Abstract:
A separable or splittable insertion sheath is for inserting a medical device into a patient. The insertion sheath includes releasably connectable ends or is configured to split into proximal and distal sections upon application of a predetermined level of pulling or twisting force to opposite ends of the insertion sheath. A medical device loaded into the insertion sheath is deployed by pulling the proximal and distal sections away from each other to expose the medical device.

Description:
[0001]     U.S. Provisional Patent Application No. 60/593,173, filed on Dec. 16, 2004 and entitled “Prosthetic Valve,” is expressly incorporated herein in its entirety by reference thereto. U.S. patent application Ser. No. ______, entitled “A Heart Valve and Method for Insertion of the Heart Valve Into a Bodily Vessel,” bearing Attorney Docket No. 13430/1, filed in the United States Patent and Trademark Office on the even date herewith is also expressly incorporated herein in its entirety by reference thereto. 
     
    
     FIELD OF THE INVENTION  
       [0002]     The present invention relates to a separable sheath and a method for insertion of a medical device into a bodily vessel using a separable sheath.  
       BACKGROUND INFORMATION  
       [0003]     Various methods exist for transcatheter implantation of a medical device into a bodily vessel of a patient. For example, angioplasty procedures may involve implantation of an expandable stent using a balloon catheter. The balloon catheter is typically advanced into the vasculature of a patient through a sheath. The sheath is at least partially withdrawn to expose the stent, which is expanded by inflating a balloon of the balloon catheter onto which the stent is disposed and in a similar manner with self-expanding stents that are currently deployed by withdrawing a sheath and exposing the device. Valves, such as heart valves, can also be implanted transcatheter into a bodily vessel, for example, to replace native valves exhibiting abnormal anatomy and/or function as a result of congenital or acquired disease. Similar to the stents, expandable valves have been implanted using balloon catheters and self-expandable stents with mounted bioprosthesis or mechanical prosthesis.  
         [0004]     Insertion of a medical device, such as a stent or valve, requires precise positioning and handling. Blood flow created by the beating of the heart and the tortuous nature of many bodily vessels increases the difficulty of such insertion. Therefore, there is believed to be a need for a medical device insertion device and method offering enhanced control and consistency.  
       SUMMARY  
       [0005]     A method according to an example embodiment of the present invention for implanting a medical device, such as a stent or valve, into a patient, includes inserting a separable or splittable sheath into the patient and pulling proximal and distal portions of the sheath away from each other so as to expose the medical device, which is at least partially disposed within an outside surface of at least one of the proximal and distal portions of the sheath. The medical device may be disposed within each of the proximal and distal portions of the sheath.  
         [0006]     When inserting a self-expandable stent, for example, shifting of the proximal portion of the sheath away from the distal portion of the sheath allows a proximal end of the stent to expand and shifting of the distal portion of the sheath allows a distal end of the stent to expand. The proximal and distal portions of the sheath may also be pulled away from each other simultaneously allowing each end of the stent to expand simultaneously.  
         [0007]     Releasably connectable ends of the proximal and distal portions of the sheath may be disconnected prior to pulling the proximal and distal portions away from each other.  
         [0008]     Ends of the proximal and distal portions may be connected by a threaded connection. Disconnection of the ends may be accomplished by rotating the proximal and distal portions about a longitudinal axis of the sheath relative to each other.  
         [0009]     Ends of the proximal and distal portions may be connected by a latch, and disconnection of the proximal and distal portion ends may be accomplished by disengaging the latch.  
         [0010]     The latch may be pivotally connected to or integral with one of the proximal and distal portions, and the other of the proximal and distal portions may include a recess configured to receive a portion of the latch. The sheath may include a line extending along a length of one of the proximal and distal portions connected to the latch configured to allow the latch to be pivoted to disconnect the proximal and distal portions. The line may be slidable relative to the sheath and may be configured such that pulling of the line pivots the latch out of the recess so as to disconnect the proximal and distal portions.  
         [0011]     The sheath may include a servo or motor configured to pivot the latch between the locked and unlocked positions. The line may be configured to transmit an electric control signal to the servo or motor to connect and/or disconnect ends of the proximal and distal portions of the sheath.  
         [0012]     Ends of the proximal and distal portions may be connected by a magnetic force. For example, an end of at least one of the proximal and distal portions may include a magnet, e.g., an electro-magnet, configured to generate a magnetic field, and an end of the other of the proximal and distal portions may include a magnetically-attractable member, a permanent magnet, an electro-magnet, etc., which is attracted to the magnetic field. Interruption of the magnetic field eliminates the magnetic force between the proximal and distal portions of the sheath and, therefore, effectively disconnects these portions.  
