Balloon Coating for Stent Retention in Delivery Systems
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Solution Overview
Problem
Current stent delivery systems face challenges with stent slippage and early unintentional release during deployment, particularly in small or heavily occluded arteries, and existing retention methods often increase the risk of failure or require expensive and bulky technologies, with some coatings being hazardous to health.
Innovation Solution
A medical device delivery system featuring a catheter shaft with an expandable member coated with a non-crosslinked polycarbonate-based thermoplastic polyurethane elastomer, applied via spray coating to the outer surface of the balloon, ensuring the coating does not cover the stent's folded areas, providing enhanced stent retention without compromising balloon function or increasing friction during deflation and retraction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a protective sheath surrounds the catheter and stent assembly, then stent retention is improved, but the profile of the catheter assembly increases
Solution Approach 1:
The invention removes the protective sheath from the system and replaces it with a coating applied directly to the balloon surface. This extraction eliminates the need for a bulky sheath while maintaining stent retention through the coating's friction and adhesion properties.
Solution Approach 2:
The coating is applied locally to the balloon surface at the stent location rather than using a comprehensive sheath. This localized application provides retention where needed while maintaining a low-profile catheter assembly throughout its length.
2Reliability
If dissolvable bands are applied to the stent surface, then stent position is maintained, but the outer diameter of the stent assembly increases significantly
Solution Approach 1:
The coating is applied only to the balloon surface at the stent location rather than surrounding the entire stent assembly with bands. This localized approach maintains stent position while avoiding significant increase in outer diameter.
Solution Approach 2:
The invention uses a thin film coating on the balloon surface instead of bulky dissolvable bands. This thin film provides the necessary retention force while adding minimal volume to the stent assembly.
3Reliability
If protrusions with shoulders are provided on the balloon, then stent retention against axial force is improved, but the device complexity increases
Solution Approach 1:
The invention changes the surface parameters of the balloon by applying a coating with specific friction and adhesion properties, rather than adding complex mechanical protrusions. This parameter change provides retention against axial force while maintaining a simple balloon structure.
4Reliability
If elastomeric sleeves are provided on the catheter balloon, then stent retention is improved, but the pressure required to inflate the balloon increases and manufacturing steps are added
Solution Approach 1:
The invention uses a thin film coating on the balloon surface instead of thick elastomeric sleeves. This thin film provides stent retention while allowing the balloon to inflate at normal pressures without the resistance caused by bulky sleeves.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively maintains stent position and prevents slippage, ensuring safe and reliable deployment while avoiding the use of hazardous materials and maintaining the balloon's functionality, with improved biocompatibility and reduced risk of damage during crimping and navigation through tortuous anatomy.
Implementation Method 1
WO 2004/020012 discloses a coating composition for use in increasing the static friction of a surface of a delivery system comprising a medical device having a surface in contact with the surface of a delivery component, the static friction of the surface being increased in an amount sufficient to substantially maintain the position of the medical device on the delivery component
Data Source
AI summary
The invention relates to a medical device delivery system comprising a catheter shaft having a proximal end and a distal end portion; an expandable member provided at the distal end portion of the shaft, the expandable member having a delivery configuration and a deployed configuration; the expandable member being folded around the catheter shaft in its delivery configuration; characterized in that a coating is disposed on at least a portion of the outer surface area of the expandable member in its delivery configuration such that the coating does not cover portions of the expandable member located inside the folds of the expandable member in its delivery configuration; and an expandable medical device is mounted on the expandable member in the delivery configuration with the coating being disposed between the expandable member and the expandable medical device.