Method of implanting a heart valve prosthesis

Abstract

A method of implanting a percutaneous heart valve prosthesis via a catheter. The heart valve includes a valve body frame made of a nickel-titanium alloy. The valve body frame is collapsible for fitting within the catheter. A flexible skirt is sutured to the valve body frame for blocking blood flow between the valve body frame and native tissue. A one-way valve is positioned within the valve body frame for permitting blood to flow from a first end of the valve body frame to a second end. The one-way valve is preferably formed by three flexible valve leaflets made from a pericardial material. A plurality of barbs are spaced about the periphery of the valve body frame. Each of the barbs points toward the first end of the valve body frame and at least some of the barbs are positioned at the second end of the valve body frame.

Claims

1. A method of implanting a valve prosthesis in a native heart valve, comprising: advancing a catheter through a patient's venous system, wherein a valve prosthesis is held in a collapsed state along a distal end portion of the catheter, the valve prosthesis comprising: a valve body frame having a first end, a second end, a longitudinal axis, and a blood flow passage extending along the longitudinal axis between the first end and the second end, the valve body frame being collapsible about the longitudinal axis to fit within the catheter for delivery, the valve body frame formed by a plurality of sub-frame members, each sub-frame member having a general form of a rhombus with acute-angled vertices and oblique-angled vertices; a flexible skirt made from polyester, the flexible skirt extending around a periphery of the valve body frame, the flexible skirt dimensioned for blocking blood flow between the valve body frame and native heart valve tissue; a one-way valve positioned within the valve body frame, the one-way valve including a plurality of flexible valve leaflets for permitting blood to flow from the first end of the valve body frame to the second end of the valve body frame, the flexible valve leaflets comprising pericardial material; and a plurality of barbs spaced about the periphery of the valve body frame, wherein at least some barbs are positioned at the oblique-angled vertices and wherein at least some barbs are positioned at the acute-angled vertices along the second end of the valve body frame, wherein each of the barbs points toward the first end of the valve body frame for engaging native heart valve tissue; releasing the valve prosthesis from the catheter and allowing the valve prosthesis to radially expand in the native heart valve; and withdrawing the catheter from the patient's venous system; wherein the barbs secure the valve prosthesis within the native heart valve and wherein the one-way valve replaces the function of the native heart valve; wherein adjacent sub-frame members are joined at the oblique-angled vertices.

2. The method of claim 1, wherein the native heart valve is a mitral valve.

3. The method of claim 2, wherein the distal end portion of the catheter is advanced through a femoral vein and toward the right atrium.

4. The method of claim 3, wherein the distal end portion of the catheter is further advanced through a puncture formed in the inter-atrial septum.

5. The method of claim 4, wherein the distal end portion of the catheter is further advanced through the left atrium and at least partially into a left ventricle.

6. The method of claim 1, wherein the valve body frame is made of a nickel-titanium alloy.

7. The method of claim 1, wherein each sub-frame member is formed of elongate valve body frame elements.

8. The method of claim 7, wherein the elongate valve body frame elements have thicknesses of about 0.3 to 0.4 mm.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Preferred forms of the present invention will now be described by way of example with reference to the accompanying drawings, wherein:

(2) FIG. 1 is a front elevation view of a percutaneous mitral valve prosthesis.

(3) FIG. 2 is a front elevation view of a sub-frame member of the valve body of the prosthesis of FIG. 1.

(4) FIG. 3 is a schematic cross sectional front elevation view of the valve body of the prosthesis of FIG. 1.

(5) FIG. 4 is a front elevation view of the valve body of the prosthesis of FIG. 1 in a collapsed state located in a catheter.

(6) FIG. 5 is a front elevation view of an alternate valve body of a percutaneous mitral valve prosthesis.

(7) FIG. 6 is a front elevation view of the anchor device of the prosthesis of FIG. 1.

(8) FIG. 7 is a plan view of the anchor device of FIG. 6.

(9) FIG. 8 is a front elevation view of the anchor device of FIG. 6 in a collapsed state located in a catheter.

