Dynamic Distal Tip for Stent Re-crossing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing intravascular medical devices face challenges in reliably re-crossing deployed stents due to mechanical interactions between the delivery wire tip and stent struts, especially when the stent is deployed in a curved vessel, leading to difficulties in guiding subsequent devices like balloon catheters.
Innovation Solution
An implant delivery system featuring a delivery catheter with an elongate delivery mechanism that includes a compressible annular bushing and a pre-shaped distal tip, allowing the bushing to expand and the tip to assume a curved geometry post-deployment, facilitating re-crossing and minimizing snagging on deployed stents, while a tubular body constrains the tip to a straight geometry during deployment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the delivery wire tip is made rigid to facilitate delivery, then delivery strength is improved, but the ability to re-cross the deployed stent is worsened due to mechanical interactions with stent struts
Solution Approach 1:
The distal tip is designed to be dynamically configurable between a constrained straight state during delivery and an unconstrained curved state during re-crossing. The pre-shaped curved tip naturally assumes its curved geometry when released from the tubular body, transforming the delivery mechanism from static to dynamic to resolve the contradiction between delivery strength and re-crossing ability.
Solution Approach 2:
The delivery wire is segmented into distinct functional zones: a rigid proximal portion for delivery strength, and a distal tip portion with specialized geometry for re-crossing. This segmentation allows each portion to be optimized independently - the proximal portion maintains rigidity for force transmission while the distal tip provides flexibility for navigating the deployed stent.
2Ease of operation
If the distal tip is pre-shaped to facilitate re-crossing, then re-crossing ability is improved, but delivery control is worsened due to the tip's natural curvature
Solution Approach 1:
The distal tip is pre-shaped with the desired curved geometry before deployment, but this geometry is temporarily suppressed by the tubular body during delivery. The pre-shaping prepares the tip for its future re-crossing function while the tubular body ensures proper delivery control, resolving the contradiction between pre-prepared re-crossing capability and delivery control.
Solution Approach 2:
The tubular body acts as an intermediary constraint that temporarily holds the pre-shaped distal tip in a straight configuration during delivery. This intermediary element allows the tip to maintain its pre-shaped memory geometry while being controlled during delivery, and then releases this constraint to allow the tip to assume its natural curved shape for re-crossing.
3Ease of operation
If the delivery catheter is removed after stent deployment, then access to the proximal vessel is improved, but re-crossing the stent is worsened due to exposed bumper edges catching on stent struts
Solution Approach 1:
The problematic bumper edges are extracted or removed from the delivery mechanism after stent deployment. By eliminating these sharp forward edges that would catch on stent struts, the system maintains proximal access while removing the source of re-crossing failures. The distal tip's curved geometry compensates for the removed bumpers by providing a smooth leading edge for re-crossing.
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
Enables reliable re-crossing of deployed stents and allows for the successful guidance of additional catheters, such as balloon catheters, to perform procedures without mechanical interference, enhancing the operational efficiency in vascular interventions.
Implementation Method 1
a compressible annular bushing disposed within the annular channel, the annular bushing configured for being placed between a compressive profile and an expanded profile
Implementation Method 2
a pre-shaped distal tip, allowing the bushing to expand and the tip to assume a curved geometry post-deployment
Data Source
AI summary
An implant delivery system includes a delivery catheter and a delivery mechanism slidably disposed in a lumen of the delivery catheter. The delivery mechanism includes an annular channel and a compressible annular bushing disposed within the annular channel. The annular bushing is configured for being placed between a compressive profile and an expanded profile. The implant delivery system further includes an implant coaxially disposed between the delivery catheter and the delivery mechanism. The delivery catheter lumen is sized to maintain an engagement element of the implant within the annular channel and to urge the annular bushing into the compressive profile. The implant constrains a distal tip of the delivery mechanism to assume a straight geometry. The distal tip is configured for assuming a curved geometry when the implant is deployed from the delivery catheter.