Department of Mechanical Engineering, Melbourne School of Engineering, University of Melbourne, Parkville, 3010 Victoria, Australia.
Department of Medicine, Faculty of Medicine, Dentistry & Health Sciences, Melbourne Medical School, University of Melbourne, Parkville, 3010 Victoria, Australia.
Eur Heart J. 2018 May 7;39(18):1602-1609. doi: 10.1093/eurheartj/ehx810.
As a sine qua non for arterial wall physiology, local hemodynamic forces such as endothelial shear stress (ESS) may influence long-term vessel changes as bioabsorbable scaffolds dissolve. The aim of this study was to perform serial computational fluid dynamic (CFD) simulations to examine immediate and long-term haemodynamic and vascular changes following bioresorbable scaffold placement.
Coronary arterial models with long-term serial assessment (baseline and 5 years) were reconstructed through fusion of intravascular optical coherence tomography and angiography. Pulsatile non-Newtonian CFD simulations were performed to calculate the ESS and relative blood viscosity. Time-averaged, systolic, and diastolic results were compared between follow-ups. Seven patients (seven lesions) were included in this analysis. A marked heterogeneity in ESS and localised regions of high blood viscosity were observed post-implantation. Percent vessel area exposed to low averaged ESS (<1 Pa) significantly decreased over 5 years (15.92% vs. 4.99%, P < 0.0001) whereas moderate (1-7 Pa) and high ESS (>7 Pa) did not significantly change (moderate ESS: 76.93% vs. 80.7%, P = 0.546; high ESS: 7.15% vs. 14.31%, P = 0.281), leading to higher ESS at follow-up. A positive correlation was observed between baseline ESS and change in lumen area at 5 years (P < 0.0001). Maximum blood viscosity significantly decreased over 5 years (4.30 ± 1.54 vs. 3.21± 0.57, P = 0.028).
Immediately after scaffold implantation, coronary arteries demonstrate an alternans of extremely low and high ESS values and localized areas of high blood viscosity. These initial local haemodynamic disturbances may trigger fibrin deposition and thrombosis. Also, low ESS can promote neointimal hyperplasia, but may also contribute to appropriate scaffold healing with normalisation of ESS and reduction in peak blood viscosity by 5 years.
作为动脉壁生理学的必要条件，局部血流动力学力（如内皮剪切应力[ESS]）可能会影响生物可吸收支架溶解后血管的长期变化。本研究旨在通过融合血管内光学相干断层扫描和血管造影进行连续计算流体动力学（CFD）模拟，以检查生物可吸收支架置入后即刻和长期的血液动力学和血管变化。
通过融合血管内光学相干断层扫描和血管造影，对具有长期连续评估（基线和 5 年）的冠状动脉模型进行重建。进行脉动非牛顿 CFD 模拟以计算 ESS 和相对血液粘度。比较随访时的时间平均、收缩期和舒张期结果。本分析纳入了 7 名患者（7 个病变）。植入后观察到 ESS 存在显著异质性和局部高血液粘度区域。5 年内暴露于低平均 ESS（<1 Pa）的血管面积百分比显著减少（15.92%比 4.99%，P<0.0001），而中等（1-7 Pa）和高 ESS（>7 Pa）则无明显变化（中等 ESS：76.93%比 80.7%，P=0.546；高 ESS：7.15%比 14.31%，P=0.281），导致随访时 ESS 升高。基线 ESS 与 5 年后管腔面积变化呈正相关（P<0.0001）。5 年内最大血液粘度显著降低（4.30±1.54 比 3.21±0.57，P=0.028）。
支架植入后即刻，冠状动脉表现出极低和极高 ESS 值以及局部高血液粘度的交替。这些初始局部血液动力学紊乱可能会引发纤维蛋白沉积和血栓形成。此外，低 ESS 可促进新生内膜增生，但也可能有助于适当的支架愈合，5 年内 ESS 正常化和峰值血液粘度降低。
