Abstract:
An aortic valve sizing obturator apparatus for employment in determining the correct size of an aortic annulus. The apparatus includes a cylindrical obturator body with a flange member formed thereabout. At least the under surface of the flange member is of a non-planar, multi-curvate configuration to thereby be complimentary in shape to the annulus of an aortic valve when seated in the annulus during size determination. Within the cylindrical obturator body can be disposed a handle connector to which a handle can be attached during placement of the obturator apparatus within an annulus. The present invention also includes methodology for determining the size of an aortic valve annulus by employing a plurality of differently-sized aortic valve sizing obturators defined above and individually seating them sequentially within the aortic annulus until an obturator that reflects annulus size is located.

Description:
This application is a continuation of U.S. application Ser. No. 08/583,811 filed Jan. 5, 1996, now abandoned. 
    
    
     FIELD OF THE INVENTION 
     The present invention pertains generally to medical devices and more particularly to an obturator apparatus insertable into an aortic valve annulus of a human heart following performance of a valvulotomy for the purpose of determining the correct size of a prosthetic valve to be surgically implanted therein. 
     BACKGROUND OF THE INVENTION 
     Surgical valvulotomy and prosthetic valve replacement has been performed in human beings for many years. Most frequently, the procedures are utilized to replace mitral or aortic valves in patients who suffer from valvular heart disease. 
     In particular, surgical replacement of the aortic valve is typically necessitated by a) obstruction (i.e., stenosis) of the aortic heart valve or b) leakage (i.e., regurgitation, incompetence or insufficiency) of blood through the aortic valve. In some patients, symptoms of both obstruction and leakage are present, this being known as &#34;mixed disease&#34; or &#34;combined lesions&#34;. Aortic valvular heart disease may be caused by a number of factors, including congenital deformations, infections, degenerative calcification, and certain rheumatological heart disorders. 
     Surgical replacement of the aortic valve is typically performed under general anesthesia, with full cardiopulmonary bypass. The leaflets of the endogenous aortic valve are removed along with any calcified surrounding tissue. This results in the formation of an annular opening at the site of the endogenous aortic valve. Thereafter, a mechanical or bioprosthetic aortic valve is then selected and sutured into the annular valve opening, as a prosthetic replacement for the surgically-removed endogenous valve. Examples of mechanical prosthetic aortic valves which have heretofore been utilized, include the Starr-Edwards™ Silastic Ball Valve (Baxter Healthcare Corporation, Edwards CVC Division, 17221 Red Hill Ave., P.O. Box 11150, Santa Ana, Calif. 92711-1150); the St. Jude Bileaflet Heart Valve (St. Jude Medical, Inc., St. Paul, Minn.) and the Medtronic-Hall Tilting Disk Valve (Medtronic Inc., Minneapolis, Minn.). Examples of bioprosthetic aortic valves which have heretofore been utilized include the Carpentier-Edwards®, PERIMOUNT™ Pericardial Bioprosthesis (Baxter Healthcare Corporation, Edwards CVS Division, 17221 Red Hill Ave., P.O. Box 11150, Santa Ana, Calif. 92711-1150) as well as the Carpentier-Edwards® Porcine Bioprosthesis (Baxter Healthcare Corporation, Edwards CVC Division, 17221 Red Hill Ave., P.O. Box 11150, Santa Ana, Calif. 92711-1150). 
     In general, these prosthetic aortic valves comprise a cylindrical valve body having a blood flow passageway extending longitudinally therethrough, and a suture ring formed annularly thereabout. The suture ring comprises suture penetrable material or a series of suture passage apertures, to facilitate anastomosis of the suture ring to the adjacent surgically-prepared aortic annulus. Because of the tricuspid configuration of the endogenous aortic valve, the natural aortic root has a non-planar, multi-curvate configuration. To correspond to such anatomical configuration of the natural aortic root, some or all of the aortic prosthetic valve of the prior art have utilized suture rings which are of a generally non-planar, multi-curvate configuration. 
     The ultimate success of any aortic valve placement procedure is dependant on a number of factors, including the correct sizing and placement of the prosthetic aortic valve. In this regard, it is common practice to utilize a sizing obturator to determine the correct size of prosthetic valve for implantation. Such sizing obturators typically comprise a series of different-sized cylindrical members which are independently attachable to a handle, and which are insertable into the surgically-prepared valve annulus to determine the actual size of the annular opening. Such sizing obturators may be color-coded for size identification. Examples of aortic and mitral valve sizing obturators of the prior art include the True-Size™ Aortic Obturator-Model 1161 and the True-Size™ Mitral Obturator-Model 1162, Baxter Healthcare Corporation, Edwards CVS Division, 17221 Red Hill Ave., P.O. Box 1150, Santa Ana, Calif. 92711-1150. 
