Ascending aorta covered stent with biomechanical property

Abstract

The invention belongs to the technical field of medical instruments, and particularly relates to an ascending aorta covered stent with biomechanical property, which comprises a support skeleton, the inner side and the outer side of the support skeleton are both covered with films, the support skeleton is formed by spirally winding functional metal wires, the functional metal wires are formed by spirally winding composite wires, and the functional metal wires are wound by the composite wires. And the composite filament is formed by weaving a plurality of strands of filaments. In terms of overall performance, the large vessel covered stent can be highly synchronized with radial expansion / retraction, circumferential stretching, longitudinal displacement and slight torsion generated by the ascending aorta in the cardiac contraction and diastole period, and therefore natural physiological movement of the aorta is effectively simulated.

Description

Technical Field

[0001] This invention belongs to the field of medical device technology, specifically relating to a endovascular stent graft with biomechanical properties for ascending aorta. Background Technology

[0002] Acute type A aortic dissection (ATAAD) is a rapidly progressing and fatal aortic disease characterized by a primary tear typically located in the ascending aorta, which can then regress to the aortic root. Current treatment for ATAAD primarily involves open surgery, such as the Bentall procedure and ascending aortic graft replacement, often combined with aortic valve replacement, coronary artery reconstruction, and aortic arch replacement. Elderly patients, those with multiple underlying diseases, or those with multiple organ dysfunction often cannot tolerate these surgeries. In recent years, minimally invasive endovascular treatment has been increasingly explored for its advantages, including minimal trauma and rapid recovery. This involves implanting a straight or branched covered stent within the aorta to close the tear and isolate the dissection.

[0003] The ascending aorta has a unique anatomical location. Its proximal end is adjacent to the heart, aortic valve, and coronary artery openings, while its distal end connects to the brachiocephalic trunk, left common carotid artery, and left subclavian artery, which are responsible for supplying blood to the brain and upper limbs. Precise spatial adaptation is required within a limited anatomical area. At the same time, as a key channel for supplying blood to the heart, it must withstand the complex mechanical loads brought about by high pressure, high-speed blood flow, and cardiac pulsation. The vessel wall not only undergoes vasodilation and vasoconstriction but also has large-scale lateral and longitudinal displacement, with a range of motion far exceeding that of other aortic segments. This requires that the covered stents used in interventional therapy be precisely positioned to avoid damage to the valves, obstruction of the coronary arteries and supra-arc branches, and have sufficient flexibility to adapt to its dynamic deformation. Furthermore, the proximal end must maintain low radial tension to prevent intimal tearing, dissection development, and related serious complications due to excessive resistance between the stent and the vessel wall.

[0004] The ascending aorta is known as the "second heart," acting as an auxiliary pump to supplement the main pumping function of the ventricles, rather than simply serving as a lumen through which blood flows. This is known as the "bellows effect," a mechanism that consists of two phases: (1) Systole: When the left ventricle contracts, it ejects blood into the ascending aorta. The elastic walls of the aorta expand, absorbing some of the heartbeat energy and storing it as potential energy. (2) Diastole: When the heart relaxes, the aortic valves close, and the elastic walls of the aorta rebound, pushing the stored potential energy back into the blood flow. This creates a continuous positive blood flow during the resting phase of the cardiac cycle, ensuring a stable supply of blood throughout the body.

[0005] Previous stent designs only met the morphological requirements of the aortic lumen, without considering its auxiliary pumping function. Our primary concern is how to maximize the retention of the heart's pumping potential energy within the stent to propel blood distally. Secondly, the heart undergoes multidimensional dynamic deformation during pulsation, including radial expansion and contraction, circumferential stretching, longitudinal displacement, and slight torsion due to spiral blood flow. Uneven local deformation may also occur in different locations. Radial and circumferential deformation reflect vascular compliance and wall stress, longitudinal displacement reflects the coupling between the heart and the aorta, while torsion and local deformation are closely related to hemodynamics and pathological changes. Existing conventional covered stents are mostly designed for the descending aorta or aortic arch, lacking adaptation to the anatomical and dynamic characteristics of the ascending aorta, and generally have the following shortcomings: 1. The auxiliary pumping function of the ascending aorta was not fully considered, thus losing its role in reserving the heart's pumping potential energy; 2. Poor mechanical compliance, lack of elastic deformable biomechanical properties, and inability to adapt to the multidimensional deformation of the aorta, which can easily lead to cladding tearing or fatigue failure, thereby affecting the stability of the aortic intima at the proximal and distal ends of the stent. 3. Inadequate skeleton and cladding design, especially overly rigid proximal design and excessive radial support, leads to excessive resistance of the stent and blood vessel, posing a risk of continuous damage to the intima and inducing retrograde tearing and extension of the aortic dissection. Summary of the Invention

[0006] The present invention provides a biomechanically viable ascending aortic endovascular stent graft to address the above-mentioned problems.

