CARDIAC SUPPORT DEVICE WITH STRUCTURED SURFACE

Description

Technical field

[0001] The present invention relates to a cardiac support device comprising an implant with a shell, wherein the shell has a structured surface that promotes the ingrowth of connective tissue. Background of the invention

[0002] Disease can reduce the heart's pumping function, a condition also known as heart failure. Heart failure is of great and growing importance from both a medical and economic perspective. In the second decade of this century, 23 million people worldwide will suffer from heart failure, with an annual incidence rate of 2 million new cases. In the USA alone, approximately 5 million people currently suffer from heart failure, with an annual incidence rate of around 550,000 new cases. Within this decade, the number of people over 50 in the USA alone will more than double to over 10 million. The same applies to the European continent.

[0003] Heart failure can be caused by impaired contractility or filling of the heart due to damage to the heart muscle (myocardium). Elevated blood pressure can lead to increased resistance to pumping, which can also negatively affect the heart's pumping function. The heart's pumping function can also be reduced by leaky valves, such as a leaky aortic or mitral valve.

[0004] Various types of heart failure can be treated with medication or surgery. In addition to other treatment methods, supporting the heart's pumping function with an implant that exerts mechanical pressure on the heart and thus improves its pumping capacity represents a promising treatment approach that addresses the various causes of heart failure.

[0005] A cardiac support device can consist of an implant with a shell. Expandable units can be attached to or within the shell, which can be used to exert mechanical pressure on the heart. The cardiac support device can include a supply unit connected to the implant. A cardiac support device with a self-expanding shell is described, among other places, in EP 2 752 209 A1.

[0006] A mechanical ventricular assist device (VAD) can also be designed without expandable units and thus be a passive VAD. Passive VADs are also known as cardiac bands, cardiac harnesses, diastolic recoil devices, or cardiac harnesses. Passive VAD is described, among other places, in EP 2 456 483 B1.

[0007] EP 3 115 023 A1 discloses a device for applying substances to the epicardial surface of the heart, wherein the device comprises a frame structure and a shell.

[0008] The object of the present invention is to improve the biocompatibility of the implant. A further object is to provide a shell that forms a suitable abutment for a cardiac support device. Summary of the invention

[0009] The present invention relates to a cardiac support device as defined in the claims. The cardiac support device according to the invention comprises an implant with a shell, the shell having an inner surface and an outer surface. The inner surface faces the heart and is designed to contact the epicardium when implanted. The outer surface faces away from the heart and is designed to contact the pericardium when implanted. The inner and outer surfaces of the shell have a textured surface that promotes the ingrowth of connective tissue. The texture that promotes tissue ingrowth can be porous and / or rough. The device can further comprise at least one expandable unit that can exert a force on the heart. The at least one expandable unit can have a textured surface that promotes tissue ingrowth.The device can also be designed without an expandable unit and thus be a passive cardiac support device. Alternatively, the cardiac support device can be an active cardiac support device and include at least one expandable unit and / or at least one electrode.

[0010] The surface of the covering can be porous. The surface of the covering can include pores, the pores having a size of 1 µm to 1000 µm, particularly 10 µm to 500 µm. Preferably, the pores have a size of 40 µm to 300 µm. The pores can promote the ingrowth of tissue, especially connective tissue.

[0011] The surface of the casing can include a rough surface. The rough surface can have a roughness of 1 µm to 1000 µm, in particular 10 µm to 500 µm. Preferably, the rough surface has a roughness of 40 µm to 300 µm.

[0012] The surface of the casing can include a surface coating. The surface coating can be a porous material. The porous material can be a foamed layer, a layer packed with small solids, a honeycomb structure, or fibers. The surface coating can also be a rough layer.

[0013] Alternatively or additionally, the rough and / or porous surface of the casing can be achieved through surface modification. The resulting surface can exhibit the pore sizes / roughnesses described above. Alternatively or additionally, a rough and / or porous surface can also be produced by primary forming.

[0014] Such porosity / roughness can promote the ingrowth of tissue, particularly connective tissue. A porous or rough structure of the implant shell can prevent macrophages or giant cells from recognizing the large, planar surface of the implant as a continuous, uninterrupted surface. Solid structures between the cavities of a porous structure, or the peaks and valleys of a rough structure, can be perceived by macrophages and giant cells as sufficiently small foreign bodies to allow encapsulation and ingrowth of connective tissue directly onto the shell's surface to be successful. Therefore, the shell's surface can exhibit a porous or rough texture with a pore size or roughness ranging from 1 µm to 1000 µm, 10 µm to 500 µm, and especially between 40 µm and 300 µm.

