Device to block blood clots

Abstract

The present invention provides a device for blocking thrombi, which is made by preforming a metal wire or tape with an oval or flat cross section into a predetermined spiral shape wound around the short side. When the formed thrombus blocking device is inserted into the target blood vessel through a tubular object, the elasticity of the material allows it to return to the predetermined shape, thereby achieving the purpose of blocking embolism. The present invention realizes a device that can easily return to the predetermined shape with a smaller curvature and causes less interference with blood flow.

Description

[Technical Field]

[0001] The present invention relates to medical devices, and more particularly to a device for blocking thrombus formation. [Background technology]

[0002] As for existing technologies, the technology mentioned in CN104736102A and BATISTE, STANLEY's patent US20080183206A1 is the only technology currently on the market (and the only one known to date) that uses a single metal wire to construct an intravascular embolic blocking device. The basic principle of CN104736102A's technology is to pre-shape a superelastic metal wire and then inject it into the lumen of the target blood vessel through a hollow needle. Once the wire enters the target lumen, it returns to its pre-shape and is stably fixed within the target blood vessel, achieving the purpose of blocking the blood clot. There are two designs available in the current patent and product information. One is to form a spiral within the blood vessel, with the axis of the spiral perpendicular to the direction of blood flow. With this design, if the spiral spacing is too small, it can block blood clots but reduces blood flow. On the other hand, if the spiral spacing is too large, emboli will leak through the gap, defeating the purpose of blocking emboli. Another design involves a single metal wire forming multiple spirals within the blood vessel, with the axes of these spirals parallel to each other but without a common axis. This design solves the problems of blood flow and embolus blocking capacity, but it uses two spirals without a common axis to achieve this technical effect. A spiral with a common axis requires a thinner metal wire to achieve the embolus blocking effect, but thinner metal wires are easily deformed by the impact of blood flow, resulting in a loss of blocking performance. On the other hand, spirals without a common axis have the problem of complex mold design and low thermal forming yield. The BATISTE, STANLEY patent uses a spiral with a common axis, but because its design is for intravenous use and the target size of the embolus to be blocked is large, it is possible to achieve the expected effect using a relatively thin metal wire and a large spiral diameter. However, if the vessel wall is highly elastic, this design may cause the device to deform as the vessel wall pulsates, further causing blood flow fluctuations. The blood flow fluctuations cause local hemodynamic turbulence, further increasing the likelihood of thrombus formation. Therefore, current technology needs to be further improved to reduce interference with blood flow and block smaller emboli.New intravascular embolic blocking devices should be able to block smaller emboli with less interference with blood flow, have a small curvature, be easy to transport, and easily return to their intended shape. Summary of the Invention [Problem to be solved by the invention]

[0003] An object of the present invention is to provide a thrombus blocking device that has a small curvature, easily returns to a predetermined shape, and interferes less with blood flow. The present invention achieves this goal by using an oval or flat metal wire or tape that is pre-formed into a predetermined spiral shape wrapped around its short side. The device is placed in a tube and, in use, is placed into the target vessel and the elasticity of the material allows it to return to the predetermined shape, blocking the embolus. Specifically, the cross section of the metal wire or tape is elliptical or streamlined, with the short side of the ellipse or streamlined shape facing the direction of blood flow and tangent to the direction of blood flow. The long side of the ellipse or streamlined shape is parallel to the direction of blood flow. The ratio of the length to the width of the cross section is 1.5 or more, and the ratio of the short side to the minimum blocking diameter is equal to or less than the maximum elastic deformation modulus of the material. In a preferred embodiment, the angle between the helical axis and the major axis of the elliptical or streamlined cross section is an acute angle, preferably less than 30 degrees. The angle between the helical axis and the width of the elliptical or streamlined cross section is also an acute angle. [Effects of the Invention]

[0004] The effect of this invention is to reduce the stress on the surface of the material by wrapping it around the short side, thereby achieving the goal of allowing the device to recover its shape. This allows for the creation of a blocking area with a small curvature and guaranteed blocking performance. Furthermore, by making the cross-sectional shape of the device elliptical or streamlined, blood flow resistance is reduced and blood is designed to flow along the device. This improves the hemodynamic environment and suppresses thrombus formation. [Brief explanation of the drawings]

[0005] [Figure 1] Overall structure of the present invention (before use) [Figure 2] Structural diagram of the embodiment [Figure 3] Cross section of a single metal wire [Figure 4] Comparison of spirals wound around the short and long sides [Figure 5] Example diagram for blood flow direction [Figure 6] Cross section AA of Figure 5 [Figure 7] Enlarged view of the area within the circle in Figure 6 BEST MODE FOR CARRYING OUT THE INVENTION

