JP5392539B2 - Stentless artificial mitral valve and prosthetic leaflet - Google Patents

Description

  The present invention relates to a stentless prosthetic mitral valve and a prosthetic valve leaflet, and more particularly, to implant a valve in a heart during valve replacement due to valvular heart disease or the like, and to make the valve behave like an actual mitral valve. The present invention relates to a stentless prosthetic valve and a prosthetic valve leaf.

  Among human heart valves, the mitral valve is a one-way valve that exists between the left atrium into which blood from the lungs flows and the left ventricle that sends the blood flowing into the left atrium to the whole body. It consists of two leaflets called the posterior leaflet and is different in structure from other heart valves such as an aortic valve composed of three leaflets. In this mitral valve, the anterior leaflet and the posterior leaflet are located in an annular portion called an annulus, and are connected to the wall of the left ventricle via a filamentous chord. Here, in the systole of the heart, the left ventricle is in a positive pressure state, and the anterior and posterior cusps are in close contact with each other to become a valve occlusion state, while in the diastole of the heart, the left ventricle is in a negative pressure state. Then, the front leaflet and the rear leaflet are pulled away from each other to open the valve.

  By the way, when mitral valve obstruction insufficiency occurs due to the lesion causing damage to the mitral valve and blood flowing back from the left ventricle to the left atrium, as one of the treatment methods, the affected mitral valve is removed. There is a prosthetic valve replacement technique that replaces the prosthetic valve.

As such a prosthetic valve, a so-called biological valve formed using a living tissue such as a pig is known. As this biological valve, a two-leaf prosthetic valve is disclosed in Patent Document 1. This document proposes two types of prosthetic valves, a stent prosthetic valve having a frame called a stent, and a stentless prosthetic valve not having a stent. The former stent prosthetic valve is composed of a stent made of a wire material and forming the outer shape of the prosthetic valve, and first and second leaflets coupled to the stent. Here, the first and second leaflets are provided in a cloak shape when flattened, and are formed by living tissue excised from the porcine aortic valve. On the other hand, the latter stentless prosthetic valve is formed by stitching the first and second leaflets to the inner surface of a tubular body formed from a living tissue.
Special Table 2007-517595

  However, since the stent prosthetic valve deteriorates and deteriorates with time, the prosthetic valve must be replaced in a relatively short cycle, and it is difficult to adopt it for young patients whose lifespan is increased. There is. That is, since the first and second leaflets are intricately coupled to the stent, mechanical stress associated with the opening / closing movement of the valve is applied to these coupling portions, which causes deterioration of the function over time. To do. In particular, compared with the aortic valve part or the like, the mitral valve part has a larger mechanical stress at the time of closing, and the above-described deterioration and degeneration progress faster. The mitral valve is connected to the papillary muscle via a chord, but when replacing the mitral valve with the artificial valve, a part of the papillary muscle that becomes a part of the wall of the left ventricle is excised. Thereafter, the prosthetic valve to be replaced is sutured only around the heart annulus. For this reason, after valve replacement surgery, part of the papillary muscle remains excised, and the strength of the left ventricular wall is lower than before surgery, which may lead to a decrease in left heart function. . Furthermore, when manufacturing the stent prosthetic valve, since the sheet-like first and second leaflets must be bonded to the surface of the stent that is three-dimensionally complicated by the wire, the prosthetic valve manufacturing process Is not only complicated, but also requires a fine position adjustment during the coupling operation of the first and second leaflets so that the desired valve opening and closing movement is possible, and the artificial valve cannot be easily manufactured. is there.

  On the other hand, in the stentless artificial valve of Patent Document 1, since the outer shape is a straight tube shape, it is difficult to implant into the heart, and a high level of procedure is required of a doctor. It is difficult to use for patients. Further, even in the stentless prosthetic valve, as in the case of the stent prosthetic valve, there is a possibility that the left heart function is deteriorated after valve replacement. Furthermore, when manufacturing the stentless prosthetic valve, the first and second leaflets are coupled to the inner peripheral surface of the straight pipe while finely adjusting the position so that the desired valve opening and closing movement is possible. Therefore, there is a problem that the connecting operation is more difficult than the stent prosthetic valve and the manufacturing process of the prosthetic valve becomes more complicated.