[0015] The invention also relates to methods for manufacturing a cardiac support device comprising an implant with a shell, wherein the shell has a structured surface that promotes the ingrowth of tissue, in particular connective tissue. One method may comprise providing a shell and applying a porous or rough coating to the surface of the shell. Alternatively or additionally, one method may comprise providing an implant with a shell and modifying the surface of the shell to create a porous or rough surface. Overview of the figures

[0016] Figure 1 shows an embodiment of an implant for a cardiac support device. Figure 2 shows a cross-section through a heart with a shell and an expandable unit Figure 3 shows the cascade of encapsulation Figure 4a -bshow a cross-section through the heart with proliferation around the myocardium, caused by a non-biocompatible sheath. Figure 5a -b show a cross-section through a heart with an encapsulated shell without proliferation around the myocardium or pericardium. Figure 6a -b shows a section through an implanted shell with a structured surface according to the invention. Figure 7a -b show an image or a schematic representation of a section through a shell according to the invention with a porous and a rough surface. Detailed description

[0017] The present invention relates to a cardiac support device as defined in the claims. Embodiments according to the invention are described in more detail below with reference to the figures.

[0018] Figure 1Figure 1 shows an example of a human heart (1) as well as a shell (38), a casing (21) with expandable units (23), sensors (33) and / or electrodes (34), a cable (32) with a connector (36), a catheter (37) of a delivery system, a pericardium (13), and a pericardial closure (35). The shell shown is made of a wire mesh. However, a shell (38) is not essential for the function of the cardiac support device (2) and can be omitted. In particular, if a casing (21) is used that can itself form a suitable support, the shell (38) can be omitted.

[0019] The shell (21) is preferably designed to at least partially enclose the heart. The shell preferably covers the lower half of the heart. Furthermore, it is advantageous if the shell and / or the expandable units of the shell do not extend beyond the plane of the heart's valves. Expandable units at the level of the heart valves can potentially impair valve function. The shell may also have recesses to better conform to the anatomy of the heart. For example, the shell may have a recess for the vena cava. This ensures a better fit and prevents contact with the vena cava. If the vena cava is compromised, it can lead to venous congestion.

[0020] In the Figure 1Numerous elements, such as expandable units (23), sensors (33), electrodes (34), cables (32), catheters (37), etc., are shown, which are also not essential to the invention. A cardiac support device (2) without an expandable unit (23) is a passive cardiac support device (2) (also known as a cardiac band, cardiac harness, diastolic recoil device, or cardiac harness) and can restrict the movement of the heart (1) during pumping activity, for example, the contraction during the ejection phase (systole) or the expansion of the heart (1) during filling (diastole) or as a result of growth. An active cardiac support device (2) can include expandable units (23) by means of which a force can be exerted on the heart wall so that the pumping function of the heart (1) is supported in systole and / or diastole.An active ventricular assist device (2) can include electrodes (34) by means of which the ECG of the heart (1) is measured for time-optimized control of the ventricular assist device (2) and / or the heart (1) is stimulated with electrical current to support its pumping function. It is also possible to use expandable units (23) and electrodes (34) to improve the pumping function of the heart (1).

[0021] Figure 2Figure 1 shows a cross-section through a heart (1) with a shell (21) according to the invention, which in the illustrated example comprises an expandable unit (23). The at least one expandable unit (23) can be positioned at any point on the outer or inner wall of the shell (21). The at least one expandable unit (23) can be a component of the shell (21). The shell (21) can form part of the expandable unit (23). The at least one expandable unit (23) can also be attached to the shell (21) by means of a positive fit, a force fit, and / or a material bond. The figure shows, by way of example, an expandable unit (23) that is attached to the inner wall of the shell (21) by means of an adhesive bond (24). The shell (21) has an inner surface facing the heart and an outer surface facing away from the heart. According to the invention, the inner and outer surfaces of the shell (21) have a structured surface (22) that promotes the ingrowth of connective tissue.The optional expandable unit (23) can also have a structured surface (22) that promotes the ingrowth of tissue, especially connective tissue.

[0022] A structured surface (22) that promotes tissue ingrowth can be porous or rough. A porous or rough surface (22) of the shell (21) and / or an expandable unit (23) can be manufactured by forming. Furthermore, a shell (21) and / or an expandable unit (23) can be provided with a porous or rough coating to create a structured surface (22) on the shell (21) and / or the expandable unit (23). Additionally, the surface of the shell (21) and / or an expandable unit (23) can be modified by surface transformation, for example, by chemical or physical surface transformation, to create a porous or rough surface (22).