(10) FIG. 9 is a schematic front elevation view of a patient depicting a guide wire accessing the patient's heart.

(11) FIG. 10 is a schematic cross-sectional front elevation view of a heart depicting a catheter advanced into the right atrium and a puncture formed in the inter-atrial septum.

(12) FIG. 11 is a cross-sectional front elevation view of the heart of FIG. 10 with the catheter advanced into the left ventricle.

(13) FIG. 12 is a schematic cross-sectional front elevation view of the heart of FIG. 10 with a percutaneous heart valve prosthesis advanced through the catheter.

(14) FIG. 13 is a schematic cross-sectional front elevation view of the heart of FIG. 10 with the valve body of the prosthesis released from the catheter into the left ventricle.

(15) FIG. 14 is a front elevation view of the heart of FIG. 10 with the catheter withdrawn into the right atrium and the prosthesis valve body located in the mitral valve orifice.

(16) FIG. 15 is a schematic cross-sectional elevation view of the heart of FIG. 10 with the prosthesis fully deployed.

(17) FIG. 16 is a front elevation view of an alternative percutaneous heart valve prosthesis.

(18) FIG. 17 is a further view of the prosthesis of FIG. 16.

(19) FIG. 18 is a front elevation view of the prosthesis of FIG. 16 in a collapsed state located in a catheter.

(20) FIG. 19 is a schematic cross-sectional front elevation view of a heart with a partially deployed prosthesis of FIG. 16.

(21) FIG. 20 is a schematic cross-sectional front elevation view of the heart of FIG. 19 with the prosthesis fully deployed.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

(22) Referring specifically to FIG. 1, a percutaneous heart valve prosthesis, in the form of a mitral valve prosthesis 1, comprises a valve body 2, first and second flexible valve elements 3, 4, an anchor device 5 and an anchor line 6 secured to and extending between the valve body 2 and the anchor device 5.

(23) The valve body 2 has a first end 7 and a second end 8. A blood flow passage 9 extends along a longitudinal axis 10 between the valve body first end 7 and the valve body second end 8. The valve body 2 is configured so as to be collapsible about the longitudinal axis 10 to enable the valve body 2 to be located in a catheter for delivery of the prosthesis 1, as will be discussed further below.

(24) The valve 2 is in the form of a collapsible valve body frame formed of elongate elastic valve body frame elements 11. Each of the valve body frame elements 11 may be suitably formed as wires of a superelastic shape memory material. A particularly suitable material is nitinol, a nickel-titanium alloy, which is known for use in percutaneous prosthesis applications. Other suitable elastic metallic materials include stainless steel, gold, other titanium alloys and cobalt chromium molybdenum. Other suitably rigid yet elastic metal alloys, or non-metallic materials, may also be utilized as desired. The valve body frame elements 11 will typically have a thickness of the order of 0.3 to 0.4 mm, however elements of varying diameter are also envisaged.

(25) The valve body frame 2 depicted in FIG. 1 comprises three valve body sub-frame members 12. One such valve body sub-frame member 12 is depicted in FIG. 2. As can best be seen from FIG. 2, each valve body sub-frame member 12 is in the general form of a deltoid, and here particularly in the form of a diamond or rhombus (that is, a deltoid with four equal length sides). Each valve body sub-frame member 12 is arranged such that the acute-angled vertices 13, 14 of the rhombus are arranged at the valve body first and second ends 7, 8, with the oblique-angled vertices 15, 16 located between the valve body first and second ends 7, 8.

(26) Each valve body sub-frame member 12 will generally be formed of two wires, kinked to form the oblique-angled vertices 15, 16, with the ends of each wire being soldered to form the acute-angled vertices 13, 14, thereby providing the rhombus form.

(27) Alternatively, the wires could be kinked to form the acute-angled vertices 13, 14, with the ends soldered at the oblique-angled vertices 15, 16.

