RU206723U1 - PERSONALIZED MITRAL VALVE PROSTHESIS RING WITH VARIABLE RIGIDITY - Google Patents

Abstract

The utility model relates to medical technology and can be used in cardiac surgery for reconstructive operations on the affected natural mitral valves of the human heart to restore their normal function. The technical result of this utility model is the creation of a prosthetic ring for mitral valve annuloplasty, which allows adaptation at the preoperative stage. its geometry to the individual characteristics of the patient - to provide the patient-specific shape and size, as well as to individually adapt the rigidity of each zone of the ring - to provide individual mobility of its areas This task is carried out due to the fact that part (s) of the prosthesis ring is made in the form of a mesh-hollow structure, which is designed individually, based on the preliminary preoperative analysis of the anatomy of the end patient, which, due to the combination of geometric elements - beams and holes, allows you to vary the geometry of the prosthesis ring and the required hardness zones.

Description

The utility model relates to medical technology and can be used in cardiac surgery for reconstructive operations on the affected native valves of the human heart to restore their normal function.

Diseases of the mitral valve have a significant prevalence in the world, affecting ~ 1.7% (according to some data, up to 2-3%) of the population of developed countries. Moreover, the frequency of their development is strictly correlated with age - in patients over 75 years of age, mitral defects reach 10%. As a result, more than 300,000 people around the world undergo open heart surgery annually to treat mitral valve defects. The most common form of clinical manifestation is mitral regurgitation with retrograde systolic flow from the left ventricle to the left atrium, the correction of which is carried out by two main methods - complete valve replacement or annuloplasty. It is annuloplasty with the improvement of constructions and approaches that is becoming the standard of mitral regurgitation interventions for most etiologies. This approach allows restoring the function of the valve and subvalvular apparatus with their preservation, which is impossible to achieve with prosthetics. The goal of annuloplasty is to restore the physiological geometry of the mitral valve through a combined operation on the leaflets and annulus fibrosus with the implantation of an annuloplasty device - a support ring.

With the development of technology and knowledge about the anatomy of the normal and pathological mitral valve, manufacturers and developers have provided the modern surgeon with a significant arsenal of designs and methods for performing annuloplasty. Thanks to this, it became possible to solve various individual tasks - an isolated change in the perimeter of the mitral valve; preservation of dynamics in the cycle "systole-diastole"; radical correction of shape and size; zoned correction (rear sash only), etc. In addition, devices have appeared that are implanted in a minimally invasive transcatheter method, which makes it possible to reduce the trauma of such a procedure, which has become especially important for high-risk patients.

Known support rings for mitral valve annuloplasty, described by a series of patents (US patent No. 9,526,615 B2, publ. 12/27/2016; No. 7,993,396 B2, publ. 08/09/2011; No. 8,382,828 B2 publ. 02/26/2013). The rings can be closed or open rigid or semi-rigid D and C-shaped contours, respectively. The authors state that the prosthetic rings are optimally sized to accommodate the most common degenerative valve pathologies: fibroelastic deficiency (FED), Marfan's disease or Barlow's disease, obtained through careful echocardiographic and intraoperative measurements. The rings can be flat or three-dimensional, i.e. have a raised portion (s) above the main plane to provide a more anatomical saddle shape. The rings can have constant or variable peripheral flexibility. These support rings are made of a metal semi-rigid core (cobalt-nickel alloy, titanium, nitinol), which is covered with a polymer material (usually silicone) and lined with synthetic fabric. These rings have proven themselves in clinical use and have proven effectiveness, which demonstrates the results of the Physio I and Physio II annuloplasty prosthesis rings (Edwards LifeSciences, USA).

The disadvantage of these technical solutions is the impossibility of fully adapting the ring model to the patient's needs - a low degree of personification of such medical devices. Each manufacturer manufactures a series of standard sizes of rings - 8-10 units, which has strictly specified proportions, which can only be changed by changing the model. Given the significant variability of the anatomy of each patient, the selection of the desired shape can be difficult, or impossible in principle, because the design of serial rings cannot provide for the required combinations of geometry and properties - height and diameter; stiffness and shape; ellipticity and height; etc. Thus, the surgeon is forced to choose the closest, but not always the optimal solution for a particular patient. That is why the global trend in the development of medicine - personification and selection of individual products with individual properties for the patient is gradually being introduced into the field of heart valve surgery, and today there are personalized approaches to mitral valve plastics. The main concept of such personification is the creation of an individual ring shape, thanks to one or another technique, as well as imparting unique non-uniform physical and mechanical properties to products - first of all, the mobility of certain areas of the product, in order to preserve natural biomechanics. Experimental studies have shown that the creation of a unique specific geometry of the prosthetic ring can improve the outcome of mitral valve anatomy correction (Sundermann S.H. et al., Interactive CardioVascular and Thoracic Surgery, 2012). At the same time, in addition to the optimal form, it is necessary to provide physiological non-uniform movements in the "systole-diastole" cycle: the largest - in the region of the anterior leaflet (zones A1, A2), with small movements of other zones (P2, P3) (Lee A.P. et al. , JACC: Cardiovasc. Imaging, 2017).

