Ureteral Stent with Pressure-Responsive Flapper Valve
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Solution Overview
Problem
Current ureteral stents cause unwanted side effects such as bladder irritation, stent migration, and urine reflux due to their design, which impede effective urine flow and comfort during urination.
Innovation Solution
A ureteral stent with an elongated tube and a collapsible anchor portion in the bladder, featuring a flapper valve mechanism that adjusts with bladder pressure to control fluid flow, reducing irritation and reflux by expanding only when necessary to accommodate urine passage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the stent expands to a larger cross-sectional size to accommodate urine passage, then urine flow is improved, but bladder irritation increases
Solution Approach 1:
The stent employs a dynamic expansion mechanism where the anchor portion transitions from a compressed low-profile state during insertion to an expanded state after deployment. This dynamic transformation allows the stent to minimize bladder irritation during insertion while providing adequate urine flow capacity when deployed, directly resolving the contradiction between flow capacity and irritation.
Solution Approach 2:
The stent design incorporates a nested structure where the anchor portion can be compressed within a delivery catheter during insertion, then expanded after deployment. This nesting capability allows the stent to pass through narrow urethral passages in a compact form while providing a larger expanded profile for optimal urine flow, thereby reducing bladder irritation during the insertion process.
2Object-affected harmful factors
If the stent maintains a smaller profile to reduce bladder irritation, then patient comfort is improved, but urine flow capacity is reduced
Solution Approach 1:
The stent transitions from a small compressed profile during insertion to a larger expanded profile after deployment, dynamically adapting its size to different operational requirements. This ensures minimal irritation during insertion while providing sufficient flow capacity when functioning, resolving the contradiction between comfort and flow capacity.
3Reliability
If the stent is designed with a flapper valve mechanism to control fluid flow, then reflux is reduced, but device complexity increases
Solution Approach 1:
The flapper valve mechanism operates autonomously based on pressure differentials across the stent. When bladder pressure exceeds ureteral pressure, the flapper valve automatically closes to prevent reflux; when ureteral pressure is higher, the valve opens to allow urine flow. This self-regulating mechanism provides reliable reflux prevention without requiring external control systems, making the added complexity manageable through passive operation.
Solution Approach 2:
The flapper valve responds to changes in pressure parameters within the urinary tract, automatically adjusting its state based on the pressure differential between the bladder and ureter. This parameter-driven operation provides intelligent reflux control that adapts to physiological conditions, achieving high reliability with relatively simple mechanical design.
4Stability of the object's composition
If the stent expands only when bladder pressure increases, then migration is minimized, but flow control complexity increases
Solution Approach 1:
The stent's expansion and flow control are driven automatically by physiological pressure changes in the bladder and ureter. The flapper valve and expandable anchor portion respond passively to pressure differentials, expanding when needed to prevent migration and controlling flow without requiring active control systems. This self-regulating behavior provides stability while keeping the control mechanism relatively simple.
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 stent design minimizes irritation, migration, and reflux by expanding only when bladder pressure increases, ensuring efficient urine flow while maintaining a smaller profile to reduce bladder irritation and allowing full fluid flow, thus enhancing patient comfort and stent stability.
Implementation Method 1
a collapsible wall expandable to a cross-sectional size greater than the cross-sectional size of the ureter
Implementation Method 2
a flapper valve having at least two valve ends coupled to the anchor portion over the port; and a flexible portion between the at least two valve ends configured to flex toward the port to cover the port when pressure increases and flex away from the port when pressure is decreased
Data Source
AI summary
The present disclosure provides a ureteral stent, having an elongated tube configured to be inserted into a ureter; a first end having a retainer portion configured to be inserted into a kidney; and a second end configured to be inserted into a bladder, the second end having an anchor portion fluidicly coupled with the first end, the second end having a collapsible wall expandable to a cross-sectional size greater than the cross-sectional size of the ureter; a tube port fluidicly coupled with the first end; and a flapper valve having at least two valve ends coupled to the anchor portion over the port; and a flexible middle portion between the at least two valve ends configured to flex toward the port to cover the port with a predetermined amount of ambient pressure in the bladder and flex away from the port when ambient pressure is lower than the predetermined amount.