Stevens Michael C, Wilson Stephen, Bradley Andrew, Fraser John, Timms Daniel
Innovative Cardiovascular Engineering and Technology Laboratory, The Prince Charles Hospital, Brisbane, Queensland, Australia; Critical Care Research Group, The Prince Charles Hospital and University of Queensland, Brisbane, Queensland, Australia; School of Information Technology and Electrical Engineering, University of Queensland, Brisbane, Queensland, Australia.
Artif Organs. 2014 Sep;38(9):766-74. doi: 10.1111/aor.12303. Epub 2014 Apr 21.
Dual rotary left ventricular assist devices (LVADs) can provide biventricular mechanical support during heart failure. Coordination of left and right pump speeds is critical not only to avoid ventricular suction and to match cardiac output with demand, but also to ensure balanced systemic and pulmonary circulatory volumes. Physiological control systems for dual LVADs must meet these objectives across a variety of clinical scenarios by automatically adjusting left and right pump speeds to avoid catastrophic physiological consequences. In this study we evaluate a novel master/slave physiological control system for dual LVADs. The master controller is a Starling-like controller, which sets flow rate as a function of end-diastolic ventricular pressure (EDP). The slave controller then maintains a linear relationship between right and left EDPs. Both left/right and right/left master/slave combinations were evaluated by subjecting them to four clinical scenarios (rest, postural change, Valsalva maneuver, and exercise) simulated in a mock circulation loop. The controller's performance was compared to constant-rotational-speed control and two other dual LVAD control systems: dual constant inlet pressure and dual Frank-Starling control. The results showed that the master/slave physiological control system produced fewer suction events than constant-speed control (6 vs. 62 over a 7-min period). Left/right master/slave control had lower risk of pulmonary congestion than the other control systems, as indicated by lower maximum EDPs (15.1 vs. 25.2-28.4 mm Hg). During exercise, master/slave control increased total flow from 5.2 to 10.1 L/min, primarily due to an increase of left and right pump speed. Use of the left pump as the master resulted in fewer suction events and lower EDPs than when the right pump was master. Based on these results, master/slave control using the left pump as the master automatically adjusts pump speed to avoid suction and increases pump flow during exercise without causing pulmonary venous congestion.
双旋转式左心室辅助装置（LVAD）可在心力衰竭期间提供双心室机械支持。左右泵速的协调不仅对于避免心室抽吸以及使心输出量与需求相匹配至关重要，而且对于确保体循环和肺循环血量平衡也很关键。双LVAD的生理控制系统必须通过自动调节左右泵速以避免灾难性的生理后果，从而在各种临床情况下实现这些目标。在本研究中，我们评估了一种用于双LVAD的新型主/从生理控制系统。主控制器是一种类似斯塔林定律的控制器，它将流速设置为舒张末期心室压力（EDP）的函数。然后，从控制器维持左右EDP之间的线性关系。通过在模拟循环回路中模拟四种临床情况（静息、体位改变、瓦尔萨尔瓦动作和运动），对左右和右左主/从组合进行了评估。将该控制器的性能与恒速控制以及其他两种双LVAD控制系统进行了比较：双恒定入口压力控制和双弗兰克-斯塔林控制。结果表明，主/从生理控制系统产生的抽吸事件比恒速控制少（在7分钟内分别为6次和62次）。左/右主/从控制比其他控制系统发生肺充血的风险更低，最大EDP更低（分别为15.1 mmHg和25.2 - 28.4 mmHg）。在运动期间，主/从控制使总流量从5.2 L/min增加到10.1 L/min，这主要是由于左右泵速的增加。与以右泵为主时相比，以左泵为主进行主/从控制导致的抽吸事件更少且EDP更低。基于这些结果，以左泵为主的主/从控制可自动调节泵速以避免抽吸，并在运动期间增加泵流量而不会导致肺静脉充血。