[0023] The ingrowth of tissue, particularly connective tissue, is advantageous from a mechanical point of view. Tissue ingrowth increases the stiffness of the shell (21). This creates a good abutment for both active and passive ventricular assist devices. In the case of an active ventricular assist device, the tissue-stiffened shell (21) provides optimal support for the expandable units (23). In the case of a passive ventricular assist device, the tissue-stiffened shell (21) forms a support that limits the expansion of the heart (1). The increase in the stiffness of the shell (21) due to ingrowth is because tissue grows into the porous or rough material of the structured surface (22), and the structured surface (22), in combination with the tissue, is better able to absorb mechanical forces. The thickness of the mechanically load-bearing portions of the shell (21) is thus increased.The thickness or height of the structured surface (22) can range from 1 µm to 5 mm, preferably from 40 µm to 3 mm. If no tissue were to grow into the rough or porous material of the structured surface (22), the material of the structured surface (22) would be able to absorb or dissipate significantly less mechanical load.

[0024] Another advantage of a shell (21) with a structured surface (22) compared to a shell (21) with an unstructured surface is, for example, that the continuous core material of the structured shell (21) can be made thinner than in a shell (21) with an unstructured surface in order to provide an equivalent abutment.

[0025] Furthermore, ingrown tissue has superior mechanical properties with respect to tensile and compressive stress compared to a continuous material, such as a plastic. Tissues generally react very softly, compliantly, and / or flexibly to compressive stress, but stiffly to tensile stress. For example, a sheath (21) that is ingrown with tissue and thus connected to the heart (1) is moved along with the contraction of the heart (1) and thus compressed. The ingrown tissue reacts very softly, compliantly, and / or flexibly to this compressive stress. The entire sheath (21) with its structured surface (22) and the ingrown tissue thus behave very softly and flexibly during the contraction of the heart (1) and therefore do not impede the contraction and the systolic movement of the heart (1).If, however, a heart (1) were to enlarge too much, for example due to excessive filling or disease-related expansion of the myocardium, the membrane (21) and the ingrown tissue would be stretched. The ingrown tissue, thus subjected to tensile stress, reacts stiffly and can resist the expansion of the myocardium. Continuous plastics, on the other hand, would react similarly stiffly to compressive and tensile stress and could impede the natural cardiac movement, especially during systole, and reduce the cardiac output (1).

[0026] Furthermore, tissue ingrowth can enable fixation of the shell (21) relative to the heart (1), thus preventing unintentional dislocation of the implant. Dislocation of the implant can result in the cardiac support device no longer being able to perform its function of supporting the heart (1).

[0027] A further advantage of a shell (21) that promotes the ingrowth of tissue, particularly connective tissue, is that inaccuracies in the fit of the shell (21) to the individual patient's heart (1) can be compensated for by tissue ingrowth. For example, a rough or porous structure (22) is compressed during implantation of the device according to the invention at locations where the implant is locally closer to the heart (1). At such locations, the tissue would then grow in a thinner layer. In contrast, a rough or porous structure (22) on the device according to the invention can expand to its manufactured thickness or height at locations where the implant is not locally too close to the heart (1), thus filling gaps between the epicardium / myocardium of the heart (1) and the continuous core material of a shell (21) and / or an expandable unit (23) after implantation.The tissue would grow into the structuring layer (22) at such locations up to the full thickness of the structured surface (22). This would selectively result in tissue growing into the structured surface (22) with locally varying thicknesses. For example, manufacturing inaccuracies can be compensated for in this way. For example, a structured surface (22) on the inside of the implant, with a structuring height of more than 0.5 mm, 1 mm, 2 mm, 3 mm, 4 mm, or 5 mm, can also compensate for manufacturing inaccuracies, such as unevenness, of 0.5 mm, 1 mm, 2 mm, 3 mm, 4 mm, or 5 mm without the implant losing its fit to the heart (1).For example, structured surfaces (22) that promote tissue ingrowth can be used to achieve a patient-specific fit through selective tissue ingrowth, without requiring a complete patient-specific adaptation of the implant shape during the manufacturing process. Excessive structuring on the inner surface of a shell (21) of an active ventricular assist device (AVAD) can impair pumping function because tissue grows into the structuring and thus between the shell (21) and the epicoardium / mycoardium. Therefore, only a thin structuring can be applied to the inner surface of a shell (21), for example, with a structuring height (22) between 10 µm and 3 mm, and particularly between 40 µm and 2 mm. A thin structuring (22) on the inner surface of an implant can achieve a high level of AVAD performance.Different textures (22) can also be applied to the inner surface of a shell (21) and the outer surface of a shell (1). A thick texture (22) on the outer surface, for example, greater than 1 mm, 2 mm, 3 mm, 4 mm, or 5 mm, allows more tissue to grow into it and can provide a better mechanical support for, for example, an expandable unit (23). However, a thin texture (22) on the outer surface of a shell (21), for example, less than 3 mm, 2 mm, 1 mm, 0.5 mm, or 0.1 mm, can also have the advantage that less tissue grows between the implant and the pericardium, resulting in smaller implant dimensions and less pericardium expansion.

[0028] Another advantage of a sheath (21) that promotes the ingrowth of tissue, especially connective tissue, is its improved biocompatibility. This and other advantages are achieved by providing a sheath (21) with a porous or rough surface (22).