(28) Adjacent valve body sub-frame members 12 are joined at their respective oblique-angled vertices 15, 16 as depicted in FIG. 1, typically by soldering. Alternatively, the adjacent valve body sub-frame members may be sutured or joined by any other suitable means. Whilst, in the valve body 2 depicted, three sub-frame members 12 are joined so as to provide a generally triangular transverse cross-section, more than three sub-frame members may be utilized as desired such that the transverse cross-section of the valve body 2 becomes gradually more circular in shape with the addition of further body sub-frame members 12.

(29) As is particularly apparent from FIG. 1, the valve body 2 is arranged such that it tapers towards the valve body first end 7. The valve body is tapered and sized such that the valve body first end 7 is able to pass through a mitral valve orifice associated with a mitral valve to be replaced, with the valve body second end 8 being sized so as not to pass through such a mitral valve orifice, when in the uncollapsed state. A mitral valve orifice in an adult person typically has a diameter of the order of 25 mm.

(30) Referring again particularly to FIG. 2, each valve body sub-frame member 12 may further comprise a collapsible diagonal element 17 extending between the oblique-angled vertices 15, 16. The diagonal elements will typically be in the form of a kinked wire formed of the same material as the remaining elements 11 of the valve body sub-frame member 12. The kink is provided in the diagonal element 17 to enable it to readily collapse to allow delivery via catheter.

(31) Referring to FIGS. 1 and 3, the valve elements 3, 4, in the form of valve leaflets, are secured to the valve body 2 on opposing sides of the bloodflow passage 9. Typically, the valve leaflets 3, 4 will be sutured to the diagonal elements 17 of the valve body sub-frame members 12. The valve leaflets 3, 4 are here overlapping, typically with a shorter leaflet 3 overlapped by a longer leaflet 4 lying between the shorter leaflet 3 and the valve body second end 8, such that, in use, the longer leaflet 4 lies on the outer or ventricular side of the valve body 2. Referring to FIG. 3, it can be seen that sub-frame members 12 are planar.

(32) The valve leaflets 3, 4 are configured in a known manner so as to open toward the valve body second end 8, allowing bloodflow through the passage 9 in a direction from the valve body first end 7 toward the valve body second end 8, and to sealingly lock in response to pressure acting in the opposite direction, so as to block bloodflow through the passage 9 in the reverse or retrograde direction. The valve leaflets may be formed of biological material, such as pericardial material, as is well known in the art, or of any other suitable flexible valve materials known in the art, including woven metallic materials or non-metallic materials such as silicone. The valve leaflets may be sutured to the diagonal element 17 around the entire periphery of the passage 9, or may be hinged only at one or more discrete points around the periphery of the passage 9. Any of various well known valve leaflet configurations may be utilized so as to provide the one way valve function required, including configurations utilizing one valve leaflet only or utilizing three or more valve leaflets as is known in the art. Alternatively, a single valve element in the general form of a windsock might be utilized.

(33) Referring to FIG. 4, the configuration of the valve body 2 facilitates it being collapsed about the longitudinal axis 10, enabling it to fit within a catheter 18 for subsequent percutaneous deployment.

(34) As depicted in FIGS. 1 and 2, prongs, typically in the form of barbs 19, may be spaced about the periphery of the valve body 2, typically at or adjacent the oblique-angled vertices 15, 16 of each sub-frame element, for engaging the native annular wall surrounding a valve orifice in use, as will be discussed below. Further barbs may be located at the acute-angled vertices 24 at the valve body second end 8. The barbs 19 will typically point toward the end 7, when the anchor line 6 is secured to the valve body first end 7.

(35) Referring to FIG. 5, a flexible skirt 20 may extend around the periphery of the valve body 2 for blocking retrograde bloodflow toward the valve body first end 7, between the valve body 2 and the native wall surrounding the mitral orifice in use. The flexible skirt 20 will typically be sutured to the diagonal element 17 of each valve body sub-frame member 12, and as such will effectively provide a continuation of the valve leaflets 3, 4 on the exterior of the valve body 2. The flexible skirt 20 may be formed of biological material, such as pericardial material, or alternatively might be formed of any suitable flexible non-biologic material, such as, for example, silicone, polyester or dacron.

