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首页> 外文期刊>Artificial Organs >In Vitro and In Vivo Characterization of Three Different Modes of Pump Operation When Using a Left Ventricular Assist Device as a Right Ventricular Assist Device
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In Vitro and In Vivo Characterization of Three Different Modes of Pump Operation When Using a Left Ventricular Assist Device as a Right Ventricular Assist Device

机译：使用左心室辅助设备作为右心室辅助设备时，三种不同模式的泵操作的体外和体内表征

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Dual rotary left ventricular assist devices (LVADs) have been used clinically to support patients with biventricular failure. However, due to the lower vascular resistance in the pulmonary circulation compared with its systemic counterpart, excessively high pulmonary flow rates are expected if the right ventricular assist device (RVAD) is operated at its design LVAD speed. Three possible approaches are available to match the LVAD to the pulmonary circulation: operating the RVAD at a lower speed than the LVAD (mode 1), operating both pumps at their design speeds (mode 2) while relying on the cardiovascular system to adapt, and operating both pumps at their design speeds while restricting the diameter of the RVAD outflow graft (mode 3). In this study, each mode was characterized using in vitro and in vivo models of biventricular heart failure supported with two VentrAssist LVADs. The effect of each mode on arterial and atrial pressures and flow rates for low, medium, and high vascular resistances and three different contractility levels were evaluated. The amount of speed/diameter adjustment required to accommodate elevated pulmonary vascular resistance (PVR) during support with mode 3 was then investigated. Mode 1 required relatively low systemic vascular resistance to achieve arterial pressures less than 100mmHg in vitro, resulting in flow rates greater than 6L/min. Mode 2 resulted in left atrial pressures above 25mmHg, unless left heart contractility was near-normal. In vitro, mode 3 resulted in expected arterial pressures and flow rates with an RVAD outflow diameter of 6.5mm. In contrast, all modes were achievable in vivo, primarily due to higher RVAD outflow graft resistance (more than 500dyns/cm(5)), caused by longer cannula. Flow rates could be maintained during instances of elevated PVR by increasing the RVAD speed or expanding the outflow graft diameter using an externally applied variable graft occlusion device. In conclusion, suitable hemodynamics could be produced by either restricting or not restricting the right outflow graft diameter; however, the latter required an operation of the RVAD at lower than design speed. Adjustments in outflow restriction and/or RVAD speed are recommended to accommodate varying PVR.
机译：临床上已使用双旋转左心室辅助设备（LVAD）来支持双心衰竭患者。但是，由于与全身性相比，肺循环中的血管阻力较低，因此，如果右心室辅助装置（RVAD）以其设计LVAD速度操作，则肺流速过高。有三种可能的方法可以使LVAD与肺循环相匹配：以比LVAD更低的速度操作RVAD（模式1），以设计速度操作两个泵（模式2），同时依赖于心血管系统来适应;以及在限制RVAD流出移植物直径（模式3）的同时，以设计速度运行两个泵。在这项研究中，每种模式的特征是使用两个VentrAssist LVAD支持的双室心力衰竭的体外和体内模型。评估了每种模式对低，中和高血管阻力以及三种不同收缩水平的动脉和心房压力以及流速的影响。然后研究了在模式3的支持过程中适应肺血管阻力（PVR）升高所需的速度/直径调节量。模式1需要相对较低的全身血管阻力才能在体外实现小于100mmHg的动脉压，从而导致流速大于6L / min。模式2导致左心房压力超过25mmHg，除非左心收缩力接近正常。在体外，模式3导致预期的动脉压和流速，RVAD流出直径为6.5mm。相比之下，所有模式在体内都是可以实现的，这主要是由于较长的插管导致更高的RVAD流出移植物阻力（大于500dyns / cm（5））。在PVR升高的情况下，可以通过使用外部应用的可变移植物阻塞装置提高RVAD速度或扩大流出移植物直径来维持流速。总之，可以通过限制或不限制正确的流出移植物直径来产生合适的血液动力学。但是，后者要求RVAD的运行速度低于设计速度。建议调整流出限制和/或RVAD速度以适应变化的PVR。

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