Stenting-induced Vasa Vasorum compression and subsequent flow resistance: a finite element study

Vascular stenting is a common intervention for the treatment for atherosclerotic plaques. However, stenting still has a significant rate of restenosis caused by intimal hyperplasia formation. In this study, we evaluate whether stent overexpansion leads to Vasa Vasorum (VV) compression, which may contribute to vascular wall hypoxia and restenosis. An idealized multilayered fibroatheroma model including Vasa Vasorum was expanded by three coronary stent designs up to a 1.3:1 stent/artery luminal diameter ratio (exp1.1, exp1.2, exp1.3) using a finite element analysis approach. Following Poiseuille's law for elliptical sections, the fold increase in flow resistance was calculated based on VV compression in the Intima (Int), Media (Med) and Adventitia (Adv). The VV beneath the plaque experiences the smallest degree of compression, while the opposite wall regions are highly affected by stent overexpansion. The highest compressions for Adv, Med and Int at exp1.1 are 60.7, 65.9, 72.3%, at exp1.2 are 62.1, 67.3, 73.5% and at expp1.3 are 63.2, 68.7, 74.8%. The consequent fold increase in resistance to flow for Adv, Med and Int at exp1.1 is 3.3, 4.4, 6.6, at exp1.2 is 3.5, 4.7, 7.2 and at exp1.3 is 3.8, 5.1, 7.9. Stent overexpansion induces significant VV compression, especially in the Intima and Media layers, in agreement with previously observed Media necrosis and loss in elasticity after stenting. The observed steep increase in flow resistance suggests the blood flow and associated oxygen delivery would drop up to five times in the Media and almost eight in the Intima, which may lead to intimal hyperplasia and restenosis.