(36) Referring to FIG. 6, the anchor device 5 will also typically comprise a collapsible anchor frame formed of elongate anchor frame elements 21. The anchor frame elements 21 will again typically be formed of a superelastic shape memory material as per the valve body elements 11, and may again be formed of nitinol or other suitable elastic materials. Here the anchor device frame 5 is formed of an array of anchor sub-frame members 22. Each anchor sub-frame member has the general form of a rhombus. Rather than being joined side to side as per the valve body sub-frame members 12, however, the anchor sub-frame members 22 are here each joined in a radial pattern at their oblique-angled vertices 23, 24.

(37) Accordingly, the anchor device 5 is collapsible from a stable substantially flat plate-like configuration (as depicted in FIGS. 6 and 7) to an unstable elongate configuration for location within a catheter 18 (as particularly depicted in FIG. 8). The anchor device 5 is provided at one end, corresponding to the oblique-angled vertices 23, with a coupling 25 for releasably coupling to a guide element as will be discussed below. The coupling 25 may suitably be in the form of a threaded aperture.

(38) The anchor line 6 will also generally be secured to the end of the anchor device 5 corresponding to the oblique-angled vertices 23, and will extend through the length of the anchor device 5 beyond the opposing oblique-angled vertices 24, such that tension applied to the anchor line 6 will tend to retain the anchor device 5 in the flat configuration. The anchor line 6 may be formed of any suitable flexible wire or cord, and may be suitably formed again of nitinol wire or stainless steel wire. Other suitable materials may include carbon fiber, polyimides or aromatic polyamides. Where elasticity in the anchor line is desired, other suitable materials may include polyether block amide (PEBAX), silicone or polyurethane.

(39) The opposing end of the anchor line 6 will typically be secured to the valve body first end 7, typically by way of three further lines 6a converging from the acute angled-vertices 13 of each-frame member 12 of the valve body 2. Where desired, further anchor lines 6 extending between the valve body 2 and anchor device 5 may be utilized.

(40) The structure of the valve body 1 and anchor device 5 may be covered with biological material or less thrombogenic material to reduce the possibility of blood clotting around the non-biological material from which the valve body 2 and anchor device 5 will typically be formed.

(41) A surgical procedure for replacement of a native mitral valve 101 utilizing the prosthesis 1 will now be described with reference to FIGS. 9 to 15. Given that the native mitral valve 101 and mitral valve orifice 102 will generally vary in size between patients, measurements of the native mitral valve 101 and orifice 102 may be made with the use of a compliant balloon and transthoracic and transesophageal echocardiography.

(42) The compliant balloon is located in the valve orifice 102 and expanded so as to move the leaflets of the native valve 101 out of the way and enable measurement of the diameter of the mitral valve orifice 102. A measurement of the distance between the native mitral valve 101 and the region of the inter-atrial septum 103 is also taken.

(43) Based on the measurements taken, a suitably sized prosthesis valve body 2 is selected to fit the size of the mitral valve orifice 102 such that the valve leaflets 3, 4, will be positioned in the vicinity of the native valve 101. The measurement of the distance between the native mitral valve 101 and the mid region of the inter-atrial septum 103 is also utilized to determine the length of the anchor line 6 extending between the valve body 2 and anchor device 5, such that the anchor line 6 will be taught when the prosthesis 1 is deployed, as will be discussed further below.

(44) The venous system of the patient to be treated is accessed via a puncture 104, typically in the groin area, accessing the femoral vein 105. Access to the venous system might alternatively be made via other large peripheral veins such as the subclavian or jugular veins. The femoral vein 105 is, however, preferred given the compressibility of the femoral vein 105 once a catheter is removed from the patient to achieve haemostasis.

(45) A guide wire 26, typically having a diameter of approximately 0.85 to 1.7 mm, is then inserted through the puncture 104 and along the femoral vein 105 and via the inferior vena cava 106 to the right atrium 107 of the patient's heart 100 as depicted in FIG. 9. If additional steadying of the guide wire 26 is desired, a snare may be introduced to the heart 100 through an arterial approach from the left or right femoral artery, aorta and aortic valve. The snare will then engage a J-tip on the end of the guide wire 26 and draw the end of the guide wire 26 through the arterial system to the exterior of the patient so that opposing ends of the guide wire 26 may be steadied.

