RU2648858C1 - Prosthetic cardiac valve - Google Patents

Abstract

FIELD: medicine.

SUBSTANCE: invention relates to implantable medical prostheses and can be used in cardiac surgery. Prosthetic cardiac valve comprises an annular body with stoppers of the locking flaps fixed in the body cavity. Part of the body cavity at the inlet is in the form of a confuser. Part of the body cavity at the outlet is made in the form of a diffuser. Part of the body cavity, located between the confuser and the diffuser, is made in the form of conjugate segments of the surfaces of three round cylinders, axes of rotation of which are parallel to the axis of rotation of the body and are displaced relative to the axis of rotation of the body by the same distance. Locking flaps are designed to interact with the diffuser surface by side planes sloped under the surface of the diffuser.

EFFECT: prosthesis makes it possible to ensure a homogeneous blood flow that overcomes the artificial valve in its path, reduce the loss of energy in the blood flow, improve the streamlining of the elements of the prosthesis with blood and, as a consequence, reduce the risk of deposition of thrombotic masses and growth of the pannus.

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Description

The invention relates to implantable medical prostheses and can be used in cardiac surgery.

Mechanical prostheses of heart valves are known, which include, as a rule, a ring-shaped body and a locking element in the form of two wings installed in the body with the possibility of alternating between open to pass the direct blood flow and closed positions to close the opening and access of limited volume of back blood flow .

An example of known constructions is the heart valve prosthesis disclosed in patent specification RU 2230531 C2, June 20, 2004, in which the presence of locking elements in the lumen of the internal passageway prevents the smoothing of the velocity profile and limits the possibility of improving the hemodynamics of valves of this type.

The closest analogue of the present invention (prototype) can be considered a prosthetic heart valve, disclosed in the description of the invention to patent RU 2370245 C2, 10.20.2009. The known prosthesis includes an annular body, bounded by the upper and lower ends, mounted in the body with the possibility of rotation to form a bore and its overlap, a locking element made in the form of three convex-concave sashes, and limiters of the movement of the sashes. A rectangular groove is made in each casement. The leaf travel stops are located on the upper end of the housing and are made in the form of hook-shaped protrusions that have a rectangular cross-section for interacting with through grooves of the wings when they are closed and opened. The leaf stoppers are equipped with stops to limit leaflet rotation. In the open position of the prosthesis, the flaps release the central part of the passage opening and pass the flow freely, without distortion.

However, when the surface of the body cavity is made in the form of a straight cylindrical surface with rather sharp transitions at the intersection with the flat surfaces of the upper and lower ends, the probability of separation zones is high. Separate flow zones at the inlet and outlet of the prosthesis contribute to disturbances and turbulence of the flow and increase the energy loss of the blood flow. The presence of tear-flow zones worsens the flow of blood over the prosthesis elements and, as a result, increases the risk of blood clots, initiates the process of pannus proliferation during endothelization of the valve cuff, which can lead to impaired mobility of the valves and prosthesis dysfunction.

The technical problem to be solved by the invention is the creation of a mechanical prosthesis with a reduced degree of disturbance of blood flow at the outlet of its body due to the reduction of the zones of separated flows of the outgoing blood stream.

The technical result of the invention is to preserve the homogeneous nature of the blood flow, overcoming the artificial valve in its path, reducing the loss of energy of the blood flow, improving the flow of blood over the prosthetic elements and, as a result, reducing the risk of thrombotic mass deposition and pannus proliferation.

The invention is expressed in the aggregate of essential features, in which a prosthetic heart valve containing an annular body with rotation limiters of the locking flaps fixed in the body cavity differs from the closest analogue in that a part of the body cavity at the inlet is made in the form of a confuser, part of the body cavity the outlet is made in the form of a diffuser, and the part of the body cavity located between the confuser and the diffuser is made in the form of interfaced segments of the surfaces of three round cylinders, the axis of rotation of which are parallel to the axis of rotation of the housing and offset relative to the axis of rotation of the housing by the same distance, while the locking flaps are configured to interact with the surface of the diffuser with side faces that are beveled under the surface of the diffuser.

