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Cardiovascular Engineering

Cardiovascular Engineering - Poster Session C

Poster H13 - Ex Vivo Analysis of Balloon-Expandable Stent Fracture within a Peripheral-Simulating Bioreactor System

Friday, October 25, 2024
10:00 AM - 11:00 AM EST
Location: Exhibit Hall E, F & G

    Presenting Author(s)

  • Aleyna E. Schuett

    Student
    Wake Forest University
    Brielle, New Jersey, United States

  • Meera P. Doran

    Undergraduate Research Student
    Wake Forest University
    Vienna, Virginia, United States

    • Last Author(s)

  • Saami K. Yazdani, PhD

    Professor
    Wake Forest University, United States

    • Co-Author(s)

  • TU

    Trey Ursillo

    Research Technician
    Wake Forest University, United States


Introduction:  Balloon-expandable stents are used to treat cardiovascular diseases including Peripheral Arterial Disease (PAD). These stents are susceptible to fractures due to the cyclical bending, twisting, and compression that occurs in peripheral arteries. Overlapping shorter coronary stents are used to treat long plaque lesions, commonly found in below-the-knee disease. To date, there have been minimal studies that focus on fracture in overlapping balloon expanding stents subjected to peripheral arterial motion. Thus, the objective of this study was to evaluate fractures in overlapping coronary bare metal balloon-expandable stents undergoing cyclical movement using a peripheral simulating bioreactor system.

Materials and

Methods:  A novel peripheral-simulating bioreactor system was utilized that consisted of 3D printed parts and four servo motors to simultaneously shorten/elongate, twist, and bend the overlapping balloon-expandable stainless steel stents. The feasibility of the bioreactor system was evaluated using both (1) mock silicone tubings made of Sylgard 184 and (2) harvested porcine carotid arteries. The geometry of the tubing and arteries were similar, with inner diameters ranging from 4.5 - 6 mm, and an average thickness of 1 mm. In each model, balloon expandable stents (4-5 mm x 12-24 mm) were deployed with an overlap of approximately 5 mm. The tests underwent a prescribed peripheral vascular motion consisting of 90° twist, 120° bend, and 30 mm compression in a CO2 incubator to control temperature and pressure. The vascular motion occurred six times per minute, with seven seconds between each cycle. Fractures were analyzed using both high-powered digital images and scanning electron microscopy.

Results, Conclusions, and Discussions: In both the silicone and porcine carotid model, the overlapping balloon-expandable stents fractured under 60 hours. The stents displayed crushing and fractures near the proximal end. Further investigation using the high-powered digital imaging and SEM analysis showed single strut fractures, multiple strut fractures, and incomplete transverse “v” gap fractures. Within the overlap region there were no fractures.
This study shows the potential of fracture of overlapping balloon expandable stainless steel stents deployed in conditions mimicking peripheral arterial motion. As there are currently no small-diameter self-expanding stents to treat below-the-knee disease, these studies are warranted to ensure the longevity of balloon expandable stainless-steel stents implanted in non-coronary environments. Additionally, these results validate the use of our mock artery to test for stent fracture on a broad scale. This unique study provides a novel platform that can be utilized to determine the susceptibility of implants designed to be deployed within the peripheral vasculature.

Acknowledgements (Optional):