Bioabsorbable Stent Radial Strength Degradation for Vessel Healing
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Solution Overview
Problem
Coronary artery disease treatment with traditional biostable stents poses challenges due to permanent mechanical and tissue interaction, leading to endothelial dysfunction, thrombosis, and limited vessel compliance, as these stents do not degrade and can cause adverse reactions over time.
Innovation Solution
A bioabsorbable polymeric stent with a scaffolding composed of a pattern of struts made from degradable materials like PLGA, which degrades over time, reducing the necrotic core's contact with the blood vessel wall, allowing the fibrous component to take its place, and eventually absorbs completely, promoting healing without long-term mechanical interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If biostable stents are used to provide long-term mechanical support, then radial strength and structural integrity are improved, but endothelial dysfunction, thrombosis, and limited vessel compliance occur due to permanent foreign material presence
Solution Approach 1:
The patent employs bioabsorbable stents made from degradable polymers (PLA, PGA, or their copolymers) that provide necessary radial strength during the critical healing period and then gradually degrade and are absorbed by the body. This temporary support structure eliminates the need for permanent foreign material, resolving the contradiction between providing adequate mechanical support and avoiding long-term adverse biological responses.
Solution Approach 2:
The patent utilizes polymers with controlled degradation rates and mechanical properties that change over time. The stent maintains adequate radial strength initially and then progressively degrades as the vessel heals and regains its own structural integrity. This dynamic parameter change allows the stent to adapt to the healing process, providing support when needed and eliminating itself when no longer required.
2Reliability
If biostable stents are used to prevent restenosis, then vessel patency is improved, but thrombosis risk increases due to permanent mechanical interaction with blood
Solution Approach 1:
The bioabsorbable stent provides temporary mechanical support to maintain vessel patency during the critical period when the vessel is most vulnerable to restenosis. As the stent degrades and is absorbed, the permanent foreign material that causes thrombosis is eliminated, while the vessel maintains its patency through natural healing processes.
Solution Approach 2:
The stent's mechanical properties and presence in the vessel change over time as it degrades. The gradual reduction in stent material reduces the surface area in contact with blood, thereby reducing thrombogenicity while maintaining sufficient structural support to prevent restenosis during the critical healing period.
3Strength
If biostable stents are used to provide continuous structural support, then radial compressive force resistance is improved, but vessel compliance and natural vasomotion are limited
Solution Approach 1:
The bioabsorbable stent provides radial support during the healing period when the vessel wall is weakest and most vulnerable to compressive forces. As the vessel heals and regains its own structural integrity, the stent degrades and is absorbed, allowing the vessel to restore its natural compliance and vasomotion without permanent mechanical constraints.
Solution Approach 2:
The stent's mechanical support capacity changes dynamically as it degrades. Initially, it provides strong radial support to counteract compressive forces on the healing vessel. Over time, as the polymer degrades, the stent's support capacity gradually reduces, allowing the vessel to progressively regain its natural compliance and mechanical properties.
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 bioabsorbable stent facilitates vessel healing by reducing restenosis risk, minimizing thrombosis, and restoring natural vessel compliance and vasomotion, as it degrades and absorbs, leaving no permanent foreign material, thus addressing the limitations of traditional biostable stents.
Implementation Method 1
A bioabsorbable polymeric stent with a scaffolding composed of a pattern of struts made from degradable materials like PLGA, which degrades over time
Implementation Method 2
the stent degrades and absorbs, leaving no permanent foreign material
Data Source
AI summary
Methods of treating a diseased blood vessel exhibiting stenosis with a bioabsorbable stent are disclosed. The implanted stent supports the section of the vessel at an increased diameter for a period of time to allow the vessel to heal. The stent loses radial strength sufficient to support the section of the vessel in less than 6 months after implantation, loses mechanical integrity, and then erodes away from the section. The biodegradable stent results in changes in properties of plaque with time as the stent degrades. The time-dependent properties include the luminal area of the plaque and plaque geometric morphology parameters.