Lo Casey, Gregory Shaun, Stevens Michael, Murphy Deirdre, Marasco Silvana
Sir Charles James Officer Brown Department of Cardiothoracic Surgery, The Alfred Hospital, Prahran, Victoria, Australia.
Innovative Cardiovascular Engineering and Technology Laboratory, Critical Care Research Group, The Prince Charles Hospital, Brisbane, Queensland, Australia.
Artif Organs. 2015 Dec;39(12):1055-61. doi: 10.1111/aor.12497. Epub 2015 May 21.
Implantable left ventricular assist devices (LVADs) have been adapted clinically for right-sided mechanical circulatory support (RVAD). Previous studies on RVAD support have established the benefits of outflow cannula restriction and rotational speed reduction, and recent literature has focused on assessing either the degree of outflow cannula restriction required to simulate left-sided afterload, or the limitation of RVAD rotational speeds. Anecdotally, the utility of outflow cannula restriction has been questioned, with suggestion that banding may be unnecessary and may be replaced simply by varying the outflow conduit length. Furthermore, many patients have a high pulmonary vascular resistance (PVR) at the time of ventricular assist device (VAD) insertion that reduces with pulmonary vascular bed remodeling. It is therefore important to assess the potential changes in flow through an RVAD as PVR changes. In this in vitro study, we observed the use of dual HeartWare HVAD devices (HeartWare Inc., Framingham, MA, USA) in biventricular support (BiVAD) configuration. We assessed the pumps' ability to maintain hemodynamic stability with and without banding; and with varying outflow cannulae length (20, 40, and 60 cm). Increased length of the outflow conduit was found to produce significantly increased afterload to the device, but this was not found to be necessary to maintain the device within the manufacturer's recommended operational parameters under a simulated normal physiological setting of mild and severe right ventricular (RV) failure. We hypothesize that 40 cm of outflow conduit, laid down along the diaphragm and then up over the RV to reach the pulmonary trunk, will generate sufficient resistance to maintain normal pump function.
可植入式左心室辅助装置（LVAD）已在临床上用于右侧机械循环支持（RVAD）。先前关于RVAD支持的研究已证实了流出道插管限制和转速降低的益处，最近的文献则专注于评估模拟左侧后负荷所需的流出道插管限制程度，或RVAD转速的限制。据传闻，流出道插管限制的效用受到质疑，有人认为束带可能不必要，可简单地通过改变流出管道长度来替代。此外，许多患者在植入心室辅助装置（VAD）时肺血管阻力（PVR）较高，随着肺血管床重塑，PVR会降低。因此，评估随着PVR变化通过RVAD的血流潜在变化很重要。在这项体外研究中，我们观察了双HeartWare HVAD装置（美国马萨诸塞州弗雷明汉市HeartWare公司）在双心室支持（BiVAD）配置中的使用。我们评估了泵在有和没有束带的情况下，以及在不同流出道插管长度（20、40和60厘米）时维持血流动力学稳定性的能力。发现流出管道长度增加会使装置的后负荷显著增加，但发现在模拟轻度和重度右心室（RV）衰竭的正常生理环境下，将装置维持在制造商推荐的操作参数范围内，这并非必要。我们假设，沿着膈肌铺设然后向上越过右心室到达肺动脉干的40厘米流出管道，将产生足够的阻力以维持正常的泵功能。