         [0013]     Rather than including two separate portions that are releasably connected end-to-end, the sheath may include a single unit, which may be split into proximal and distal portions, for example, circumferentially, by pulling opposite ends of the sheath away from each other. The sheath may also be split by twisting the proximal and distal portions relative to each other.  
         [0014]     The splittable sheath may include a weakened section or frangible section at a predetermined location along the length of the sheath to provide that the splitting of the sheath occurs a desired predetermined location on the sheath. Pulling the proximal and distal ends of the sheath away from each other at a predetermined pulling force or twisting the ends of the sheath relative to each other at a predetermined twisting force may cause failure at the weakened or frangible section thus splitting the sheath into proximal and distal portions. The wall of the sheath may have a reduced thickness or may be cut at the weakened section so as to facilitate splitting of the sheath.  
         [0015]     The medical device may include any type of device that may be inserted via transcatheter deployment such as a stent, an endovascular graft, a valve, etc. The medical device may also include any of the devices described in U.S. patent application Ser. No. ______, entitled “A Heart Valve and Method for Insertion of the Heart Valve Into a Bodily Vessel,” bearing Attorney Docket No. 13430/1, filed in the United States Patent and Trademark Office on the even date herewith, which is expressly incorporated herein in its entirety by reference thereto. For example, the medical device may include a valve having separate first and second expandable sections. One of the expandable sections may be disposed or contained within one of the proximal and distal portions or on one side of the weakened section, and the other expandable section may be disposed or contained within the other of the proximal and distal portions or on another side of the weakened section.  
         [0016]     The first and second expandable sections may be spaced apart and connected by struts. The struts may span the connection point or weakened section between the two expandable sections.  
         [0017]     The first expandable section may be arranged as a valve, and the second expandable section may be configured to anchor the medical device in the patient.  
         [0018]     The sheath may be inserted into the patient over a guidewire. The guidewire may be inserted through the femoral vein, inferior vena cava (IVC), right atrium (RA), left atrium (LA), left ventricle (LV), ascending and descending aorta (AO), abdominal aorta, and iliac artery, and may be exteriorized through the femoral artery.  
         [0019]     The sheath may be positioned in the patient such that a distal end of the proximal portion and a proximal end of the distal portion of the sheath are adjacent to a deployment site for the medical device. For example, the deployment site may be in the aorta of the patient.  
         [0020]     The medical device may be advanced into position in the sheath connected to or mounted on an insertion device, such as a balloon catheter. The medical device may be preloaded into the sheath prior to insertion of the sheath or may be advanced, for example, mounted on a balloon catheter, into an already inserted sheath.  
         [0021]     The medical device may be arranged as a valve and may include a valve portion and anchor portion connected to the valve portion by one or more connectors. The valve portion and the anchor portion may be configured to be delivered into the bodily vessel in a low profile and to be expanded to a larger profile, and the anchor portion may be adapted to anchor the valve in place in the bodily vessel.  
         [0022]     The anchor portion may be mechanically expandable (such as by a balloon inflation, a wrench, electrically, magnetically, etc.), self-expandable, and/or may be made from a shape-memory material, and may be constructed from an absorbable or non-absorbable material. The connector may include a strut extending along substantially an entire length of the valve portion, either longitudinally and/or perpendicularly in a circumferential manner at the level of the valve.  
         [0023]     The valve portion may be substantially tubular and may include a plurality of flaps configured to allow fluid to pass therethrough in only one direction.  
         [0024]     The valve portion may be made from biological materials, such as (a) small intestine sub-mucosa, (b) large tubular vascular structure, (c) pericardial tissue, (d) fascia lata, or (e) nano-synthesized material, such as stretchable Nitinol, etc. The valve portion may also be made from other biocompatible materials, such as ePTFE, silk, Elast-Eon™, etc.  
         [0025]     The valve portion may be made of an invaginated tube, and an inner wall of the invaginated tube may be incised in at least two locations to form the flaps or leaflets, which permit unidirectional blood flow. The valve portion may be stentless. Alternatively, the valve portion may include a stent to maintain its expanded position.  
         [0026]     The anchor portion may include a stent and may be tapered toward the valve portion, for example, in a cylindrical or truncated conical form.  
         [0027]     The connector may have a C-shaped terminal end that is proximal to the anchor to support the radial expansion of the tissue valve.  