Known prosthetic rings, the personification of which is made after implantation, due to physical impact (US patent No. 8,821,570 B2, publ. 09/02/2014; US patent No. 7,722,668 B2, publ. 05/25/2010; EU patent No. 3569195 A1, publ. 20.11.2019) ... The main element of these rings is made of materials capable of absorbing and deforming under the action of an external energy source, which can be, for example, acoustic, radio frequency, light, temperature or magnetic energy. The most common design is a core made of shape memory material (Nitinol), which is heated in the right places using miniature electrodes after the prosthetic ring has been implanted. As a result, the core material changes its shape and / or size, for example, shortening, which changes the shape and diameter of the entire product as a whole. For some products (US patent No. 8,821,570 B2, publ. 09/02/2014) such a transformation is possible even after the complete completion of the implantation procedure due to external electrodes removed percutaneously outside the patient's body and connected to an external source of thermal energy. At the same time, due to the creation of seals in certain sections of the spiral, it is possible to pointwise change the rigidity of the contour.

Providing such a transformation is possible due to the specific geometry of the core:

a) by the type of a spiral or several spirals;

b) telescopic implementation, in which part of the ring prosthesis is pushed inside itself due to the tubular structure.

The disadvantage of these technical solutions is the need to apply physical impact, i.e. the presence, albeit miniature, but additional equipment - a heater, a system for creating magnetic fields, acoustic exposure. Such a component requires additional skills from the surgeon in the work, and an understanding of what shape changes can be obtained. In addition, such a physical shaping effect on the ring core may be irreversible, i. E. changing the diameter of the ring or its shape incorrectly, there is a high risk of failure to correct the error. The technique of working with materials with shape memory has the ability to redefine the product by cooling it, but these technical solutions do not imply such a construct - the reverse extraction of thermal energy (cooling). The effect of magnetic or acoustic, in principle, does not have an antagonist, i.e. they cannot be undone. This problem becomes especially relevant for the variant of shaping after the complete completion of the procedure - with the help of electrodes brought out to the surface of the skin, in which an error in shaping will lead to the need for repeated intervention - transcatheter or open.

Another option for personifying and changing the shape of the prosthetic ring is the mechanical action described in (US patent No. 9,713,530 B2, published on July 25, 2017 and US patent No. 8,961,602 B2, published on February 24, 2015), implemented in the form of deformation of the ring using tensioners. The prosthetic ring is presented in the form of a folded springy structure, inside which there is a tightening thread, due to the shortening of which, the perimeter and shape of the ring are changed. This solution makes it possible to personalize the prosthetic ring during the procedure, while making such a change is reversible. By achieving the required degree of tension / release in the right places, the surgeon provides the required profile of the ring.

The disadvantage of these technical solutions is the impossibility to change the three-dimensional shape of the ring - height, bending in the necessary places, because the springy form of the structure is designed to change only the length of the perimeter and, therefore, the diameters of the ring, but not others - no less important characteristics that ensure the saddle shape and / or rigidity.

The closest to the claimed technical solution is a design (US patent No. 10,265,171 B2, publ. 04/23/2019), which implements the principle of creating a stable personalized mitral prosthesis ring based on a stranded wire component with a thermally fixed shape. The technical solution is based on a flexible metal (nitinol or nickel-cobalt alloy) wire of several strands, which is given the required patient-specific shape by baking in a mold above 500 ° C. This design, on the one hand, remains flexible enough to be delivered using minimally invasive transcatheter methods. On the other hand, during implantation, the prosthetic ring will take on a given shape, changing the shape of the mitral valve after it. In addition, such a ring can be given a unique size and geometry - diameters, heights, saddle shape, perimeter, optimally suited to the end patient.

The disadvantage of this technical solution is due to the method of imparting the final geometry - high-temperature molding (baking). To use such a prosthesis-ring, you need special equipment (oven), tooling (mold) to give the necessary bends and the shape of the ring; it is necessary to understand the modes of heat treatment, which lengthens the preparation for the implantation procedure and increases the complexity of the intervention in general. Another disadvantage of this technical solution is the personification of only the geometry, but not the properties (rigidity) of the prosthesis ring for certain zones of the central wire component.

