Department of Biomedical Engineering, University of Michigan, Ann Arbor, Mich.
Department of Surgery, University of Michigan, Ann Arbor, Mich.
J Vasc Surg. 2020 Feb;71(2):505-516.e4. doi: 10.1016/j.jvs.2019.02.063. Epub 2019 May 29.
Suprarenal abdominal aortic coarctation (SAAC) alters flow and pressure patterns to the kidneys and is often associated with severe angiotensin-mediated hypertension refractory to drug therapy. SAAC is most often treated by a thoracoabdominal bypass (TAB) or patch aortoplasty (PA). It is currently unclear what effect these interventions have on renal flow and pressure waveforms. This study, using retrospective data from a patient with SAAC subjected to a TAB, undertook computational modeling to analyze aortorenal blood flow preoperatively as well as postoperatively after a variety of TAB and PA interventions.
Patient-specific anatomic models were constructed from preoperative computed tomography angiograms of a 9-year-old child with an isolated SAAC. Fluid-structure interaction (FSI) simulations of hemodynamics were performed to analyze preoperative renal flow and pressure waveforms. A parametric study was then performed to examine the hemodynamic impact of different bypass diameters and patch oversizing.
Preoperative FSI results documented diastole-dominated renal perfusion with considerable high-frequency disturbances in blood flow and pressure. The postoperative TAB right and left kidney volumes increased by 58% and 79%, respectively, reflecting the increased renal artery blood flows calculated by the FSI analysis. Postoperative increases in systolic flow accompanied decreases in high-frequency disturbances, aortic pressure, and collateral flow after all surgical interventions. In general, lesser degrees of high-frequency disturbances followed PA interventions. High-frequency disturbances were eliminated with the 0% PA in contrast to the 30% and 50% PA oversizing and TAB interventions, in which these flow disturbances remained.
Both TAB and PA dramatically improved renal artery flow and pressure waveforms, although disturbed renal waveforms remained in many of the surgical scenarios. Importantly, only the 0% PA oversizing scenario eliminated all high-frequency disturbances, resulting in nearly normal aortorenal blood flow. The study also establishes the relevance of patient-specific computational modeling in planning interventions for the midaortic syndrome.
肾上腹主动脉缩窄（SAAC）改变了肾脏的血流和压力模式，常伴有严重的血管紧张素介导的高血压，对药物治疗有抗性。SAAC 通常通过胸腹主动脉旁路（TAB）或补片主动脉成形术（PA）治疗。目前尚不清楚这些干预措施对肾血流和压力波形有何影响。本研究使用来自接受 TAB 的 SAAC 患者的回顾性数据，通过计算建模分析了各种 TAB 和 PA 干预措施前后的主动脉-肾血流。
从一位 9 岁患有孤立性 SAAC 的儿童的术前 CT 血管造影中构建了患者特异性解剖模型。进行血流动力学的流固耦合（FSI）模拟，以分析术前的肾脏血流和压力波形。然后进行了参数研究，以检查不同旁路直径和补片超尺寸对血流动力学的影响。
术前 FSI 结果记录了舒张期主导的肾脏灌注，血流和压力中有相当大的高频干扰。术后 TAB 右肾和左肾体积分别增加了 58%和 79%，这反映了 FSI 分析计算出的肾动脉血流增加。所有手术干预后，收缩期血流增加，高频干扰、主动脉压和侧支血流减少。一般来说，PA 干预后高频干扰较小。与 30%和 50%PA 过度扩张以及 TAB 干预相比，PA 干预的 0%过度扩张消除了高频干扰，血流干扰仍然存在。
TAB 和 PA 都极大地改善了肾动脉的血流和压力波形，但在许多手术情况下，仍存在紊乱的肾波。重要的是，只有 PA 过度扩张的 0% 方案消除了所有高频干扰，导致几乎正常的主动脉-肾血流。该研究还证明了患者特异性计算建模在计划中主动脉综合征干预中的相关性。
