Osypka Anna, Meissner Florian, Ozturk Deniz, Windisch Roxane, Vestner Heiko, Costa Galbas Michelle, Czerny Martin, Bothe Wolfgang
Department of Cardiovascular Surgery, Medical Center-University of Freiburg, Faculty of Medicine, University of Freiburg, Hugstetterstr. 55, 79106 Freiburg, Germany.
Department of Medical Simulations, Medividia, Herent, Belgium.
Interdiscip Cardiovasc Thorac Surg. 2025 Mar 5;40(3). doi: 10.1093/icvts/ivaf031.
Implantation of left ventricular assist devices conventionally requires a sternotomy and cardiopulmonary bypass. An experimental accessory was designed to redirect the device's outflow graft through the left ventricle into the ascending aorta. This design allows for implantation via left thoracotomy only but resulted in significant pressure loss both in vitro and in vivo. We evaluated the reasons for the pressure loss of the experimental accessory by quantifying pressure distribution and flow profiles using computational fluid dynamics simulation tools.
A computational fluid dynamics model based on the accessory's geometry was used to simulate nominal blood flow through the model. Quantities of interest included pressure and flow velocity. Pressure differences between the pump inlet and outlet were calculated at different rotational speeds (4000, 5200, 6400 rpm) and pump flow rates (1, 5, 8.4 L/min). Results were compared with simulations of a generic left ventricular assist device to determine the accessory's impact.
Natural pump characteristics were observed, as increased rotational speed caused an increase in pressure head with a constant flow rate. For all cases, a greater decrease in pressure head was seen between 5 and 8.4 L/min than between 1 and 5 L/min. Curvature intensity and channel bifurcation in the outflow were the main contributors to downstream pressure loss.
The next iteration of the left ventricular assist device accessory should focus on minimizing curvatures and avoiding bifurcations in the outflow. Further development may allow for less invasive left ventricular assist device implantation with negligible alterations in pump performance.
传统上，植入左心室辅助装置需要进行胸骨切开术并使用体外循环。设计了一种实验性附件，用于将该装置的流出移植物通过左心室重新引导至升主动脉。这种设计仅允许通过左胸廓切开术进行植入，但在体外和体内均导致了显著的压力损失。我们使用计算流体动力学模拟工具对压力分布和血流剖面进行量化，以评估实验性附件压力损失的原因。
基于该附件几何结构的计算流体动力学模型用于模拟通过该模型的正常血流。感兴趣的量包括压力和流速。在不同转速（4000、5200、6400转/分钟）和泵流速（1、5、8.4升/分钟）下计算泵入口和出口之间的压力差。将结果与通用左心室辅助装置的模拟结果进行比较，以确定该附件的影响。
观察到了自然的泵特性，即转速增加会导致在恒定流速下压力头增加。对于所有情况，在流速从5升/分钟增加到8.4升/分钟时，压力头的下降幅度大于从1升/分钟增加到5升/分钟时。流出道中的曲率强度和通道分叉是下游压力损失的主要原因。
左心室辅助装置附件的下一次迭代应着重于使曲率最小化并避免流出道中的分叉。进一步的研发可能会实现侵入性较小的左心室辅助装置植入，同时泵性能的改变可忽略不计。