The technical result of this useful model is the creation of a prosthetic ring for mitral valve annuloplasty, which allows to adapt its geometry at the preoperative stage to the individual characteristics of the patient - to provide the patient-specific shape and size, as well as to adapt the rigidity of each zone of the ring in isolation - to provide its individual mobility areas.

This task is carried out due to the fact that part (s) of the prosthesis ring is made (s) in the form of a discontinuous mesh-hollow structure, which is designed individually, based on a preliminary preoperative analysis of the anatomy of a particular patient, which is due to a combination of geometric elements - beams and holes , allows you to vary the geometry of the prosthesis ring and the required stiffness of the zones. Thus, the personification of form and properties is carried out at the preoperative stage due to the possibility of using rapid prototyping technologies.

The claimed device consists of a central non-planar metal core, closed kidney-shaped, forming a single central passage opening, and divided into at least two zones.

The difference is the implementation of at least one of the zones of the metal core in the form of a discontinuous mesh-hollow structure, which is a combination of round holes and beams, and the rest of the core zones are made in the form of a solid structure.

The principle and examples of the implementation of the claimed technical solution are presented in the figures:

in fig. 1A is a diagrammatic top view of a central metal core showing a six-membered zoning variation indicated in different colors;

in fig. 1B - the same for a four-zone design, indicated by different colors;

in fig. 1B - the same for two-term zoning, indicated by different colors;

in fig. 2A shows an example of one of the zones of the metal core in the form of a mesh-hollow structure providing mobility and flexibility in accordance with the patient-specific biomechanics of the mitral annulus fibrosus;

in fig. 2B - the same, an example of the opposite zone in the form of a mesh-hollow structure;

in fig. 2B - the same, an example of the simultaneous execution of two opposite zones in the form of a mesh-hollow structure;

in fig. 2G - the same, an example of the simultaneous execution of two adjacent zones in the form of a mesh-hollow structure;

in fig. 2D - the same, an example of the simultaneous execution of three unconnected zones in the form of a mesh-hollow structure;

in fig. 2E is the same, an example of the simultaneous execution of three adjacent zones in the area of the rear flap in the form of a mesh-hollow structure;

in fig. 2G - the same, an example of the simultaneous execution of four non-adjacent zones in the form of a mesh-hollow structure;

in fig. 2I - the same, an example of the simultaneous execution of four adjacent zones in the form of a mesh-hollow structure;

in fig. 2K - the same, an example of the simultaneous execution of five zones in a mesh-hollow structure;

in fig. 2L - the same, another combination of five zones;

in fig. 3A shows an exemplary embodiment of a mesh-hollow area based on large discrete circles;

in fig. 3B shows an example of a mesh-hollow zone based on small densely spaced circles;

in fig. 3B shows an example of a hollow mesh zone based on a pentahedron;

in fig. 3D shows an example of a mesh-hollow zone based on a hexagon;

in fig. 3D shows an example of a mesh-hollow zone based on a square section and a rhombus;

in fig. 4A shows a design variant combining two mesh-hollow zones of different design - with holes in the form of small circles and holes in the form of squares;

in fig. 4B shows a design option that combines two mesh-hollow zones of different designs - with holes in the form of small circles and large circles;

in fig. 5A is an isometric diagram of a central metal core showing a non-planar shape, an example of a six-zone design;

in fig. 5B - the same, describing a variant of a significant lift in the region of the posterior sash to adapt to a more patient-specific geometry of the support ring, an example of a six-zone design.

in fig. 5B shows an example of an asymmetric frame with widening in one of the zones (rear sash 3, P3).

in fig. 5D shows an example of an asymmetric frame in such a way as to ensure a reduction in length due to compression in two regions (front flap 1 and rear flap 1, i.e. A1 and P3).

Design.

The claimed device is a closed solid frame 1 of a non-planar shape, made in the form of a kidney-shaped shape, variable rigidity (Fig. 1A, 2A). The frame is zoned into at least two zones (Fig. 1A-B), for which an isolated or combined design in the form of a mesh-hollow structure 2 is possible. In this case, the remaining zones of the frame are made in the form of a solid structure 3 that does not contain holes or cavities. The purpose of creating a mesh-hollow structure 2 is to change the rigidity and mobility of the zone (s) to which it is applied, in order to provide the required biomechanics, laid down by the developer / designer of the personalized device. Thus, the prosthetic ring is a closed combination of mesh-hollow 2 and solid 3 zones.

