School of Chemistry, Chemical Engineering and Biotechnology, Nanyang Technological University, Singapore, Singapore.
Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore.
Sci Rep. 2023 Aug 23;13(1):13760. doi: 10.1038/s41598-023-40323-1.
The visceral hybrid procedure combining retrograde visceral bypass grafting and completion endovascular stent grafting is a feasible alternative to conventional open surgical or wholly endovascular repairs of thoracoabdominal aneurysms (TAAA). However, the wide variability in visceral hybrid configurations means that a priori prediction of surgical outcome based on haemodynamic flow profiles such as velocity pattern and wall shear stress post repair remain challenging. We sought to appraise the clinical relevance of computational fluid dynamics (CFD) analyses in the setting of visceral hybrid TAAA repairs. Two patients, one with a type III and the other with a type V TAAA, underwent successful elective and emergency visceral hybrid repairs, respectively. Flow patterns and haemodynamic parameters were analysed using reconstructed pre- and post-operative CT scans. Both type III and type V TAAAs showed highly disturbed flow patterns with varying helicity values preoperatively within their respective aneurysms. Low time-averaged wall shear stress (TAWSS) and high endothelial cell action potential (ECAP) and relative residence time (RRT) associated with thrombogenic susceptibility was observed in the posterior aspect of both TAAAs preoperatively. Despite differing bypass configurations in the elective and emergency repairs, both treatment options appear to improve haemodynamic performance compared to preoperative study. However, we observed reduced TAWSS in the right iliac artery (portending a theoretical risk of future graft and possibly limb thrombosis), after the elective type III visceral hybrid repair, but not the emergency type V repair. We surmise that this difference may be attributed to the higher neo-bifurcation of the aortic stent graft in the type III as compared to the type V repair. Our results demonstrate that CFD can be used in complicated visceral hybrid repair to yield potentially actionable predictive insights with implications on surveillance and enhanced post-operative management, even in patients with complicated geometrical bypass configurations.
内脏杂交手术结合逆行内脏旁路移植和完成腔内支架移植是治疗胸腹主动脉瘤（TAAA）的传统开放手术或完全腔内修复的可行替代方法。然而，内脏杂交术式的广泛变化意味着根据修复后的血流模式（如速度模式和壁切应力）等血流动力学特征对手术结果进行预先预测仍然具有挑战性。我们试图评估计算流体动力学（CFD）分析在内脏杂交 TAAA 修复中的临床相关性。两名患者，一名患有 III 型 TAAA，另一名患有 V 型 TAAA，分别成功进行了择期和急诊内脏杂交修复。使用重建的术前和术后 CT 扫描分析血流模式和血流动力学参数。III 型和 V 型 TAAA 术前在各自的动脉瘤内均表现出高度紊乱的血流模式，且螺旋值不同。术前在两个 TAAA 的后腹侧观察到低时间平均壁切应力（TAWSS）、高内皮细胞动作电位（ECAP）和相对驻留时间（RRT）与血栓形成易感性相关。尽管择期和急诊修复中的旁路配置不同，但两种治疗选择似乎都比术前研究改善了血流动力学性能。然而，我们观察到在择期 III 型内脏杂交修复后，右髂动脉的 TAWSS 降低（预示着未来移植和可能肢体血栓形成的理论风险），但急诊 V 型修复后没有。我们推测，这种差异可能归因于 III 型修复中主动脉支架移植物的新分支比 V 型修复更高。我们的结果表明，CFD 可用于复杂的内脏杂交修复，以产生潜在的可操作的预测见解，对监测和增强术后管理具有影响，即使对于具有复杂几何旁路配置的患者也是如此。