  The present invention has been devised by paying attention to such problems, and its purpose is to make the valve behavior close to the actual without using a stent and to reduce the function of the heart after valve replacement. An object of the present invention is to provide a stentless artificial mitral valve and an artificial leaflet that can be expected to be suppressed.

  Another object of the present invention is to provide a stentless prosthetic mitral valve that can be implanted into the heart relatively easily and that is simple in construction and easy to manufacture.

(1) In order to achieve the above object, the present invention provides a stentless prosthetic mitral valve comprising a ring and an artificial leaflet that continues along the periphery of the ring.
The ring is composed of an anterior apex region and a posterior apex region that are bisected along the circumferential direction,
The artificial leaflet includes a bilaterally symmetric front leaflet forming member continuous to the front apex region, and a bilaterally symmetric back leaf tip forming member continuous to the back leaf side region,
The front leaflet forming member includes an upper edge joined to the ring, and a lower edge that is continuous with the upper edge and forms a bifurcated portion that opens downward.
The upper edge is a pair of left and right inclined edges that are inclined inwardly upward from the left and right ends, and a curve that is positioned between each of the inclined edges and that conforms to the curved shape of a portion of the front apex region. Composed of edges and
The rear leaflet forming member has a configuration in which an upper edge joined to the ring and a lower edge that is continuous with the upper edge and forms a bifurcated portion that is open on the lower side.

(2) Further, the present invention is an artificial leaflet that functions as an artificial valve implanted in the heart,
Consists of a front cusp forming member and a posterior cusp forming member that are symmetrical to each other,
The anterior cusp forming member includes an upper edge sewn to the annulus of the heart, and a lower edge that is continuous with the upper edge and forms a bifurcated portion that opens downward.
The upper edge is composed of a pair of left and right inclined edges that are inclined inwardly upward from the left and right ends, and a curved curved edge positioned between the inclined edges.
The posterior leaflet forming member is configured to include an upper edge sewn to the annulus, and a lower edge that is continuous with the upper edge and forms a bifurcated portion that is open on the lower side.

  In the claims and the specification, “up”, “down”, “left”, and “right” used for the artificial leaflets are “up” and “up” in the state of FIG. 2 unless otherwise specified. “Lower”, “Left”, and “Right”.

  According to the present invention, since it is formed without using a stent, there is no mechanical stress due to the presence of the stent, and deterioration over time of the prosthetic valve can be suppressed compared to a stent prosthetic valve. In addition, according to the experiments of the present inventors described later, it was demonstrated that when placed under the same pulsation as an actual heart, the valve behavior and hemodynamics very close to those of a human mitral valve are exhibited. Furthermore, by stitching each bifurcated portion of the anterior cusp forming member and posterior cusp forming member to the papillary muscle of the heart, the bifurcated portion functions like a chordae that existed before valve replacement, and partially resects It can be expected that the papillary muscle is strengthened and the decrease in left heart function due to resection of the diseased mitral valve is suppressed.

  Further, according to the stentless artificial mitral valve of the present invention, since the ring can be sutured to the heart annulus and the bifurcated portion can be simply sutured to the papillary muscle, it can be implanted into the heart. It can be used for infants with small hearts. Furthermore, the stentless prosthetic mitral valve has a simple structure, and it is only necessary to connect the artificial leaflet along the periphery of the ring when manufacturing the artificial valve. This eliminates the need for a simple coupling and simplifies manufacturing.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 shows a schematic perspective view of a stentless artificial mitral valve according to the present embodiment, and FIG. 2 shows a schematic development view of the stentless artificial mitral valve. In these drawings, the stentless prosthetic mitral valve 10 is an artificial mitral valve capable of performing valve behavior almost equivalent to that of a human mitral valve, and has a bicuspid valve structure composed of two leaflets. ing. The stentless artificial mitral valve 10 includes a sheet-like artificial leaflet 11 that forms a leaflet corresponding to the anterior leaflet and the posterior leaflet of the mitral valve, and a ring 12 that supports the artificial leaflet 11. Has been.

  The artificial leaflet 11 is formed by a bovine pericardium fixed with glutaraldehyde, and includes an anterior cusp forming member 14 and a posterior cusp forming member 15 that are symmetrical to each other. The artificial leaflet 11 can also be formed of a biomaterial collected from another animal or the like, or an artificial material such as biocompatible latex.