[0007] To achieve the above objectives, the present invention employs the following technical solution: A biomechanically viable ascending aortic endovascular stent graft includes a supporting framework covered with a thin film on both the inner and outer sides of the supporting framework. The supporting framework is formed by spirally winding functional metal wires, which are formed by spirally winding composite wires, which are woven from multiple strands of fine filaments.

[0008] Furthermore, the pitch of the support frame gradually increases from the proximal end to the distal end.

[0009] Furthermore, multiple axial reinforcing ribs are evenly distributed on the support frame, and the axial reinforcing ribs are made of functional metal wires.

[0010] Furthermore, multiple corrugated circumferential reinforcing ribs are evenly distributed on the supporting frame.

[0011] Furthermore, multiple pleated areas are spaced apart on the film along the radial direction of the support frame. Each pleated area is composed of multiple axially spaced pleats, so that the diameter of the film can be increased or decreased. The film is pleated in the axial direction of the support frame so that the film can be stretched or shortened with the support frame.

[0012] Furthermore, the film is made of any one of expanded polytetrafluoroethylene, medical polyurethane, or medical polyethylene terephthalate.

[0013] Furthermore, the inner film is turned outwards and sealed to the outer film to form a flanged structure.

[0014] Furthermore, the filament is made of nickel-titanium alloy or cobalt-chromium alloy.

[0015] Compared with the prior art, the present invention has the following advantages: This invention enhances the strength of composite filaments by weaving multiple strands of fine filaments into composite filaments. These composite filaments are then spirally wound into functional metal wires, which are then spirally wound into a support frame. This allows the support frame to elastically expand and contract in the radial direction to adapt to changes in the pulsatility of the ascending aorta and to store the potential energy for cardiac pumping. Simultaneously, the support frame also has a certain degree of extensibility in the axial direction, ensuring synchronization with the longitudinal movement of the aorta. Furthermore, the support frame of this application also possesses a certain degree of deformation capability in the torsional direction, enabling it to adapt to slight torsional movements of the aorta caused by spiral blood flow. The structural design of the support frame in this invention, combined with a gradient pitch distribution and a wave-shaped annular reinforcing rib design, provides stable support and safe proximal low-resistance anchoring, while exhibiting good flexibility and adaptability at the distal end. This significantly reduces the risk of intimal damage caused by excessive radial tension and is compatible with large-scale displacement of the ascending aorta. Simultaneously, this design enhances the fatigue resistance, corrosion resistance, and durability of the support frame, ensuring its stability under long-term cyclic loading. The membrane of this invention employs a unique double-layer design, with membranes covering both the inner and outer sides of the supporting framework, forming a composite "sandwich" structure that completely encapsulates and seals the supporting framework within it. This design aims to completely prevent the supporting framework from directly contacting and rubbing against the vascular endothelium, thereby effectively inhibiting intimal hyperplasia and inflammatory responses. Simultaneously, the outer membrane also provides a protective layer for the supporting framework, preventing damage from blood flow impact and improving overall durability. The film in this invention has folds in both the axial and radial directions, which allows the film to stretch, expand, and twist along with the support frame as the support frame stretches, expands, and twists. This avoids stress concentration in the film when the support frame deforms and reduces the risk of wrinkling, creases, and fatigue cracks in the film.

[0016] The inner membrane of this invention is turned outward and sealed to the outer membrane. This design can provide a smooth compliant transition and maintain a wall seal under the radial expansion and contraction, longitudinal displacement and slight torsion of the cardiac cycle, effectively suppressing port tearing and Type I internal leakage, while improving long-term sealing and fatigue resistance. The covered stent of this invention, in terms of overall performance, can maintain a high degree of synchronization with the radial expansion / retraction, circumferential expansion, longitudinal displacement, and slight torsion of the ascending aorta during the cardiac systolic and diastolic cycles, thereby effectively mimicking the natural physiological movement of the aorta. Through this design, the covered stent not only seals the dissection tear after implantation but also possesses biomechanical properties, preserving the "bellows effect" of the ascending aorta. It absorbs and releases potential energy during the cardiac cycle, storing the pumping potential energy of the heart and continuing to pump blood distally during diastole, thus maintaining stable hemodynamics. Compared to traditional rigid stents, this invention has significant advantages in the following aspects: 1. Excellent compliance: The supporting framework and membrane work synergistically to adapt to the multi-dimensional dynamic deformation of the ascending aorta, effectively avoiding intimal damage caused by differences in structural rigidity. 2. Enhanced stability: The low radial tension design at the proximal end ensures anchoring and fixation while reducing continuous stress on the aortic wall, decreasing the risk of retrograde dissection propagation and vascular tearing. 3. Excellent Durability: The pleated design of the membrane provides additional elastic margin, enabling the stent to exhibit excellent fatigue resistance under long-term cyclic loading, reducing membrane cracking and fatigue failure of the supporting skeleton. 4. Reliable Sealing: The membrane is made of a flexible polymer material and features a flanged structure at the port, significantly improving blood isolation and reducing the risk of type I endoleak. 5. Improved Hemodynamics: By retaining some elastic energy storage and diastolic rebound, this invention can improve aortic compliance to a certain extent, maintaining continuous perfusion of distal organs. Attached Figure Description

[0017] Figure 1 This is a schematic diagram showing the connection between the support frame, axial stiffeners, and circumferential stiffeners of the present invention. Figure 2 This is a schematic diagram of the structure of the present invention; Figure 3 This is a diagram showing the application of the present invention in blood vessels.

