Description:FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
(Section 10 and Rule 13)

1. TITLE OF THE INVENTION: TRANS-CATHETER PROSTHETIC HEART VALVE SYSTEM
2. APPLICANT:
Meril Life Sciences Pvt. Ltd., an Indian company of the address Survey No. 135/139, Bilakhia House Muktanand Marg, Chala, Vapi, Gujarat 396191, India

The following specification particularly describes the invention and the manner in which it is to be performed:

FIELD OF INVENTION
[01] The present invention relates to a prosthetic system. More specifically, the present invention relates to a trans-catheter prosthetic heart valve system.
BACKGROUND OF INVENTION
[02] Symptomatic severe aortic valve stenosis affects 3-5% of population over the age of 65 years globally. In Asian countries, the aortic valve anatomy also presents high degree of bicuspid valve anatomy (up to 40% of severe aortic valve stenosis) and these valves tend to degenerate in the fifth decade of the patient’s life. Currently, no medications are available to prevent severe aortic valve stenosis which is a degenerative disease. Only replacement of the native valve is the option for the affected patient.
[03] The function of a prosthetic heart valve is to replace a diseased native heart valve. The replacement procedure may be surgical (using open heart surgery) or percutaneous (using transcatheter procedure).
[04] In the surgical procedure, generally referred to as Surgical Aortic Valve Replacement (SAVR), the leaflets of the native heart valve are excised and the annulus is sculpted to receive a prosthetic valve. For many years, the definitive treatment for such disorders was the surgical repair or replacement of the valve during open heart surgery, but such surgeries are prone to many complications. Some patients do not survive the surgical procedure due to the trauma associated with the procedure and duration of the extracorporeal blood circulation. In addition, SAVR procedure is known to have longer hospitalization and prolonged recovery for the patients. Due to this, a number of patients are deemed inoperable and hence remain untreated.
[05] Against the surgical procedure (SAVR), a percutaneous catheterization technique has been developed for introducing and implanting a prosthetic heart valve using a flexible catheter that is considerably less invasive than an open-heart surgery. In this technique, generally known as Transcatheter Aortic Valve Implantation (TAVI) or as Transcatheter Aortic Valve Replacement (TAVR), a prosthetic valve is mounted by crimping on a balloon located at the distal end of a flexible catheter. The catheter is most commonly introduced into a blood vessel usually through a peripheral artery (less frequently via a vein); most likely a common femoral or sometimes axillary or carotid artery of the patient or rarely via a transapical route amongst other access routes. The catheter with the prosthetic valve crimped on the balloon is then advanced through the blood vessel till the crimped valve reaches the implantation site. The valve is allowed to expand to its functional size at the site of the defective native valve by inflating the balloon on which the valve is mounted. Alternatively, the valve may have a self-expanding stent or a support frame that expands the valve to its functional size by withdrawing the restricting sheath surrounding the prosthetic valve. The former prosthetic valve is termed as a “balloon-expandable” valve and the latter as a “self-expanding” valve.
[06] Both the balloon-expandable and self-expandable valves incorporate a support frame or a stent that is typically a tubular scaffold structure and a plurality of leaflets, typically, three leaflets.
[07] The design of the support frame plays an important role in the performance of the prosthetic valve. For achieving long term performance of the prosthetic valve, the support frame should have adequate radial strength to resist radially collapsing or compressive arterial forces. The support frame should also have adequate fatigue resistance to resist arterial cyclic forces imposed by opening and closing of the prosthetic valve during systolic and diastolic cycles. In view of these requirements, the design of the support frame of a transcatheter prosthetic heart valve should be based on structural robustness, sufficient radial strength or stiffness, and high fatigue strength. Further, the size and/or axial length of the support frame is desirably optimized to ensure enhanced interface with the native anatomy.
[08] In addition to the above-mentioned features, foreshortening during expansion of the frame of the THV is an important characteristic of the frame structure. It is understood and acknowledged that lower foreshortening is better since it allows the operator to deploy the THV at the intended site across the annulus and generate desired clinical outcome. The frame design impacts frame foreshortening and thus, influences its predictiveness during deployment.
[09] The known commercially available TAVI/TAVR frames are balloon expandable (made from cobalt-chromium alloys, stainless steel and other such materials) or self-expandable (made from shape memory alloys such as Nitinol). In either case, the THV frame is usually composed of several rows of tessellating geometrical cells in shape of diamonds, hexagons, etc. arranged in a homogenous pattern or a heterogeneous mix.
[010] Further, the foreshortening characteristic of a frame dictates the position of the un-deployed frame of the THV at the aortic annulus. It is well-known to the skilled person that the overall length of the frame reduces when the THV is expanded from its crimped condition to its deployed size.
[011] Some of the known procedural and clinical complications resulting from geographically misplaced THVs, as listed below, have been extensively published.
1. Paravalvular leak (PVL) or regurgitation.
2. Iatrogenic damage to conduction system resulting in implantation of a permanent pacemaker.
3. Obstruction of coronary artery ostia.
4. Interaction with previously implanted heart valve (surgical or mechanical) in mitral position.
5. Inadvertent embolization of THV toward left ventricle or toward ascending aorta.
[012] In each case, the procedural adverse event has an impact on patient survival and thus precise positioning and predictive accuracy in THV frame deployment becomes an important unmet clinical need.
[013] It is thus desired to devise a prosthetic valve system including the prosthetic frame that is prone to minimum foreshortening.
SUMMARY
[014] Particular embodiments of the present disclosure are described herein below with reference to the accompanying drawings; however, it is to be understood that the disclosed embodiments are mere examples of the disclosure, which may be embodied in various forms. Well-known functions or constructions are not described in detail to avoid obscuring the present disclosure in unnecessary detail. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a basis for the claims and as a representative basis for teaching one skilled in the art to variously employ the present disclosure in virtually any appropriately detailed structure.
[015] The present disclosure relates to a prosthetic valve. The prosthetic valve includes a radially collapsible and expandable support frame having a distal end, a proximal end and a plurality of rows of cells extending axially between the distal end and the proximal end. The rows include an upper row of cells that comprises interlaced chevron shaped decagonal cells creating alternate sequence of links, each link includes a straight strut portion followed by either one of rhombus bodies or diamond shaped cells at each junction; and a lower row of cells, adjacent to the upper row of cells that comprises interlaced octagonal cells creating alternate sequence of diamond shaped cells at each junction.
BRIEF DESCRIPTION OF THE DRAWINGS
[016] The summary above, as well as the following detailed description of illustrative embodiments, is better understood when read in conjunction with the appended figures. For the purpose of illustrating the present disclosure, various exemplary embodiments are shown in the figures. However, the disclosure is not limited to the description and figures disclosed herein. Moreover, those familiar with the art will understand that the figures are not to scale. Wherever possible, like elements have been indicated by identical numbers.
[017] Fig. 1a depicts a support frame 101 of exemplary trans catheter prosthetic heart valve (THV) 100 with an internal skirt 105 according to an embodiment of the present disclosure.
[018] Fig. 1b depicts the support frame 101 of the exemplary trans catheter prosthetic heart valve (THV) 100 with an external skirt 107 according to an embodiment of the present disclosure.
[019] Fig. 2 depicts a support frame 101 according to an embodiment of the present disclosure.
[020] Fig. 2a depicts a commissure attachment area 101d according to an embodiment of the present disclosure.
[021] Fig. 2b depicts a plane view of the support frame 101 and enlarged portions (Fig. 2b1 and Fig. 2b2) thereof according to an embodiment of the present disclosure.
[022] Fig. 2c depicts a wireframe according to an embodiment of the present disclosure.
[023] Fig. 3 depicts a leaflet 103 according to an embodiment of the present disclosure.
[024] Fig. 3a depicts a leaflet 103x according to another embodiment of the present disclosure.
[025] Fig. 4 depicts a delivery catheter 200, according to an embodiment of the present disclosure.
[026] Fig. 5 depicts an enlarge view of the delivery catheter 200 according to an embodiment of the present disclosure.
