Department of Mechanical and Materials Engineering, University of Nebraska-Lincoln, Lincoln, NE, 68588-0656, USA.
Department of Interventional Radiology, The First Affiliated Hospital of Zhengzhou University, Henan Province, China.
Comput Biol Med. 2018 Sep 1;100:43-49. doi: 10.1016/j.compbiomed.2018.06.031. Epub 2018 Jun 28.
Stenting is one of the major treatments for malignant esophageal cancer. However, stent migration compromises clinical outcomes. A flared end design of the stent diminishes its migration. The goal of this work is to quantitatively characterize stent migration to develop new strategies for better clinical outcomes.
An esophageal stent with flared ends and a straight counterpart were virtually deployed in an esophagus with asymmetric stricture using the finite element method. The resulted esophagus shape, wall stress, and migration resistance force of the stent were quantified and compared.
The lumen gain for both the flared stent and the straight one exhibited no significant difference. The flared stent induced a significantly larger contact force and thus a larger stress onto the esophagus wall. In addition, more migration resistance force was required to pull the flared stent through the esophagus. This force was inversely related to the occurrence rate of stent migration. A doubled strut diameter also increased the migration resistance force by approximately 56%. An increased friction coefficient from 0.1 to 0.3 also boosted the migration resistance force by approximately 39%.
The mechanical advantage of the flared stent was unveiled by the significantly increased contact force, which provided the anchoring effect to resist stent migration. Both the strut diameter and friction coefficient positively correlated with the migration resistance force, and thus the occurrence of stent migration.
支架置入术是治疗恶性食管癌的主要方法之一。然而，支架迁移会影响临床结果。支架的喇叭口端设计可减少其迁移。本研究旨在定量分析支架迁移，以制定新的策略来获得更好的临床结果。
采用有限元方法，对具有喇叭口端和直型端的食管支架进行虚拟置入，模拟具有不对称性狭窄的食管。对支架置入后的食管形态、壁面应力和支架迁移阻力进行定量比较和分析。
喇叭口支架和直型支架的管腔扩张率无显著差异。喇叭口支架在食管壁上产生的接触力和壁面应力显著大于直型支架。此外，要使喇叭口支架穿过食管，需要施加更大的迁移阻力。该阻力与支架迁移的发生率呈反比。支架的支柱直径增加一倍，可使迁移阻力增加约 56%。摩擦系数从 0.1 增加到 0.3，也可使迁移阻力增加约 39%。
喇叭口支架的显著优势在于其增加的接触力，这为支架提供了抗迁移的锚固作用。支柱直径和摩擦系数与迁移阻力呈正相关，进而与支架迁移的发生呈正相关。