  As shown in FIG. 2, the front leaflet forming member 14 is connected to an upper edge 17 constituting an upper end portion thereof, and a boundary portion 18 positioned at the lowermost end of the upper edge 17, and a bifurcated portion 20 having a lower side opened. And a lower edge 22 that forms

  The upper edge 17 is connected to a pair of left and right inclined edges 24, 24 that are inclined inwardly upward from boundary portions 18, 18 at both left and right ends of the lower edge 22, and the inclined edges 24, 24. 24 and a curved edge 25 located in the vicinity of the center in the left-right direction. Here, the inclined edges 24, 24 extend substantially linearly between the boundary portions 18, 18 and the curved edge 25. The curved edge 25 has a curved shape having substantially the same curvature as a reference region 48 that is a part of a front apex region 44 described later in the ring 12.

  The lower edge 22 is a semi-parabolic side end edge 27, 27 extending inwardly downward from each of the left and right boundary portions 18, 18, and a horizontal extension extending inwardly from the side end edges 27, 27, respectively. It consists of edges 28 and 28 and a parabolic center edge 29 extending upward from the inner end of each horizontal edge 28 and 28.

  The maximum height L1 from the boundary portion 18 at the upper edge 17 is set to be shorter than the maximum height L2 at the lower edge 22.

  Further, the concave distance L3 in the vertical direction of the central edge 29 is set to be shorter than the maximum height L2.

  The rear leaflet forming member 15 is generally smaller in size than the front leaflet forming member 14, and is connected to an upper edge 31 that extends substantially horizontally and boundary portions 33, 33 at both left and right ends of the upper edge 31. At the same time, it comprises a lower edge 37 forming a bifurcated portion 35 whose lower side is open.

  The lower edge 37 includes skirt-shaped side edges 39 and 39 extending linearly so as to gradually spread outward from the boundary portions 33 and 33, and inner edges from the side edge edges 39 and 39, respectively. It consists of horizontal edges 40, 40 extending in a substantially horizontal direction, and a parabolic center edge 42 extending upward from the inner end of each horizontal edge 40, 40.

  The height L4 of the side edges 39, 39 is set to be longer than the concave distance L5 in the vertical direction of the central edge 42.

  The ring 12 has a substantially elliptical shape in plan view and can be elastically deformed. The ring 12 includes an anterior apex region 44 and a posterior apex region 45 that are divided into two along the circumferential direction.

  The front apex side region 44 is configured such that the upper edge 17 of the front apex forming member 14 is joined to the inner peripheral edge portion thereof, the reference region 48 to which the curved edge 25 is joined, and the left and right sides of the reference region 48. Located on both sides, it is divided into two remaining regions 49 and 49 where the inclined edges 24 and 24 are joined. Although the reference region 48 is not particularly limited, the reference region 48 is provided at a circumference of about 1/3 of the entire circumference of the ring 12. Further, each remaining region 49, 49 is provided with a circumferential length shorter than the length of each inclined edge 24, 24, and when the inclined edge 24, 24 is joined to the remaining region 49, 49, the front of the vicinity thereof. A certain amount of slack and wrinkles are generated on the surface of the point forming member 14.

  The rear apex side region 45 is provided at a position facing the reference region 48, and the upper edge 31 of the rear apex forming member 15 is joined thereto. The rear apex region 45 is provided with a peripheral length that is shorter than the peripheral length of the reference region 48 and that allows the rear apex forming member 15 to be joined substantially without slack.

  The ring 12 may be anything as long as it is a ring made of a material having biocompatibility, such as various rings conventionally used as an artificial valve annulus.

  Next, the assembly procedure of the stentless artificial valve 10 will be described.

  First, as shown in FIG. 3, the front leaflet forming member 14 is joined to the ring 12. Here, the curved edge 25 having the same curvature as that of the reference region 48 is stitched to the inner peripheral edge of the reference region 48 (see FIG. 2) of the ring 12 with a thread, and then inclined to the inner peripheral edge of the remaining regions 49 and 49. The edges 24, 24 are stitched with thread. Then, the upper edge 31 of the posterior apex forming member 15 is sewn with a thread to the inner periphery of the posterior apex region 45 of the ring 12. In this state, the front leaflet forming member 14 and the back leaflet forming member 15 are joined to the ring 12 with almost no gap in the circumferential direction, and wrinkles due to slack occur on the surface of the front leaflet forming member 14 in the vicinity of the remaining regions 49 and 49. It becomes a state.