     One drawback associated with aortic valve sizing obturators of the prior art is that such obturators typically comprise a generally cylindrical obturator body having a flat annular flange extending therearound. The flat annular flange is typically advanced into abutment with, but does not actually seat or nest within, the non-planar, three-peaked anatomy of the natural aortic root, which defines the superior aspect of the aortic annulus. 
     SUMMARY OF THE INVENTION 
     In view of the importance of ascertaining the correct size and configuration of the prosthetic aortic valve to be utilized, there exists a need in the art for the development of a new sizing obturator device which has a non-planar, multi-curvate flange configured to directly seat or nest within the three-peaked normal anatomy of the superior aspect of the annular, thereby providing the surgeon with an accurate, preliminary reading of the correct size and configuration of non-planar, multi-curvate suture ring to be utilized. 
     Accordingly, a primary object of the present invention is to provide a sizing obturator which has a cylindrical body which may be inserted through the annulus, and a flange member which is configured to be substantially complimentary to the configuration of the superior aspect of the aortic annulus, within which a prosthetic valve is to be subsequently implanted. 
     Another object of the present invention is to provide such a sizing obturator whose cylindrical body has, disposed therein, a connector member which is connectable to a handle usable during obturator placement. 
     Yet another object of the present invention is to provide methodology employing the above-defined obturator in a plurality of sizes to thereby accurately reflect aortic annulus size for subsequent prosthetic valve implantation. 
     These and other objects of the present invention will become apparent throughout the description of the invention which now follows. 
     The present invention is an aortic valve sizing obturator apparatus for employment in determining the correct size of an aortic annulus so that a correctly sized prosthetic valve can be chosen for subsequent placement within the annulus. The apparatus comprises a cylindrical obturator body having a top end, a bottom end, an inner surface, an outer surface, and a first outer diameter. A flange member is formed about the obturator body and has an upper surface, an under surface, and a second outer diameter which is greater than the first outer diameter of the obturator body. The undersurface of the flange member is of a non-planar, multi-curvate (i.e., having more than one curve formed therein) configuration to thereby be complimentary in shape to the superior aspect of the aortic annulus such that the flange may be seated or nested within the supra-annular anatomy (three peaked configuration of the aortic root during size determination. Within the cylindrical obturator body, there may be disposed a handle connector apparatus, to which a separate handle can be attached to facilitate insertion and placement of the obturator apparatus during the sizing procedure. 
     The present invention also includes methodology for determining the size of an aortic valve annulus for subsequent placement therein of a prosthetic aortic valve. This methodology employs a plurality of aortic valve sizing obturators defined above and includes placing of one or more obturators, one at a time, into an aortic valve annulus such that the flange member is seated in a complimentary relationship with the configuration of the annulus. This procedure continues until a properly sized obturator that reflects the size of the aortic annulus, is located. 
     By employing the present invention in a procedure wherein a prosthetic aortic valve is to be implanted, a surgeon is able to accurately determine the size needed for the replacement valve. Achieving such accuracy is greatly enhanced because of the non-planar, multi-curvate flange member described above which permits seating of the flange in a complimentary relationship with the configuration of the aortic annulus to thereby gain a more accurate reflection of the size of the annulus and of the consequent replacement valve. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is top perspective view of a preferred aortic valve sizing obturator of the present invention. 
     FIG. 2 is a top plan view of the preferred aortic valve sizing obturator of FIG. 1. 
     FIG. 3 is a side elevational view of the preferred aortic valve sizing obturator of FIG. 1. 
     FIG. 4 is a cross sectional view through line 4--4 of FIG. 2. 
     FIG. 5 is a cross sectional view through line 5--5 of FIG. 2. 
     FIG. 6a is a perspective view of a prior art handle member which may be utilized in conjunction with the preferred aortic valve sizing obturator of the present invention. 
     FIG. 6b is a perspective view of an alternative, bendable, handle member which may be utilized in conjunction with the aortic valve sizing obturator of the present invention. 
     FIG. 7 is a perspective schematic view of a portion of a human heart, showing the manner in which the preferred aortic valve sizing obturator of the present invention is inserted into the surgically-prepared aortic annulus. 