[0029] The presence of a porous or rough surface (22) can affect the biocompatibility of the implant and the patient's immune response to the implant. In simplified terms, the human body has several immune responses to a recognized implanted foreign body. These are (i) the degradation of the foreign body, (ii) the death of tissue surrounding the foreign body, which is particularly common with toxic foreign bodies, and (iii) the encapsulation of the foreign body.

[0030] Material degradation is not desirable in the device according to the invention. By appropriately selecting the materials, it can be ensured that the implant does not degrade within a predetermined period. For example, many silicones and some polyurethanes and polyesters are resistant to hydrolytic cleavage or oxidative degradation. Furthermore, it is desirable for the device according to the invention that the materials, or any degradation products or leachable components that may arise, are non-toxic.

[0031] After implantation of the device according to the invention, the body attempts to encapsulate the implant, which is located at least partially around the ventricles of a heart. The cascade that occurs in this process is described in Figure 3The following diagram, adapted from Szycher (Szycher's Handbook of Polyurethanes, Second Edition, CRC Press, 2013), illustrates the process of encapsulation. Initially, an acute inflammatory phase occurs, during which leukocytes are present, triggering an increasing influx of macrophages. In a subsequent chronic inflammatory phase, the number of leukocytes decreases, while macrophage influx remains high, with the onset of giant cell formation. Macrophages and giant cells are responsible for the encapsulation or entrapment ("phagocytosis") of a foreign body (macrophages for foreign bodies < 10 µm, giant cells for foreign bodies approximately 10–100 µm). Macrophages activate fibroblasts. Toward the end of the chronic phase, these fibroblasts produce connective tissue, particularly collagen, which can be understood as matrix tissue for the healing process and represents the completion of the cascade.

[0032] If a foreign body has an unstructured surface and is too large for a giant cell to engulf, this can lead to frustrated phagocytosis. Giant cells accumulate, secreting further pro-inflammatory cytokines that recruit more macrophages and generate even more giant cells. This can be understood as an overreaction of the immune system, whereby the inflammatory process is repeatedly reignited on the surface of the implant, while in areas further away from the implant, the inflammatory process is complete, and collagen layers and granulation tissue are present. Over periods of days or even longer, millimeter- or centimeter-thick layers of collagen and / or granulation tissue can build up, manifesting, for example, as a growth.

[0033] A cross-sectional image showing growths (15, 16) around the myocardium (11) of a heart, as if caused by a non-biocompatible shell (21) without a structured surface, is schematically shown in Figure 4a and photographically in Figure 4b The figures show that the older layers of a completed inflammatory process are already present near the heart (15), whereas in the outer layers, located close to the implant surface, the deposits (16), e.g., fibrinous deposits (16), of chronic and acute inflammatory processes are visible. The outermost layer (21) is not shown in Figure b. Comparable growths (15, 16) can also occur on the pericardium (not shown in the figures), which may be caused by a non-biocompatible surface on the outer, non-heart-facing surface of the implant.

[0034] Growths (15, 16) can lead to a loss of fit or displacement of the implant and impair the heart's natural pumping function. This process can also lead to implant rejection or high energy consumption, potentially resulting in failure of the ventricular assist device.

[0035] A porous or rough surface structure of the shell (21) prevents macrophages or giant cells from recognizing the large, planar surface of the implant as a continuous, uninterrupted surface. Solid structures between the cavities of a porous structure or the peaks and valleys of a rough structure can be perceived by macrophages and giant cells as sufficiently small foreign bodies to allow successful encapsulation and ingrowth of tissue, particularly connective tissue, directly onto the surface of the implant. The surface of the shell (21) can therefore have a porous or rough surface with a pore size or roughness in the range of 1 µm to 1000 µm, 10 µm to 500 µm, and particularly between 40 µm and 300 µm.

[0036] The surface of the envelope (21) can have a porous or rough surface (22), which particularly favors or promotes the ingrowth of connective tissue. For this to occur, the roughness or porosity should be in the range of approximately > 40 µm. With roughness or porosity of approximately < 40 µm, cell ingrowth is favored over ingrowth of connective tissue. Once the entire surface is encapsulated with connective tissue, no further inflammatory phases occur. The encapsulation process is complete. A surface of the envelope (21) ingrown with connective tissue is shown schematically in Figure 5a and photographically in Figure 5b As shown, no inflammatory layers or growths form between the epicardium / myocardium (11) and the implant and / or between the implant and the pericardium (13). The shell (21) thus remains flexible and simultaneously forms a support for the heart and / or expandable units (23).

