Self-Expanding Stent and Delivery System for Aortic Valve Replacement

Area of Science:

• Cardiovascular Surgery
• Biomedical Engineering
• Medical Imaging

Background:

• Traditional aortic valve replacement necessitates sternotomy and cardiopulmonary bypass (CPB).
• Transcatheter aortic valve replacement (TAVR) offers a less invasive alternative for high-risk patients.
• Current TAVR methods require precise valve deployment, which can be challenging.

Purpose of the Study:

• To develop and evaluate a novel self-expanding nitinol stent for minimally invasive aortic valve replacement.
• To assess a delivery device designed for transapical TAVR under real-time magnetic resonance imaging (MRI) guidance.
• To improve the accuracy and predictability of bioprosthetic aortic valve implantation.

Main Methods:

• Development of a nitinol self-expanding stent with an integrated MRI passive marker.
• Design of a delivery device featuring an MRI active marker for real-time MRI guidance.
• Ex vivo and in vivo (porcine model) testing to evaluate stent performance, valve integrity, and implantation accuracy.
• Measurement of radial forces and chronic outward forces.

Main Results:

• The self-expanding stent demonstrated adequate reinforcement of the bioprosthetic aortic valve.
• The MRI markers facilitated precise and predictable orientation and positioning of the implanted valve.
• The stent design allows for potential retraction if necessary.
• Ex vivo and in vivo results confirmed ease of implantation and proper seating of the valve prosthesis.
• Histopathology confirmed the stent's biocompatibility and functionality.

Conclusions:

• The novel self-expanding nitinol stent system provides a precise and reliable method for transapical TAVR.
• Real-time MRI guidance with integrated markers enhances implantation accuracy and predictability.
• This technology holds promise for improved long-term heart function due to better prosthesis fixation.