Gohean Jeffrey R, Larson Erik R, Hsi Brian H, Kurusz Mark, Smalling Richard W, Longoria Raul G
From the *Windmill Cardiovascular Systems, Austin, Texas; †Division of Cardiovascular Medicine, University of Texas Medical School at Houston and The Memorial Hermann Heart and Vascular Institute, Houston, Texas; and ‡Department of Mechanical Engineering, University of Texas at Austin, Austin, Texas.
ASAIO J. 2017 Mar/Apr;63(2):198-206. doi: 10.1097/MAT.0000000000000460.
This article provides an overview of the design challenges associated with scaling the low-shear pulsatile TORVAD ventricular assist device (VAD) for treating pediatric heart failure. A cardiovascular system model was used to determine that a 15 ml stroke volume device with a maximum flow rate of 4 L/min can provide full support to pediatric patients with body surface areas between 0.6 and 1.5 m. Low-shear stress in the blood is preserved as the device is scaled down and remains at least two orders of magnitude less than continuous flow VADs. A new magnetic linkage coupling the rotor and piston has been optimized using a finite element model (FEM) resulting in increased heat transfer to the blood while reducing the overall size of TORVAD. Motor FEM has also been used to reduce motor size and improve motor efficiency and heat transfer. FEM analysis predicts no more than 1°C temperature rise on any blood or tissue contacting surface of the device. The iterative computational approach established provides a methodology for developing a TORVAD platform technology with various device sizes for supporting the circulation of infants to adults.
本文概述了扩大低剪切搏动性TORVAD心室辅助装置（VAD）规模以治疗小儿心力衰竭所面临的设计挑战。使用心血管系统模型确定，一个冲程容积为15毫升、最大流速为4升/分钟的装置可为体表面积在0.6至1.5平方米之间的小儿患者提供全面支持。随着装置尺寸缩小，血液中的低剪切应力得以保留，并且比连续流VAD至少低两个数量级。一种连接转子和活塞的新型磁链已通过有限元模型（FEM）进行了优化，从而在减小TORVAD整体尺寸的同时增加了向血液的热传递。电机有限元模型也被用于减小电机尺寸、提高电机效率和热传递。有限元分析预测，该装置任何与血液或组织接触的表面温度升高不超过1摄氏度。所建立的迭代计算方法为开发具有各种装置尺寸的TORVAD平台技术提供了一种方法，该技术可支持从婴儿到成人的血液循环。
