Abstract:
Apparatus for implanting a heart valve and removing debris from a blood vessel, composed of: a collapsible and deployable filter for blocking debris in a blood vessel in a patient&#39;s body; a circular cuff coupled to a small diameter end of the filter and defining a through passage extending from the small diameter end, the cuff having, at a first end, an internal diameter coaxial with a circular opening at the small diameter end of the filter; a first sheath for housing the filter in its collapsed state and having a length sufficient to extend out of a patient&#39;s body when the filter is at a desired location in a blood vessel; and an assembly for implanting a prosthetic valve in the patient&#39;s heart, said assembly comprising a second sheath and a catheter housed in the second sheath and carrying an implantable valve.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    The present invention relates to an apparatus and procedure for aiding medical treatments in the blood circulation system of a patient, and in particular for preventing the circulation of embolic debris, or blood clots, resulting from such treatments. The invention is primarily, but not exclusively, concerned with providing protection in connection with procedures like those for implanting a prosthetic heart valve. 
         [0002]    There are known procedures, known as transcatheter aortic valve implantation (TAVI), in which a prosthetic heart valve is implanted at the site of a defective native valve, or of a previously implanted defective prosthetic valve. In these procedures, the new prosthetic valve and its guiding structure are introduced by a transcutaneous catheterization technique. For example, for implanting a prosthetic aortic heart valve, the valve and delivery components may be introduced through an incision in the groin or arm and along a blood vessel path to the desired location. 
         [0003]    Such a procedure is disclosed, for example, in U.S. Pat. No. 7,585,321, which issued to Alan Cribier on Sep. 8, 2009, the entire disclosure of which is incorporated herein by reference. Such valves and their associated guiding devices are marketed by Medtronic and by Edwards Lifesciences, one example of the Edwards valves being marketed under the trade name Sapien. 
         [0004]    Although such prosthetic valves have been used successfully to provide a replacement for stenotic native heart valves or defective prosthetic valves, known implantation procedures can result in the creation of embolic debris, which will flow downstream through the circulatory system and will, in a certain percentage of cases, cause blockages in smaller blood vessels. 
         [0005]    This adverse result can be alleviated by associating the TAVI assembly with an emboli filter, as disclosed in copending U.S. application Ser. No. 13/835,816, the disclosure of which is incorporated herein by reference. 
       BRIEF SUMMARY OF INVENTION 
       [0006]    The present invention provides an apparatus and procedure to prevent the circulation of embolic debris resulting from procedures carried out in the blood circulatory system, one such procedure being, for example, the implantation of a prosthetic heart valve, while facilitating introduction of the apparatus into the patient&#39;s body. 
         [0007]    The components of embodiments of the invention may be conveyed to the treatment site along various blood vessel paths and may all be introduced via the same path. For example, if the components are to be positioned in, or pass through, the aorta, the, or each, component can be introduced through an incision in a groin and the associated femoral artery, or through an incision in an arm and the associated subclavian artery predicated on the available sizes of the filter and TAVI device. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]      FIG. 1  is a simplified pictorial view of an embodiment of apparatus according to the present invention. 
           [0009]      FIGS. 2 and 3  are simplified cross-sectional views of a filter and associated components of a heart valve delivery system. 
           [0010]      FIG. 4  is a pictorial view of a further component of an apparatus according to the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0011]      FIG. 1  is a representation of the portions of the circulatory system that are relevant to the present invention. These include the heart left ventricle  12 , the aortic valve  14 , the ascending aorta  16 , the innominate artery  18 , the carotid artery  20  on the left side, the subclavian artery  22  on the left side and the descending aorta  24 . Descending aorta  24  communicates with the iliacs (not shown in  FIG. 1 ) that lead to the right and left femoral arteries that are accessible through the groin. 
         [0012]    The apparatus according to the invention includes a first sheath  30 , a collapsible and deployable filter  34  provided with control wires  38 , a second sheath  42  for guiding a valve implantation assembly  46  and as is conventional in the art, a guide wire (not shown) that will be introduced through sheath  42  and through the aortic valve to guide subsequent positioning of assembly  46 . Prior to deployment, filter  34  may be collapsed within sheath  30 , possibly at the distal end thereof and filter  34  is deployed prior to valve implantation. 
         [0013]    Filter  34  is provided with an axially extending cuff  50 , to be described in detail below. 