(46) A catheter 18, typically having an internal diameter of at least 8 French (approximately 2.8 mm) is then advanced over the guide wire 26 and into the right atrium 107. Referring to FIG. 10, a puncture 108 is then made in the inter-atrial septum 103 using conventional equipment advanced via the catheter 18 in the known manner. The guide wire 26 and catheter 18 are then further advanced through the septal puncture 108 into the left atrium 109, through the native mitral valve 101 and into the left ventricle 110 as shown in FIG. 11. The first end 27 of the catheter 18 is thus located in the left ventricle 110 whilst the opposing second end of the catheter 18 is still located on the exterior of the patient.

(47) The mitral valve prosthesis 1 is then collapsed and fed into the second end of the catheter 18, with the second end 8 of the collapsed valve body 2 leading. An elongate prosthesis guide element 29 is detachably attached to the prosthesis 1, here by way of the screw threaded coupling 25 of the anchor device 5. The prosthesis guide element 29 may be a further guide wire with a cooperating screw threaded coupling 30 on its end, or alternatively might be a narrower catheter. The prosthesis 1 is advanced along the catheter 18 toward the catheter first end 27 as shown in FIG. 12. Rather than using a screw threaded coupling arrangement 25, 30 to couple the anchor device 25 and prosthesis guide element 29, a clip, clamp or the like may be utilized.

(48) The prosthesis 1 is advanced until the valve body 1 is released past the catheter first end 27 and into the left ventricle 110 as shown in FIG. 13. As the valve body 2 is released from the catheter first end 27, the elasticity of the valve body frame results in the valve body 2 extending to its uncollapsed state. The valve body 2 remains attached to the anchor device 5 by way of the anchor line 6.

(49) Referring to FIG. 14, the catheter 18 is then withdrawn through the puncture 108 such that the catheter first end 27 is located in the right atrium 107. Simultaneously, the prosthesis guide element 29 is withdrawn so as to draw the expanded valve body 2 toward the native mitral valve orifice 102 and left atrium 109. As the valve body first end 7 is sized to enable it to pass through the mitral valve orifice 102, and the valve body 2 is tapered such that the valve body second end 8 is sized so as not to pass through the mitral valve orifice 102, the valve body 2 engages the annular wall 111 of the mitral valve orifice and thus becomes wedged within the valve orifice 102. The valve body diagonal elements 17 and valve leaflets 3, 4 are ideally positioned adjacent the native mitral valve 101, whose leaflets are pushed away and crushed against the mitral valve orifice wall 111 by the valve body 2. Accordingly, with the native mitral valve 101 being pushed away from the mitral valve orifice 102, there is no need to remove the native mitral valve 101.

(50) The barbs 19 protruding from the valve body 2 and facing towards the valve body first end 7 (and thus the left atrium 109) pierce into the valve orifice wall 111 as the valve body 2 is wedged into position. The barbs 19 located adjacent the valve leaflets 3, 4 engage the valve orifice wall 111 in the vicinity of the native valve leaflets, whilst the barbs 19 at the valve body second end 8 engage additional cardiac structure surrounding the lower end of the valve orifice 102 within the left ventricle 110.

(51) The peripheral skirt 20 extending about the valve body 2 is located on the ventricular side of the mitral valve orifice 102, so as to seal between the periphery of the valve body 2 and the mitral valve orifice wall 111 when the left ventricle 110 contracts and pressurises during ventricular systole.

(52) The catheter 18 is then further retracted such that the anchor device 5 is released from the catheter first end 27. As the anchor device 5 is released it expands to its uncollapsed state and, with appropriate sizing of the anchor line 6, engages the inter-atrial septum 103 from within the right atrium 107, as shown in FIG. 15. The catheter 18 and guide wire 26 are then drawn back through the venous system and removed from the patient to complete the procedure. At any stage during the deployment process, the anchor device 5 and valve body 2 may be retracted back into the catheter 18 and removed if any difficulties are encountered.