[027] Fig. 6 depicts an aortic annulus 1 according to an embodiment of the present disclosure.
[028] Fig. 6a depicts an enlarged view of the aortic annulus 1 according to an embodiment of the present disclosure.
[029] Fig. 7 depicts the support frame 101 crimped and mounted over the balloon catheter 200 according to an embodiment of the present disclosure.
[030] Figs. 8-10 depict various alignment of the support frame 101 at the aortic annulus 1 according to an embodiment of the present disclosure.
[031] Fig. 11 depicts the support frame 101 deployed at the aortic annulus 1 according to an embodiment of the present disclosure.
[032] Fig. 12 depicts anatomy of the human heart H schematically in a simplified manner.
[033] Fig. 12a is a schematic simplified representation of the human heart H (like Fig. 14) for illustrating the transeptal procedure.
[034] Fig. 13 shows the details of the balloon 201’ which is similar to the balloon 201 depicted in Fig. 4.
[035] Fig. 14 depicts a schematic representation of left atrium LA with THV 100 implanted at within the degenerated surgical bioprosthetic valve 1701.
[036] Fig. 15 depicts a schematic representation of left atrium LA with THV 100 implanted at within the damaged/degenerated annuloplasty ring 1801.
[037] Fig. 16 depicts schematically the frame 101 of the THV 100 mounted on the balloon 201’ under collapsed condition as visible under fluoroscopy.
[038] Figs. 17-19 depict various alignment of the landing zone marker M4 with the suture ring.
[039] Figs. 20-22 depict various alignment of the landing zone marker M4 with the annuloplasty ring.
DETAILED DESCRIPTION OF ACCOMPANYING DRAWINGS
[040] Prior to describing the invention in detail, definitions of certain words or phrases used throughout this patent document will be defined: the terms "include" and "comprise", as well as derivatives thereof, mean inclusion without limitation; the term "or" is inclusive, meaning and/or; the phrases "coupled with" and "associated therewith", as well as derivatives thereof, may mean to include, be included within, interconnect with, contain, be contained within, connect to or with, couple to or with, be communicable with, cooperate with, interleave, juxtapose, be proximate to, be bound to or with, have a property of, or the like; Definitions of certain words and phrases are provided throughout this patent document, and those of ordinary skill in the art will understand that such definitions apply in many, if not most, instances to prior as well as future uses of such defined words and phrases.
[041] Reference throughout this specification to “one embodiment,” “an embodiment,” or similar language means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment. Thus, appearances of the phrases “in one embodiment,” “in an embodiment,” and similar language throughout this specification may, but do not necessarily, all refer to the same embodiment, but mean “one or more but not all embodiments” unless expressly specified otherwise. The terms “including,” “comprising,” “having,” and variations thereof mean “including but not limited to” unless expressly specified otherwise. An enumerated listing of items does not imply that any or all of the items are mutually exclusive and/or mutually inclusive, unless expressly specified otherwise. The terms “a,” “an,” and “the” also refer to “one or more” unless expressly specified otherwise.
[042] Although the operations of exemplary embodiments of the disclosed method may be described in a particular, sequential order for convenient presentation, it should be understood that the disclosed embodiments can encompass an order of operations other than the particular, sequential order disclosed. For example, operations described sequentially may in some cases be rearranged or performed concurrently. Further, descriptions and disclosures provided in association with one particular embodiment are not limited to that embodiment, and may be applied to any embodiment disclosed herein. Moreover, for the sake of simplicity, the attached figures may not show the various ways in which the disclosed system, method, and apparatus can be used in combination with other systems, methods, and apparatuses.
[043] Furthermore, the described features, advantages, and characteristics of the embodiments may be combined in any suitable manner. One skilled in the relevant art will recognize that the embodiments may be practiced without one or more of the specific features or advantages of a particular embodiment. In other instances, additional features and advantages may be recognized in certain embodiments that may not be present in all embodiments. These features and advantages of the embodiments will become more fully apparent from the following description and apportioned claims, or may be learned by the practice of embodiments as set forth hereinafter.
[044] It should be noted that in the figures and the description to follow, the terms “frame” or “stent” or “frame” or “scaffold structure” or “support frame” or “scaffold” refer to the metallic frame of this invention. These terms are used interchangeably but carry the same meaning. The terms “trans-catheter prosthetic heart valve”, “prosthetic heart valve”, “valve” or “prosthetic valve” refer to an assembled prosthetic valve of the present invention using a support frame and other components like leaflets of animal tissue, skirt, etc. These terms are also used interchangeably. The term “native valve” is used for the natural valve in human heart.
[045] Likewise, the terms ‘delivery system’, ‘delivery catheter’, ‘catheter’, ‘balloon catheter’, ‘delivery balloon catheter’ refer to the delivery apparatus used in the present invention. These terms are used interchangeably but carry the same meaning.
[046] The present invention discloses a balloon expandable prosthetic heart valve system (or system). The system of the present invention includes a trans-catheter prosthetic heart valve (THV) and a THV delivery system. The THV of the present invention may be implanted via a catheterization technique in a human stenosed aortic orifice using the THV delivery system. The THV and the THV delivery system work in unison to achieve an improved performance of the system.
[047] The THV includes a flexible frame which can expand and collapse, a plurality of leaflets (preferentially three leaflets) formed from animal tissue or synthetic material, and at least one of an internal skirt and an external skirt that are attached to the frame.
[048] The frame of the THV in the present invention offers several structural and clinical advantages over the conventional frames and mitigates the disadvantages offered by the same. The frame of the THV of the present invention includes interlaced decagonal and octagonal cells which incorporate a rhombus body (with holes) or a diamond shaped cell at each cell intersection. Such a structure enhances columnar strength thereby resulting in improved radial strength and fatigue resistance.
[049] The frame includes two tessellating rows of cells – a row of decagonal cells and a row of octagonal cells placed one above the other. The reduction in number of rows and the specific shape of the cells, result in reduced foreshortening of the frame on radial expansion which makes it easier for the operator to implant the prosthetic heart valve accurately. The unique frame design of the THV of the instant invention offers reduced foreshortening without compromising on the radial strength and fatigue resistance of the frame.
[050] The foreshortening is virtually eliminated from the outflow zone (usually the aortic end) with a marginal foreshortening of 10-12% at its inflow zone (usually the ventricular end). The outflow zone includes a predefined cell design and chevron shaped free edge of the THV frame that results in virtually no foreshortening. The expansion of the cells with the chevron shaped free edge in the outflow zone of the frame does not exhibit foreshortening. Due to this unique characteristic, the operator does not need to keep an eye on the aortic end of the THV frame during expansion. This results in saving procedural time, positively influencing the THV deployment and also reducing the learning curve for new operators (interventional cardiologists), eventually supporting the potential growth in TVR/TAVI procedures globally.
[051] The foreshortening of the frame at the inflow zone of this THV frame is thus mediated only by opening of nested “angled struts” at the inflow edge and the inverted “angled struts” at the intermediate-row forming the junction of inflow-outflow zone rows.
[052] This offers the operator total control of the THV frame under expansion, leading to accurate deployment of the THV frame. Accurate deployment further leads to predictable procedural and clinical outcomes such as Lower MACCE (Major Adverse Cardiac and Cerebrovascular Events), lower para valvular leakage (PVL), lower new permanent pacemaker implantation (PPI), possibility of shallow or deep THV frame deployment depending upon patient’s anatomic and/or clinical presentation such as bicuspids aortic valves; narrow or wide left ventricular outflow tract (LVOT); presence of septal bulge; concomitant presence of surgical valve in mitral position; narrow or calcified sino-tubular junction (STJ), etc.
[053] Further, the delivery system helps in accurate placement and precise deployment of the THV of the present invention at the orthotopic position. This is achieved due to the design of the structure of the prosthetic aortic valve and the delivery system of this invention.