         [0014]    The apparatus according to the invention may further include a small diameter catheter  54  intended to supply contrast fluid to the region of valve  14  in order to aid positioning of assembly  46 . Catheter  54  may be introduced along the same blood vessel path as the other components of the apparatus, or, alternatively, as shown in broken lines  54 ′, through, for example, the left subclavian artery. 
         [0015]    In the performance of a procedure according to the invention, first sheath  30  is introduced through an incision in the groin, the femoral artery, descending aorta  24  and ascending aorta  16  to a location such as shown in  FIG. 1 . During this insertion, filter  34  is housed in a collapsed state within first sheath  30 , possibly adjacent the distal end of that sheath. Then, while holding filter  34  in position with the aid of control wires  38 , first sheath  30  is retracted by a distance sufficient to enable filter  34  to expand to bring the large diameter, open lower end of filter  34  into contact with the entire periphery of the artery wall. The large diameter lower end of filter  34  is preferably located at the mid area of the ascending aorta, and not either the level of the aortic valve or at a level just below innominate artyery  18 . Then, second sheath  42  is introduced through first sheath  30  and is extended through cuff  50  of filter  34 . Then, the guide wire (not shown) is introduced through sheath  42 , far enough to pass through the aortic valve. Then, valve assembly  46  is introduced through second sheath  42  and is extended out of second sheath  42 , guided by the guide wire, and is positioned to implant a prosthetic valve at the location of valve  14 . During this procedure, contrast fluid may be introduced into the treatment region through catheter  54  to aid positioning of valve assembly  46 . 
         [0016]    Upon completion of the implantation procedure, which is carried out in a conventional manner, second sheath  42  and assembly  46  are withdrawn, while debris resulting from the implantation procedure is trapped by filter  34  or flows through the passage provided by cuff  50  into sheath  30 . This debris may be collected at the proximal end of sheath  30  along with blood, as will be described in greater detail below. 
         [0017]    When essentially all debris has been trapped in either filter  34  or withdrawn through first sheath  30 , filter  34  is retracted into sheath  30 , and sheath  30 , with filter  34  housed therein, is withdrawn from the patient&#39;s body, together with sheath  42  and valve assembly  46 . 
         [0018]    The apparatus could also be introduced along a path defined by a slit in the arm and the corresponding subclavian artery, depending on the available sizes of these structures. 
         [0019]    Sheath  42  preferably has a diameter not greater than 5 mm and assembly  46  is of a type having a diameter of 3-4 mm. 
         [0020]      FIG. 2  illustrates one embodiment of a filter  34  forming a component of apparatus according to the invention. Filter  34  is composed of a wire framework  60  made of a memory metal such as nitinol, and a filter fabric  64  of appropriate pore size to trap debris while allowing the passage of blood, supported by framework  60 . 
         [0021]    Filter  34  has a generally conical structure with a small diameter end, at the top in  FIG. 2 , and a large diameter end, at the bottom in  FIG. 2 . Framework  60  is composed of a small diameter ring at the top, a large diameter ring at the bottom and an appropriate number of longitudinal struts between the rings. In addition, at least the rings may be made radiopaque to assist proper positioning of filter  34  in the aorta. In the expanded state of filter  34 , the diameter of the small diameter end can be of the order of 4-6 mm, and preferably 4-5 mm, and the maximum diameter of the large diameter end can be of the order of 30-40 mm. 
         [0022]    According to a presently preferred embodiment of the invention, the large diameter end of filter  34  is formed to have a generally oval shape with a major diameter of about 40 mm and a minor diameter of the order of 30 mm. This allows the lower end of the filter to better conform to the somewhat oval shape of a normal aorta. 
         [0023]    Of course, the dimensions of filter  34  can be varied to conform to aortas having different sizes, for example in children. 
         [0024]    Filter  34  may be provided with a side opening  68  in which filter fabric is not present. Side opening  104  is closed by a series of flaps of a suitable material, constructed to normally be closed. Side opening  68  is provided to receive catheter  54  so that the catheter can be advance to a point where its distal, or outlet, end is in the vicinity of aortic valve  14 . 
         [0025]    Alternatively, side opening  68  need not be provided and catheter  54  can be advanced to the desired location between filter  34  and aorta  16 . 
         [0026]    Cuff  50  is cylindrical and coaxial with the longitudinal axis of deployed filter  34  and may be secured to the small diameter ring of framework  60 . Cuff  50  extends from the small diameter end of filter  34  to the center of the open large diameter end and defines a through passage having a diameter of the order of 3-5 mm and preferably 3-4 mm. 
