HEART VALVE

Abstract: Bileaflet biconical heart valve which duplicates the hemodynamics of a natural heart valve in the human heart where tips of biconical halves of the heart valve pivot out­ wardly in a manner representing that of natural heart valve tissue. In one embodiment of the present invention, biconical halves move about outflow pivots while in two other embodi­ ments, the biconical halves pivot on outflow pivots where each biconical half pivots about or on two spaced pivots extending inwardly from an orifice ring at adjacent lower ends of each biconical half.

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention pertains to a prosthetic heart valve and, more importantly, pertains to a bileaflet biconical heart valve for surgical implantation. 2. Description of the Prior Art In prosthetic heart valves of the prior art attempts have been made to mimic the hemodynamic characteristics of the natural heart valve. In particular, in prior art heart valves attempts have been made by using occluding leaflets to duplicate the rapid closure of the natural heart valve. However, these attempts have not been well attained. The movement of the tips of the natural heart valve regulates the hemodynamic flow of the blood, as well as other characteristics of passage of the blood through the human heart. Attempts have been made to have the tips of mechanical heart valves move outwardly in a manner similar to that of natural heart valves, but they have been unsuccessful. Furthermore, the prior art mechanical or tissue valves have not provided for an oval shape which approximates some of the existing natural heart valves. This is especially important as the average heart valve in an individual is not always round, but sometimes approximates an oval geometrical cross-sectional configuration. US-A- 4 363 142 of Meyer discloses a prosthetic heart valve having a pair of occluding leaflets of cylindrical or elliptical shape mounted in an annular housing by means of a pivot mechanism comprising projections on the leaflets and corresponding recesses in the annular housing. In order for this heart valve to function, the housing in the area of the pivot must take the form of a planar surface so that the leaflets are retained during opening and closing while allowing for washing to prevent accumulation of material in the vicinity of the pivot. This requirement results in an undesirable reduction of the cross-sectional area of the valve. US-A- 4 488 318 of Kaster discloses a prosthetic heart valve having a pair of occluding leaflets of semi-conical shape mounted in an annular housing for pivotal movement between open and closed positions. However, Kaster locates the pivot mechanism for the leaflets above (i.e. downstream of) the level of the valve housing. Although this allows the housing to have an annular inner wall with no flat sides, it suffers from the substantial disadvantage that, because the pivot mechanism is located above the base edge of the leaflets, translational movement of the leaflets is required in order to allow them to open and close. This additional, translational movemnent increases the opening and closing times of the valve. The present invention overcomes the disadvantages of the prior art by providing a bileaflet biconical heart valve which duplicates the natural movements of a human heart valve and closely approximates the hemodynamic flow through the heart valve. The bileaflet biconical heart valve can be manufactured with either a circular or oval geometrical cross-section. Accordingly, the present invention provides a prosthetic heart valve comprising: an orifice ring (12) having an inner surface; two opposed, pivotally mounted, biconical occluding leaflets (14 and 16) each mounted on a pair of pivots with respect to the orifice ring for pivotal movement between an open position and a closed position, the leaflets having curved base edges (30 and 32) whose size and configuration correspond to the size and configuration of said inner surface of the orifice ring; and limit stops to determine said open position; characterised in that: the pivots comprise opposing pairs of symmetrically spaced pivots (42 and 44, and 46 and 48) extending inwardly from a lower portion of the orifice ring, said pivots each contacting a pivot portion of said base edges (30 and 32), whereby the leaflets can move pivotally on the pivots; the valve includes leaflet-retaining protrusions (34 and 36, 144-150 and 244-250); the valve includes a pair of opposing closure protrusions (38 and 40, 132 and 134 and 232 and 234) extending inwardly from a mid-portion