[054] The THV 100 in accordance with an embodiment of the present invention is represented in Figs. 1a & 1b. Fig. 1a shows THV 100 with an internal skirt 105 only, while Fig. 1b shows THV 100 with the internal skirt 105 and an external skirt 107. As the THV 100 is implanted in a human stenosed aortic orifice, the THV 100 may also be referred as a ‘prosthetic aortic valve’.
[055] The THV 100 includes a frame 101 (or support frame 101), a plurality of leaflets 103/103x, an internal skirt 105 (as shown in FIG. 1a) and an external skirt 107 (as shown in FIG. 1b). Fig. 2 depicts the frame 101 in an embodiment of the present invention.
[056] The frame 101 of THV 100 is radially expandable and radially collapsible. The THV 100 is suitable for mounting on a balloon of a delivery catheter in a radially collapsed condition. The balloon delivery catheter along with THV 100 in collapsed condition, is navigated to the implantation site. THV 100 is implanted in the human stenosed aortic orifice by radially expanding THV 100 by inflating the balloon. In an embodiment, the THV 100 exhibits fluoroscopic properties.
[057] As shown in Fig. 2, the THV 100 includes an inflow end 100a (also referred as “lower end” or “distal end”) at an inflow zone and an outflow end 100b (also referred as “upper end” or “proximal end”) at an outflow zone. Blood enters the THV 100 at the inflow end 100a and leaves at the outflow end 100b. The leaflets prevent the blood flow in reverse direction. The frame 101 is cylindrical in shape.
[058] The exploded views of an exemplary embodiment of the frame 101 of the present invention are shown in Figs. 2b and 2b1-2b2. The frame 101 of the exemplary embodiment is a balloon-expandable frame. Alternately, the frame 101 may be a self-expandable frame.
[059] The frame 101 may be formed by following any pre-defined methodology known in the art. For example, the frame of THV 100 may be formed by laser cutting a metal tube. The metal tube may be made from a metal or a metal alloy, including but not limited to, stainless steel, cobalt-chromium alloy, cobalt-chromium-nickel alloy, cobalt-chromium-nickel-molybdenum alloy such as MP35N, Nitinol, titanium etc. The material used for the frame 101 may be fluoroscopic. In a preferred embodiment of the present invention, the frame 101 is balloon expandable and is made from a tube of cobalt-chromium-nickel-molybdenum alloy viz. MP35N which ensures optimal radial strength, radiopacity and prompt MRI compatibility of the support frame 101.
[060] The structure of the frame 101 of an exemplary embodiment is shown in Figs. 2, and 2b. Fig. 2 shows a prospective view of the frame 101. Fig 2b depicts the cylindrical frame structure when the cylindrical portion of the frame is cut vertically along its axial length and flattened. It should be noted in relation to Fig. 2b that the frame scaffold design is shown laid flat for convenience purpose only and the frame 101 may not be created from a flat metal sheet.
[061] The frame 101 includes two rows of cells; a lower row of cells 101b1 and an upper row of cells 101b2. The two rows of tessellating cells (for example, polygonal cells) are placed one above the other (adjacently placed) extending between the distal end (inflow end 100a) and the proximal end (outflow end 100b) of the frame.
[062] Referring to Fig. 2b, the frame 101 is a radially collapsible and expandable support frame 101 having a distal end, a proximal end and three circumferentially extending rows of angled struts having an upper row 10a at the proximal end 100b of the frame, a lower row 10c at the distal end 100a of the frame and an intermediate row 10b located between the proximal row 10a and the distal row 10c. In the said context, a distal position refers to a position away from the operator. The lower row 10c is towards the inflow end 100a of the support frame 101 and the upper row 10a is towards the outflow end 100b of the support frame 101. Though the frame 101 is described with three circumferentially extending rows of angled struts, other variations of the frame including multiple intermediate rows of angled struts are within the teachings of the present disclosure.
[063] Any two consecutive angled struts of a circumferentially extending row of angled struts, form a peak or a valley. The peak or valley provide an undulating shape to each row of angled struts. The peaks of the angled struts of one circumferentially extending row of the angled struts face the peaks or valleys of the angled struts of an adjacent circumferentially extending row of the angled struts. Thus, a peak in one circumferentially extending row of angled struts has a corresponding peak or valley in the adjacent circumferentially extending row of angled struts facing each other. The peaks P1 of the upper row 10a of angled struts face the peaks P2 of the intermediate row 10b of angled struts, and the peaks P2 of the intermediate row 10b of angled struts face the valleys V3 of the lower row 10c of angled struts.
[064] In an embodiment, the angle (‘A’) between two angled struts in FIG. 2b is around 116°. However, it should be noted that the said angle may be less than or more than 116°.
[065] The two adjacent rows of angled struts are connected to each other to form cells which form the scaffold structure of frame 101. In an embodiment, the scaffold structure of the frame is made up of two adjacently placed rows of cells between the distal end and the proximal end of the frame 101. For instance, the rows of angled struts 10a and 10b are connected to each other to form the upper row of cells 101b2. Similarly, the rows of angled struts 10b and 10c are connected to each other to form the lower row of cells 101b1.
[066] Referring to Fig. 2b and the blown-up views View Y (Fig. 2b1) and View Z (Fig. 2b1), the peaks P1 of the upper row 10a of angled struts are connected to the corresponding peaks P2 of the intermediate row 10b of angled struts by links L. A link L comprises a straight portion ‘S’ and either a diamond shaped cell 101c2 or a rhombus body 101d which may have holes. The links L along with the upper and intermediate rows of angled struts form an upper row of cells 101b2. The upper row of cells 101b2 includes interlaced decagonal cells with chevron shape.
[067] The valleys V2 of the intermediate row 10b of angled struts are connected to the corresponding peaks P3 of the lower row 10c of angled struts by diamond shaped cells 101c1. The diamond shaped cells 101c1 along with the intermediate and lower rows of angled struts form a lower row of cells 101b1. The lower row of cells includes interlaced octagonal cells creating a sequence of diamond shaped cells at each junction.
[068] The decagonal cell 101b2 in the upper row of cells is shown schematically in Fig. 2c with all ten sides and angles marked sequentially as 1 to 10 and 1’ to 10’ respectively. Similarly, the octagonal cell 101b1 in the lower row of cells is shown in Fig. 2c with all eight sides and angles marked sequentially as A to H and A’ to H’ respectively.
[069] The sum of the angles formed by a polygon is (n-2)*180° where n denotes the number of sides. Hence, for a decagon (with 10 sides), the sum of the angles would be 1440° and an octagon (with 8 sides), the sum of the angles would be 1080°. Accordingly, sum of all angles of any of the decagonal cells 101b2 (1’ to 10’) is 1440° and that of the octagonal cells 101b1 (A’ to H’) is 1080°.
[070] Each link L connecting the two adjacent rows of angled struts 10a and 10b has a diamond shaped cell 101c2 which is defined by two pairs of crooked struts (s1’/s2’ and s3’/s4’ as shown in Fig. 2b1) which form the diamond shaped cells 101c2. Similarly, the diamond shaped cell 101c1 connecting the two adjacent rows of angled struts 10b and 10c are defined by two pairs of crooked struts (s1/s2 and s3/s4 as shown in Fig. 2b1) which form the diamond shaped cells 101c1. This means that a diamond shaped cell 101c1 or 101c2 is formed by the pairs of crooked struts s1/s2 and s3/s4 or s1’/s2’ and s3’/s4’ enclosing an open diamond shaped structure within. The interconnection of the one row and the adjacent row of angled struts 10a/10b/10c thus results in a cell structure having interlaced octagonal and decagonal cells 101b1 and 101b2 respectively, and diamond shaped cells 101c1/101c2 or solid rhombus bodies 101d with holes enhance columnar strength of the frame 101 resulting in improved radial strength and fatigue resistance of the frame 101.