  In this assembled state, the front leaflet forming member 14 and the back leaflet forming member 15 are suspended downward from the inner peripheral edge of the ring 12, and the inside of the ring 12 serves as a blood flow path 51.

  In the stentless artificial mitral valve 10 as described above, the outer peripheral edge portion of the ring 12 is stitched to the annulus of the heart (not shown), and the bifurcated portions 20 and 35 of the anterior cusp forming member 14 and the posterior cusp forming member 15 are provided. Is implanted in the heart by being sutured to the papillary muscle of the left ventricle (not shown).

  The stentless artificial mitral valve 10 implanted in this way behaves as follows.

  During the systole of the heart, each surface of the anterior cusp forming member 14 and the posterior cusp forming member 15 suspended from the ring 12 by the positive pressure in the left ventricle and the rise of the papillary muscles is in the direction of the ring 12. And the flow path 51 is blocked by the respective surfaces (see FIG. 4A). On the other hand, in the diastole of the heart, the bifurcated portions 20 and 35 are pulled downward by the negative pressure in the left ventricle and the lowering of the papillary muscle, and a flow path 51 is formed inside the ring 12 (same as above). (Refer figure (B)).

  Next, using the mitral valve simulator (not shown) developed by the present inventors, an experiment for demonstrating the above valve behavior and hemodynamics in the flow path 51 was performed.

  The mitral valve simulator is a known device that can simulate the behavior and blood flow state of the mitral valve site in the heart of a human body (Hiroshi Kasegawa, “Experimental study of Edge to Edge method”, heart , Nippon Heart Foundation, August 15, 2007, Vol. 39, No. 8, separate volume, p710-p713), and detailed description of the device configuration is omitted here.

  In this experiment, the stentless prosthetic mitral valve 10 was set in the mitral valve simulator in the same manner as implantation in the human body, and the mitral valve simulator was driven. The behavior of the stentless artificial mitral valve 10 was photographed with a digital video camera, and the flow rate before and after the stentless artificial mitral valve 10 was measured. The driving conditions of the mitral valve simulator at this time were set to conditions corresponding to a predetermined heart state, that is, a pulsation rate of 70 BPM, a systolic rate of 35%, a left ventricular positive pressure of 200 mmHg, and a left ventricular negative pressure of 50 mmHg. .

  The size of the stentless artificial valve 10 used in this experiment was as follows. That is, L1 = 20 mm, L2 = 40 mm, L3 = 25 mm, L4 = 35 mm, and L5 = 20 mm. Further, the width of the front point forming member 14 in the left-right direction is 75 mm, the height of the inclined edges 24, 24 in the up-down direction is 16 mm, the width of the horizontal edges 28, 28 in the left-right direction is 7 mm, and the center edge 29 The width in the left-right direction was 34 mm. Furthermore, the horizontal width of the upper edge 31 of the rear leaflet forming member 15 was 20 mm, the horizontal width of the horizontal edges 40 and 40 was 7 mm, and the horizontal width of the central edge 29 was 20 mm.

  As a result of the above experiment, the valve behavior shown in FIG. 4 was obtained. In other words, in the systole, as shown in FIG. 5A, the surfaces of the front leaflet forming member 14 and the back leaf forming member 15 are lifted and closely joined to each other, and the flow path 51 is closed. It became a state. This joining state became very close to the blockage by joining the front cusp of the actual mitral valve, and the hinge part 53 close to the commissure part seen in the actual mitral valve was formed. On the other hand, in the expansion period, as shown in (B) of the figure, the flow path 51 having a sufficient effective valve opening area is formed, and at this time, the resistance to the flow in the flow path is small and practical. It was also demonstrated that a good flow condition was obtained.

  Therefore, according to such an embodiment, a valve behavior close to an actual mitral valve can be realized.