of the orifice ring to determine said closed position; and the limit stops include an opposing pair of leaflet stops (60 and 62, 124-130 and 224-230) extending from an upper portion of the orifice ring to determine said open position. The heart valve of the present invention provides for rapid closure of its biconical occluding leaflets, and the hemodynamic flow of blood through the valve approximates the hemodynamic flow of blood through a natural heart valve. This is particularly important where the prosthetic heart valve is utilized in a mitral heart valve application, though the prosthetic valves of the invention can be used in aortic valve applications also. Although, in the embodiments of the invention described below with reference to the accompanying drawings, the orifice ring has a circular configuration, it can be manufactured in an oval geometrical configuration to approximate the geometrical cross-sectional configuration of a natural heart valve. According to one embodiment of the present invention, there is provided a bileaflet biconical heart valve with opposing symmetrical bileaflet half portions which float about two outflow pivot pins for each bileaflet between opposing symmetrical leaflet retaining bosses and closure protrusions extending outwardly from within the orifice ring in an opposing symmetrical relationship. The leaflet retaining bosses include rotational guides, stop seats, and stop surfaces for each bileaflet. Another embodiment of the present invention provides a bileaflet biconical heart valve including an orifice ring, opposing symmetrical outflow pivot pins supporting each biconical occluder halves on opposing pivot points at a lower portion of the biconical half within the orifice ring, a plurality of spaced opposing leaflet retaining protrusions; a plurality of leaflet stop bosses spaced about each of the biconical halves and extending outwardly within the orifice ring for closure of each of the biconical halves, and two opposing closure protrusions for extending outwardly from the interior of the orifice ring. A further embodiment of the present invention provides a bileaflet biconical heart valve of the last embodiment where the elongated leaflet retainer protrusions are significantly reduced in size forming leaflet retainer protrusions. One significant aspect and feature of the present invention is that the prosthetic heart valve includes two biconical occluding leaflets which duplicate the natural heart valve rhythm. The tips of the biconical occluding leaflets move out in a manner like that of a natural heart valve and simulate the natural tissue of a natural heart valve. A further significant aspect of the present invention is a bileaflet biconical heart valve which can be manufactured into an oval geometrical cross-section configuration, which is particularly important, as natural heart valves are not always circular, but tend to approximate more closely that of an oval configuration. There is now described, by way of example and with reference to the accompanying drawings, preferred embodiments of the invention: In the drawings: FIG. 1 illustrates a top view of a bileaflet biconical heart valve of the present invention; FIG. 2 illustrates a bottom view; FIG. 3 illustrates a view taken along line 3-3, excluding leaflet halves, of FIG. 1; FIG. 4 illustrates a side view partially in cross-section with biconical occluding leaflet halves closed; FIG. 5 illustrates a view in cross-section with the biconical halves open; FIG. 6 illustrates a top view with the biconical halves open; FIG. 7 illustrates a bottom view with the biconical halves open; FIG. 8 illustrates a second embodiment of the present invention of a top view of a bileaflet biconical heart valve; FIG. 9 illustrates a bottom view; FIG. 10 illustrates a view taken along line 10-10, excluding leaflet halves, of FIG 8; FIG. 11 illustrates a side view partially in cross-section with biconical occluding leaflet halves closed; FIG. 12 illustrates a view in cross-section with the biconical halves open; FIG. 13 illustrates a top view with the biconical halves open; FIG. 14 illustrates a bottom view with the biconical halves open; FIG. 15 illustrates a third embodiment of the present invention of a top view of a bileaflet biconical heart valve; FIG. 16 illustrates a bottom view; FIG. 17 illustrates a view taken along line 17-17, excluding leaflet halves, of FIG. 15; FIG. 18 illustrates a side view partially in cross-section with biconical occluding leaflet halves closed; FIG. 19 illustrates a view in cross-section with the biconical halves open; FIG. 20 