[071] The upper row of cells 101b2 includes three solid rhombus bodies 101d with holes, spaced angularly at 120° with respect to each other, forming three commissure attachment areas. To each commissure attachment area, the commissural tabs of the two adjacent leaflets are attached. In an exemplary embodiment, each rhombus body 101d has four holes. Fig. 2a shows the details of the rhombus body 101d with four holes 101d1 which are provided for suturing the commissural tabs of two adjacent leaflets 103/103x. The commissural tabs of two adjacent leaflets 103/103x form commissures. It may be noted that the number of holes may be less than or more than four. Similarly, the number of rhombus bodies with holes may be more or less than three depending on the number of leaflets in the THV for which the frame is made.
[072] In a preferred embodiment and as shown in Fig. 2b, the upper row of decagonal cells 101b2 occupy around 55% of the total height H of the frame; while the lower row of octagonal cells 101b1 occupy around 45% of the total height H of the frame. The larger cells in the upper (outflow) part of the frame keeps coronary ostia unjailed to allow unrestricted flow of blood from the aorta to the coronary arteries. However, the size of the cells in the upper and lower rows of cells may be equal.
[073] In an embodiment, at least one radiopaque marker (not shown) may be provided on the frame 101 on any of the struts preferably on the crooked struts (s1, s2, s3, s4) forming the diamond shaped cells 101c1 (located in the lower row of cells 101b1) for easy visualization under fluoroscopy. However, the radiopaque markers may be provided on other struts.
[074] The THV 100 of the present invention further includes a plurality of leaflets. In an embodiment depicted in Figs. 1a and 1b, the THV 100 includes three leaflets 103/103x. The leaflets 103/103x may be made from any bio-compatible material with sufficient flexibility to allow movement of leaflets. For example, in the present invention, the leaflets of a preferred embodiment are made from an animal tissue such as bovine pericardial tissue. Alternately, the leaflets may be formed from a biocompatible polymeric synthetic material such as a fabric.
[075] The leaflets allow unidirectional flow of blood from the inflow end 100a of THV 100 to the outflow end 100b and prevent the flow of blood in the reverse direction. This is achieved by opening and closing the leaflets during systolic and diastolic cycles. A leaflet typically includes a body, an upper edge and at least one, normally two, oppositely disposed side tabs (or commissure tabs). One of the side tabs of a leaflet is paired with a side tab of an adjacent leaflet to form the commissure by suturing to a commissure attachment area (namely, the rhombus body 101d) of the frame 101. The commissure tab can be attached to the support frame either directly or through an intermediate fabric layer to prevent direct contact of the leaflet with the frame. The upper edge is kept free for coaptation with the corresponding free edges of the other leaflets.
[076] Two exemplary depictions of the leaflets are illustrated in Figs. 3 and 3a. The upper edge of the leaflets can be relatively straight with or without an apex. A commissure tab is provided at each side of the leaflet at its upper edge. Further, the leaflet includes one of a scalloped lower edge attached to the internal skirt or, a straight lower edge and two side edges attached to the internal skirt. A person skilled in the art is well-aware of the details of a leaflet and such details can be practiced along with the teachings of the present disclosure.
[077] Referring to Fig. 1a, the internal skirt 105 is attached to the inner (or internal) surface of the frame 101 and in a preferred embodiment, covers the internal surface of the lower row of the octagonal cells 101b1 at least partially. The lower edge of the leaflets 103 or 103x may be attached to the inner surface of the internal skirt 105. The internal skirt 105 prevents leakage of blood from the openings of the cells 101b1 of the frame 101 in the lower row and also prevents inadvertent damage of the leaflets 103/103x of THV 100 by calcium spicules present in diseased native valve.
[078] Referring to Fig. 1b, the external skirt 107 of an exemplary embodiment is attached to the outer (or external) surface of the frame 101. The external skirt 107 covers the external surface of the lower row of the octagonal cells 101b1 at least partially and includes an upper end 107b and a lower end 107a. In an embodiment, the upper end 107b may be attached to the internal skirt 105 and the frame 101 via suturing. In the same embodiment, the lower end 107a of the external skirt 107 is attached to the lower end 105a of the internal skirt 105 by suturing. The external skirt 107 has excess material which fits loose onto the frame 101 forming a slack when the frame 101 is in radially expanded condition. The excess material of the loose external skirt 107 fills the irregular inner surface of the aortic annulus (which also has native leaflets) and plugs micro channels. This prevents or minimizes the paravalvular leakage. The slack reduces when the frame 101 is in a radially collapsed condition.
[079] The internal skirt 105 and the external skirt 107 of a preferred embodiment may be made from a fabric such as PET. However, any other biocompatible fabric or animal tissue with required flexibility, strength and porosity can be used for making the internal skirt 105/external skirt 107.
[080] The delivery system i.e. a delivery catheter 200 for the THV 100 of this invention will now be described. Fig. 4 depicts an exemplary delivery catheter 200. The delivery catheter 200 is utilized for deploying the THV 100 within a diseased native valve at a target location. The frame structure of THV 100 and the delivery catheter 200 of the instant invention provide an easy and accurate method for deployment of the THV 100 at the target location.
[081] The delivery catheter 200 as shown in FIG. 4 is a balloon catheter. The exemplary delivery catheter 200 includes a proximal end A and a distal end B. The delivery catheter 200 further includes a balloon 201 at its distal end B (shown in Fig. 5), an outer shaft 203, an inner shaft 205, an optional support tube 207, one or more stoppers 209, a handle 211 and a connector 213 at the proximal end. The distal end refers to the end away from the operator as mentioned earlier.
[082] The outer shaft 203 is in the form of an elongated external tube referred also as ‘elongated shaft’. The outer shaft 203 defines an outer lumen through which the inner shaft 205 extends coaxially. The inner shaft 205 defines an inner lumen. A guidewire passes through the inner lumen.
[083] The outer shaft 203 and the inner shaft 205 (also referred to as “inner lumen”) have respective proximal and distal ends (A and B respectively). Proximal end is towards the handle 211 i.e. towards the operator. The opposite end towards the balloon 201 is the distal end which is away from the operator. The proximal ends of the outer shaft 203 and the inner shaft 205 may pass through the handle 211 and may be attached to the connector 213. The connector 213 may be a Y-shaped connector having a port 213A for exit of a guidewire and a port 213B for injecting inflation fluid into the catheter 200. The guidewire port 213A is in communication with the inner lumen 205. The port 213B for inflation fluid is in communication with the annular space between the two shafts 203 and 205.
[084] An exemplary embodiment of the balloon 201 is shown in Fig. 5. The balloon 201 is attached to the distal end of the outer shaft 203. The inner lumen 205 extends through the balloon 201 and it ends into a soft tip 215 at a distal most end of the catheter 200. The guidewire (not shown) enters the guidewire lumen at the distal end of the soft tip 215 of the catheter 200, passes through the inner lumen, passes through the balloon 201 and exits from the connector 213 at guide wire port 213a.
[085] The balloon 201 is an inflatable balloon that is radially expanded by injecting pressurised inflation fluid into the balloon 201 through the annular space between the outer shaft 203 and the inner shaft 205.
[086] In a preferred embodiment, a support tube 207 is attached to the distal end of the outer shaft 203. The support tube 207 extends within the balloon 201 and the inner shaft 205 passes through the support tube 207 coaxially as more clearly shown in the FIG. 5.
[087] As shown in FIG. 5, the support tube 207 includes a proximal end 207a and a distal end 207b. The proximal end 207a is attached to the outer shaft 203. The distal end 207b is a free end and overhangs within the balloon 201.
[088] The delivery catheter 200 may include at least one stopper made from a resilient and biocompatible material. The stopper prevents the THV 100 from shifting on or dislodging from the balloon 201 during insertion of the crimped THV 100 into the patient’s vasculature. A preferred embodiment of Fig. 5 is provided with two stoppers; a proximal stopper 209a and a distal stopper 209b. The proximal and distal stoppers 209a, 209b are attached to the outer surface of the support tube 207.
[089] The proximal stopper 209a and the distal stopper 209b may be spaced apart at a pre-defined distance. In the preferred embodiment, the clear gap between the distal end of the proximal stopper 209a and the proximal end of the distal stopper 209b is little more than the length of the crimped THV 100. The THV 100 is crimped on the balloon 201 within this gap. The clear gap as defined above may vary depending upon the length of the crimped THV 100.
