Ghanbarzadeh-Dagheyan Ashkan, van Helvert Majorie, van de Velde Lennart, Reijnen Michel M P J, Versluis Michel, Groot Jebbink Erik
Multi-Modality Medical Imaging, Technical Medical (TechMed) Centre, University of Twente, Enschede, The Netherlands.
Biomedical Photonic Imaging Group, Technical Medical (TechMed) Centre, University of Twente, Enschede, The Netherlands.
J Endovasc Ther. 2024 Oct 13:15266028241283326. doi: 10.1177/15266028241283326.
Helical stents have been developed to treat peripheral arterial disease (PAD) in the superficial femoral artery (SFA), with the premise that their particular geometry could promote swirling flow in the blood. The aim of this work is to provide evidence on the existence of this swirling flow by quantifying its signatures.
This study consists of in vitro and in vivo parts. For the in vitro part, 3 helical stent models of different helicity degrees and 1 straight model were fabricated, and the flow was assessed at the inlet and outlet of each model. For the in vivo part, only 1 patient, treated with the helical stent, was eligible to participate in the study. The stent implanted in the SFA of the patient was evaluated in 2 leg postures (straight and flexed), and flow was assessed in 12 locations along the SFA. The in vivo study was approved by an ethical board (NL80130.091.21) in the Netherlands. High-frame-rate ultrasound was used to acquire data from the regions of interest (ROIs), using microbubbles as contrast agents. After processing the data via a correlation-based algorithm (echo particle image velocimetry or echoPIV), the velocity vector field within each ROI was extracted and analyzed for parameters such as vector complexity and velocity profile skewedness.
The results show that in the outlet of the helical stents, when compared with the inlet, the flow vector field is more complex and the velocity profile is more skewed. For the in vivo case, the outcomes demonstrate more complexity and higher variability in the sign of skewedness inside the stent when compared with the flow in the proximal to the stent.
Helical stents make the vector field of the flow more complex and the velocity profile more skewed, both of which are signatures of swirling flow. Further studies are needed to evaluate whether these features can benefit patients in terms of patency rates.
This study demonstrates that helical stent models alter the blood flow when compared with straight stent models. Particularly, the flow grows more complex and its velocity profile becomes more skewed, both of which hint at the existence of swirling flow inside the helical stent. These observations, alongside with population-based studies that are currently being carried out, may provide the evidence that helical stents have some advantages over straight stents for the patients.
螺旋支架已被开发用于治疗股浅动脉（SFA）的外周动脉疾病（PAD），其前提是其特殊的几何形状可促进血液中的涡流。这项工作的目的是通过量化其特征来提供这种涡流存在的证据。
本研究包括体外和体内两部分。体外部分，制作了3个不同螺旋度的螺旋支架模型和1个直支架模型，并在每个模型的入口和出口处评估血流。体内部分，只有1名接受螺旋支架治疗的患者符合参与研究的条件。对植入该患者SFA的支架在2种腿部姿势（伸直和弯曲）下进行评估，并在沿SFA的12个位置评估血流。体内研究获得了荷兰一个伦理委员会（NL80130.091.21）的批准。使用高帧率超声，以微泡作为对比剂，从感兴趣区域（ROI）获取数据。通过基于相关性的算法（回声粒子图像测速法或echoPIV）处理数据后，提取每个ROI内的速度矢量场，并分析诸如矢量复杂性和速度剖面偏斜度等参数。
结果表明，在螺旋支架的出口处，与入口相比，血流矢量场更复杂，速度剖面更偏斜。对于体内情况，结果表明与支架近端的血流相比，支架内偏斜度的符号更复杂且变异性更高。
螺旋支架使血流的矢量场更复杂，速度剖面更偏斜，这两者都是涡流的特征。需要进一步研究来评估这些特征是否能在通畅率方面使患者受益。
本研究表明，与直支架模型相比，螺旋支架模型会改变血流。特别是，血流变得更加复杂，其速度剖面变得更加偏斜，这两者都暗示螺旋支架内存在涡流。这些观察结果，连同目前正在进行的基于人群的研究，可能提供证据表明螺旋支架对患者而言比直支架具有一些优势。
