Effects of balloon dilatation on ePTFE structural characteristics

Area of Science:

• Biomaterials Science
• Cardiovascular Engineering
• Medical Device Technology

Background:

• Endovascular stent grafts are crucial for treating cardiovascular disease with less invasive approaches.
• These devices, comprising metallic stents and prosthetic vascular grafts, require balloon dilatation for deployment.
• The impact of this deployment process on the graft material's structural integrity is not fully understood.

Purpose of the Study:

• To investigate the structural alterations in expanded polytetrafluoroethylene (ePTFE) after balloon dilatation.
• To assess the effect of repetitive balloon inflations on ePTFE recoil and microstructure.

Main Methods:

• Two types of ePTFE (thin wall and standard wall) were subjected to balloon dilatation using noncompliant angioplasty balloons.
• Material recoil was measured by comparing outer diameters before and after balloon removal.
• Scanning electron microscopy was used to analyze changes in wall thickness, internodal distance, nodal width, interfiber distance, and fiber width.

Main Results:

• Both ePTFE types exhibited approximately 20% recoil after initial dilatation, decreasing to 10% after eight repetitive dilatations.
• Scanning electron microscopy revealed significant reductions in wall thickness, nodal thickness, and interfiber distance.
• Fiber width decreased in 3 mm ePTFE but not in 4 mm ePTFE after dilatation.

Conclusions:

• Balloon dilatation significantly alters the physical structure of ePTFE used in cardiovascular stent grafts.
• Repetitive dilatations lead to reduced material recoil and microstructural changes, potentially affecting long-term device performance.
• These findings highlight the importance of considering material deformation during stent graft deployment.