(53) The anchor device 5 thus securely anchors the valve body 2 in the mitral valve orifice 102 against migration towards the left ventricle 110 during atrial systole, when the left atrium 109 contracts and pressurizes. The tapered configuration of the valve body 2, effectively wedging the valve body 2 into the mitral valve orifice 102, anchors the valve body 2 against migration towards the left atrium 109 during ventricular systole. The barbs 19 additionally anchor the valve body 2 against migration towards the left atrium 109.

(54) Once the prosthesis is successfully in place, the prosthesis guide element 29 is detached from the anchor device 5, by rotating the prosthesis guide element 29 to thereby decouple the threaded coupling.

(55) The entire procedure may be performed under the guidance of fluoroscopy, transthoracic and transesophageal echocardiography in a known manner.

(56) The valve leaflets 3, 4 replace the function of the native mitral valve leaflets, allowing bloodflow from the left atrium 109 to the left ventricle 110 through the mitral valve orifice 102 and bloodflow passage 9 of the valve body 2 during atrial systole, whilst blocking retrograde flow from the left ventricle 110 to the left atrium 109 during ventricular systole. The peripheral skirt 20 further blocks bloodflow through any gaps between the valve body 2 and the mitral valve orifice wall 111 in the retrograde direction during ventricular systole.

(57) In addition to, or in place of, the barbs 19 and tapered shape of the valve body 2 anchoring the valve body 2 against migration towards the left atrium 109, a further anchor device 5 might be utilized to anchor the valve body 2 to the inter-ventricular septum 112. Similarly, the tapered form of the valve body 2 might be utilized in conjunction with other mechanisms for securing the valve body 2 against migration towards the left ventricle rather than utilizing the anchor device. It is further envisaged that the general valve prosthesis configuration may be utilized for other types of heart valve prosthesis, for replacement of the aortic semiluminar valve, pulmonary semiluminar valve or tricuspid valve, utilizing alternative structures of the heart for securing the anchor device.

(58) An alternate form of valve prosthesis 201 is depicted in FIGS. 16 to 20. The prosthesis 201 has an anchor device 5 much the same as that of the prosthesis 1 of FIG. 1, however the valve body 202 is in the general form of a collapsible cylindrical ring. The collapsible ring 202 is formed of a squat cylinder and may have a woven construction formed of elongate elastic elements, typically metallic wire. Again, a particularly suitable material is a superelastic shape memory material such as nitinol. The valve body ring 202 should be sized so as to have an undeformed diameter slightly larger than that of the mitral valve orifice 102, such that when deployed, a compressive force is applied to the wall 111 of the valve orifice 102 to assist retaining the valve body in place. Care should be taken, however, not to oversize the valve body ring 202 such that an excessive compressive force is applied to the mitral valve orifice wall 111 which, as discussed above, may result in collapsing of the aortic outflow tract.

(59) The valve body ring 202 is arranged such that it may be collapsed into a cylindrical shape of reduced diameter, enabling it to be loaded into a catheter 18, as depicted in FIG. 18 in a similar manner to the valve body 2 described above.

(60) Valve leaflets 3, 4, as described above in relation to the first prosthesis 1, are secured to the valve body ring 202, again typically by suturing. Here three anchor lines 6 secure the valve body ring 202 to the anchoring device 5, with the anchor line 6 being secured at points spaced equidistantly about the valve body ring 202.

(61) Prongs 19 protrude from the valve body ring 202 toward the anchoring device 5 for engaging the valve orifice wall 111 in much the same manner as discussed above.

(62) Referring to FIGS. 19 and 20, deployment of the prosthesis 201 is generally the same as that described above in relation to the first prosthesis 1, with the primary difference being the lack of a tapered body that is wedged into the mitral valve orifice 102 to assist anchoring against migration towards the left atrium 109. The valve body ring 202 thus relies on the barbs 19 and compressive force applied to the mitral valve orifice wall 111 to prevent migration towards the left atrium 109.