fitting study of the implantable artificial organ. A three-dimensional image of the chest cavity was reconstructed from human CT scan images. After removing the ventricles, the pump unit was implanted and connected to atriums and blood vessels on the computer model to decide a suitable design and fitting.Pocket infection is a serious major problem for the patients with an implantable VAD or TAH system. For reducing the risk of this type of infection, it is a reasonable approach to coat the device outer surface with tissue-compatible soft material that can alleviate mechanical vibration of the device and stress between the rigid device and the surrounding tissue. We developed a novel porous device-coating material that imparts excellent tissue-compatibility. This material, consisting of segmented polyurethane with a 3D reticulated structure, has tissue-like flexibility and sufficient mechanical strength. The test materials were potted in a silicone tube, and implanted into subcutaneous tissue of an adult goat. After 1 year implantation, no inflammatory or necrotic foci were observed in the infiltrated tissue, thus demonstrating sufficient tissue ingrowth into the material to form tight interconnections. In conclusion, the newly developed material may be a suitable outer surface coating material for implantable artificial heart. Less