In special cases of its implementation or use, the prosthesis can be made of pyrocarbon and contain a confuser surface oriented to the axis of rotation of the body at an angle of 6-10 °; diffuser surface oriented to the axis of rotation of the housing at an angle of 15-45 °; a part of the body cavity between the confuser and the diffuser, made in the form of mating segments of the surfaces of three round cylinders, the axis of rotation of which are offset relative to the axis of rotation of the body by the width of the diffuser; rotation limiters in the form of three hook-shaped protrusions placed on the end of the housing at the outlet, and locking flaps with through grooves for rotation limiters; rotation limiters located on the symmetry axes of the locking flaps; rotation limiters and rotation axes of three round cylinders located on the symmetry axes of the locking flaps; flaps with convex external surfaces and with concave internal surfaces and a body with an external annular groove for attaching the sewing cuff.

The influence of the features of the invention on its technical result is manifested in the fact that the prosthesis of the heart valve:

- minimizes the intensity of the formation of disturbances and zones of blood stagnation, reducing the energy loss of the blood flow spent on passing through an artificial valve;

- improves blood flow around prosthetic elements, reducing the risk of thrombosis and excessive growth of the pannus;

- provides high efficiency of the valve cross section, practically without resistance to flow when the valves are open;

- retains unchanged the shape of the structure of the blood flow, similar to the physiological;

- improves the flow around the zones of interaction of the locking flaps with a travel stop as the most possible zones of blood clots;

- lowers the mechanical trauma of blood cells when closing the prosthesis;

- eliminates mechanical vibrations (flutter) of the locking valve flaps when opening.

The studies showed that to ensure the achievement of the technical result, it is necessary to perform prosthetic surfaces with certain ranges of tilt angles of the confuser and the diffuser, as well as with a certain range of numerical values characterizing the execution of the part of the prosthesis body cavity located between the confuser and the diffuser.

To determine the boundary values of the numerical ranges, we used the method for calculating the hydraulic resistance known for the study of heart valves (Landau L.D., Lifshits E.M. - Theoretical Physics. T. 6. Hydrodynamics. 3rd ed., Rev. M .: Nauka Edited by Phys.-Math. Lit., 1986. Idelchik I.E. Handbook of Hydraulic Resistance / Edited by M.O. Steinberg, 3rd ed., Revised and revised M .: Mechanical Engineering, 1992).

The invention is illustrated by drawings, where in FIG. 1 and 2 show a prosthetic heart valve with closed flaps, respectively, a front view and a side view of the outlet of the annular body, and in FIG. Figures 3 and 4 show a tricuspid prosthetic valve of the heart valve with open leaves, respectively, a front view and a view from the side of the inlet of the annular body.

The heart valve prosthesis comprises an annular body 1 with rotation limiters 2 of the locking flaps 3 fixed in the body cavity 1. Part of the body cavity 1 at the inlet 4 is made in the form of a confuser 5. Part of the body cavity 1 at the outlet 6 is made in the form of a diffuser 7. Part 8 of the cavity of the housing 1, located between the confuser 5 and the diffuser 7, is made in the form of conjugated segments 9 of the surfaces of three round cylinders, the axis of rotation of which are parallel to the axis of rotation of the housing 1 and offset relative to the axis of rotation orpusa 1 the same distance. The locking sash 3 is made with the possibility of interaction with the surface of the diffuser 7 side faces 10, beveled under the surface of the diffuser 7.

The locking flaps 3 can have through grooves 11 for the rotation limiters 2. The rotation limiters 2 can be made in the form of three hook-shaped protrusions at the end of the ring-shaped housing 1, located at the outlet 6. An outer annular groove 12 can be made on the housing 1 for attaching the cuff .

When excessive pressure occurs from the inlet 4 of the cavity of the annular body 1, the locking flaps 3 rotate from the closed position to the equilibrium state in the open position.

When turning through the grooves 11 of the locking flaps 3 interact with the limiters of rotation 2.

Blood flows in the forward direction, and the central part of the inlet 3 of the housing 1 passes freely without distortion. The locking flaps 3 occupy an almost vertical position, without creating resistance to flow. The execution of the outer surfaces of the locking flaps 3 convex-concave provides the prosthesis with a greater opening.

