Geometrically Tunable Hydrogel Shunt for Growth-Adaptive Blood Flow
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Solution Overview
Problem
Conventional fixed-diameter shunts used in the Norwood procedure for patients with single ventricle physiology fail to maintain adequate blood oxygenation due to physiological changes during growth, leading to high mortality and complications from imbalanced blood flow.
Innovation Solution
A geometrically tunable hydrogel-based shunt prosthesis with a hydrogel-coated inner wall that adjusts its inner diameter through controlled crosslinking, allowing for autonomous expansion to match patient growth and development, thereby maintaining balanced blood flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fixed-diameter shunt is used in the Norwood procedure, then the shunt structure is simple and easy to manufacture, but the shunt cannot maintain adequate blood oxygenation due to physiological changes during patient growth
Solution Approach 1:
The shunt incorporates a hydrogel-coated inner wall that can dynamically change its inner diameter through controlled crosslinking. The hydrogel layer transitions from a swollen state (larger inner diameter) to a contracted state (smaller inner diameter) by adjusting crosslinking density, allowing the shunt to adapt to changing physiological conditions and patient growth over time.
Solution Approach 2:
The invention changes the physical parameter of the shunt's inner diameter by controlling the crosslinking density of the hydrogel coating. By varying the crosslinking degree, the hydrogel's swelling ratio changes, which directly adjusts the inner diameter and cross-sectional area of the shunt lumen, thereby maintaining appropriate blood flow distribution as the patient grows.
2Reliability
If the shunt inner diameter is increased to accommodate patient growth, then blood flow distribution improves, but the risk of thrombosis increases due to altered flow dynamics
Solution Approach 1:
The hydrogel coating provides dynamic adjustment of the inner diameter, allowing the shunt to optimize blood flow characteristics at different growth stages. By controlling the degree of swelling or contraction, the shunt can maintain flow velocities and patterns that minimize thrombosis risk while ensuring adequate blood distribution to both systemic and pulmonary circulations.
Solution Approach 2:
The invention utilizes parameter changes in the hydrogel's swelling ratio to adjust the inner diameter. This controlled parameter change allows optimization of flow dynamics - maintaining sufficient velocity to prevent stasis and thrombosis while distributing blood flow appropriately between the two circulations as the patient's physiological needs change.
3Adaptability or versatility
If a hydrogel-coated shunt with tunable geometry is used, then adaptability to physiological changes improves, but the device complexity increases
Solution Approach 1:
The invention uses a thin hydrogel film coated on the inner wall of the shunt. This thin film layer provides the necessary geometric tunability through its swelling and contracting properties without significantly increasing the overall device complexity. The hydrogel film integrates seamlessly with the existing shunt structure, adding functionality with minimal added complexity.
Solution Approach 2:
The shunt employs a composite structure combining a synthetic tube substrate with a hydrogel coating layer. This composite material approach allows the shunt to maintain the mechanical strength and structural integrity of the synthetic tube while adding the adaptive geometric properties of the hydrogel, achieving tunability without excessive complexity.
4Reliability
If the hydrogel crosslinking density is controlled to adjust inner diameter, then blood flow balance is maintained, but the control mechanism becomes more complex
Solution Approach 1:
The hydrogel coating can autonomously adjust its crosslinking density and corresponding inner diameter in response to physiological stimuli or pre-programmed degradation patterns. This self-service capability allows the shunt to maintain blood flow balance automatically without requiring complex external control mechanisms, reducing overall system complexity while ensuring reliable flow distribution.
Solution Approach 2:
The hydrogel is pre-designed with specific crosslinking characteristics and degradation patterns that anticipate future physiological changes. The crosslinking density is preliminarily configured to evolve in a predictable manner, allowing the shunt to maintain appropriate blood flow balance as the patient grows without requiring real-time complex control interventions.
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 tunable shunt prosthesis reduces complications and mortality by dynamically adjusting to physiological changes, ensuring appropriate blood flow distribution and reducing thrombosis risk.
Implementation Method 1
The thickness of the layer of hydrogel is reducable in vivo over a predetmined period of time in a controlable manner by control of a crosslinking density of the layer of hydrogel
Data Source
AI summary
A shunt prosthesis comprises a synthetic tube having an inner wall defining a fixed inner diameter of the synthetic tube and a layer of hydrogel of a predetermined thickness coating the inner wall of the synthetic tube such that the layer of hydrogel has a fixed outer diameter and such that an inner diameter of the layer of hydrogel defines a diameter of a lumen extending through and defined by the shunt prosthesis. The layer of hydrogel being configured such that the predetermined thickness of the layer of hydrogel is reducable in vivo over a predetmined period of time by controlling the crosslinking density of the layer of hydrogel. A method of controlling flow through a shunt prosthesis is also provided.