[0037] According to the invention, the shell (21) of the implant can have a porous surface (22) characterized by cavities within the continuum of the shell (21). With sufficiently high porosity, a porous material can be permeated by gases, liquids, or solids. Porosity can be expressed as a ratio of cavities to continuum. Porosity generally always leads to a decrease in the density of a workpiece. The cavities within a continuum can be geometrically undefined, irregular, and of complex shapes, for example, when produced by flocking, sintering, or leaching. Foaming can result in more regular geometries, resembling, for example, spheres or ellipsoids.

[0038] Regardless of the manufacturing process, porosity can be described by pore size. Pore size can be specified as the largest possible diameter of a sphere that can be precisely inscribed within a cavity. A porous material can contain a large number of cavities of varying pore sizes. Therefore, the term "pore size" will be used here to refer to the size of the predominant pores and / or the intended functional pore size. In addition to this pore size, smaller and / or larger pores may be present due to the manufacturing process, without this always being explicitly stated.

[0039] Porosity can also be quantified using pore density. Pore density can be expressed as the number of (sectioned) pores along a straight line through the material, as the number of pores in an imaginary or actual cross-section of the material, or as the number of pores in a defined volume of the material. Porosity can also be expressed as the ratio of void volume to the total volume of a body.

[0040] Pore ​​size, pore density, and the void-to-total-volume ratio are not independent parameters. They can be converted into one another through calculations. Therefore, the following discussion primarily focuses on the pore size, which also implies corresponding values ​​for pore density and void-to-total-volume ratio.

[0041] Porous materials can exhibit open or closed porosity. In open porosity, the individual pores are openly connected at contact points without an intermediate wall. In closed porosity, adjacent pores are not connected to each other but share at least one wall between the cavities.

[0042] In the device according to the invention, the shell (21) of the implant can also have a rough surface (22). Roughness describes a surface irregularity. A rough surface (22) can appear microscopically as a surface where the surface height differs in certain areas, usually by less than 1 mm. Roughness can be specified, for example, as roughness depth, maximum roughness depth, average roughness depth, arithmetic mean roughness value, smoothing depth, and / or profile bearing area. Roughness values ​​can also be specified in relation to an area. There are usually relationships between the roughness values, and many of them can be converted into one another. Therefore, in the following, roughness is specified as the arithmetic mean roughness value, with correspondingly converted values ​​applying to the other roughness values ​​without requiring separate specification.

[0043] In the device according to the invention, the shell (21) of the implant can comprise a rough surface (22) with or without the at least one expandable unit (23). In the device according to the invention, the shell (21) of the implant can comprise a combined porous and rough surface (22) with or without the at least one expandable unit (23).

[0044] The porous or rough surface (22) according to the invention promotes the ingrowth of tissue, in particular connective tissue, and thus prevents proliferation. Figures 6a and 6b Each shows a section through a successfully encapsulated capsule (21), which has a porous or rough surface (22) on both the cardiac and non-cardiac sides. It is clearly visible that there are no growths or inflammations on the myocardium (11) and pericardium (13). Figure 6aThe diagram schematically shows how tissue has grown into the structured surface (22) immediately following the pericardium (13) or the epicardium (12). Figure 6b The image shows a histological section with pericardium (13) and a membrane (21) into whose structured surface tissue has grown.

[0045] Figure 7a and bFigure 2 shows a cross-section through a shell (21) according to the invention. It is clearly visible that the upper surface of the shell (21) has a porous structure (22) and the lower surface of the shell has a rough surface (22). Both surface structures (22) promote the ingrowth of tissue, in particular connective tissue. Depending on the degree of porosity or roughness of the surface (22), targeted ingrowth of connective tissue can be promoted. The thicker the structures (22) are, the more connective tissue grows in and the longer it takes for the ingrowth of connective tissue to be complete. After ingrowth, the shell (21) is also fixed to the pericardium and thus forms an optimal support for expandable units and / or the heart. A structure as described in Figure 21 is also attached to the pericardium, thus providing optimal support for expandable units and / or the heart. Figure 1The depicted shell made of a mesh or with struts can thus be omitted. It is also possible for only certain areas of a shell (21) to have a structured surface (22), while other areas do not. Different areas can have surfaces (22) with varying degrees of structured texture. For example, areas behind an expandable unit can have a higher degree of structuring (22), for instance, to provide better mechanical resistance. Furthermore, areas behind or in front of expandable units or electrodes can have a higher degree of structuring (22) to allow more tissue to grow into the structured surface (22), thereby achieving better protection against injury to the epicardium, pericardium, and / or myocardium, as well as surrounding structures or organs, from the electrodes or elements of an expandable unit.Furthermore, areas behind or in front of expandable units or electrodes may have a less pronounced structuring to accommodate the thickness of these elements and to compensate for the unevenness they cause on the implant surface.

[0046] The different heights of the structuring (22) allow for a flat surface of the implant.