illustrates a top view with the biconical halves open; and, FIG. 21 illustrates a bottom view with the biconical halves open. DESCRIPTION OF THE PREFERRED EMBODIMENTS In FIG. 1, which illustrates a top view of a bileaflet biconical heart valve 10, the heart valve includes a valve housing orifice ring 12, and biconical occluding leaflet halves 14 and 16, including chamfered machined leaflet valve corners 18, 20, 22 and 24 as shown in FIG. 2, for closing occluding leaflet halves 14 and 16 which include closure surfaces 26 and 28 and round beveled closure surfaces 30 and 32. Leaflet retaining bosses 34 and 36 align on opposing ends of the closure access of the valve and extend inwardly from opposing upper, mid, and lower portions of the orifice ring 12. Closure protrusions 38 and 40 determine the closure access of the leaflets 14 and 16 and extend inwardly from opposing mid portions of the orifice ring 12. The leaflet retaining bosses 34 and 36 and leaflet closure protrusions 38 and 40, symmetrically extend inwardly from the orifice ring 12 as also illustrated in FIG. 3. Corresponding and opposing outflow pivot pins 42 and 44 and 46 and 48, illustrated in hidden lines, extend inwardly from a lower portion of the orifice ring 12, providing for pivoting of the leaflets during movement of the biconical occluding leaflet halves 14 and 16 which ride on each of the partially rounded pivot pins 42, 44, 46, and 48. FIG. 2 illustrates a bottom view of the biconical heart valve 10 of FIG. 1 wherein the valve has been rotated about its pictorial vertical axis, and where all numerals correspond to those elements previously described. Shown in particular, in hidden lines, are leaflet retaining bosses 34 and 36. Opposing leaflet retaining boss center members 58 and 59 are also illustrated, which are later described in detail. FIG. 3 illustrates a view taken along line 3-3, excluding leaflet halves 14 and 16 of FIG. 1 where all numerals correspond to those elements previously described. The outflow pivots 44 and 48 include flat portions 52 and 50. The leaflet retaining boss 34 includes symmetrical opposing rotational guides 54 and 56, center member 58, stop seats 60 and 62, and small stop surfaces 64 and 66, as well as large stop surfaces 68 and 70. Like associated elements on the like opposing side of the heart valve 10 are not numbered for purpose of brevity in the specification and drawing. The closure protrusions 38 and 40 include closure protrusion surfaces 72 and 74, respectively. FIG. 4 illustrates a side view, partially in section, showing the biconical leaflet halves 14 and 16 in a closed position, as illustrated in FIGS. 1 and 2. All numerals correspond to those elements previously described. Tips 76 and 78 of each of the leaflets are illustrated. FIG. 5 illustrates a side view in section of the biconical leaflet halves 14 and 16 in an open position, providing for the passage of blood in a hemodynamic flow which approximates that of a natural valve. All numerals correspond to those previously described. FIG. 6 illustrates a top view, in full, of FIG. 5. All numerals correspond to those previously described. The position of tips 76 and 78 are noted. The opening resembles a modified hexagon cross-section. FIG. 7 illustrates a bottom view of FIG. 6 where all numerals correspond to those elements previously described. MODE OF OPERATION The heart valve 10 of the present invention can be manufactured in a plurality of sized diameters. The particular size of the heart valve is determined by the sewing ring, not illustrated, around the outer diameter of the orifice ring 12. Sewing rings are known in the prior art which usually are a knitted teflon ring. Prior to implant, a surgeon will size the diameter of the tissue orifice, such as through the use of heart valve sizers which are also known in the prior art. Once a diameter of the heart valve implant is determined, the appropriate diameter heart valve can be selected from surgical supply stock accordingly. The diameter of the mitral or aortic valves will vary, of course, from one individual to another individual, and of course being dependent upon an adult male, an adult female, or a small child. The orifice ring 12 can be manufactured from a suitable material, such as titanium or stainless steel. The bileaflets 16 and 14 can be manufactured from Pyrolite carbon. These materials are currently used in heart valves and approved for use by the FDA. The materials are light weight and radiopaque, which are particularly lended to these types of applications. The orifice ring 12, including the leaflet retaining