Abstract

BackgroundPercutaneous transluminal coronary angioplasty (PTCA) balloon catheters must withstand high pressures required for the lesion treatment, pushing loads during insertion, and pulling loads during withdrawal. These loads pose a challenge especially for polymeric tubular shafts with small cross sections. In order to enable new design innovations and to better understand the mechanics of current catheter technologies, the tensile properties of polyamide (PA) 12 were investigated. PA 12 dog bone specimens and medical PA 12 tubes were either stored at ambient temperature and humidity or conditioned in water, and subjected to tensile loads at different temperatures. In addition, the effect on the tensile properties of the necking process, a forming process to reduce the wall thickness of the tubes, was determined.ResultsThe tested tubes showed a reduction in both Young’s Modulus (− 41.5%) and yield stress (− 29.2%) compared to standardized specimens. Furthermore, an increase in temperature and water absorption softens the material and reduces the mechanical properties like the Young’s Modulus and the yield stress. It was found that the material strengthens during the necking process. Likely due to the orientation of the polymers chain molecules in load direction (Rösler et al., 2007), the Young’s Modulus of the material could be increased by 43.5%. Furthermore, the absence of a yield point after necking allows for a greater loading capacity of the material without unstable neck growth. Besides the strengthening, the ultimate strain is reduced by 50%. This indicates that the necking process induces plastic deformation.ConclusionThe investigation showed that the environmental conditions like temperature and humidity can influence mechanical properties. It could also be shown that pre-forming processes such as necking can enhance the mechanical properties, such as the Young’s Modulus, while reducing the wall thickness. These findings suggest possible further development of catheters with a small cross section and higher mechanical strength and highlight the importance to account for the targeted operating temperature during the design process.

Highlights

  • Percutaneous transluminal coronary angioplasty (PTCA) balloon catheters must withstand high pressures required for the lesion treatment, pushing loads during insertion, and pulling loads during withdrawal

  • The investigation showed that the environmental conditions like temperature and humidity can influence mechanical properties

  • It could be shown that pre-forming processes such as necking can enhance the mechanical properties, such as the Young’s Modulus, while reducing the wall thickness

Read more

Summary

Introduction

Percutaneous transluminal coronary angioplasty (PTCA) balloon catheters must withstand high pressures required for the lesion treatment, pushing loads during insertion, and pulling loads during withdrawal. These loads pose a challenge especially for polymeric tubular shafts with small cross sections. Polymers offer specific properties, such as a high compliance, low weight, good biocompatibility, as well as allow building affordable single-use devices such as percutaneous transluminal coronary angioplasty (PTCA) balloon catheters. Current demographic changes promote cardiovascular risk factors like hypertension and obesity Such factors favor calcified and resistant stenoses, which in return increase the mechanical loads on PTCA balloon catheters [2], and at the same time, require smaller cross sections for treatment of narrow stenoses. In combination with a small cross section, these loads impose a challenge especially to the polymer shaft

Objectives
Methods
Results
Discussion
Conclusion
Full Text
Published version (Free)

Talk to us

Join us for a 30 min session where you can share your feedback and ask us any queries you have

Schedule a call