[0047] A casing (21) with a porous or rough surface (22) can be made from a wide variety of materials. The porous or rough surface (22) can be achieved by applying a coating, which may be made of the same or a different material as the casing (21). The porous or rough surface (22) can also be achieved by modifying the material of the casing (21), resulting in a material that is either the same or a modified version. Suitable materials for the casing (21) and / or the applied coating include, but are not limited to, PLA, PGA, PCL, PLLA, PLGA, PE, PTFE, ePTFE, polyester (e.g., PET), silicone, polyurethane, and numerous other plastics or spider silk.

[0048] The following describes various methods for manufacturing an implant comprising a shell with a porous or rough surface. Similarly, the subsequent descriptions for manufacturing a shell with a structured surface also apply to the manufacturing of an expandable unit with a structured surface. A shell and / or an expandable unit with a porous or rough surface can be produced by forming, by applying a porous or rough coating to a core material of a shell and / or an expandable unit, or by surface modification of a non-structured surface.

[0049] The porous or rough surface may already be present in the raw material for the casing, or it may be created during manufacturing, or it may be added after the casing has been shaped, for example in the form of a coating.

[0050] Materials that inherently have a porous or rough surface include, among others, foamed materials. Depending on the manufacturing process, these can exhibit varying degrees of porosity or roughness. During production, the foamed material can be treated with a gas-generating reagent. For example, water added during the process can react with functional groups in a plastic to produce a gas (e.g., CO₂), the release of which leads to foam formation and thus to surface texturing. An alternative to producing a foam-like material is 3D printing. Another alternative is the "leaching" process. In these processes, substances are added that are subsequently removed after polymerization of the plastic, for example, through crystallization, dissolution with a suitable solvent, or thermal melting.

[0051] Another material that inherently possesses a porous or rough surface is fibrous materials. Fiber materials can be produced, for example, by weaving, felting, braiding, or other processes. Therefore, casings made from these materials also exhibit a porous or rough surface. A casing according to the invention can be produced from a fibrous material by forming (e.g., shaping under the influence of heat) or by sewing. The casing according to the invention can also be produced by coating such fibrous materials as a structured surface onto a core material of a casing.

[0052] Other materials that inherently have a porous or rough surface can also be layers packed with small solid particles (see "sintering" or flocking) or a honeycomb structure.

[0053] Materials that do not inherently have a porous or rough surface can acquire one through surface modification, for example, by removing material from the casing. Suitable methods for material removal include chemical processes (e.g., leaching, etching, foaming, etc.) or physical processes (e.g., drilling, laser drilling, irradiation, electrical discharge machining (EDM), sandblasting, embossing, rolling, etc.).

[0054] It is also possible to create a rough or porous surface during the shaping process. The shell can be formed, for example, by dipping or casting. For this, a positive mold of a heart can be dipped at least once into a solution of liquid plastic (e.g., silicone, polyurethane, polyester) or coated with a solution of liquid plastic. The thickness of the shell material can be adjusted by the number of dipping or casting processes. Fewer dipping or casting processes result in thinner shells, while more dipping and casting processes result in thicker shells.

[0055] Between dipping or casting processes, pauses may be necessary for drying and bonding of the newly applied plastic (polymerization). Surface structuring can be achieved, for example, by applying structuring elements (e.g., flakes, spheres, crystals, geometrically defined or undefined bodies, foams, and / or spherical segments) to a dipped or cast shell whose outer plastic layers have not yet fully polymerized.

[0056] A shell with a structured surface that promotes tissue ingrowth can, for example, be manufactured using a casting process. This also applies to the casting of a shell (including injection molding, dipping, vulcanizing, etc.).

[0057] A rough or porous surface can also be achieved, for example, by creating irregularities on the surface of the mold itself. Surface irregularities and / or textures can be produced by etching, drilling, laser drilling, irradiation, electrical discharge machining (EDM), sandblasting, embossing, rolling, roughening, grinding, or milling the surface of the mold. When the shell is removed from the mold after casting, it exhibits the corresponding negative image of the mold's surface irregularity / texture as its textured surface.

[0058] Alternatively or additionally, a structuring element with a rough and / or porous surface can be applied to the mold, for example, textured paper, matting film, or structured foil. After the shell has been cast, the structuring element can be peeled off, leaving a corresponding textured surface on the shell.

[0059] Alternatively or additionally, a structured surface of a cover, which promotes tissue ingrowth, can be achieved by applying a rough or porous coating to the cover. Such a rough or porous coating can be applied to a cover in a flat form, for example as a cloth, film, or sheet, with thicknesses ranging from 0.1 mm to 10 mm, 0.5 mm to 5 mm, or particularly between 1.5 mm and 4 mm, and can be stretched or pulled over the cover.

