Double-crowned valved stents for off-pump mitral valve replacement

Area of Science:

• Cardiovascular Surgery
• Biomedical Engineering
• Medical Device Development

Background:

• Mitral valve replacement is a critical cardiac procedure.
• Off-pump techniques aim to reduce surgical risks.
• Valved stents offer a potential minimally invasive alternative.

Purpose of the Study:

• To design and evaluate an animal model for off-pump mitral valve replacement.
• To assess the feasibility of using self-expanding valved stents for mitral valve implantation.
• To investigate the procedural success and initial outcomes of this novel approach.

Main Methods:

• A valved stent was constructed using a glutaraldehyde-preserved homograft within a Dacron tube, secured by nitinol Z-stents.
• The device was implanted in the mitral position in adult pigs under general anesthesia via thoracotomy.
• Intravascular ultrasound (IVUS) and intracardiac ultrasound (ICUS) were used for deployment guidance and valve function assessment.
• Hemodynamic parameters and short-term survival were monitored.

Main Results:

• The procedure was successfully performed in 8 animals, with correct stent positioning in 7.
• Mild mitral regurgitation was observed in 3 animals; mean pressure gradients were low.
• One animal experienced left ventricular outflow tract (LVOT) occlusion due to stent displacement.
• Mean survival time was approximately 97.5 minutes.

Conclusions:

• Off-pump implantation of self-expandable valved stents in the mitral position is technically feasible in an animal model.
• The study highlights the potential of this technique for future clinical application.
• Further investigations are required to confirm safety and efficacy in human patients.