IMPACT OF CALCIUM QUANTIFICATIONS ON STENT EXPANSIONS.

Severely calcified plaque is of great concern when planning and implementing a stenting intervention. In this work, computational models were developed to investigate the influence of calcium characteristics on stenting outcomes. The commonly used clinical measurements of calcium (i.e., the arc angle, maximum thickness, length, and volume) were varied to estimate stenting outcomes in terms of lumen gain, stent underexpansion, strut malapposition, and stress or strain distributions of the stenotic lesion. Results have shown that stenting outcomes were most sensitive to the arc angle of the calcium. A thick calcium with a large arc angle resulted in poor stenting outcomes, such as severe stent underexpansion, D-shaped lumen, increased strut malapposition, and large stresses or strains in the plaque. This was attributed to the circumferential stretch of the tissue. Specifically, the non-calcium component was stretched significantly more than the calcium. The circumferential stretch ratios of calcium and non-calcium component were approximately 2.35 and 1.44, respectively, regardless of calcium characteristics. In addition, the peak stress or strain within the artery and non-calcium component of the plaque occurred at the area adjacent to calcium edges (i.e., the interface between the calcium and the non-calcium component) coincident with the location of peak malapposition. It is worth noting that the calcium played a protective role for the artery underneath, which was at the expense of the overstretch and stress concentrations in the other portion of the artery.