[090] A person skilled in the art is well-aware of the details of a stopper and such details can be practiced along with the teachings of the present disclosure.
[091] The support tube 207 described above enables accurate attachment of the stoppers 209a, 209b and provides free passage to inflation fluid into the balloon 201. A delivery system without the support tube 207 would also function. In this case, the stoppers may be located on the inner shaft 205 and the inflation fluid will enter the balloon 201 at its proximal end from the annular space between the inner shaft 205 and the outer shaft 203.
[092] The support tube 207 of the present invention may include a plurality of radiopaque marker bands (or markers). In a preferred embodiment, the support tube 207 includes four radiopaque marker bands including a proximal marker band M1, a distal marker band M2, a middle marker band M3 and a landing zone marker band M4. In case the delivery catheter 200 does not have a support tube 207, the said markers may be provided on the inner shaft 205 on the portion located within the balloon 201. The marker bands may be made of any biocompatible radiopaque material known in the art such as platinum, platinum-iridium alloy, tantalum, gold etc. Radiopaque markers in a preferred embodiment of the catheter of the instant invention are made from platinum-iridium alloy.
[093] As the name suggests, the proximal marker band M1 and the distal marker band M2 are disposed towards the proximal end 207a and the distal end 207b of the support tube 207 respectively. The middle marker band M3 is located between the proximal and distal marker bands M1, M2 equidistant from M1 and M2. The placement of the landing zone marker M4 is calculated basis one of more parameters including without limitation the length of a frame, foreshortening properties of the frame, number of rows of cells, shape of cells, position of the leaflets, anchoring zone of the frame (that is, position where the frame is anchored to the native annulus or annulus of previously implanted THV or annuloplasty ring), etc. The placement of the landing zone marker M4 thus calculated, helps an operator in accurate placement of the THV 100 as described later.
[094] In an exemplary embodiment of the frame depicted in Fig. 2b, the landing zone marker M4 is placed between the distal and mid marker bands M2, M3 at a distance of around 32-34% of the distance between proximal and distal markers M1, M2 from the distal end marker M2 i.e. dimension B is 32-34% of dimension A as shown in FIG. 5. This distance is for the frame depicted in Fig. 2b. For any other frame with a different scaffold structure and shape of cells, etc., the placement of the landing zone marker M4 can be predetermined on the basis of aforesaid parameters.
[095] The distal edge of the proximal marker M1 is in line with the distal edge of the proximal stopper 209a as shown by the broken line L1. Similarly, the proximal edge of the distal marker M2 is in line with the proximal edge of the distal stopper 209b as shown by the broken line L2. This feature fixes exact location of all the radiopaque markers. Again, as mentioned above, this feature is applicable to the embodiment of THV 100 with the frame depicted in Fig. 2b.
[096] The landing zone marker M4 plays a guiding role in accurate positioning of the THV 100 at the implantation site to achieve implantation at the most preferred location viz. orthotopic position.
[097] The distal end of the shaft of the exemplary catheter 200 may be configured to be flexed in a controlled manner for easy passage through aortic arc. In an alternate embodiment, the distal end of the shaft of catheter 200 may not be configured to be flexed. In yet another alternate embodiment, the distal end of the shaft of the catheter 200 may be pre-shaped with a fixed radius for easy passage through aortic arc. The pre-shaping of the catheter shaft can be achieved by known methods such as thermal treatment.
[098] FIG. 6 depicts the aortic root complex 1. Aortic root is the dilated first part of aorta attached to the heart at its end. It is a part of the ascending aorta (AA) 2 containing the native aortic valve. There are generally three cusps of the native aortic valve. The coronary arteries originate from the vicinity of the aortic bulb from two of the three cusps. The Right Coronary Artery (RCA) 3 originates from Right Coronary Cusp (RCC) and the Left Coronary Artery (LCA) 4 originates from Left Coronary Cusp (LCC). The remaining cusp is termed Non-Coronary Cusp (NCC) as no coronary artery originates in the vicinity of this cusp. There are two distinct demarcation planes, one is the Virtual Annular Plane (VAP) 6 and the second is Sino tubular Junction (SJ) 7. In a standard procedure under fluoroscopic guidance, the native coronary cusps are made co-planar wherein the hinge point of each cusp is in a straight line and all the three cusps are well separated. The VAP 6 thus achieved can be visible under fluoroscopy and is a guiding feature to position the prosthetic valve at the optimal location for implantation.
[099] During a THV replacement procedure, under fluoroscopic guidance, the three native coronary cusps (sinuses) RCC, LCC, NCC are visually aligned in a co-planar view wherein non-coronary cusp (NCC) appears to the right of the patient and the left coronary cusp (LCC) appears to the left of the patient with the RCC lying in the center. This is shown schematically in Fig. 6a. It may be noted that the fluoroscopic view is a mirror image of the true anatomical/AP view. Hence, in the schematic image of Figs. 6 and 6a, NCC appears to the right of the patient and the LCC appears to the left of the patient.
[0100] As mentioned above, accurate placement and precise deployment of a prosthetic valve in aorta is very important to achieve optimal performance i.e. reduced valve gradients (sustained hemodynamics), absence of paravalvular regurgitation and avoiding any iatrogenic damage to conduction system that necessitates a new permanent pacemaker implantation. The ideal location of implantation of a prosthetic valve in aorta is preferably the orthotopic position where the attempt is to superimpose the prosthetic annulus (neo-annulus) to the native annulus ring. As mentioned above, implanting the prosthetic valve at this location has three important advantages, viz. (a) better anatomical placement of the prosthetic valve whereby the frame is held firmly within the stenosed annulus, thereby offering geographical fix, (b) minimal protrusion of valve in left ventricle, thereby not disturbing cardiac conduction system, and (c) minimizing obstruction to ostia of coronary arteries located along the coronary sinus of valsalva or may be above the sino-tubular junction.
[0101] As shown in Fig. 2b, the frame 101 of the THV 100 has three circumferentially extending rows of angled struts 10a, 10b, 10c that are interconnected by links L and diamond shaped cells 101c1. The THV 100 is crimped on the balloon 201 between the two stoppers 209a, 209b and two extreme radiopaque markers M1, M2. Fig. 7 depicts schematically the frame 101 of the THV 100 mounted on the balloon 201 under collapsed condition, as visible under fluoroscopy. A and B indicate proximal and distal ends respectively. The other components of the THV are not shown for clarity and only the frame would be visible clearly under fluoroscopy as it is made from radiopaque material.
[0102] The angled struts of the row of angled struts on the inflow end 100a of the frame 101 (row 10c, refer to Fig. 2, 2b) play an important role in accurate placement of the THV 200 at the orthotopic position. Fig. 7 depicts the lower row 10c at the distal end B where the angled struts Vs are seen nested close to each other in the exploded View X, Fig. 7. The converging of these angled struts Vs commences at the distal end of the landing zone marker M4 and the apex Ax of an angled strut Vs is visibly away from the distal edge of the landing zone marker M4 towards the distal direction B.
[0103] As mentioned above, during implantation of a prosthetic heart valve, a pigtail catheter 8 is introduced into the vasculature of the patient. The pigtail catheter 8 is shown in Fig. 8. The curved distal edge 8a of the pigtail catheter 8 is ideally placed at the base of the non-coronary cusp NCC of the aortic annulus. Alternately, the curved distal edge 8a of the pigtail catheter 8 may be placed at the base of right or left coronary cusps i.e. RCC or LCC (though not ideal) and also at the sino tubular junction 7 (STJ). The decision of the location of this placement is usually taken by the operator based on aortic root anatomy. The curved distal edge 8a of the pigtail catheter 8 can be used as a landmark for accurate placement of the prosthetic heart valve in aorta. For this, the curved distal edge 8a of the pigtail catheter 8 is made to rest on the base of a cusp (NCC, RCC or LCC) at the aortic root; preferably on the base of the non-coronary cusp NCC.