  In addition, the stent 12 prosthetic mitral valve 10 can be implanted in the heart relatively easily by stitching the ring 12 to the annulus of the heart and the bifurcated portions 20 and 35 to the papillary muscle of the left ventricle. In particular, it is useful for application to an infant with a small heart.

  Furthermore, the stentless prosthetic mitral valve 10 is implanted with the bifurcated portions 20 and 35 sutured to the papillary muscle, so that after the replacement with the stentless prosthetic valve 10, the bifurcated portions 20 and 35 cause the left ventricular wall. The part is reinforced, and it can be expected to suppress the decrease in the function of the left ventricle after the operation.

  Further, since the stent-less artificial mitral valve 10 can be formed simply by stitching the artificial valve leaf 11 to the inner peripheral edge of the ring 12, it can be easily manufactured without fine adjustment.

  Further, if a decellularized pericardium is used for the artificial leaflet 11, the calcification of the artificial leaflet 11 over time can be suppressed, and the durability of the stentless artificial mitral valve 10 can be further improved. Can be made.

  In the above-described embodiment, the heart is implanted in a state where the artificial leaflet 11 is attached to the ring 12 in advance. However, the present invention does not use the ring 12 and the anterior leaflet forming member 14 and The posterior tip forming member 15 may be sutured directly to the heart annulus.

  The stentless prosthetic mitral valve 10 can be applied not only for mitral valve replacement but also for other valve replacement as long as there is no hindrance.

  In addition, the shape and structure of each member in the present invention are not limited to the illustrated examples, and various modifications are possible as long as substantially the same operation is achieved.

The schematic perspective view of the stent-less artificial mitral valve concerning this embodiment. FIG. 3 is a schematic development view of the stentless artificial mitral valve. The partially exploded front view for demonstrating the assembly procedure of the said stentless artificial mitral valve. (A) is a schematic plan view depicting the valve behavior of the stentless prosthetic mitral valve during systole, and (B) is a schematic plan view depicting the valve behavior during diastole as well.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Stentless artificial mitral valve 11 Artificial leaflet 12 Ring 14 Front cusp forming member 15 Rear cusp forming member 17 Upper edge 20 Bifurcated part 22 Lower edge 24 Inclined edge 25 Curved edge 31 Upper edge 35 Bifurcated part 37 Lower edge 44 Front cusp Side area 45 Rear apex area 48 Reference area

Claims (2)

In a stentless prosthetic mitral valve comprising a ring and a prosthetic valve leaflet extending along the periphery of the ring,
The ring is configured by an anterior apex region divided into two along the circumferential direction , and a posterior apex region with a circumferential length shorter than the circumferential length of the anterior apex region ,
The artificial leaflet includes a bilaterally symmetric front leaflet forming member continuous with the front leaflet side region, and a bilaterally symmetrical back leaf tip forming member continuous with the back leaflet side region without being joined to the front leaflet forming member,
The anterior leaflet forming member, the upper edge being joined to said ring, together with the connected to the upper edge, and a lower edge which forms a bifurcated portion which opens downward, and overall than the rear apex forming member Provided in a large size ,
The upper edge is a pair of left and right inclined edges that are inclined inwardly upward from the left and right ends, and a curve that is positioned between each of the inclined edges and that conforms to the curved shape of a portion of the front apex region. Composed of edges and
The rear leaflet forming member includes an upper edge that extends substantially horizontally and is joined to the ring, and a lower edge that is continuous with the upper edge and forms a bifurcated portion that is open on the lower side. Stentless artificial mitral valve. An artificial leaflet that functions as a prosthetic valve implanted in the heart,
Each is provided symmetrically, and is constituted by an anterior cusp forming member and a posterior cusp forming member that are not joined to each other,
The anterior cusp forming member includes an upper edge sewn to the annulus of the heart, a lower edge that is continuous with the upper edge and forms a bifurcated portion that opens downward , and from the posterior cusp forming member Is also provided in a large size overall
The upper edge is composed of a pair of left and right inclined edges that are inclined inwardly upward from the left and right ends, and a curved curved edge positioned between the inclined edges.
The posterior leaflet forming member includes an upper edge that extends substantially horizontally and is sewn to the annulus, and a lower edge that is continuous with the upper edge and forms a bifurcated portion that opens to the lower side. Artificial leaflets.

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