The number of zones that can be mesh-hollow is at least one (Fig. 2A-E). In this case, such zones can be the following combinations, an example of the implementation of which is shown in the following figures:

1. any one zone (Fig. 2A, B);

2. any two zones - opposite, located side by side (Fig. 2C, D);

3. any three zones - located separately, located side by side (in the neighborhood) (Fig. 2D, E).

4. any four zones - adjacent or adjacent (in the neighborhood) (Fig.2G, I).

5. any five zones (Fig. 2K, L).

The formation of a mesh-hollow structure 2 is carried out by creating holes 4 of different shapes, which include, but are not limited to: circles (Fig.3A, B), ovals (Fig.2G), pentagons (Fig.3B), hexagons (Fig.3D ), quadrangles - squares or rhombuses (Fig. 3D). In this case, all mesh-hollow zones 2 can be made with the same shape of holes (Fig. 2B) or different, for example, one of the zones - with circles, the other - with squares (Fig. 4A). For the case of execution of mesh-hollow zones 2 of holes 4 of the same shape, they can differ in size, for example, small dense circles for one and large scattered circles for another zone (Fig. 4B). The size of the round holes 4 can range from 0.05 to 0.95 mm in diameter. The size of the holes in the form of polyhedrons (four-, five-, hexagons) can be from 0.05 to 0.95 mm along the length of the side. The size of the oval holes can be 0.0555 to 0.95 mm for the major axis of the ellipse, and 0.05 to 0.855 mm, the compression ratio of the ellipse (ellipticity) from 0.9 to 0.5. The density of holes 4 can be 0.2-5 per 1 mm ^{2 of the} area of the outer surface of the frame.

Regardless of the design of the zone in the form of a mesh-hollow 2 or one-piece 3 construction, the geometric shape of the zone can be varied in such a way as to provide an optimal patient-specific final shape - height, diameters, bends (Fig.5A-D). Thus, it is possible to create a closed symmetric or asymmetric kidney-shaped structure with a diameter of 15-45 mm, a height of 1-25 mm.

Materials.

The frame 1, regardless of the design of each of the zones - mesh-hollow 2 or solid 3, can be made of metal materials, examples of which may be, but are not limited to:

1. titanium and its alloys: incl. powder or porous (CL 42TI; CL 41TI ELI);

2. stainless steel of medical alloys, incl. powder (304, 316, CL 92PH alloys);

3. Super-elastic titanium nickelide or with shape memory effect: wire, or tubular, or sheet (SE506, SE508, SE510).

Also, the frame 1 can be made of polymeric biocompatible materials that are approved for use in implantable devices for long-term contact with blood. An example of such materials are representatives of the group of polyethylene, polyvinyl chloride, fluoroplastic, polyacrylates, group of polyamides; materials based on lactic and / or glycolic acid, as well as their polyester combinations; polyetheretherketones.

Functioning.

The function of the frame 1 is to create the necessary rigidity to return the shape of the pathologically altered annulus fibrosus to normal. In this case, the frame 1, due to its zoned, mesh-hollow structure 2, can flexibly bend in this zone (s) 2 and, therefore, provide the overall mobility of the frame, depending on the requirements for a particular patient. For example, when executed in the form of a mesh-hollow structure of 2 lateral opposing zones (Fig. 2B), the possibility of greater mobility along the short axis of the kidney-shaped ring is provided. In the case of a technical device with three adjacent mesh-hollow zones 2 in the region corresponding to the posterior leaflet of the mitral valve (Fig. 2E), greater mobility of the posterior fold is provided.

Manufacturing methods.

The fabrication of the frame 1 is carried out according to known technologies, for example, using additive technologies - 3D-printing with metals or polymers based on laser sintering technology, extrusion by layer-by-layer fusion, photopolymerization, or a combination of appropriate techniques. In addition, subtractive technologies can be used for manufacturing - laser cutting, computer numerical control (CNC) milling, electroerosion, evaporation, material dissolution, drilling, turning, gluing, planing, or a combination of appropriate techniques. Another manufacturing method can be casting based on known technologies - injection molding, compression, vacuum, mechanical or free forming, thermoforming, sintering, hot bending, or a combination of appropriate techniques. It is also possible to use combinations of the described technologies from different groups, for example, 3D-printing and electroerosion; milling, laser cutting and drilling; etc.

Product personification, calculation.