[0104] For accurate placement of the THV 100, the balloon delivery catheter 200 is advanced across the aortic annulus till the distal edge (inflow edge) of the landing zone marker M4 is aligned with the curved distal edge 8a of the pigtail catheter 8 as visible under fluoroscopic guidance. This scenario is depicted in Fig. 8 and an exploded View A is provided for clarity. Under fluoroscopy, the frame 101 of the THV 100 is visible with clarity. A brief angiogram with a small volume of diluted contrast helps opacify and locates the virtual annular plane 6. This helps the operator to ensure precise positioning of THV 100 prior to its deployment. Under rapid pacing of the heart, due to its aforementioned foreshortening characteristics, when expanded to its nominal diameter at this location, the THV 100 gets deployed at an optimal position in the aortic annulus. This is made possible because the foreshortening of the frame 101 of THV 100 is mediated only by the expansion of the angled struts Vs at the inflow zone and there is no foreshortening at the outflow zone. Hence, the positioning is totally predictable when the valve is expanded to its nominal diameter.
[0105] As mentioned above, the curved distal edge 8a of the pigtail catheter 8 is made to rest on the base of a cusp (ideally NCC or even RCC or LCC) at the aortic root and hence, the distal edge (inflow edge) of the landing zone marker M4 is brought in line with the base of the cusp at the aortic root; in other words, in line with the virtual annular plane 6 as the native coronary cusps are made co-planar wherein the hinge point of each cusp is in a straight line and all the three cusps are well separated (refer to Fig. 6a). The virtual annular plane 6 can be visible under fluoroscopy and is also an alternate guiding feature to position the THV 100 at the optimal location for implantation.
[0106] As described above, the positioning is achievable when the THV 100 is expanded to its nominal diameter which is an ideal situation. In a real case, the operator may be required to over-expand or in some cases, under-expand the THV 100 for proper deployment. In such a situation, the operator may have to make little adjustment in locating the landing zone marker relative to the distal edge 8a of the pigtail catheter 8 i.e. the base of the cusp at the aortic root and the virtual annular plane 6. This adjustment is, however, very small i.e. to the extent of maximum 3 mm. The length of the landing zone marker M4 is preferably kept 3 mm which the operator may use as an indicator for adjusting the position of the crimped THV 100 to arrive at desired placement location. The operator may, for example, match the center of the landing zone marker M4 with the distal edge 8a of the pigtail catheter 8 or the virtual annular plane 6. This situation is shown in Fig. 9 and exploded View B. In another situation, the operator may, for example, match the proximal edge of the landing zone marker M4 with the distal edge 8a of the pigtail catheter 8 or the virtual annular plane 6. This situation is shown in Fig. 10 and exploded View C.
[0107] It may be noted that the above scenario is applicable to the frame scaffold design depicted in Figs. 1 and 1b. A skilled person would realize that for other scaffold designs, the length of the landing zone marker may be less than or more than 3 mm.
[0108] In some situations, based on the anatomy of the aortic root of the patient, the operator may decide to place the distal end of the pigtail catheter 8 at another location, for example, at the sino-tubular junction 7 (refer to Fig. 6). In such a situation, the operator would have to determine the location of the virtual annular plane 6 with the help of fluoroscopy as detailed above and position the THV 100 such that appropriate location of the landing zone marker M4 (e.g. the distal edge, the center, the proximal edge) is in line with the virtual annular plane 6.
[0109] In any situation, the virtual annular plane 6 which is visible under fluoroscopy is a guiding feature to position the THV 100 at the optimal location for implantation. As mentioned above, this is made possible because in the frame of THV 100, the foreshortening is mediated only by the expansion of the angled struts Vs at the inflow zone and there is no foreshortening at the outflow zone. Hence, this is totally predictable when the THV is expanded to its nominal diameter.
[0110] Fig. 11 depicts the aortic root complex schematically with THV 100 implanted at the orthotopic position. Only the frame of THV 100 (without leaflets/skirts etc.) is shown for clarity. LCA is left coronary artery. RCA is right coronary artery. 8 is the pigtail catheter. In an embodiment, as shown in Fig. 11, 80%-85% of the length of the expanded THV 100 remains above aortic annulus (virtual annular plane) 6 while, the residual 15%-20% of the length of the expanded THV 100 dwells in the sub-valvular space i.e. below the virtual annular plane 6. This 80-20 or 85-15 aorta to ventricle position is possible due to reduced foreshortening of the frame of the THV 100 of the instant invention.
[0111] In the above description, the THV of the instant invention is presented as an aortic prosthetic valve. The description includes details related to its implantation to replace degenerated native aortic valve. However, the THV of the instant invention is also suitable for mitral/tricuspid implantation to replace degenerated previously implanted surgical prosthetic valve in mitral/tricuspid position or degenerated native mitral/tricuspid valve previously repaired by annuloplasty ring (also referred to as ring). Before describing the implantation of the THV 100 in the mitral context, a brief description of the human anatomy depicting mitral valve is disclosed for clear understanding of the teachings of the present disclosure.
[0112] Mitral and Tricuspid heart valve replacement is usually done with a bioprosthetic surgical tissue valve in case there is a degeneration of native valve. Annular repair of mitral and tricuspid heart valve is done in situations where the valve leaflets and apparatus (chordae and papillary muscles) are undamaged. In such situations the repair device is called annuloplasty ring (also referred to as ‘ring’). In case the surgically implanted bioprosthetic valve or surgically implanted annuloplasty ring fails or gets degenerated, surgical redo of degenerated bioprosthetic heart valve in mitral/tricuspid position is often associated with higher operative risk of surgical mortality. In such cases, transcatheter mitral/tricuspid valve in valve or valve in ring interventions are known to be safe and offer lower procedural risks allowing for successful clinical outcomes.
[0113] In case of Mitral procedure, in order to access the Mitral Valve, one must cross the septal wall that divides right and left atria (interatrial septum) via the thin fossa ovalis (described below). The common route to mitral valve is normally through common femoral vein to inferior vena cava to right atrium (alternatively one may also reach right atrium via superior vena cava) where the interatrial septum (IS) is crossed by puncturing the wall at fossa ovalis to left atrium and across the mitral valve. Interatrial septal wall is marked by a small oval shaped (or round shaped in a few cases) depression called fossa ovalis. Fossa ovalis (FO) is a preferred site for transseptal puncture as it offers a safe and effective entry point for transseptal puncture because of the following advantages: (a) FO is relatively easy to access, (b) The tissue covering FO is thinner compared to other parts of the IS, (c) FO is away from the tricuspid and mitral valves as well as other critical structures. In case of Tricuspid procedure, in order to get access to the Tricuspid Valve, one simply goes from right atrium to right ventricle via the tricuspid valve. The route to tricuspid valve is normally through common femoral vein to inferior vena cava to right atrium and across the tricuspid valve to right ventricle (alternatively one may also reach right ventricle via superior vena cava).
[0114] If transcatheter mitral/tricuspid valve in valve or valve in ring intervention procedure is done in an existing failed bioprosthetic valve in Mitral position, it is called Transcatheter Mitral Valve in Valve (V-i-V) Replacement (TMVR). If this procedure is done in an existing failed annuloplasty ring in Mitral position, it is called Transcatheter Mitral Valve in Ring (V-i-R) Replacement. If this procedure is done in an existing failed bioprosthetic valve in Tricuspid position, it is called Transcatheter Tricuspid Valve in Valve (V-i-V) Replacement (TTVR). If this procedure is done in an existing failed annuloplasty ring in Tricuspid position, it is called Transcatheter Tricuspid Valve in Ring (V-i-R) Replacement. The THV 100 of the instant invention is suitable for mitral/tricuspid implantation using V-i-V (TMVR/TTVR) and V-i-R procedures. The THV 100 of the instant invention is also suitable for replacing degenerated previously implanted prosthetic valve in aortic position.
