Development of Bionic Baroreflex System for Treatment of Orthostatic Hypotension due to Shy-Drager Syndrome

背景：我们开发了一种用于治疗barreflex failure的仿生技术，并测试了其在barreflex failure大鼠平头倾斜（HUT）时动脉压恢复的效果。方法与结果：仿生压力反射系统（BBS）是一个由计算机控制的负反馈系统，是人工血管舒缩中枢。它通过放置在主动脉弓上的微压计来感知全身动脉压（SAP），并自动计算脉冲序列的频率，以刺激交感传出神经。我们选择腹腔神经节作为BBS的交感血管运动界面，因为由内脏大神经支配的腹腔血管床是动脉压反射控制的主要效应机制。为了使该系统具有仿生性，我们将人工血管收缩中心（H_<BRP→STM>）的操作规则主动匹配到天然血管收缩中心的操作规则。首先，我们确定了SAP的原生压力反射控制（H_< native >）和SAP对腹腔神经节电刺激的响应（H_<STM→SAP>）的开环传递函数。从H_<Native>/H_<STM→SAP>计算出H_<BRP→STM>，并将运算规则移植到计算机中。在10只压力反射衰竭的大鼠中，我们评估了在HUT诱导的快速降压过程中BBS的表现。突然的直立倾斜使SAP在2秒内下降了34±6 mmHg，在10秒内下降了52±5 mmHg。另一方面，在实时执行BBS时，HUT后SAP在2秒内下降了21±5 mmHg，在10秒内下降了15±6 mmHg。这些由BBS控制的动脉反应与由天然气压反射控制的动脉反应难以区分。结论：我们得出的结论是，BBS恢复了barreflex功能衰竭大鼠的天然barreflex功能。

Background : We developed a bionic technology for the treatment of baroreflex failure, and tested its efficacy in restoration of arterial pressure against head-up tilt (HUT) in rats with baroreflex failure.Methods and Results : The bionic baroreflex system (BBS) was a negative feedback system controlled by a computer, the artificial vasomotor center. It sensed systemic arterial pressure (SAP) through a micromanometer placed in the aortic arch and automatically computed the frequency of a pulse train to stimulate sympathetic efferent nerves. We selected the celiac ganglion as the sympathetic vasomotor interface for the BBS, because the abdominal vascular bed innervated by the greater splanchnic nerve is a major effector mechanism for the baroreflex control of arterial pressure. To make this system to be BIONIC, the operational rule of the artificial vasomotor center (H_<BRP→STM>) was actively matched to that of the native center. First, we identified the open-loop transfer functions of the native baroreflex control of SAP (H_<Native>) and the response of SAP to electrical stimulation of the celiac ganglion (H_<STM→SAP>). We computed H_<BRP→STM> from H_<Native>/H_<STM→SAP>, and transplanted the operational rule into the computer. In 10 rats with baroreflex failure, we evaluated the performance of the BBS during rapid hypotension induced by HUT. Abrupt head-up tilting dropped SAP by 34±6 mmHg in 2 sec, and by 52±5 mmHg in 10 sec. During real-time execution of the BBS, on the other hand, the fall in SAP was 21±5 mmHg at 2 sec, and 15±6 mmHg at 10 sec after HUT. These arterial responses controlled by the BBS were indistinguishable from those by the native baroreflex.Conclusions : We concluded that the BBS revitalized the native baroreflex function in rats with baroreflex failure.