The calculation of the location of the holes 4, forming the mesh-hollow structure 2: their number, shape, areas for use, is carried out at the stage of preoperative planning by means of preliminary multidisciplinary analysis. This analysis is based on the following data: the available literary knowledge about the biomechanics of the normal and pathologically altered fibrous ring of the mitral valve; requirements of the surgeon and / or surgical team planning the intervention; safety requirements for the strength and durability of the functioning of the entire personalized prosthesis for mitral valve annuloplasty; calculated data on the stress-strain state of the prosthesis-ring and other, potentially weighty arguments and hypotheses.

Biomechanical aspects of this planning include, but are not limited to, data on changes in the diameters of the annulus fibrosus in the systole-diastole cycle, changes in the height and angle of planarity, described, for example, in the articles:

F. Mahmood, J. H. Gorman, B. Subramaniam, R. C. Gorman, P.J. Panzica, R.C. Hagberg, A.B. Lerner, P.E. Hess, A. Maslow, K.R. Khabbaz, "Changes in mitral valve annular geometry after repair: Saddle-shaped versus flat annuloplasty rings," Ann. Thorac. Surg., 2010, doi: 10.1016 / j.athoracsur.2010.03.119.

I.Yu. Zhuravleva, P.M. Sharifulin, A.V. Bogachev-Prokofiev, D.V. Nushtaev, O. Yu. Malakhova, D.P. Demidov, A.M. Karaskov, "Creation of a 3D model of the left heart from echocardiography: a tool for the development of transcatheter valves", Russian Journal of Cardiology, no. 8, pp. 75-81, Jan. 2017, doi: 10.15829 / 1560-4071-2017-8-75-81.

F. Mahmood, B. Subramaniam, J.H. Gorman, R.M. Levine, R.C. Gorman, A. Maslow, P.J. Panzica, R.M. Hagberg, S. Karthik, K.R. Khabbaz, "Three-Dimensional Echocardiographic Assessment of Changes in Mitral Valve Geometry After Valve Repair", Ann. Thorac. Surg., 2009, doi: 10.1016 / j.athoracsur.2009.07.007.

M. Ryomoto, M. Mitsuno, M. Yamamura, H. Tanaka, S. Fukui, N. Tsujiya, T. Kajiyama, Y. Miyamoto, "Is physiologic annular dynamics preserved after mitral valve repair with rigid or semirigid ring?", Ann. Thorac. Surg., 2014, doi: 10.1016 / j.athoracsur.2013.09.077.

Requirements of surgical specialists may include requirements to ensure the required diameter (s) of the ring prosthesis to ensure the effectiveness of the entire annuloplasty procedure, requirements to ensure safety and injury to surrounding tissues - for example, the circumflex artery passing near the intervention area.

The design safety requirements for the strength and durability of the functioning of the entire personalized prosthesis for mitral valve annuloplasty can be the design requirements for the resistance to fracture formation under a single load, as well as the number of compression / extension cycles under repeated exposure (200 million cycles), which are regulated by GOST RF.

The calculated data on the stress-strain state are the results of numerical or analytical calculations using known technologies and approaches - the finite element method, the finite difference method, the immersed boundary method, or a combination of the corresponding methods.

Thus, on the basis of a set of data, the team planning the intervention determines the geometry (shape) of the zones, the need to implement it in the form of a mesh-hollow 2 or one-piece 3 structure and the parameters of the mesh-hollow structure. After that, the manufacturer, using the manufacturing technologies and materials described above, makes an individual, personalized prosthetic ring, provides sterilization, packaging according to known technologies and transfers it to the consumer.

Usage example.

The surgical team performing the intervention on the mitral valve, after receiving a personalized mitral valve annuloplasty prosthesis from the manufacturer, implants it under the sterile conditions of the operating room using known technologies. For example, in the following scenario:

After providing standard surgical access to the mitral valve, using cardiopulmonary bypass, the operating nurse opens the package with the device, removes it, maintaining sterility, and then hands it over to the operating surgeon. The surgeon fixes the prosthetic ring to the native fibrous annulus of the mitral valve using surgical suture material, applying 4-15 separate U-shaped sutures or using a continuous suture, thereby attracting biological tissues to the frame and restoring the obturator function of the valve - annuloplasty. After that, the surgeon ties the knots, makes sure that the sutures are correctly sutured - there is no detachment of the prosthetic ring around the perimeter from the patient's tissues, no threads get into the area of the valve opening, and completes the intervention according to the standard scenario.

Claims (1)

Personalized mitral valve annuloplasty prosthesis, consisting of a central non-planar metal core, closed kidney-shaped, forming a single central passage opening, and divided into at least two zones, characterized in that at least one of the zones of the central metal core is made in the form of a discontinuous a mesh-hollow structure, which is a combination of round holes and beams, and the rest of the core zones are made in the form of a solid structure.

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