Molecular weight characterization of virgin and explanted polyester arterial prostheses

Area of Science:

• Biomaterials Science
• Polymer Chemistry
• Medical Device Engineering

Background:

• Poly(ethylene terephthalate) (PET) is widely used in vascular prostheses.
• Understanding the long-term stability of PET prostheses is crucial for clinical success.
• Macromolecular properties influence the performance and degradation of medical implants.

Purpose of the Study:

• To investigate the macromolecular properties of new and explanted poly(ethylene terephthalate) arterial prostheses.
• To compare the characteristics of prostheses made with texturized versus untexturized yarns.
• To assess the impact of implantation time on the molecular integrity of PET grafts.

Main Methods:

• Gel permeation chromatography (GPC) was used to determine average molecular weights and polydispersity.
• Differential scanning calorimetry (DSC) was employed to analyze the degree of crystallinity and crystal size distribution.
• Analysis included 17 unused commercial arterial grafts and a series of explanted grafts.

Main Results:

• Unused grafts showed minimal differences in molecular weight and crystallinity.
• Texturized yarns resulted in broader DSC curves, suggesting increased crystal heterogeneity.
• Explanted grafts exhibited significantly lower average molecular weights compared to unused controls.
• Molecular weight reduction in explants was largely independent of implantation time.
• Polydispersity index and crystallinity remained constant over time in explants.

Conclusions:

• The texturizing process in PET arterial prostheses can influence their crystalline structure.
• Implantation leads to a significant reduction in the molecular weight of PET prostheses.
• The observed molecular weight degradation appears to be time-independent for explanted grafts.
• These findings provide insights into the long-term behavior of PET vascular grafts in vivo.