bosses 34 and 36, the closure protrusions 38 and 40, and the pivots 42-48 can all be manufactured from a single metallic unit, such as by computer machining the orifice ring and components from a single piece of titanium, for example. In describing the mode of operation of the bileaflet biconical heart valve 10, as illustrated in FIGS. 1-7, movement of the leaflets 14 and 16 are identical with respect to each other about the pivots 42-48. FIGS. 1, 2, and 4 illustrate the leaflets 14 and 16 in a closed position at rest, resting on the pivots 42-48, which are aligned against the leaflet retaining boss center members 58 and 59. Each of the leaflets 14 and 16 are in a free floating, non-binding position with respect to the internal wall of the orifice ring 12 and provide for mating of the closure surfaces 26 and 28 in a closed position. The leaflets rest against the surfaces 72 and 74 of the closure protrusions 38 and 40 in a rest position, as well as against the center members 58 and 59, and on the pivots 42-48. The leaflets 14 and 16 pivot based on pressure differentials during blood flow. Each of the leaflets 14 and 16 move between a closed position of FIGS. 1, 2 and 4 to an open position of FIGS. 5-7. The leaflet retaining bosses 34 and 36 maintain the leaflets within the orifice ring during pivoting movement, and provide for movement of each of the leaflets conforming to the aligned surfaces of the leaflet retaining bosses 34 and 36. The leaflets move in such a manner that the tips 76 and 78 of each of the leaflets can be described as an arcuate movement path. FIG. 5 best illustrates the leaflets 14 and 16 in a fully open position where the leaflets have moved over and about the pivots 44 and 46, and rest on the flat portions of 50 and 52 of the pivots in a fully opened position. The pressure differential between the proximal side and distal side of the heart valve provides for the pivoting action of each of the leaflets, based on the flow of the blood. The pivoting of the leaflet is provided by the rotational guides 54 and 56, as illustrated in FIG. 3, for which the edges 18 and 20 of each leaflet pivots about and the leaflet subsequently comes to a fully opened position against stop surfaces 64 and 66, as well as 68 and 70 of bosses 34 and 36. FIGS. 6 and 7 illustrates the leaflets 14 and 16 in a fully opened position providing for free flow of optimized volume of blood through the central orifice created by the tips 76 and 78 of the respect leaflets. The outward bound shape of the valve in a fully opened position resembles a slightly elongated hexagonal opening providing for minimum blood flow turbulence during the flow of blood through the valve 12. The closure of the heart valve 10 is accounted for by a decrease in pressure on the proximal side with respect to the distal side in that blood flows back through the valve orifice. As a consequence, the reverse flow pivots the leaflets downwardly to a position as illustrated in FIGS. 1, 2, and 4. The free floating leaflets respond quickly to reverse blood flow through the valve providing rapid closure. The closure between the surfaces 26 and 28 is so minimal as to provide for a negligible, if any, leakage of blood when the leaflets are closed. SECOND EMBODIMENT FIG. 8, which illustrates a top view of bileaflet biconical heart valve 100, the present invention, shows the heart valve 100 including a valve housing orifice ring 102 and biconical occluding leaflet halves 104 and 106 as later described. Leaflet halves 104 and 106 include closure surfaces 108 and 110, round beveled closure surfaces 112 and 114, and pivot slots 116, 122, 118, and 120, respectively. Opposing aligned leaflet stop bosses 124 and 126 and 128 and 130, symmetrically align on opposing interior upper portions of the orifice ring 102. Closure protrusions 132 and 134 extend inwardly from the mid portion of orifice ring 102 and determine the closure of the leaflets 104 and 106, respectively. The leaflet stop bosses 124-130 and leaflet closure protrusions 132 and 134 extend inwardly from the orifice ring 102. Corresponding and opposing outflow pivots 136 and 138 and 140 and 142, illustrated in hidden lines, extend inwardly in a lower portion of ring 102, as illustrated, providing for pivoting of the leaflets 104 and 106 on pivots 136-142 during movement of the biconical leaflet occluding halves 104 and 106. Elongated leaflet retainer protrusions 144, 146, 148 and 150 extend inwardly from a mid portion of the orifice ring 102 enhancing rotational engagement of biconical occluding leaflet halves 104 and 106 about the outflow pivots 