[0006] The present invention relates to a device for blocking blood clots, characterized in that it is made of a metal flat wire or tape with an oval, flat or streamlined cross section, which is pre-processed and molded into a predetermined shape, such as a spiral or vortex, and can be used as a blood clot blocking device implanted in a blood vessel. The molded thrombus blocking device is placed in a tubular object and introduced into the target blood vessel through the tubular object during use. The elasticity of the material allows the device to return to its intended shape, achieving the goal of blocking thrombus. The oval flat wire is wound around the short side, reducing the stress on the surface of the material and allowing the thrombus blocking device to regain its shape. This method allows for the production of a blocking area with a small curvature and guaranteed blocking performance. The cross section of the thrombus blocking device is preferably elliptical or streamlined, and is arranged so that the short side of the ellipse or streamlined cross section faces the direction of blood flow, which reduces blood flow resistance and distances the separation point from the thrombus blocking device, thereby maintaining laminar blood flow along the thrombus blocking device as much as possible. Furthermore, the long sides of the cross section of the device for blocking thrombus are parallel to the direction of blood flow, and the impact force exerted by the blood flow on the short sides is converted into a bending moment relative to the long sides. The bending and rigidity of the long sides are greater, so that the deformation of the device for blocking thrombus when it receives an impact can be kept small, and the device can maintain its shape. The invention will now be described in detail with reference to the drawings and examples. First, please refer to Figure 1. Figure 1 is a diagram of the overall structure of the present invention (before use). As shown in Figure 1, the device for blocking blood clots in an embodiment of the present invention is composed of a curved shape wound with a single metal wire (see Figure 1). The overall structure of this embodiment consists of three parts: a device for blocking blood clots 101, a connecting ring 102, and a pull string 103. The device for blocking blood clots 101 is spiral-shaped and formed using a superelastic metal wire with a flat cross section, with an acute angle between the axis of the spiral and the width of the flat metal wire. This minimizes deformation of the device for blocking blood clots 101 and allows the metal wire to return to its original shape even after passing through a long straight pipe. Furthermore, the thickness of the device for blocking blood clots in the axial direction is greater than that of the flat metal wire (usually 1.5 times or more the thickness of the flat metal wire), thereby minimizing deformation of the device for blocking blood clots 101 when it is impacted by blood flow. This prevents turbulence caused by deformation of the blood flow. Furthermore, when thrombus accumulates on the thrombus-blocking device 101 and is subjected to the impact of blood flow, the cross section of the flat metal wire generates large local stress, which can cut the soft thrombus into small masses and avoid partial thrombus embolism. The connecting ring 102 is preferably made of a biodegradable metal material, such as a magnesium alloy or an iron alloy, or a highly biocompatible non-degradable material, such as a titanium alloy or stainless steel, and serves to connect the thrombus-blocking device 101 to the pull string 103. After implantation, the connecting ring 102 remains in the blood vessel wall for a certain period of time, during which time the connecting ring 102 undergoes endothelialization, with the rate of endothelialization being faster than the rate of degradation. The pull string 103 is intended to allow the thrombus-blocking device to be immediately removed by pulling out the pull string 103 if an unexpected problem occurs after implantation in the blood vessel. The pull string 103 is made of an absorbable suture that can withstand tension. Figure 2 shows a structural diagram of an embodiment of the present invention. The thrombus blocking device 105 is made of a single superelastic metal wire, with a spiral shape formed using a superelastic metal wire with a flat cross section. The fixing portion 107 can fix the thrombus blocking device to the blood vessel wall by tension. The diameter of the central blocking portion 108 is smaller than the smallest diameter of the target thrombus. The advantage of this embodiment is that foreign matter does not lie on the blood vessel wall. In the previous embodiment, the foreign matter may eventually be decomposed and endothelialized, but this does not happen in this embodiment. FIG. 3 shows a cross-section of a single metal wire of the present invention. From FIG. 3, it can be seen that the cross-section of the single metal wire is nearly elliptical, including a major axis 112 and a minor axis 115. The minor axis 115 of the single metal wire faces the direction of blood flow and is oriented tangent to the direction of blood flow. Furthermore, the ratio of the minor axis 115 to the minimum cutoff diameter 109 must be less than or equal to the maximum elastic deformation modulus of the material. Figure 4 shows a comparison of spirals wound around the short side and around the long side. For an oval flat metal wire, winding it around the short side reduces stress on the material surface and allows the device to recover its shape. In Figure 4, the left side shows the spiral wound around the long side, while the right side shows the spiral wound around the short side. Figure 5 shows an embodiment of the present invention facing the direction of blood flow. Figure 5 shows the thrombus blocking device 105 facing the direction of blood flow, with the minimum blocking diameter 109 being the smallest diameter spiral loop of the thrombus blocking device 105. FIG. 6 shows a cross-sectional view taken along the line AA in FIG. 5. FIG. 7 shows an enlarged view of the portion within the circle in FIG. 6. In this embodiment, the cross-section of the single metal wire is streamlined. In the portion within the circle 110, the angle 113 between the long axis 112 of the cross-section of the single metal wire and the main helical axis 111 of the thrombus blocking device is an acute angle of less than 45 degrees, preferably less than 30 degrees. In this case, when blood impinges on the short side of the cross-section, the blood flows along the surface of the thrombus blocking device, making it difficult for local vortex or rotational flow to occur. When the angle is within the acute angle range, negative pressure is not generated in the local flow field of the blood flow. In practical use, finite element analysis was used to simulate the effect of different cross-sectional designs of the clot blocking device on the pressure and blood flow on the blood vessel wall. In the simulation, the blood vessel wall was assumed to be in a systolic (high pressure) state, and its inner diameter was 10% smaller than the outer diameter of the clot blocking device. The systolic pressure was 120mmHg, the diastolic pressure was 80mmHg, and the pressure and flow velocity changes of the major branch arteries (brachial artery, carotid artery) were used as boundary conditions. The results are as follows: The thrombus-occluding device with a circular cross section and a diameter of 0.25 mm exerted a maximum instantaneous pressure of 52.3±7.8 kPa against the vessel wall. The local blood pressure difference before and after the device, which had a circular cross-section and a diameter of 0.25 mm, was approximately 7.5 mmHg. The device for blocking blood clots, with an elliptical cross section measuring 0.25mm in major axis and 0.12mm in minor axis, exerted a maximum instantaneous pressure of 27.6±4KPa on the blood vessel wall. The local blood pressure difference before and after the oval-section clot-blocking device was approximately 5.7 mmHg. Compared with circular cross sections, elliptical cross sections exert less pressure on the local vessel wall and are less likely to cause vascular lumen proliferation. Furthermore, the blood flow pressure drop of an elliptical cross section is much smaller than that of a circular cross section, which better maintains the pressure and flow rate of each segment of blood flow and reduces the impact on local blood flow. This effect is particularly pronounced when the length-to-width ratio of an elliptical cross section is 1.5 or greater. Those skilled in the art may make other modifications within the scope of the creative spirit of the present invention, and all such modifications derived from the creative spirit of the present invention shall fall within the scope of protection of the present invention. [Industrial Applicability]