     FIG. 7a is an enlarged elevational view of a portion of FIG. 7. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The following detailed description and the accompanying drawings are provided for the purpose of describing and illustrating a presently preferred embodiment of the invention only, and are not intended to limit the scope of the invention in any way. 
     With reference to the drawings, the preferred aortic valve sizing obturator 10 of the present invention comprises a cylindrical obturator body 12 having an outer surface 14 and an inner surface 16, and a non-planar, multi-curvate annular flange 18 extending outwardly about one end of the cylindrical obturator body 12. The non-planar, multi-curvate annular flange 18 has an upper surface 20, and a lower surface 22. (As used in this patent application, the term &#34;multi-curvate&#34; means having more than one curve formed therein.) 
     The end of the cylindrical obturator body 12 upon which the non-planar, multi-curvate flange 18 is positioned, and the configuration of the non-planar, multi-curvate flange 18 itself, are characterized by the presence of three equally-spaced-apart blunt peaks 24a, 24b, 24c having three generally arcuate depressions 26a, 26b, 26c extending therebetween, as shown. 
     Three (3) radial strut members 28a, 28b, 28c extend inwardly from the inner surface 16 of the cylindrical obturator body 12 at locations which are immediately below each of the discrete blunt peaks 24a, 24b, 24c formed in the non-planar, multi-curvate flange 18. A cylindrical inner member 30 is positioned coaxially within the central bore 32 of the cylindrical obturator body 12, and is supported and held in fixed position by the strut members 28a, 28b, 28c. A hollow inner bore 34 extends longitudinally through the inner cylindrical member 30, and internal threads 36 are formed on the inner surface of such longitudinal bore 34. 
     A single longitudinal axis LA as illustrated in FIG. 4 is projectable longitudinally through the cylindrical obturator body 12, such that the obturator body 12 and inner cylindrical member 30 are coaxially disposed about such common longitudinal axis LA. 
     FIG. 6a-6b show two prior art stainless steel handles which may be utilized in conjunction with the preferred aortic valve sizing obturator shown in FIGS. 1-5. Specifically, FIG. 6a shows a reusable handle comprising an elongate rigid handle member 40 having an externally threaded distal projection 42 extending from the distal end thereof. The externally threaded projection 42 is insertable into the upper end of the bore 34 of the inner cylindrical member 30 of the preferred aortic valve sizing obturator 10 of the present invention such that the external threads of projection 42 may be rotatably engaged with the internal threads 36 formed within the bore 34 of the inner cylindrical member 30, thereby attaching the elongate handle member 40 to the aortic valve sizing obturator 10. The particular handle shown in FIG. 6a has been commercially available as Handle Model 1108, Baxter Healthcare Corporation, Edwards CVC Division, 17221 Red Hill Ave., P.O. Box 11150, Santa Ana, Calif. 92711-1150. 
     FIG. 6b shows an alternative handle which comprises a segmented rigid handle member 40a having a bendable segment 46 disposed therewithin, and an externally threaded distal projection 42a extending from the distal end thereof. A flanged bushing 44 is formed proximal to the externally threaded distal portion 42a, as shown. The bendable segment 46 of this handle may be manually bent or preformed by the surgeon to a desired configuration to facilitate insertion and positioning of the aortic valve sizing obturator 10. The particular handle shown in FIG. 6b has been commercially available as Handle Model 1111, Baxter Healthcare Corporation Edwards CVC Division, 17221 Red Hill Ave., P.O. Box 11150, Santa Ana, Calif. 92711-1150. 
     The aortic valve sizing obturator 10 may be formed of any suitable material including rigid, autoclavable thermoplastic material such as polysulfonate. The obturators 10 will typically be provided in a kit consisting of a series of different-sized obturators 10, corresponding to the available sizes of the particular prosthetic heart valves for which the obturator 10 is to be employed. For example, the following table shows examples of specific component dimensions (in millimeters) of standard, commercially available sizes of the Carpentier-Edwards® PERIMOUNT™ Pericardial Aortic Bioprosthesis referred to hereabove: 
     
         ______________________________________Mounting Diameter (Annulus)           19    21      23  25    27  29Internal Diameter (Stent I.D.)           18    20      22  24    26  28Profile Height  13    14      15  16    17  18External Sewing Ring Diameter           28    31      33  35    38  40______________________________________ 
    
     When the sizing obturator 10 of the present invention is to be used for determining the correct size of the Model 2700 Aortic Bioprosthesis to be employed, the manufacturer will typically provide a kit having a series of different-sized obturators 10, which correspond directly to the available sizes of the Model 2700 Aortic Valvular Prosthesis. In this regard, if an obturator 10 having a mounting diameter (i.e., the diameter of the outer surface 14 of the cylindrical obturator body 12) of 19 is found to provide the best fit within the surgically-prepared valve annulus, a Model 2700 prosthetic valve having a mounting diameter of 19 will typically be selected. Also, because the sizing obturator 10 of the present invention is provided with a non-planar, multi-curvate flange 18, such flange may be directly nested or seated within the surgically-prepared natural valve annulus to provide a direct and precise indication of the correct external sewing ring diameter desired. 
