Understanding the haemodynamic environment of the pulmonary bifurcation is important in adults with repaired conotruncal congenital heart disease. In these patients, dysfunction of the pulmonary valve and narrowing of the branch pulmonary arteries are common and can have serious clinical consequences. The aim of this study was to numerically investigate the underlying blood flow characteristics in the pulmonary trunk under a range of simplified conditions. For that, an in-depth analysis was conducted in idealised two-dimensional geometries that facilitate parametric investigation of healthy and abnormal conditions. Subtle variations in morphology influenced the haemodynamic environment and wall shear stress distribution. The pressure in the left pulmonary artery was generally higher than that in the right and main arteries, but was markedly reduced in the presence of a local stenosis. Different downstream pressure conditions altered the branch flow ratio, from 50:50% to more realistic 60:40% ratios in the right and left pulmonary artery, respectively. Despite some simplifications, this study highlights some previously undocumented aspects of the flow in bifurcating geometries, by clarifying the role of the stagnation point location on wall shear stress and differential branch pressures. In addition, measurements of the mean pressure ratios in the pulmonary bifurcation are discussed in the context of a new haemodynamic index which could potentially contribute to the assessment of left pulmonary artery stenosis in tetralogy of Fallot patients. Further studies are required to confirm the results in patient-specific models with personalised physiological flow conditions.

了解肺分叉的血流动力学环境对于患有先天性先天性心脏病修复的成人很重要。在这些患者中，肺动脉瓣功能障碍和肺动脉分支变窄很常见，可能会导致严重的临床后果。本研究的目的是在一系列简化条件下对肺干中潜在的血流特征进行数值研究。为此，在理想化的二维几何结构中进行了深入分析，以促进对健康和异常条件的参数研究。形态的细微变化影响了血液动力学环境和壁剪切应力分布。左肺动脉压力普遍高于右主动脉，但在局部狭窄的情况下显着减少。不同的下游压力条件改变了分支流量比，分别从右肺动脉和左肺动脉的 50:50% 变为更现实的 60:40%。尽管进行了一些简化，但本研究通过阐明停滞点位置对壁面剪应力和不同分支压力的作用，突出了分叉几何中流动的一些以前未记录的方面。此外，在新的血液动力学指数的背景下讨论了肺分叉平均压力比的测量，该指数可能有助于评估法洛四联症患者的左肺动脉狭窄。需要进一步研究以确认具有个性化生理流动条件的患者特定模型的结果。