Fetal Shunt Anchor Design for Stable In Utero Placement
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Solution Overview
Problem
Current methods for treating fetal lower urinary tract obstruction in utero, such as percutaneous vesicoamniotic shunting, face high malfunction rates and associated risks, including dislodgement and complications like ascites and premature delivery, due to the inability to maintain the shunt's position effectively.
Innovation Solution
A medical device featuring a flexible catheter with an anchor system, including proximal and distal disk-shaped members that expand radially to secure the catheter in place between the fetal bladder and skin, ensuring stable fluid drainage and preventing dislodgement, combined with a delivery system for precise placement and confirmation using ultrasound and endoscopy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If percutaneous vesicoamniotic shunting is performed to treat fetal lower urinary tract obstruction, then fluid drainage is achieved, but the shunt may dislodge or malfunction up to 60% of the time
Solution Approach 1:
The shunt device is divided into multiple functional segments: a proximal catheter portion for bladder drainage, a distal catheter portion for amniotic fluid drainage, and separate anchor structures for each. This segmentation allows each component to be optimized for its specific function while maintaining overall stability through multiple independent anchoring points.
Solution Approach 2:
The catheter includes curved pig-tail shaped loops at both proximal and distal ends that are formed to be resilient. These curved structures provide mechanical stability and resistance to dislodgement while accommodating fetal movement and growth. The curved geometry also facilitates fluid flow while maintaining secure positioning.
2Device complexity
If conventional shunts are used without anchors, then the device is simpler, but the shunt pulls from the skin into the fetal abdomen resulting in iatrogenic ascites
Solution Approach 1:
The anchor system is segmented into distinct proximal and distal anchors, each independently positioned and secured. This allows the anchors to provide stable fixation without requiring complex integrated structures, maintaining relative simplicity while preventing shunt migration and ascites.
Solution Approach 2:
The anchor acts as an intermediary element between the catheter and the surrounding tissues (bladder wall and abdominal wall). This intermediary structure provides secure mechanical fixation, preventing the shunt from pulling into the abdomen while maintaining a relatively simple overall device architecture.
3Reliability
If shunt replacement is performed to address malfunction, then drainage function is restored, but perinatal loss rate increases by approximately 4% per instance
Solution Approach 1:
The shunt is pre-formed with resilient curved pig-tail loops and integrated anchors during manufacturing, ensuring proper positioning and stability are built-in before implantation. This preliminary configuration reduces the likelihood of malfunction and the need for replacement, thereby minimizing perinatal loss risk.
Solution Approach 2:
The resilient curved pig-tail structures and anchor systems provide built-in mechanical cushioning and stabilization, anticipating and preventing dislodgement before it occurs. This proactive design reduces the frequency of shunt replacement and associated perinatal complications.
4Reliability
If endoscopy is used to ablate posterior urethral valves, then obstruction is treated, but differential diagnosis between type III posterior urethral valves and urethral atresia becomes difficult or impossible
Solution Approach 1:
The shunt device serves as an intermediary tool that facilitates both treatment and diagnostic capabilities. By providing stable access to the bladder and urinary tract, the anchored shunt enables precise endoscopic visualization and intervention while maintaining the ability to differentiate between various obstructive conditions through controlled endoscopic examination.
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 device effectively maintains shunt position and function, reducing the risk of complications like ascites and premature delivery, and allows for reliable drainage and confirmation of correct placement, improving the management of fetal LUTO beyond previous technologies.
Implementation Method 1
proximal and distal disk-shaped members that expand radially to secure the catheter in place
Implementation Method 2
The catheter defines one or more proximal ports, one or more distal ports, a longitudinal axis, and a lumen providing fluid communication between the ports
Implementation Method 3
combined with a delivery system for precise placement and confirmation using ultrasound and endoscopy
Implementation Method 4
The anchor has a resilient proximal member and a resilient distal member spaced a longitudinal distance apart, and both of the proximal member and distal member extend radially outward
Data Source
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AI summary
A medical device, system, and method are described for treating in utero a fetus with a lower urinary tract obstruction. An implantable medical device may have a flexible catheter and an anchor. The catheter may define a proximal port, a distal port, a longitudinal axis, and a lumen providing fluid communication between the ports. The anchor may be affixed to the catheter at a position between the ports, and may have a resilient proximal member and a resilient distal member spaced a longitudinal distance apart, the proximal member and distal member each extending radially outward with respect to the longitudinal axis. An elongate delivery member may be releasably affixed to the medical device, and the medical device may be delivered through a tubular sheath defining a sheath lumen.