     It will be appreciated that, in most aortic valve replacement surgeries, the prosthetic valve is implanted in a supra-annular position wherein the suture ring of the prosthetic valve is positioned superior to the surgically-prepared valve annulus. Alternatively, however, it may sometimes be desirable to implant the prosthetic valve in an intra-annular position, wherein the entire suture ring of the prosthetic valve is positioned within the surgically-prepared valve annulus and an everting mattress suture technique is employed to anastomose the prosthetic valve in such intra-annular position. In this regard, when it is desired to utilize the typical supra-annular positioning of the prosthetic valve, the sizing obturator 10 will be inserted such that the non-planar, multi-curvate flange 18 is nested or seated in a supra-annular position which is analogous to the intended positioning of the suturing ring of the prosthetic valve. Alternatively, however, if it is intended to implant the prosthetic valve in an intra-annular position, the sizing obturator 10 of the present invention will be initially placed such that the non-planar, multi-curvate annular flange 18 is located in the desired intra-annular position. 
     FIGS. 7-7a provide a schematic illustration of the typical manner in which the aortic valve sizing obturator 10 of the present invention may be utilized to determine the correct prosthetic valve size to be used for supra-annular implantation in a human heart. In the showing of the human heart provided in FIG. 7, the major anatomical structures are labeled accordingly to the following legend: 
     A=Aorta 
     AA=Aortic Annulus 
     M=Myocardium 
     IVS=Interventricular Septum 
     RV=Right Ventricle 
     RA=Right Atrium 
     LV=Left Ventricle 
     SVC=Superior Vena Cava 
     As shown, a handle such as that shown in FIG. 6b is initially inserted and engaged into the upper end of the hollow bore 34 of the sizing obturator 10, and the threaded distal projection 42a of the handle is rotatably advanced such that its external threads will rotatably engage the internal threads 36 formed within the bore 34 of the obturator 10. In this manner, the handle of the type shown in FIG. 6b is firmly attached to the obturator 10, and extends in a longitudinally coaxial fashion from the upper end of the obturator 10, as shown. 
     The diseased or damaged aortic valve leaflets, and all associated structures deemed necessary, are surgically removed. The surgeon may also remove any calcium from the valve annulus, to ensure proper seating of the suture ring of the prosthetic valve. 
     After the aortic valve annulus has been surgically prepared, the aortic valve sizing obturator 10 of the present invention will be inserted such that the cylindrical obturator body 12 passes downwardly through the surgically-prepared valve annulus with little resistance. The obturator 10 is then rotatably reoriented and further advanced until the undersurface 22 of the non-planar, multi-curvate flange becomes nested or seated within the non-planar, multi-curvate anatomical structure of the natural aortic root. In this manner, the surgeon may visually verify that the diameter of the cylindrical obturator body 12 and non-planar, multi-curvate annular flange 18 are correct for that particular patient. Thereafter, the surgeon may select a prosthetic aortic valve which has a mounting (annulus) diameter and external sewing ring diameter the same as that of the obturator 10 which was found to correctly fit within the patient&#39;s aortic valve annulus. Thereafter, the obturator 10 and accompanying handle may be extracted and removed, and the selected prosthetic aortic valve may be sutured into place. Following use, the handle may be rotatably detached and removed from the obturator 10, and both the stainless steel handle and the molded plastic obturator may be autoclaved or otherwise sterilized for subsequent reuse. 
     It will be appreciated that the present invention has been described hereabove with reference to certain presently preferred embodiments only, and no effort has been made to exhaustively describe all possible embodiments in which the invention may take physical form. It will be appreciated by those skilled in the art that various addition, deletions, modifications and alterations may be made to the above-described embodiment without departing from the intended spirit and scope of the present invention. Accordingly, it is intended that all such additions, deletions, modifications and alterations be included within the scope of the following claims.