Development of New Circulatory Assist Device-Split-Circulation Assits Device

分流循环辅助装置（SCAD）通过降主动脉闭塞将体循环分为两部分;上部由主动脉内球囊反搏（IABP）辅助的心脏维持，下部由经皮心肺支持（PCPS）维持。1)SCAD通过从上循环中排除PCPS的可变“旁路流速”，使心脏性能的评估更容易。2)SCAD可增强IABP的作用。3)SCAD在上循环中设置与下循环中不同的动脉压，例如，通过在肾功能不全患者中保持最小可能的主动脉压，同时保持最大可能的肾动脉压。为动物实验制作的SCAD导管有一个12-cc的抽吸球囊和两个4-cc的闭塞球囊，它们交替膨胀，从而防止Adamkiewicz动脉的持续缺血。导管管身在球囊节段（7 Fr）处更小，而另一节段更大（8 Fr），以防止球囊节段在包裹球囊时体积过大。设计了两个球囊的控制器，通过设定两个球囊充气重叠时的重叠期（OP），实现了循环的连续分流。OP和从一次充气到下一次充气的相位分别设定在1.5至7.5秒和20至60秒的范围内。即使OP设置为1.5秒，200 mmHg的充气压力也可确保平均血压为100 mmHg时的连续分流循环。SCAD导管和控制器在5只犬中进行了测试。球囊反搏和持续分流循环均获成功。经2 ~ 3小时的抽吸后，在球囊抽吸和闭塞的部位未观察到明显的损伤。

The split-circulation assist device (SCAD) divides the systemic circulation in two by descending aortic occlusion ; the upper part is maintained by the heart assisted by intraaortic balloon pumping (IABP), and the lower is by percutaneous cardiopulmonary support (PCPS). 1) SCAD made easier the assessment of cardiac performance by excluding the variable 'bypass flow rate' of PCPS from the upper circulation. 2) SCAD increased the IABP effects. 3) SCAD set different arterial pressure in the upper circulation from that in the lower one, for example, by maintaining a minimum possible aortic pressure while keeping the maximum possible renal artery pressure in patients with renal dysfunction. A SCAD catheter made for animal experiment had a 12-cc pumping balloon and two 4-cc occlusion balloons, which were inflated alternately, thereby preventing the continuous ischemia to Adamkiewicz arteries. The catheter shaft was mad smaller at the balloon segment (7 Fr) whereas the other segment was 1arger (8 Fr) in order to prevent the balloon segment from being bulky when the balloons were wrapped. This structure also maintained high performance of IABP.A con troller for the two balloons was developed and programmed to split the circulation continuously by setting an overlap period (OP) when the inflation of both balloons were overlapped. The OP and the phase from one inflation to the next were set at ranges of 1.5 to 7.5 and 20 to 60 sec, respectively. An inflation pressure of 200 mmHg ensured the continuous split-circulation against mean blood pressure of 100 mmHg even when the OP was set at 1.5 sec. The SCAD catheter and the controller were tested in five dogs. The balloon pumping and the continuous split-circulation were successful in all the cases. After 2 to 3 hr pumping, no obvious injury was observed at the sites of balloon pumping an occlusion.