136-142. FIG. 9 illustrates a bottom view of the biconical heart valve 100 of FIG. 8 wherein the valve has been rotated about its pictorial vertical axis. All numerals correspond to those elements previously described. FIG. 10 illustrates a section view taken along line 10-10, excluding leaflet halves 104 and 106, of FIG. 8 where the numerals correspond to those elements previously described. The outflow pivots 138 and 142, stop bosses 124 and 128 and elongated leaf retainer protrusions 146 and 148 extend inwardly from orifice ring 102. The closure protrusions 132 and 134 include closure protrusion surfaces 152 and 154, respectively. FIG. 11 illustrates a side view, partially in section, showing the biconical leaflet halves 104 and 106 in a closed position, as previously illustrated in FIGS. 8 and 9. All numerals correspond to those elements previously described. Tips 155 and 157 of each of the leaflets are illustrated. FIG. 12 illustrates a side view in section of the biconical leaflet halves 104 and 106 in an open position, providing for the passage of blood in a hemodynamic flow which approximates that of a natural heart valve. All numerals correspond to those elements previously described. FIG. 13 illustrates a top view, in full, of FIG. 12. All numerals correspond to those previously described. The occluding leaflets are in an open position. FIG. 14 illustrates a bottom view of FIG. 13 where all numerals correspond to those elements previously described. MODE OF OPERATION OF SECOND EMBODIMENT The operation of the heart valve 100 of FIGS. 8-14 is similar in theory to that of FIGS. 1-7; although, the structure of the heart valve 100 is slightly different. The leaflets 104 and 106, pivot on pivots 136-142 in pivot slots 116-122 in lieu of FIGS. 1-7 where the leaflets 14 and 16 pivot about the pivots 42-48. In FIGS. 8-14, the leaflets are actually hinged on the pivots as best illustrated in FIG. 12, illustrating pivot slots 116 and 118 in each of the leaflets 104 and 106, for pivoting about the pivots 138 and 142 in a rotational manner. Pivoting of each of the leaflets in a rotational manner is controlled by the elongated leaflet retainer protrusions 144-150. In a fully opened position, the leaflets will stop against the stop bosses 124-130, while in a closed position the leaflets will rest against closure protrusion surfaces 152 and 154 of closure protrusions 132 and 134. FIGS. 8, 9, and 11 illustrate the heart valve in a closed position, while FIGS. 12-14 illustrate the heart valve in an open position. THIRD EMBODIMENT FIG. 15, which illustrates a top view of the bileaflet biconical heart valve 200, the present invention, shows the heart valve 200 including a valve housing orifice ring 202 and biconical occluding leaflet halves 204 and 206 as later described. Leaflet halves 204 and 206 include closure surfaces 208 and 210, round beveled closure surfaces 212 and 214, and pivot slots 216, 218, 220, and 222. Opposing aligned leaflet stop bosses 224 and 226 and 228 and 230 symmetrically align on opposing interior upper portions of the orifice ring 202. Closure protrusions 232 and 234 extend inwardly from the mid portion of orifice ring 202 determining the closure of the leaflets 204 and 206, respectively. The leaflet stop bosses 224-230 and leaflet closure protrusions 232 and 234 extend inwardly from the orifice ring 202. Corresponding and opposing outflow pivots 236 and 238 and 240 and 242, illustrated in hidden lines, extend inwardly from the lower portion of the orifice ring 202 as illustrated, providing for pivoting of the leaflets 204 and 206 during movement of the biconical leaflet occluding halves 204 and 206. Conical like leaflet retainer protrusions 244, 246, 248 and 250 extend inwardly from orifice ring 202 to ensure engagement of biconical leaflet halves 204 and 206 upon outflow pivots 236-242. FIG. 16 illustrates a bottom view of the biconical heart valve 200 of FIG. 15 wherein the valve has been rotated about its pictorial vertical axis. All numerals correspond to those elements previously described. FIG. 17 illustrates a sectional view taken along line 17-17, excluding leaflet halves 204 and 206, of FIG. 15 where the numerals correspond to those elements previously described. The outflow pivots 238 and 242, stop bosses 224 and 230, and conical leaf retainer protrusions 246 and 248 extend inwardly from orifice ring 202. The closure protrusions 232 and 234 include closure protrusion surfaces 252 and 254, respectively. FIG. 18 illustrates a side view, partially in section, showing the biconical leaflet halves 204 and 206 in a