Fukamachi K, Harasaki H, Massiello A L, Chen J F, Kiraly R J
Department of Biomedical Engineering, Cleveland Clinic Foundation, OH 44195, USA.
ASAIO J. 1996 Sep-Oct;42(5):M589-92. doi: 10.1097/00002480-199609000-00056.
Unlike in animal experiments, the pump orientation of a total artificial heart (TAH) can change remarkably in humans with the recipient's posture (upright, supine, or prone), thus affecting its filling characteristics. The left master alternate control mode of the Cleveland Clinic-Nimbus (CC-N) TAH adjusts beat rate by maintaining the left pump at 90% filling, producing a Frank-Starling like preload sensitivity. In order to verify that the CC-N TAH functions properly regardless of the gravity effects on pump filling, the preload sensitivity curves of the CC-N TAH were evaluated on a mock circulatory loop with the simulated supine (right pump up) and prone (left pump up) positions in humans. The right preload sensitivity was slightly higher when the right pump was up versus down, and likewise the left preload sensitivity was higher when the left pump was up versus down. Despite these gravity effects on pump filling, right and left preload sensitivity remained within physiologic range and the automatic control of the CC-N TAH functioned properly without significant postural effects.
与动物实验不同，全人工心脏（TAH）的泵方向在人类患者处于不同姿势（直立、仰卧或俯卧）时会发生显著变化，从而影响其充盈特性。克利夫兰诊所 - 宁布斯（CC - N）TAH的左主交替控制模式通过将左泵维持在90%的充盈状态来调整心率，产生类似Frank - Starling机制的前负荷敏感性。为了验证CC - N TAH在不考虑重力对泵充盈影响的情况下能否正常工作，在模拟人体仰卧（右泵向上）和俯卧（左泵向上）位置的模拟循环回路上评估了CC - N TAH的前负荷敏感性曲线。当右泵向上时，右前负荷敏感性略高于右泵向下时；同样，当左泵向上时，左前负荷敏感性高于左泵向下时。尽管重力对泵充盈有这些影响，但左右前负荷敏感性仍保持在生理范围内，并且CC - N TAH的自动控制功能正常，没有明显的姿势影响。