[0115] The native mitral valve is anatomically connected to the aortic valve and posteriorly placed. The anterior leaflet of the mitral valve towards the aortic side creates the left ventricular outflow tract (LVOT). During TMVR, especially ViV procedure, it is common practice to measure neo-LVOT to ensure that the THV device within the failed surgical valve does not cause neo-LVOT obstruction (Neo-LVOTO). This is done using CT measurement and is known to the experts in the field.
[0116] The native tricuspid valve is located between the right atrium and the right ventricle. The blood flows from RA across the tricuspid valve towards the RV and then into the pulmonary artery. Like there is LVOT, there is also a right ventricular outflow tract RVOT. Unlike the potential for anterior mitral valve leaflet to cause neo-LVOTO, the chances of neo-RVOTO obstructing flow to pulmonary valve is unlikely due to its anatomical location.
[0117] Short frame balloon expandable valves are treatment of choice due to their lower foot-print and ability to be negotiated easily across the fossa ovalis. Further, short frame height prevents neo-left ventricular outflow tract obstruction (neo-LVOTO).
[0118] Fig. 12 depicts anatomy of the human heart H schematically in a simplified manner. The representation of anatomical vertical section of the heart is only schematic and not drawn with precision. A skilled person is well familiar with function and anatomy of human heart. The four chambers of heart are shown in Fig. 12 as left atrium LA, left ventricle LV, right atrium RA and right ventricle RV. LA and RA are separated by a wall of muscular tissue – interatrial septum IS. LV and RV are separated by a wall VS - ventricular septum. LA and LV are in communication through mitral valve MV. RA and RV are in communication through tricuspid valve TV.
[0119] Normally, the access to the mitral valve is achieved by transseptal approach through right atrium as mentioned above. The procedure involves assess first to RA via common femoral vein and inferior vena cava VC as depicted in Fig. 12a showing human heart H depicted in Fig. 12. The alternate route through superior vana cava is not shown. RA and RV are separated by the interatrial septum IS which is a solid muscular wall. IS wall is marked by a small oval shaped (or round shaped in a few cases) depression called fossa ovalis. Fossa ovalis (FO) is a preferred site for transseptal puncture as it offers a safe and effective entry point for transseptal puncture as mentioned above.
[0120] Using routine trans esophageal echo-based (TEE) imaging, a guide wire (GW) is placed across the fossa-ovalis FO using trans-septal puncture techniques into LA crossing mitral annulus. Fig. 12a is a schematic simplified representation of the human heart H (like Fig. 12) for illustrating the transeptal procedure. As shown in Fig. 12a, the balloon expandable THV system BS is introduced over the guide wire GW where the THV 100 is crimped.
[0121] A skilled person would readily realize that to approach the tricuspid valve TV, it is not necessary to cross the IA wall and hence, transseptal puncture is not required.
[0122] The delivery system 200 depicted in Figs. 4 and 5 is suitable for implantation of THV 100 in mitral/tricuspid position. Fig. 13 shows the details of the balloon 201’ which is similar to the balloon 201 depicted in Fig. 5. Hence, the nomenclature of various components in Fig. 13 are same as that in Fig. 5. However, the location of the landing zone marker band M4 is changed compared to that shown in Fig. 5. As shown in Fig. 13, the landing zone marker M4 is placed between the proximal and mid marker bands M1, M3 at a distance of around 32-34% of the distance between proximal and distal markers M1, M2 from the proximal end marker M2 i.e. dimension B is 32-34% of dimension A as shown in FIG. 13.
[0123] The distal edge of the proximal marker M1 is in line with the distal edge of the proximal stopper 209a as shown by the broken line L1. Similarly, the proximal edge of the distal marker M2 is in line with the proximal edge of the distal stopper 209b as shown by the broken line L2. This feature fixes exact location of all the radiopaque markers.
[0124] Accurate placement and precise deployment of a prosthetic valve in mitral/tricuspid position is very important to achieve optimal performance; implanting the prosthetic valve at optimal location achieves better anatomical placement of the THV 100 whereby the frame is held firmly within the degenerated bioprosthetic valve annulus or annulus of the previously implanted annuloplasty ring, thereby offering precision geographical fix.
[0125] When THV 100 is crimped on the balloon 201’ (with changed location of radiopaque marker M4) of the delivery catheter 200, the in-flow zone of the THV 100 is towards the proximal end and the out-flow zone towards distal end (towards the tip 215). This positioning is technically reverse crimping to that done in the case of THV for aortic implantation described above. The THV system is maneuvered across the fossa ovalis FO and further advanced towards neo mitral annulus to cross the degenerated bioprosthetic valve or the previously implanted annuloplasty ring. Depending on (a) the anatomical presentation of the failed bioprosthetic valve/annuloplasty ring in mitral position, (b) the neo-LVOT area available (calculated during pre-procedure planning), (c) the foreshortening characteristics of THV frame of the prosthetic valve to be implanted (THV 100) and (d) the nominally expanded THV 100 frame height, the THV 100 is positioned across the in-flow zone of the bioprosthetic valve in most balanced footprint of the THV 100 in the left ventricle.
[0126] Fig. 14 depicts a schematic representation of view J (refer to Fig. 12) showing left atrium LA with THV 100 implanted at within the degenerated surgical bioprosthetic valve 1701. Only the frame of THV 100 (without leaflets/skirts etc.) is shown for clarity. The inflow end 100a of the THV 100 is towards RLA and the outflow end 100b is towards LV. Left ventricle LV and right atrium RA are marked for reference. Virtual annular plane 6 (refer to Fig. 6) (deployment zone) is also marked. The native leaflets of the mitral valve are marked as Lf. The suture ring of the bioprosthetic valve 1701 is marked as 1702. In an embodiment, as shown in Fig. 14, 80%-85% of the length of the expanded THV 100 remains below the aortic annulus (virtual annular plane) 6 while, the residual 15%-20% of the length of the expanded THV 100 dwells above the virtual annular plane 6. This 80-20 or 85-15 ventricle to atrium positioning is possible due to reduced foreshortening of the frame of the THV of the instant invention.
[0127] Fig. 15 depicts a schematic representation of view J similar to Fig. 14, showing left atrium LA with THV 100 implanted at within the damaged/degenerated annuloplasty ring 1801. Only the frame of THV 100 (without leaflets/skirts etc.) is shown for clarity. The inflow end 100a of the THV 100 is towards RLA and the outflow end 100b is towards LV. Left ventricle LV and right atrium RA are marked for reference. Virtual annular plane 6 (refer to Fig. 6) (deployment zone) is also marked. The native leaflets of the mitral valve are marked as Lf. Like in Fig. 14 and as shown in Fig. 15, for an exemplary embodiment, 80%-85% of the length of the expanded THV 100 remains below the aortic annulus (virtual annular plane) 6 while, the residual 15%-20% of the length of the expanded THV 100 dwells above the virtual annular plane 6. This 80-20 or 85-15 ventricle to atrium positioning is possible due to reduced foreshortening of the frame of the THV of the instant invention.
[0128] The THV 100 is crimped on the balloon 201’ between the two stoppers 209a, 209b and two extreme radiopaque markers M1, M2. Fig. 16 depicts schematically the frame 101 of the THV 100 as depicted in FIG. 2 mounted on the balloon 201’ under collapsed condition as visible under fluoroscopy. A and B indicate proximal and distal ends respectively. The other components (e.g. leaflets, skirts etc.) of the THV 100 are not shown for clarity and only the frame 101 would be visible clearly under fluoroscopy as it is made from radiopaque material.
[0129] The angled struts of the row of angled struts on the inflow end 100a of the frame 101 (row 10c, refer to Fig. 2b) play an important role in accurate placement of the THV 100. Fig. 16 depicts the lower row 10c at the proximal end A where the V-struts Vs are seen nested close to each other in the exploded View X’, Fig. 16. The converging of these V-struts Vs commences at the proximal end (the edge towards the inflow end of the frame) of the landing zone marker M4 and the apex Ax of a V-strut Vs is visibly away from the proximal edge of the landing zone marker M4 towards the proximal direction A.