         [0028]     The connector may include a T-shaped retainer securing the tubular tissue of the external portion of the invaginated tube to each connector.  
         [0029]     The T-shaped retainer may be disposed within a slot in the connector, and the valve portion may be arranged between each T-shaped retainer and connector.  
         [0030]     The valve portion may be created and secured to the connectors utilizing one or more of, for example, glue, rivets, suture, staples, etc.  
         [0031]     The connector may be constructed as part of the anchor device or may be attached to the anchor, for example, utilizing one or more of a chemical or physical adherence technique, suture, staples, rivets, etc. A portion of the connector in contact with the valve portion may be ribbed and/or may include bores. The connector may be of sufficient length to allow the anchoring portion to fully expand while the valve portion remains in a low profile state.  
         [0032]     A valve for placement in a bodily vessel includes: a stentless valve portion and an anchor portion situated end-to-end with the valve portion. Alternatively, the valve portion may include a stent to maintain its expanded position. Both expanded components may be attached so as to form a cylindrical or ovoid structure, with the anchor portion being self-expanding so as to attach to the walls of the bodily vessel. The stentless valve may be directly adherent end-to-end to the anchor portion which thereby obviates the necessity for a connector, such as a strut attachment, between the anchor and the valve. During insertion, the valve portion may be contained within one of the proximal and distal portions of the sheath and the anchor portion may be contained within the other of the proximal and distal portions of the sheath.  
         [0033]     A method for insertion of a valve includes: a) placing a guide wire through the femoral vein, inferior vena cava (IVC), right atrium (RA), left atrium (LA), left ventricle (LV), ascending and descending aorta (AO), abdominal aorta, iliac artery, and exteriorizing the guide wire through the femoral artery; b) passing an insertion sheath, e.g., a sheath splittable (capable of being divided, for example, circumferentially) into proximal and distal portions or a sheath having releasably connectable proximal and distal portions, over the guide wire such that a distal end of the sheath is exteriorized through the femoral artery; c) passing an insertion device, such as a balloon catheter, over the guide wire and through the sheath such that a valve device of the present invention mounted to the insertion device is in deployment position near the anatomical location of the native aortic valve, wherein, when a balloon catheter is used, an anchoring portion of the valve device is disposed over a distal balloon and a stentless valve portion is disposed over a proximal balloon of the balloon catheter, and wherein a proximal end of the distal portion of the sheath is disposed over the anchoring portion and a distal end of the proximal portion of the sheath is disposed over the valve portion of the valve device; d) at least partially withdrawing the proximal portion of the sheath from the patient via the femoral vein so as to expose the valve portion; e) inflating the proximal balloon of the balloon catheter so as to expand the valve portion of the valve device, the valve device now being fully deployed; f) deflating the proximal balloon of the balloon catheter; g) at least partially withdrawing a distal portion of the sheath through the femoral artery cannulation site (which may optionally include a sheath system) so as to expose the anchoring portion; h) inflating the distal balloon so as to expand the anchoring portion; i) deflating the distal balloon; and j) removing the balloon catheter, guide wire and sheath from the patient.  
         [0034]     The distal balloon of the balloon catheter may be deflated before or after deflation of the proximal balloon.  
         [0035]     The guide wire may be placed in step (a) using any suitable guide wire insertion method. For example, the guide wire may be placed using the techniques of transseptal catheterization, which involves floating a balloon catheter in the direction of blood flow through the left atrium, left ventricle, and into the aorta, which is then retrogradely snared. In a version of the conventional technique, the insertion sheath is advanced into the left atrium (LA) using its own dilator. The dilator is pulled out and the balloon catheter is then advanced through the sheath and exteriorized in the left atrium (LA). Once in the left atrium (LA), a balloon on the balloon catheter is inflated and floated out of the left ventricle (LV) through the aortic valve into the descending aorta, across the aortic arch and into the descending aorta. The wire is then be passed through the floating balloon catheter and exteriorized in the descending aorta. Once the balloon catheter is exteriorized, a retrograde advanced snare device is advanced retrogradely through the femoral artery and snares the tip of the wire and exteriorizes the wire out through the femoral artery, thereby completing the loop through the heart from the femoral vein to the femoral artery. See, for example, Babic et al.,  Percutaneous Mitral Valvuloplasty: Retrograde, Transarterial Double - Balloon Technique Utilizing the Transseptal Approach,  Catheterization and Cardiovascular Diagnosis, 14:229-237 (1988), which is expressly incorporated herein in its entirety by reference thereto. The transseptal sheath may be sufficiently large to provide passage of the guidewire and splittable or releasably connectable two-part sheath through it into the ascending aorta.  