[0007] The present invention provides a device for blocking thrombi, which is made by preforming a metal wire or tape with an oval or flat cross section into a predetermined spiral shape wound around the short side. When the formed thrombus blocking device is inserted into the target blood vessel through a tubular object, the elasticity of the material allows it to return to the predetermined shape, thereby achieving the purpose of blocking embolism. The present invention realizes a device that can easily return to the predetermined shape with a smaller curvature and causes less interference with blood flow.

Claims

1. The present invention provides a device for blocking blood clots, which uses a metal wire or tape, oval or flat in cross section, pre-formed into a predetermined spiral shape wrapped around the short side. The shaped thrombus blocking device is inserted into the target blood vessel through the tubing during use, and the elasticity of the material allows it to return to its predetermined shape, thereby achieving the purpose of blocking emboli. The present invention realizes a device that can easily return to its predetermined shape with a smaller curvature and has less interference with blood flow.

2. In the above-mentioned thrombus blocking device, the cross section of the metal wire or metal tape is elliptical or streamlined.

3. The above-mentioned thrombus blocking device is characterized in that the short side of the elliptical or streamlined shape faces the direction of blood flow and is disposed so as to be in contact with the direction of blood flow.

4. The above-mentioned thrombus blocking device is characterized in that the long side of the elliptical or streamlined shape is parallel to the direction of blood flow.

5. The above-mentioned thrombus blocking device is characterized in that the length to width ratio of the elliptical or streamlined cross section is 1.5 or more.

6. The above-mentioned thrombus blocking device is characterized in that the ratio of the short side to the minimum blocking diameter is equal to or less than the maximum elastic deformation rate of the material.

7. The above-mentioned thrombus blocking device is characterized in that the angle between the axis of the spiral and the major axis of the elliptical or streamlined cross section is an acute angle.

8. In the above-mentioned thrombus blocking device, the angle is 30 degrees or less.

9. The above-mentioned thrombus blocking device is characterized in that the angle between the axis of the spiral and the width of the elliptical or streamlined cross section is an acute angle.

Images