Mechanistic evaluation of long-term in-stent restenosis based on models of tissue damage and growth.

Development and application of advanced mechanical models of soft tissues and their growth represent one of the main directions in modern mechanics of solids. Such models are increasingly used to deal with complex biomedical problems. Prediction of in-stent restenosis for patients treated with coronary stents remains a highly challenging task. Using a finite element method, this paper presents a mechanistic approach to evaluate the development of in-stent restenosis in an artery following stent implantation. Hyperelastic models with damage, verified with experimental results, are used to describe the level of tissue damage in arterial layers and plaque caused by such intervention. A tissue-growth model, associated with vessel damage, is adopted to describe the growth behaviour of a media layer after stent implantation. Narrowing of lumen diameter with time is used to quantify the development of in-stent restenosis in the vessel after stenting. It is demonstrated that stent designs and materials strongly affect the stenting-induced damage in the media layer and the subsequent development of in-stent restenosis. The larger the artery expansion achieved during balloon inflation, the higher the damage introduced to the media layer, leading to an increased level of in-stent restenosis. In addition, the development of in-stent restenosis is directly correlated with the artery expansion during the stent deployment. The correlation is further used to predict the effect of a complex clinical procedure, such as stent overlapping, on the level of in-stent restenosis developed after percutaneous coronary intervention.

软组织及其生长的先进力学模型的开发与应用是现代固体力学的主要方向之一。这类模型越来越多地用于处理复杂的生物医学问题。对接受冠状动脉支架治疗的患者进行支架内再狭窄的预测仍然是一项极具挑战性的任务。本文利用有限元方法，提出了一种力学方法来评估支架植入后动脉内支架内再狭窄的发展。经过实验结果验证的含损伤的超弹性模型被用于描述此类干预对动脉层和斑块造成的组织损伤程度。采用与血管损伤相关的组织生长模型来描述支架植入后中膜层的生长行为。以管腔直径随时间的缩小来量化支架植入后血管内支架内再狭窄的发展。研究表明，支架的设计和材料对支架植入引起的中膜层损伤以及随后的支架内再狭窄发展有很大影响。球囊扩张过程中动脉扩张越大，对中膜层造成的损伤就越高，从而导致支架内再狭窄程度增加。此外，支架内再狭窄的发展与支架展开过程中的动脉扩张直接相关。这种相关性被进一步用于预测复杂临床操作（如支架重叠）对经皮冠状动脉介入治疗后支架内再狭窄程度的影响。