Smooth narrowing at an angle of 6-10 ° made in the form of a confuser 5 of the cavity part of the annular body 1 from the inlet side 4 reduces the energy loss of the blood flow and improves the flow of blood over the prosthesis elements.

Smooth expansion at an angle of 15-45 ° of the cavity of the annular body 1, made in the form of a diffuser 7, can significantly reduce the intensity of the formation of vortices and separation zones emerging from the outlet 6 of the stream. As a result, there is a reduction in the energy loss of the blood flow, an improvement in the flow of blood around the prosthesis elements and, as a result, a decrease in the risk of blood clots and an increase in pannus.

Part 8 of the cavity of the housing 1, located between the confuser 5 and the diffuser 7, made in the form of mating segments of the surfaces of three round cylinders, the axis of rotation of which are parallel to the axis of rotation of the housing 1 and offset relative to the axis of rotation of the housing 1 by the width of the diffuser, increases the effective area of the passage opening prosthesis, which also leads to a decrease in the loss of energy of the blood flow through the prosthesis.

When closing the valve prosthesis, the locking flaps 3 are rotated in the opposite direction until they stop in the cavity of the housing 1 of their side faces 10, under the surface of the housing 1, made in the form of a diffuser 7.

Example

Were made 3 experimental samples of prosthetic heart valves with a landing diameter of 27 mm Ring-shaped housings with rotation limiters and locking flaps are made of pyrolytic carbon. Part of the body cavity at the inlet is made in the form of a confuser, part of the body cavity at the outlet is made in the form of a diffuser, and the part of the body cavity located between the confuser and the diffuser is made in the form of mating segments of the surfaces of three round cylinders, the axis of rotation of which are parallel to the axis the rotation of the housing and are offset relative to the axis of rotation of the housing by the same distance, while the locking flaps are made with the possibility of interaction with the surface of the diffuser by the side faces, sk sewn under the surface of the diffuser.

Samples were tested on a test bench in a steady stream and with a volume flow of 20 l / min.

The results of hydrodynamic tests are shown in table 1.

The performance of the test samples exceeds the requirements of ISO 5840.

Claims (10)

1. A heart valve prosthesis comprising a ring-shaped body with rotation limiters of the locking flaps fixed in the body cavity, characterized in that a part of the body cavity at the inlet is made in the form of a confuser, part of the body cavity at the outlet is made in the form of a diffuser, and part of the body cavity located between the confuser and the diffuser, made in the form of mating segments of the surfaces of three round cylinders, the axis of rotation of which are parallel to the axis of rotation of the housing and offset relative to the axis rotation of the body at the same distance, while the locking flaps are made with the possibility of interaction with the surface of the diffuser with side faces, beveled under the surface of the diffuser. 2. The prosthesis according to claim 1, characterized in that it is made of pyrocarbon. 3. The prosthesis according to claim 1, characterized in that the surface of the confuser is oriented to the axis of rotation of the body at an angle of 6-10 °. 4. The prosthesis according to claim 1, characterized in that the surface of the diffuser is oriented to the axis of rotation of the body at an angle of 15-45 °. 5. The prosthesis according to claim 1, characterized in that the part of the body cavity between the confuser and the diffuser is made in the form of interfaced segments of the surfaces of three round cylinders, the axis of rotation of which are offset relative to the axis of rotation of the body by the width of the diffuser. 6. The prosthesis according to claim 1, characterized in that the rotation limiters are made in the form of three hook-shaped protrusions located on the end of the housing at the outlet, and the locking flaps are made with through grooves for the rotation limiters. 7. The prosthesis according to claim 1, characterized in that the rotation limiters are located on the symmetry axes of the locking flaps. 8. The prosthesis according to claim 1, characterized in that the rotation limiters and the axis of rotation of the three round cylinders are located on the symmetry axes of the locking flaps. 9. The prosthesis according to claim 1, characterized in that the flaps are made with convex external surfaces and with concave internal surfaces. 10. The prosthesis according to claim 1, characterized in that the body is made with an outer annular groove for attaching the sewing cuff.

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