[0060] A rough or porous coating applied to a shell can be elastic / deformable before application, even in a round, cylindrical form such as a hose or tube, with a wall thickness of, for example, 0.1 mm to 10 mm, 0.5 mm to 5 mm, or particularly between 1.5 mm and 4 mm. It can then be pulled / tensioned over the shell. The coating can be applied, for example, to a dipped or cast shell whose outer plastic layers are not yet fully polymerized. The coating is then stretched / pressed onto the shell until it has fully polymerized, thus bonding it to the shell. This process creates a stable bond between the applied coating and the shell that does not detach even under stress. The bond between the shell and the coating can be material-bonded and / or form-fit.

[0061] In this process, the thickness of the flat coating can be effectively reduced by drawing it over the shell and penetrating the not yet fully polymerized plastic mass, resulting in slightly thinner thicknesses than the original material. Furthermore, this method can lead to some distortion of the cavity geometries. For example, round cavities can be stretched by drawing them over the shell / mold, resulting in elongated cavities. In the case of spherical cavities, ellipsoidal cavities would then be created during manufacturing. Additionally, this manufacturing method can induce stresses in the shell and the coating due to deformation during the joining process. These stresses can cause deformations of the shell and coating in the finished product, resulting in a device that no longer conforms to the original heart shape.In this case, it may be necessary, for example, to heat-treat the shell with the coating on the positive mold to reduce or eliminate any stresses (annealing, tempering, normalizing, stress-relief annealing). The pore size / roughness of the coating's base material can be selected so that the pore size after manufacturing corresponds to the desired pore size.

[0062] Furthermore, a thermoforming or deep-drawing process can be performed on the coating to be applied before it is bonded to the shell. A pre-formed coating can thus be bonded to the shell without stress, preventing the formation of stresses that could degrade the bond between the shell and the coating.

[0063] If the shell is fully polymerized before the coating is applied, an adhesive can also be applied to the shell or to a pre-formed or non-pre-formed coating. The shell and the coating can thus be bonded together via an adhesive process. The adhesive can also be a hot-melt adhesive, in which case the shell and coating are simply brought into contact with each other initially, and the bond is activated by heating the contacting elements.

[0064] The casing can also be manufactured using thermoforming. In thermoforming, a thermoplastic material is shaped into the desired form using a positive or negative mold of a heart shape under the influence of heat. The raw material can be in flat or cylindrical form, for example, as a film, sheet, sheet, or as a tubular or tube-like semi-finished product. When using a negative mold of the heart shape, heated material can be drawn into the mold using a vacuum or negative pressure. The negative mold thus forms the outer contour / the side of the casing furthest from the heart. When using a positive mold of the heart shape, heated material can be drawn over the mold with or without a vacuum or negative pressure. The positive mold thus forms the inner contour / the side of the casing closest to the heart.Whether using a positive or negative mold, the mold surface can be designed in such a way that a textured pattern is created in the plastic of the shell during thermoforming. For example, the mold can have a roughened surface with a roughness or porosity of approximately > 40 µm. This surface texture can then be reproduced on the manufactured shell.

[0065] The porous or rough coating can also be bonded to the shell using thermal joining processes. For example, a coating not yet bonded to the implant can be applied to or over the negative / positive mold before thermoforming the shell. When the heated shell material is then drawn into or over the mold during the thermoforming process, the coating can bond with the molten shell material.

[0066] A pre-formed shell can also be reheated and / or partially melted on its surface, and a rough or porous coating can then be thermally bonded to the core material of the shell, for example, by applying pressure. For this purpose, the surface of a shell or coating can also be treated with a hot-melt adhesive or with a plastic that has a lower melting point than the core material of the shell or the coating material.

[0067] A shell with a structured surface, which promotes tissue ingrowth, can alternatively or additionally be produced by surface modification.

[0068] If a shell is manufactured using casting techniques, a sacrificial material can be applied to the surface of the mold, which is then removed after the shell is cast. A simple example of a sacrificial material is salt crystals. If these are applied to the mold before casting and then washed off with water afterward, a porous or rough surface is created. By selecting a suitable grain size for the salt crystals, the desired porosity or roughness can be achieved on the shell.

[0069] Additionally or alternatively, structuring additives, such as foaming or matting additives, can be added to a raw material and / or a semi-finished product. The raw material and / or semi-finished product can then be subjected to forming (primary forming or reshaping). After forming, the additives can be activated via chemical or physical mechanisms (e.g., leaching, dissolving, swelling, melting, etc.), thereby creating a structured surface through chemical reaction or mechanical mechanisms (e.g., surface cracking due to the release of reaction products from the additives).

[0070] A manufactured shell can be structured on its surface by perforating or drilling, for example laser drilling, in order to create a roughness or porosity of, for example, approximately > 40 µm following a casting, dipping or thermoforming process.