         [0036]     The anchoring portion may be self-expandable. When a balloon catheter is used, it need only have a single balloon for inflation of the valve portion of the valve device. Alternatively, the distal balloon may be used in conjunction with a self-expandable anchoring portion, for example, to provide complete expansion of the anchoring portion.  
         [0037]     A valve system includes a medical device, such as a valve or stent, and an insertion sheath sized for insertion of the medical device into a bodily vessel. The insertion sheath may either (i) include proximal and distal portions that are releasably connectable to each other or (ii) may be configured to split into the proximal and distal portions at a predetermined location upon pulling of the proximal and distal portions away from each other at a predetermined pulling force or twisting the proximal and distal portions relative to each other at a predetermined twisting force. The medical device may be configured to be delivered into the bodily vessel through or in the insertion sheath and positionable within the sheath such that pulling of the proximal and distal portions away from each other exposes the medical device. The proximal and distal portions of the insertion sheath may be releasably connected, for example, by a threaded connection, a magnetic connection, a latch, etc.  
         [0038]     The sheath may include a sealable chamber which is configured to be sealed when the proximal and distal portion are connected and opened when the proximal and distal portions are separated.  
         [0039]     Exemplary embodiments of the present invention are described in more detail below with reference to the appended Figures. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0040]      FIG. 1   a  is a cross-sectional view of an insertion sheath system according to an exemplary embodiment of the present invention inserted over a guidewire into the heart and vasculature of a patient, illustrated in cross-section.  
         [0041]      FIG. 1   b  illustrates the insertion sheath system illustrated in  FIG. 1   a  with proximal and distal portions of the sheath disconnected and shifted away from each other exposing a stent illustrated in side view.  
         [0042]      FIG. 1   c  is a side view of a fully deployed stent in the aorta.  
         [0043]      FIG. 2   a  illustrates the insertion sheath system illustrated in  FIG. 1   a  inserted over a balloon catheter illustrated in an inflated state expanding the stent.  
         [0044]      FIG. 2   b  illustrates the insertion sheath system illustrated in  FIG. 2   a  with a balloon of the balloon catheter in a deflated state.  
         [0045]      FIG. 3  is a side view of valve according to an exemplary embodiment of the present invention.  
         [0046]      FIG. 4   a  is a side view of an insertion sheath according to an exemplary embodiment of the present invention inserted into the heart and vasculature of a patient, illustrated in cross-section.  
         [0047]      FIG. 4   b  illustrates the sheath illustrated in  FIG. 4   a  with a proximal portion partially retracted revealing a proximal balloon of a balloon catheter extending through the sheath, which has been inflated to expand a valve portion of the valve included inside the insertion sheath.  
         [0048]      FIG. 4   c  illustrates the balloon catheter illustrated in  FIG. 4   b  with the proximal balloon deflated and with a distal portion of the insertion sheath removed revealing the distal balloon of the balloon catheter, which has been inflated to expand an anchor portion of the valve.  
         [0049]      FIG. 4   d  is a side view of the valve illustrated in  FIG. 4   c  fully implanted into the aorta.  
         [0050]      FIG. 5A  is a perspective view of the valve portion of the valve illustrated in  FIG. 3  in a closed state illustrated without an optional cloth covering and the connectors and with a portion of the valve wall removed.  
         [0051]      FIG. 5B  is a perspective view of the valve portion of the valve illustrated in  FIG. 5A  in a closed state.  
         [0052]      FIG. 5C  is a perspective view of the valve portion of the valve illustrated in  FIG. 3  in an open state illustrated without an optional cloth covering and the connectors.  
         [0053]      FIG. 5D  is a perspective view of the valve portion of the valve illustrated in  FIG. 5C  with a portion of the valve wall removed.  
         [0054]      FIG. 6  is a cross-sectional view of the valve taken along line  6 - 6  in  FIG. 3  illustrating a cross-sectional shape of connectors.  
         [0055]      FIG. 7  is a cross-sectional view of the valve taken along line  7 - 7  in  FIG. 3  illustrating a connection between a connector and the valve portion.  
         [0056]      FIG. 8A  is a side view of a valve according to an exemplary embodiment of the present invention.  
         [0057]      FIG. 8B  is a side view of a valve according to an exemplary embodiment of the present invention.  