[0018] In the figure, the supporting skeleton is 1, the membrane is 2, the axial stiffener is 3, the circumferential stiffener is 4, and the folded area is 5. Detailed Implementation

[0019] To further illustrate the technical solution of the present invention, the present invention will be further described below through embodiments.

[0020] like Figure 1 , Figure 2As shown, a biomechanically viable ascending aortic endovascular stent graft includes a supporting framework 1, with a thin film 2 covering both the inner and outer sides of the supporting framework 1. The supporting framework 1 is spirally wound with functional metal wires, which are spirally wound with composite wires. The composite wires are woven from multiple strands of fine filaments, which are made of nickel-titanium alloy or cobalt-chromium alloy, and have a diameter of 0.03-0.08 mm. mm, the pitch of the support frame 1 gradually increases from the proximal end to the distal end, a plurality of axial reinforcing ribs 3 are evenly distributed on the support frame 1, the axial reinforcing ribs 3 are made of functional metal wire, a plurality of corrugated circumferential reinforcing ribs 4 are evenly distributed on the support frame 1, a plurality of pleated areas 5 are spaced apart along the radial direction of the support frame 1 on the film 2, each pleated area 5 is composed of a plurality of equidistant axial pleats, so that the diameter of the film 2 can be increased or decreased, the film 2 is pleated in the axial direction of the support frame 1 so that the film 2 can be stretched or shortened with the support frame 1, the inner layer of the film 2 is turned outward and sealed to the outer layer of the film 2 to form a turned-out structure, the material of the film 2 is any one of expanded polytetrafluoroethylene, medical polyurethane or medical polyethylene terephthalate. Expanded polytetrafluoroethylene (ePTFE) not only has good blood compatibility, low permeability, and flexibility, but its microporous structure also facilitates cell adhesion and tissue repair. Medical polyurethane has extremely high elasticity and fatigue resistance, which can ensure that the sandwich structure does not undergo interlaminar delamination or tearing despite repeated deformation of the support skeleton 1, providing continuous cushioning for the support skeleton 1. Medical polyethylene terephthalate (PET) can improve the tensile and tear resistance of the overall structure with its high mechanical strength.

[0021] The foregoing has shown and described the main features and advantages of the present invention. It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.

[0022] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A biomechanically viable ascending aortic endovascular stent graft, characterized in that: It includes a support frame (1), and a film (2) is covered on both the inner and outer sides of the support frame (1). The support frame (1) is made of functional metal wire spirally wound, and the functional metal wire is made of composite wire spirally wound, and the composite wire is woven from multiple strands of fine filaments.

2. The ascending aortic endovascular stent with biomechanical properties according to claim 1, characterized in that: The pitch of the support frame (1) gradually increases from the proximal end to the distal end.

3. The ascending aortic endovascular stent with biomechanical properties according to claim 2, characterized in that: Multiple axial reinforcing ribs (3) are evenly distributed on the support frame (1), and the axial reinforcing ribs (3) are made of functional metal wire.

4. The ascending aortic endovascular stent with biomechanical properties according to claim 3, characterized in that: Multiple corrugated circumferential reinforcing ribs (4) are evenly distributed on the support frame (1).

5. The ascending aortic endovascular stent with biomechanical properties according to claim 4, characterized in that: Multiple pleated areas (5) are spaced apart on the film (2) along the radial direction of the support frame (1). Each pleated area (5) is composed of multiple axial pleats that are equidistantly arranged along the axial direction of the support frame (1) so that the diameter of the film (2) can be increased or decreased. The film (2) is pleated in the axial direction of the support frame (1) so that the film (2) can be stretched or shortened with the support frame (1).

6. The ascending aortic endovascular stent with biomechanical properties according to claim 1, characterized in that: The film (2) is made of any one of expanded polytetrafluoroethylene, medical polyurethane, or medical polyethylene terephthalate.

7. The ascending aortic endovascular stent with biomechanical properties according to claim 1, characterized in that: The inner film (2) is turned outward and sealed to the outer film (2) to form a flanged structure.

8. The ascending aortic endovascular stent with biomechanical properties according to claim 1, characterized in that: The filament is made of nickel-titanium alloy or cobalt-chromium alloy.

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