Effects of Stent Design and Atherosclerotic Plaque Composition on Arterial Wall Biomechanics

Abstract

¤ ¤Purpose: To examine the solid mechanical effects of varying stent design and atherosclerotic plaque stiffness on the biomechanical environment induced in a diseased artery wall model. Methods: Computational modeling techniques were employed to investigate the final radius of the lumen and artery wall stresses after stent implantation. Two stent designs were studied (one stiff and one less stiff). The stenotic artery was modeled as an axisymmetrical diseased vessel with a 20% stenosis by diameter. The material properties of the diseased tissue in the artery models varied. Atherosclerotic plaques half as stiff (0.53), of equal stiffness (1.03), or twice as stiff (2.03) as the artery wall were investigated. Results: Final lumen radius was dependent on stent design, and the stiffer stent deformed the artery to an approximately 10% greater radius than the more compliant design. Alternatively, circumferential stress levels were dependent on both stent design and plaque material properties. Overall, the stiffer stent subjected the artery wall to much higher stress values than the more compliant design, with differences in peak values of 0.50, 0.31, and 0.09 MPa for the 2.03, 1.03, and 0.53 stiff plaques, respectively. Conclusion: Evidence suggests that a judicious choice of stent design can minimize stress while maintaining a patent lumen in stenotic arteries. If confronted with a rigid, calcified plaque, stent design is more important, as design differences can impose dramatically different stress fields, while still providing arterial patency. Alternatively, stent design is not as much of an issue when treating a soft, lipid-laden plaque, as stress fields do not vary significantly among stent designs. J Endovasc Ther 2008;15:643-654

Association of serum lipids with arterial stiffness in a population-based study in Beijing

“…One of the more obvious mechanisms is the development of atherosclerotic plaques [33]. Atherosclerosis in the coronary arteries (and at other sites) has been consistently associated with increased arterial stiffness.…”

The consequences of the mechanical environment of peripheral arteries for nitinol stenting

“…Although the bending cycle simulated here is not predicted to cause fatigue failure of the stent (FOS greater than one for all integration points), this is for an idealised artery and a relatively short stent. A calcified or eccentric plaque [32], a longer lesion (and stent) or a more irregular vessel geometry would be amongst the factors that could reduce the factor of safety and lead to stent fatigue fracture.…”

Nitinol Stent Oversizing in Patients Undergoing Popliteal Artery Revascularization: A Finite Element Study

“…3,4,15,18,23,33 However, the only numerical studies conducted on stent mis-sizing were found to be on balloon-expandable stents deployed in straight cylindrical models of healthy 3,18 or calcified coronary arteries. 37 Due to the significant differences in their deployment procedures, the results from these studies could not be adopted for self-expandable Nitinol stents. Thus, the aim of the present study was to quantify the biomechanical effects of Nitinol stent oversizing using numerical models of non-calcified popliteal arteries obtained from patients undergoing endovascular revascularization.…”