Laboratory of Biological Structure Mechanics, Department of Chemistry, Materials and Chemical Engineering "Giulio Natta", Politecnico di Milano, Milan, Italy.
CBSET Inc, Lexington, MA, USA.
Ann Biomed Eng. 2023 Dec;51(12):2908-2922. doi: 10.1007/s10439-023-03359-y. Epub 2023 Sep 26.
Drug-Coated Balloons have shown promising results as a minimally invasive approach to treat stenotic arteries, but recent animal studies have revealed limited, non-uniform coating transfer onto the arterial lumen. In vitro data suggested that local coating transfer tracks the local Contact Pressure (CP) between the balloon and the endothelium. Therefore, this work aimed to investigate in silico how different interventional and device parameters may affect the spatial distribution of CP during the inflation of an angioplasty balloon within idealized vessels that resemble healthy femoral arteries in size and compliance. An angioplasty balloon computational model was developed, considering longitudinal non-uniform wall thickness, due to its forming process, and the folding procedure of the balloon. To identify the conditions leading to non-uniform CP, sensitivity finite element analyses were performed comparing different values for balloon working length, longitudinally varying wall thickness, friction coefficient on the balloon-vessel interface, vessel wall stiffness and thickness, and balloon-to-vessel diameter ratio. Findings indicate a significant irregularity of contact between the balloon and the vessel, mainly affected by the balloon's unfolding and longitudinal thickness variation. Mirroring published data on coating transfer distribution in animal studies, the interfacial CP distribution was maximal at the middle of the balloon treatment site, while exhibiting a circumferential pattern of linear peaks as a consequence of the particular balloon-vessel interaction during unfolding. A high ratio of balloon-to-vessel diameter, higher vessel stiffness, and thickness was found to increase significantly the amplitude and spatial distribution of the CP, while a higher friction coefficient at the balloon-to-vessel interface further exacerbated the non-uniformity of CP. Evaluation of balloon design effects revealed that the thicker tapered part caused CP reduction in the areas that interacted with the extremities of the balloon, whereas total length only weakly impacted the CP. Taken together, this study offers a deeper understanding of the factors influencing the irregularity of balloon-tissue contact, a key step toward uniformity in drug-coating transfer and potential clinical effectiveness.
药物涂层球囊作为一种微创治疗狭窄动脉的方法显示出良好的效果，但最近的动物研究表明，药物涂层在动脉管腔上的转移有限且不均匀。体外数据表明，局部涂层转移与球囊和内皮之间的局部接触压力 (CP) 有关。因此，这项工作旨在研究不同的介入和设备参数如何在理想化的血管中充气时影响 CP 在空间上的分布，这些理想化的血管在大小和顺应性上类似于健康的股动脉。考虑到血管成形球囊的形成过程和折叠过程，建立了血管成形球囊计算模型，考虑了纵向非均匀壁厚度。为了确定导致 CP 不均匀的条件，进行了敏感性有限元分析，比较了不同的球囊工作长度、纵向变化的壁厚度、球囊-血管界面上的摩擦系数、血管壁刚度和厚度以及球囊-血管直径比的值。结果表明，球囊与血管之间的接触非常不规则，主要受球囊的展开和纵向厚度变化的影响。与动物研究中涂层转移分布的已发表数据相吻合，界面 CP 分布在球囊治疗部位的中间达到最大值，同时由于球囊在展开过程中的特殊相互作用，呈现出线性峰值的圆周模式。发现球囊-血管直径比高、血管刚度和厚度高会显著增加 CP 的幅度和空间分布，而球囊-血管界面上的摩擦系数高会进一步加剧 CP 的不均匀性。对球囊设计效果的评估表明，较厚的锥形部分会导致与球囊末端相互作用的区域 CP 降低，而总长度对 CP 的影响较弱。总的来说，这项研究更深入地了解了影响球囊-组织接触不规则性的因素，这是实现药物涂层均匀转移和潜在临床效果的关键一步。
