TOWARD COMMERCIALIZATION OF TOTALLY IMPLANTABLE, ULTRACOMPACT TOTAL ARTIFICIAL HEART AND VENTRICULAR ASSIST SYSTEMS

本课题研制了超紧凑型、完全植入式全人工心脏（TAH）和心室辅助系统（搏动型和非搏动型），并在体外和体内对它们的性能进行了评价。TAH为一体式设计，在左右推板式血泵之间安装了紧凑型机电致动器。血泵的冲程长度和冲程容积为12 mm和55 cc。VAD采用与TAH相同的部件设计，用背板覆盖TAH右侧。TAH的尺寸为90 mm直径、70 mm厚度、400 cc体积和450 g重量，而VAD的尺寸为90 mm、56 mm、275 cc和460 g。VAD和TAH比目前临床上可用的系统小得多。(As对于装置的性能，TAH和VAD都产生8L/min的最大流量。VAD的功率要求范围为5 - 8 W，以在泵后负荷100 mm时产生4 - 8 L/min的流量 ...更多信息 Hg.另一方面，TAH需要大约10至15瓦特来产生4至8 L/min的流量，左后负荷和右后负荷分别为100和25 mmHg。VAD的最大电液转换效率为23%，而TAH为13.5%。作为完全植入式系统的配套部件，还设计并组装了顺应性腔和可充电电池。VAD的顺应性室排量为75 cc，TAH为55 cc。采用聚氨酯浸涂法制作顺应性室的柔性膜片，对其中1头VAD和6头TAH的小牛进行了VAD和TAH的解剖拟合和存活研究。至于VAD，血液从左心室心尖部排出，并通过VAD返回降主动脉。顺应性腔被植入胸腔，驱动线在皮肤下穿隧到体外并连接到驱动器。由于在手术过程中出现了心室颤动，动物只能存活24小时。然而，整个植入过程已经成功完成。关于TAH，在前2头小牛中进行了解剖学拟合研究，随后在其余4头小牛中植入了TAH。行心肺转流术切除自体心脏，然后植入TAH。在最后一头小牛#0107中，所有手术均成功完成，使用TAH获得30小时存活。动物拔管后自行站立。由于左泵流量减少，该动物在术后30小时被处死。需要改进左右流量平衡程序，以更好地控制左心房和右心房压力以及左泵流量。我们将继续进行TAH的体内评价，重点是耐久性和生物相容性方面，以开发临床上可用的完全植入式TAH系统。除了搏动系统，我们还设计和评价了单枢轴轴承支撑的离心血泵。通过泵的性能、溶血试验和两个月的耐久性试验，评价其作为左心室辅助装置的可行性。为了对植入人工心脏系统的患者进行监测，我们开发了一种反射式光学传感器，用于监测人工心脏内血液的血红蛋白含量和氧饱和度。虽然在体外已经显示出优异的结果，但必须进行动物评价以评价其在体内的长期性能。少

In this project, ultracompact, totally implantable total artificial heart (TAH) and ventricular assist system, pulsatile and nonpulsatile, have been developed and their performances were evaluated in vitro and in vivo using calves. The TAH is a one-piece design sandwiching a compact electromechanical actuator between the left and right pusher-plate type blood pumps. The stroke length and stroke volume of the blood pump are 12mm and 55cc. The VAD was designed using the same components as those of TAH by covering the TAH's right side with a back-plate. The dimensions of the TAH are 90mm diameter, 70mm thickness, 400cc volume and 450g weight, while those of the VAD are 90mm, 56mm, 275cc and 460g. The VAD and TAH are much smaller than the currently clinically available systems. (As for performance of the devices, both TAH and VAD generated the maximum flow of 8L/min. The power requirement for VAD ranged from 5 to 8 watts to generate the flow of 4 to 8 L/min against the pump afterload 100mm … More Hg. On the other hand, the TAH required approximately 10 to 15 watts to generate the flowof 4 to 8 L/min against the left and right afterload of 100 and 25mmHg, respectively. The maximum electrical to hydraulic conversion efficiency was 23% for VAD, while for TAH 13.5%. As the associated components for totally implantable system, compliance chamber and rechargeable batteries were also designed and assembled. The displaced volume of the compliance chamber for VAD is 75cc, while for TAH 55cc. The flexing diaphragm of the compliance chamber was made of polyurethane through dip-coating technique.The anatomical fitting and survival studies with VAD and TAH were performed in one calf for VAD and a total of 6 calves for TAH. As for VAD, the blood was drained from the left ventricular apex and returned to the descending aorta through the VAD. The compliance chamber was implanted in the thoracic cavity and drive line was tunneled underneath the skin to outside the body and connected to the driver. Because of the ventricular fibrillation developed during the surgery, the animal could survive only 24 hours. However, entire implantation procedure has been worked out successfully. Concerning TAH, in the first two calves anatomical fitting study was carried out, followed with TAH implantation in the remaining 4 calves. The heart-lung bypass was performed to excise the native heart, followed with implantation of the TAH. In the last calf # 0107, all the procedure successfully worked out to obtain 30 hour survival with the TAH. The animal was extubated and stood up on his own. The animal was sacrificed 30 hour postoperatively due to reduced left pump flow. Left-right flow balance procedure needs to be improved to better control left and right atrial pressure together with left pump flow. We will continue with in vivo evaluation of the TAH, focusing on durability and biocompatibility aspects, to develop clinically usable totally implantable TAH system.In addition to pulsatile systems, we also designed and evaluated a single pivot bearing supported centrifugal blood pump. Pump performance, hemolysis test as well as two month durability studies were carried out to evaluate its feasibility as a left ventricular assist device. We will move onto animal study in the next phase.In order to monitor the patients implanted with artificial heart systems, a reflectance type optical sensor was developed to monitor hemoglobin content and oxygen saturation of the blood inside the artificial heart. Although excellent results have been shown in vitro, animal evaluation must be conducted to evaluate its long term performance in vivo. Less