Finite element analysis of stent implantation in a three-dimensional reconstructed arterial segment

Virtual Reality-Assisted Percutaneous Transluminal Angioplasty for Interventional Treatment of Lower-Extremity Arteriosclerosis Obliterans

This study was to evaluate the biomechanical characteristics of the vascular wall during virtual reality- (VR-) assisted percutaneous transluminal angioplasty (PTA) and its effect on the treatment of lower-extremity arteriosclerosis obliterans (LEAO). In this study, a three-dimensional (3D) model and a finite-element model of arteries were constructed first, and various fluid mechanics were analyzed. Then, the virtual expansion simulation (VES) of individualized PTA was performed based on the ABAQUS/Explicit module to analyze the interaction between the balloon and the blood vessel at different times and the changes in the vascular shape and structural stress distribution. Finally, an LEAO animal model was constructed. Based on conventional PTA (PTA group) and VR-assisted PTA (VR-PTA) treatment, the morphological changes of vascular lumen of the two animal models were evaluated. The results showed that the normal, stenotic blood vessels and blood models were successfully constructed; the pressure of the stenotic blood vessel at the stenosis decreased obviously and the shear stress of blood vessel wall increased compared with that of the normal blood vessels, and there may be a blood reflux area in the poststenosis stage. The simulation results of the VES showed that the maximum principal stress value at 3 mm of the marginal vessel was much lower than that at 5 mm (about 10% lower), so the maximum principal stress change within 2 mm of the balloon-expanded vessel was the most obvious. The treatment results of the animal model showed that the VR-PTA group showed an obvious increase in the diameter of the vascular lumen, a decrease in the intima and media area, and a decrease in the thickness of the vessel wall in contrast to the PTA group (P < 0.05), which had an important effect on the reconstruction and expansion of the vascular lumen. The VR-PTA treatment on LEAO was realized in this study, which provided critical reference for the follow-up application of VR technology in the evaluation of surgical plan and research on biomechanical mechanisms of restenosis after PTA.

Ex Vivo Evaluation of IVUS-VH Imaging and the Role of Plaque Structure on Peripheral Artery Disease

Peripheral artery disease (PAD) results from the buildup of atherosclerotic plaque in the arterial wall, can progress to severe ischemia and lead to tissue necrosis and limb amputation. We evaluated a means of assessing PAD mechanics ex vivo using ten human peripheral arteries with PAD. Pressure-inflation testing was performed at six physiological pressure intervals ranging from 10-200 mmHg. These vessels were imaged with IVUS-VH to determine plaque composition and change in vessel structure with pressure. Statistical analysis was performed to determine which plaque structures and distributions of these structures had the greatest influence on wall deformation. We found that fibrous plaque, necrotic core, and calcification had a statistically significant effect on all variables (p<0.05). The presence of large concentrations of fibrous plaque was linked to reduced vessel compliance and ellipticity, which could lead to stent fractures and restenosis. For the plaque distribution we found that clustered necrotic core increased overall compliance while clustered calcification decreased overall compliance. The effect of plaque distribution on vessel wall deformation must be considered equally important to plaque concentration.