Kawahito K, Benkowski R, Otsubo S, Rosenbaum B, Moreland R, Noon G P, Nosé Y, Debakey M E
Baylor College of Medicine, Department of Surgery, Houston, TX 77030, USA.
ASAIO J. 1996 Sep-Oct;42(5):M754-7. doi: 10.1097/00002480-199609000-00090.
The authors investigated the antithombogenicity of the NASA/DeBakey axial flow ventricular assist device in an ex vivo calf model. The device is 3 inches in length and 1 inch in largest diameter. The pump weighs 53 g and displaces 15 ml. The unit consists of three major components: a flow straightener, a spinning inducer/impeller, and a diffuser. The impeller has rod shaped permanent magnets embedded within the six blades and is activated magnetically by a motor stator that is positioned outside the flow tube. Previous 2 day screening tests demonstrated an antithrombogenic configuration in short-term implantation. Based on the results of these 2 day screening tests, five pumps with the best configuration were implanted into a calf for 2 weeks for anti thrombogenicity confirmation. Pumps were implanted paracorporeally, and heparin was used to maintain activated clotting time to approximately 250 sec. Each pump was changed every 2 weeks as planned. During the experiment, all pumps demonstrated stable pumping. The required electric power was 7 to 8 watts and pump flow was maintained at 4 L/min. The calf was in excellent condition. Liver and renal function were maintained, plasma free hemoglobin was kept at less than 4 mg/dl (3.3 +/- 0.3 mg/dl), and lactate dehydrogenase was 1043 +/- 36 units/L. In this experimental series, all five pumps passed the 2 week implantation. Two week ex vivo test results indicated very slight thrombus in the hub areas of some pumps. For the next phase of the implantation study, minor design optimization is necessary to completely eliminate thrombus formation. According to our step by step approach, the in vivo test aiming for long-term implantation is ongoing.
作者在离体小牛模型中研究了美国国家航空航天局/德巴基轴流心室辅助装置的抗血栓形成特性。该装置长3英寸，最大直径1英寸。泵重53克，排量为15毫升。该装置由三个主要部件组成：一个整流器、一个旋转诱导轮/叶轮和一个扩散器。叶轮的六个叶片内嵌入了棒状永久磁铁，并由位于流管外部的电动定子通过磁力激活。之前的两天筛选测试表明，短期植入时该装置具有抗血栓形成的结构。基于这两天筛选测试的结果，将五个结构最佳的泵植入一头小牛体内两周，以确认其抗血栓形成能力。泵通过体外旁置方式植入，使用肝素将活化凝血时间维持在约250秒。每个泵按计划每两周更换一次。在实验过程中，所有泵的泵送均保持稳定。所需电力为7至8瓦，泵流量维持在4升/分钟。小牛状况良好。肝功能和肾功能维持正常，血浆游离血红蛋白保持在低于4毫克/分升（3.3±0.3毫克/分升），乳酸脱氢酶为1043±36单位/升。在这个实验系列中，所有五个泵都通过了两周的植入测试。两周的体外测试结果表明，一些泵的轮毂区域有非常轻微的血栓形成。对于植入研究的下一阶段，需要进行微小的设计优化以完全消除血栓形成。根据我们的逐步方法，旨在进行长期植入的体内测试正在进行中。