[0071] The material of a shell can also be only partially structured. For example, areas beneath which an expandable unit is located may not be drilled or perforated to prevent leaks that could lead to the exchange of fluids across the implant boundaries with the body or bodily fluids. Furthermore, the structuring can be applied at varying depths. Perforations or drill holes, or structuring in general, can extend through the entire shell material or only partially into the material. For instance, it is advantageous for the structuring of at least one expandable unit, or in areas of the shell beneath which an expandable unit is located, to extend only partially into the core material of the shell.For example, structuring / drilling / perforations can be limited to half the depth of the core material or be less than 200 µm, less than 100 µm, or less than 50 µm deep. This can prevent leaks or extend the lifespan of the implant / shell / at least one expandable unit.

[0072] Different areas of a shell can be structured using the same or different methods. For example, the heart-facing and non-heart-facing sides of a shell can be given a porous or rough texture using the same or different methods. For example, a texture on one side can be created by forming and on the other side by adding a coating. For example, a layer on one side can be created by coating and on the other side by surface transformation. For example, a coating on one side can be thermally bonded and on the other side by adhesive.

[0073] Suitable materials for the shell (21) and / or the applied coating include PLA, PGA, PCL, PLLA, PLGA, PE, PTFE, ePTFE, polyester (e.g. PET), silicone, polyurethane and numerous other plastics or spider silk.

[0074] Among polyurethanes, polyester urethanes, polyether urethanes and especially polycarbonate urethanes are suitable.

[0075] Polyester urethanes are stable against oxidative degradation and have good mechanical properties (high strength, abrasion resistance), but are susceptible to hydrolytic cleavage, which is particularly disadvantageous for implantations in moist environments, for example in the human body.

[0076] Polyether urethanes are more stable against hydrolytic cleavage, which makes them better suited for use in the moist body environment than polyester urethanes, but are susceptible to oxidative degradation.

[0077] Polycarbonate urethanes are more resistant to hydrolytic cleavage than polyether urethanes and more resistant to oxidative degradation than polyester urethanes. Therefore, polycarbonate urethanes may be better suited for permanent implantation in moist environments than polyester or polyether urethanes and can achieve longer lifetimes under hydrolytic, oxidative, enzymatic, and mechanical stress. Examples of polycarbonate urethanes include DSM Bionate® < PCU, DSM Bionate® < II PCU, and Lubrizol Carbothane™ < TPU (aliphatic, aromatic).

Claims

1. Heart assist device comprising an implant having a sheath (21), wherein the sheath (21) has an inner surface (22) and an outer surface (22), the inner surface (22) faces towards the heart and is configured to touch the epicardium (12) when implanted, the outer surface (22) faces away from the heart and is configured to touch the pericardium (13) when implanted, characterized in that the inner and the outer surface (22) of the sheath (21) has a structured surface (22) which promotes the ingrowth of connective tissue.

2. Heart assist device according to Claim 1, wherein the surface (22) of the sheath (21) comprises a porous surface (22).

3. Heart assist device according to Claim 1 or 2, wherein the surface (22) of the sheath (21) comprises pores, wherein the pores have a size of 1 µm to 1000 µm, in particular from 10 µm to 500 µm.

4. Heart assist device according to Claim 3, wherein the pores have a size of 40 µm to 300 µm.

5. Heart assist device according to Claim 1, wherein the surface (22) of the sheath (21) comprises a rough surface (22).

6. Heart assist device according to any of the preceding claims, wherein the surface (22) of the sheath (21) comprises a surface coating.

7. Heart assist device according to Claim 6, wherein the surface coating of the sheath (21) comprises a porous material.

8. Heart assist device according to Claim 7, wherein the porous material comprises a foamed layer.

9. Heart assist device according to Claim 7, wherein the porous material comprises fibres.

10. Heart assist device according to any of Claims 1 to 5, wherein the structured surface (22) of the sheath (21) is obtained by a surface conversion.

11. Heart assist device according to Claim 10, wherein the surface conversion of the sheath (21) generates a porous surface (22).

12. Heart assist device according to any of the preceding claims, wherein the heart assist device is an active heart assist device.

13. Heart assist device according to Claim 12, wherein the active heart assist device comprises at least one expandable unit (23).

14. Heart assist device according to any of Claims 1 to 11, wherein the heart assist device is a passive heart assist device.

15. Method for producing a heart assist device comprising: providing an implant having a sheath (21), wherein the sheath (21) has an inner and an outer surface (22), wherein the inner surface (22) faces towards the heart and is configured to touch the epicardium (12) when implanted, wherein the outer surface (22) faces away from the heart and is configured to touch the pericardium (13) when implanted, characterized by application of a porous or rough coating to the inner and the outer surface (22) of the sheath (21), wherein the coating promotes the ingrowth of connective tissue; or conversion of the inner and the outer surface (22) of the sheath (21), such that a porous or rough surface (22) which promotes the ingrowth of connective tissue is formed.