[0130] For accurate placement, the THV 100, balloon delivery catheter 200 is advanced across the annulus of degenerated bioprosthetic mitral valve 1701 till the proximal edge of the landing zone marker M4 comes in line i.e. matched with the upper edge of the suture ring 1702 of the bioprosthetic valve 1701. This scenario is depicted in Fig. 17 and exploded View A’ for clarity. Under fluoroscopy, the frame 101 of the THV 100 is visible with clarity. A brief angiogram with a small volume of diluted contrast helps opacify and locates the annular plane 6 and suture ring 1702 of bioprosthetic valve 1701. This helps the operator to ensure precise positioning of THV 100 prior to its deployment. Under rapid pacing of the heart, due to its aforementioned foreshortening characteristics, when expanded to its nominal diameter at this location, the THV 100 gets deployed at optimal position in the annulus of the bioprosthetic valve 1701. This is made possible because the foreshortening of the frame 101 of THV 100 is mediated only by the expansion of the V-struts Vs at the inflow zone and there is no foreshortening at the outflow zone. Hence, this is totally predictable when the Valve is expanded to its nominal diameter.
[0131] As described above, the positioning is achievable when the THV 100 is expanded to its nominal diameter which is an ideal situation. In a real case, the operator may be required to over-expand or in some cases, under-expand the THV 100 for proper deployment. In such a situation, the operator may have to make little adjustment in locating the landing zone marker relative to the proximal edge of the suture ring 1702 of the bioprosthetic valve 1701. This adjustment is, however, very small i.e. to the extent of maximum 3 mm. The length of the landing zone marker M4 is preferably kept 3 mm which the operator may use as an indicator for adjusting the position of the crimped THV 100 to arrive at desired placement location. The operator may, for example, match the center of the landing zone marker M4 with the proximal edge of the suture ring 1702. This situation is shown in Fig. 18 and exploded View B’. In another situation, the operator may, for example, match the distal edge of the landing zone marker M4 with the proximal edge of the suture ring 1702. This situation is shown in Fig. 19 and exploded View C’.
[0132] For accurate placement, the THV 100 in the annulus of the damaged/degenerated annuloplasty ring (ring) 1801, balloon delivery catheter 200 is advanced across the annulus of the ring till the proximal edge of the landing zone marker M4 comes in line i.e. matched with the upper edge of the ring 1801. This scenario is depicted in Fig. 20 and exploded View A’’ for clarity. Under fluoroscopy, the frame 101 of the THV 100 is visible with clarity. A brief angiogram with a small volume of diluted contrast helps opacify and locates the annular plane 6 and the ring 1801. Under rapid pacing of the heart, due to its aforementioned foreshortening characteristics, when expanded to its nominal diameter at this location, the THV 100 gets deployed at optimal position in the annulus of the ring 1801. This is made possible because the foreshortening of the frame 101 of THV 100 is mediated only by the expansion of the V-struts Vs at the inflow zone and there is no foreshortening at the outflow zone. Hence, this is totally predictable when the Valve is expanded to its nominal diameter.
[0133] As described above, the positioning is achievable when the THV 100 is expanded to its nominal diameter which is an ideal situation. In a real case, the operator may be required to over-expand or in some cases, under-expand the THV 100 for proper deployment. In such a situation, the operator may have to make little adjustment in locating the landing zone marker relative to the upper (proximal) edge of the annuloplasty ring 1801. This adjustment is, however, very small i.e. to the extent of maximum 3 mm. The length of the landing zone marker M4 is preferably kept 3 mm which the operator may use as an indicator for adjusting the position of the crimped THV 100 to arrive at desired placement location. The operator may, for example, match the center of the landing zone marker M4 with the upper (proximal) edge of the annuloplasty ring 1801. This situation is shown in Fig. 21 and exploded View B”. In another situation, the operator may, for example, match the distal edge of the landing zone marker M4 with the upper (proximal) edge of the annuloplasty ring 1801. This situation is shown in Fig. 22 and exploded View C”.
[0134] The scope of the invention is only limited by the appended patent claims. More generally, those skilled in the art will readily appreciate that all parameters, dimensions, materials, and configurations described herein are meant to be exemplary and that the actual parameters, dimensions, materials, and/or configurations will depend upon the specific application or applications for which the teachings of the present invention is/are used. , Claims:WE CLAIM:
1. A prosthetic valve comprising:
• a radially collapsible and expandable support frame having a distal end, a proximal end and a plurality of rows of cells extending axially between the distal end and the proximal end, wherein the rows include:
o an upper row of cells that comprises interlaced chevron shaped decagonal cells creating alternate sequence of links, each link includes a straight strut portion followed by either one of rhombus bodies or diamond shaped cells at each junction; and
o a lower row of cells, adjacent to the upper row of cells that comprises interlaced octagonal cells creating alternate sequence of diamond shaped cells at each junction.
2. The prosthetic valve as claimed in claim 1 wherein, the upper row of cells includes:
• an upper row and an intermediate row of angled struts, two consecutive angled struts of the upper row or the intermediate row forming a peak or a valley;
• wherein the peaks of the upper row of angled struts face the peaks of the intermediate row of angled struts and are connected to each other by the links.
3. The prosthetic valve as claimed in claim 1 wherein, the lower row of cells includes:
• a lower row and an intermediate row of angled struts having an undulating shape, two consecutive angled struts of the intermediate row or the lower row forming a peak or a valley,
• wherein the valleys of the intermediate row of angled struts face the peaks of the lower row of angled struts and are connected to each other by diamond shaped cells.
4. The prosthetic valve as claimed in claim 1 wherein, the cells in the upper row of cells are larger than the cells in the lower row of cells.
5. The prosthetic valve as claimed in claim 1 wherein, the upper row of cells occupies around 55% of total height of the support frame.
6. The prosthetic valve as claimed in claim 1 wherein, the cells in the upper row and the lower row are of the same size.
7. The prosthetic valve as claimed in claim 1 wherein, the frame includes three commissure attachment areas spaced angularly at 120° with respect to each other.
8. The prosthetic valve as claimed in claim 1 wherein, the support frame is made of a fluoroscopic material.
9. The prosthetic valve as claimed in claim 1 wherein, the support frame is made from a metal or a metal alloy.
10. The prosthetic valve as claimed in claim 9 wherein, the metal alloy includes one of cobalt-chromium-nickel alloy or cobalt-chromium-nickel-molybdenum alloy MP35N.
11. The prosthetic valve as claimed in claim 1 wherein, the prosthetic valve includes a plurality of leaflets.
12. The prosthetic valve as claimed in claim 11 wherein, the leaflets are made from a biocompatible material including one of an animal tissue or a biocompatible polymeric synthetic material.
13. The prosthetic valve as claimed in claim 12 wherein, the animal tissue includes bovine pericardium.
14. The prosthetic valve as claimed in claim 12 wherein, the polymeric synthetic material includes a fabric material.
15. The prosthetic valve as claimed in claim 11 wherein, each leaflet includes:
• a relatively straight upper edge with or without an apex,
• one commissure tab at each side of the leaflet at its upper edge, and
• at least one of a scalloped lower edge attached to the internal skirt or a straight lower edge and two side edges attached to the internal skirt,
wherein, the upper edge is kept free for coaptation.
16. The prosthetic valve as claimed in claim 11 wherein, a commissure tab is attached to the support frame either directly or through an intermediate fabric layer to prevent direct contact of the leaflet with the frame.
17. The prosthetic valve as claimed in claim 1 wherein, the prosthetic valve includes at least one of:
• an internal skirt covering an internal surface of the lower row of cells at least partially; and
• an external skirt covering an external surface of the lower row of cells of the support frame at least partially,
wherein the internal skirt and the external skirt ate made of a fabric material or an animal tissue material.
18. The prosthetic valve as claimed in claim 17 wherein, the external skirt includes excess material such that the external skirt forms a slack when the support frame is in a radially expanded condition and the slack reduces when the support frame is in the radially collapsed condition.