closed position, as previously illustrated in FIGS. 15 and 16. All numerals correspond to those elements previously described. FIG. 19 illustrates a side view in section of the biconical leaflet halves 204 and 206 in an open position, providing for the passage of blood in a hemodynamic flow which approximates that of a natural heart valve. All numerals correspond to those elements previously described. FIG. 20 illustrates a top view, in full, of FIG. 19. All numerals correspond to those previously described. The occluding leaflets are in an open position. FIG. 21 illustrates a bottom view of FIG. 20 where all numerals correspond to those elements previously described. MODE OF OPERATION OF THIRD EMBODIMENT FIGS. 15 - 21 are identical in operation to FIGS. 8-14. The particular main difference between the structures is that the leaflet retainer protrusions 244 - 250 are conical in shape and are considerably smaller than the elongated retainer protrusions of FIGS. 8 - 14. Also, the leaflet stop bosses 224 - 230 are somewhat smaller than the leaflet stop bosses of FIGS. 8 - 14. Also, leaflet closure protrustions 232 and 234 are considerably smaller than the closure protrusions of FIGS. 8 - 14. Otherwise, the structure of the valve is similar, not only in structure but in operation, to that of FIGS. 8 -14. For purposes of brevity, the mode of operation should be referred to for FIGS. 8 - 14 with respect to the third embodiment of FIGS. 15 - 21. An advantage of the heart valves described above with reference to the accompanying drawings is that they duplicate the natural rhythm and hemodynamic flow of a natural heart valve in that the occluding leaflets move in a similar fashion to natural tissue of a natural heart valve. Another advantage is that movement of the tips of the occluding leaflets approximates movement of tissue of a natural heart valve.

Claims: A prosthetic heart valve comprising: an orifice ring (12) having an inner surface; two opposed, pivotally mounted, biconical occluding leaflets (14 and 16) each mounted on a pair of pivots with respect to the orifice ring for pivotal movement between an open position and a closed position, the leaflets having curved base edges (30 and 32) whose size and configuration correspond to the size and configuration of said inner surface of the orifice ring; and limit stops to determine said open position; characterised in that: the pivots comprise opposing pairs of symmetrically spaced pivots (42 and 44, and 46 and 48) extending inwardly from a lower portion of the orifice ring, said pivots each contacting a pivot portion of said base edges (30 and 32), whereby the leaflets can move pivotally on the pivots; the valve includes leaflet-retaining protrusions (34 and 36, 144-150 and 244-250); the valve includes a pair of opposing closure protrusions (38 and 40, 132 and 134 and 232 and 234) extending inwardly from a mid-portion of the orifice ring to determine said closed position; and the limit stops include an opposing pair of leaflet stops (60 and 62, 124-130 and 224-230) extending from an upper portion of the orifice ring to determine said open position. A prosthetic heart valve according to Claim 1, in which said pivot portions each comprises a portion of the respective base edge (30, 32). A prosthetic heart valve according to Claim 2, in which the pivots each has a substantially flat portion (50, 52) at an angle with respect to the plane of the orifice ring, on which rest the leaflets when the valve is in said open position. A prosthetic heart valve according to Claim 1, in which the leaflet-retaining protrusions include two rotational guides (53, 55 and 54, 56) disposed in diametrically opposed relationship with respect to the orifice ring, to guide the respective base edges of the leaflets during said pivotal movement. A prosthetic heart valve according to Claim 1, in which said pivot portions comprise pivot slots (116, 118, 120, 122) in the base edges of the leaflets, the pivot slots engaging the pivots (138, 142, 140, 136), respectively. A prosthetic heart valve according to Claim 1, in which the pivots are partially rounded pivot pins on which ride the biconical occluding leaflets (14, 16). A prosthetic heart valve according to Claim 5, in which the leaflet-retaining protrusions (144,146,148,150) are of elongated shape. A prosthetic heart valve according to Claim 5, in which the leaflet-retaining protrusions (244,246,248,250) are of conical shape.

Inventors: SORENSEN, RAHBEK H., WOIEN, ARNE
Applicants: MEDTRONIC BLOOD SYSTEMS, INC.
Application year: 1986
Main classification: A61F2
IPC codes: A61F2