         [0027]    Cuff  50  will not extend beyond the opening, i.e., the large diameter end, of filter  34 . The through passage in cuff  50  is dimensioned to allow sheath  42  to enter the through passage with ease and to be guided toward the location of the heart valve and ventricle. Filter  34  and cuff  34  are arranged so that their longitudinal axes extend substantially parallel to one another and point, to the extent possible, toward the center of valve  14 . 
         [0028]    Cuff  50  is constructed to be stable and relatively stiff The through passage in cuff  50  preferable tapers at least slightly from the top to the bottom of filter  34  to allow sheath  42  to be inserted easily into that passage while being guided by the lower portion of the passage. This will help to facilitate the valve implantation procedure since multiple attempts may be needed to position and implant the valve. Cuff  50  also helps to prevent the motion of sheath  42  from being transmitted to the filter and from destabilizing it. 
         [0029]    Cuff  50  is preferably constructed of polymeric material and is dimensioned to be larger than the valve assembly by an amount sufficient to prevent friction from interfering with deployment of the valve assembly. For a valve assembly that is 3 to 4 mm in diameter, filter 34 should have a radially compressed diameter of at least 4-5 mm to enable the large diameter end of the filter to assume the required deployed, radially expanded, diameter of 32-40 mm. 
         [0030]    Cuff  50  preferably has an increased wall thickness at its lower end, as shown, to help restrict lateral motion of sheath  42 . 
         [0031]    The stability of filter  34  is maintained by the laterally expanded large diameter end, which exerts pressure against the wall of the aorta. Since the aorta pulsates, the filter will have to be in constant contact, both when the heart pumps during systole and when the heart relaxes during diastole. 
         [0032]    The filter is further stabilized by allowing the first sheath  30  to be held against the top of filter  34  such that upward motion of the filter can be prevented. This is accomplished by advancing sheath  30 , if necessary, to hold filter  34  in place. 
         [0033]      FIG. 3  is a view similar to that of  FIG. 2  of a novel filter  80  according to the invention, which may be used in the apparatus according to the invention in place of filter  34 . 
         [0034]    Filter  80  differs from filter  34  essentially by being provided, adjacent its large diameter end, with a cylindrical peripheral wall portion  84 . The purpose of this peripheral wall portion is to increase the contact area between filter  80  and the aorta wall, and will be particularly useful in the case of so-called porcelain aorta, which is calcification of the aorta wall that reduces, and can even eliminate, the flexibility of the aorta, and thus its ability to confirm to the shape of the large diameter end of a filter. 
         [0035]    Preferably, cylindrical peripheral wall portion  84  will have a longitudinal length, in the direction between the small diameter end and the large diameter end of filter  80 , of at least 3 mm. 
         [0036]    A further component of apparatus according to the present invention is a multi-position valve  80 , shown in  FIG. 4 . Valve  80  preferably has four ports A, B, C and D and is constructed, in a manner known in the art, to either block port A, or to connect port A to any one of ports B, C and D. 
         [0037]    Port A is configured to be removably connected in a sealed manner to the proximal end of sheath  30  when the other components of the apparatus,  34 ,  38  and  42  are not present within sheath  30 . 
         [0038]    Port B may be placed in communication with port A at the beginning of a procedure, before components  34 ,  38  and  42  have been introduced, and port B may be connected to a source of anticoagulant to be delivered, if needed, if needed to the vicinity of valve  14 . Port C can be attached to a pressure monitor and placed in communication with port A to measure the pressure within sheath  30  after withdrawal of sheath  42  and valve implantation assembly  46 . 
         [0039]    At the end of a procedure, after components  34 ,  38  and  42  have been withdrawn from sheath  30 , port A of valve  80  will be reconnected to sheath  30  and port D will be placed in communication with port A to allow blood and debris to flow to a filter  84 . Filtered blood may then be returned to a blood vessel in the patient&#39;s body. 
         [0040]    Valve  80  also has a position in which port A is blocked. 
         [0041]    While the description above refers to particular embodiments of the present invention, it will be understood that many modifications may be made without departing from the spirit thereof. The accompanying claims are intended to cover such modifications as would fall within the true scope and spirit of the present invention. 
         [0042]    The presently disclosed embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims, rather than the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.