Piskin Senol, Ündar Akif, Pekkan Kerem
Department of Mechanical Engineering, Koc University, Istanbul, Turkey.
Pediatric Cardiovascular Research Center, Department of Pediatrics, Surgery and Bioengineering, Penn State Hershey College of Medicine, Hershey, PA, USA.
Artif Organs. 2015 Oct;39(10):E164-75. doi: 10.1111/aor.12468. Epub 2015 May 1.
Cardiopulmonary bypass (CPB) procedure is employed to repair most congenital heart defects (CHD). Cannulation is a critical component of this procedure where the location and diameter of cannula controls the hemodynamic performance. State-of-the-art computational studies of neonatal CPB employed an isolated aortic arch region by truncating the three-dimensional (3D) patient-specific cerebral system. The present work expanded these studies where the 3D patient-specific MRI reconstruction of the cerebral system, including the Circle of Willis (CoW), is integrated with a hypoplastic neonatal aortic arch. The inlet of the arterial cannula is assigned a steady velocity boundary condition of the CPB pump, while all outlets are modeled as resistance boundary conditions, thus allowing acute comparisons between different cannula configurations. Three-dimensional (3D) flow simulations in the aortic arch model are performed at a Reynolds number of 2150 using an experimentally validated commercial solver. Results demonstrate that the inclusion of 3D CoW is essential to predict the accurate head-neck blood perfusion and therefore critical in deciding the neonatal aortic cannulation strategy preoperatively. Using this integrated model two CPB configurations are studied, where the cannulas were placed at innominate artery (IA) (IA-cannula configuration) and ductus arteriosus (DA) (DA-cannula configuration). Configuration change produced significant differences in flow splits and local hemodynamics of blood flow throughout the whole aortic arch, neck and cerebral arteries. Percent flow rate differences between the IA- and DA-cannula configurations are computed to be: 19%, for descending aorta, 198% for ascending aorta (perfusing coronary arteries), 91% for right anterior cerebral artery, and 68% for left anterior cerebral artery. Another important finding is the retrograde flow at vertebral arteries for IA-cannula configuration, but not for DA-cannula. These results may help to translate better neonatal arterial cannulae design for minimizing cerebral complications during CPB procedures.
体外循环（CPB）手术用于修复大多数先天性心脏病（CHD）。插管是该手术的关键组成部分，插管的位置和直径控制着血流动力学表现。新生儿CPB的最新计算研究通过截断三维（3D）患者特异性脑系统采用了孤立的主动脉弓区域。本研究扩展了这些研究，将包括 Willis 环（CoW）在内的脑系统的3D患者特异性MRI重建与发育不全的新生儿主动脉弓相结合。动脉插管的入口被指定为CPB泵的稳定速度边界条件，而所有出口被建模为阻力边界条件，从而可以对不同的插管配置进行急性比较。使用经过实验验证的商业求解器在Reynolds数为2150的情况下对主动脉弓模型进行三维（3D）血流模拟。结果表明，纳入3D CoW对于预测准确的头颈部血流灌注至关重要，因此在术前决定新生儿主动脉插管策略时至关重要。使用该集成模型研究了两种CPB配置，其中插管分别置于无名动脉（IA）（IA插管配置）和动脉导管（DA）（DA插管配置）。配置变化在整个主动脉弓、颈部和脑动脉的血流分流和局部血流动力学方面产生了显著差异。IA和DA插管配置之间的流量百分比差异计算如下：降主动脉为19%，升主动脉（灌注冠状动脉）为198%，右大脑前动脉为91%，左大脑前动脉为68%。另一个重要发现是IA插管配置的椎动脉有逆流，而DA插管配置则没有。这些结果可能有助于更好地设计新生儿动脉插管，以尽量减少CPB手术期间的脑部并发症。