         [0058]      FIG. 9  is a longitudinal cross-sectional view of a threaded connection connecting proximal and distal portions of the insertion sheath.  
         [0059]      FIG. 10  is a longitudinal cross-sectional view of a threaded connection of the insertion sheath.  
         [0060]      FIG. 11  is a perspective view of an insertion sheath including a magnetic connector system connecting proximal and distal portions of the insertion sheath.  
         [0061]      FIG. 12  is a longitudinal cross-sectional view of a latch connection connecting proximal and distal portions of the insertion sheath.  
         [0062]      FIG. 13  is a longitudinal cross-sectional view of a latch connection connecting proximal and distal portions of the insertion sheath. 
     
    
     DETAILED DESCRIPTION  
       [0063]      FIG. 1   a  illustrates an insertion sheath  10  inserted into a patient over a guidewire  12 . The patient&#39;s heart  14  and vasculature are illustrates in cross-section. The guidewire  12  may be placed using any suitable guide wire insertion method. For example, the guide wire  12  may be placed using the techniques of transseptal catheterization, which includes floating a balloon catheter in the direction of blood flow through the left atrium (LA), left ventricle (LV), and into the aorta (AO), which is then retrogradely snared. In a version of a conventional technique, the insertion sheath is advanced into the left atrium (LA) using its own dilator. The dilator is pulled out and the balloon catheter is then advanced through the sheath and exteriorized in the left atrium (LA). Once in the left atrium (LA), a balloon on the balloon catheter is inflated and floated out of the left ventricle (LV) through the aortic valve into the descending aorta, across the aortic arch and into the descending aorta. The wire is then passed through the floating balloon catheter and exteriorized in the descending aorta. Once the balloon catheter is exteriorized, a retrograde advanced snare device is advanced retrogradely through the femoral artery and snares the tip of the wire and exteriorizes the wire out through the femoral artery, thereby completing the loop through the heart from the femoral vein to the femoral artery. See, for example, Babic et al.,  Percutaneous Mitral Valvuloplasty: Retrograde, Transarterial Double - Balloon Technique Utilizing the Transseptal Approach,  Catheterization and Cardiovascular Diagnosis, 14:229-237 (1988), which is expressly incorporated herein in its entirety by reference thereto. The transseptal sheath may be sufficiently large to enable passage of the guidewire  12  and splittable or releasably connectable two-part sheath  10  through it into the ascending aorta.  
         [0064]     The sheath  10  may be implanted using a retrograde approach, e.g., approaching the aortic valve from the descending aorta, or using an antegrade approach, e.g., approaching the aortic valve from the left ventricle after performing, for example, a transseptal puncture.  
         [0065]     The sheath  10  may be separable into a proximal portion  16  and a distal portion  18 . The sheath  10  may be positioned, for example, such that contact point  20 , i.e., the location where the connecting ends of the proximal and distal portions  16 ,  18  come together, is located in a narrowed portion  22  of the aorta (AO). X-ray supervision, injection of X-ray traceable liquids, intravascular or intracardiac ultrasound, ultrasonic measuring, etc., may be used to assist in positioning the sheath  10 . A medical device, such as an expandable stent  24 , may be arranged in a low profile state within a proximal end of the distal portion  18  of the sheath  10  and within a distal end of the proximal portion  16  of the sheath  10 . Shifting of the proximal and distal portions  16 ,  18  of the sheath  10  away from each other in the direction of arrows  26  illustrated in  FIG. 1   b  exposes the stent  24  and allows it to expand and enlarge the narrowed portion  22  of the aorta (AO).  FIG. 1   b  illustrates the proximal and distal portions  16 ,  18  of the sheath  10  partially withdrawn exposing a middle portion of the stent  24 .  FIG. 1   c  illustrates the stent  24  fully expanded and successfully enlarging the previously narrowed lumen in the aorta. The sheath  10  and guide wire  12  have been removed from the patient.  
         [0066]     The stent  24  may be preloaded into the sheath  10  prior to insertion of the sheath  10  into the patient and may be advanced with the sheath  10  into the patient. The stent  24  may also be connected to or mounted on an insertion device, such as a balloon catheter  28 , which may be advanced into the sheath  10  prior to or after insertion of the sheath  10  into the patient, or may be expanded using a retractable self expanding stent or any other retractable expandable device capable of expanding the stent  24 . The balloon catheter  28  with the stent  24  disposed thereon may be positioned in the sheath  10  such that a portion of the stent  24  is arranged within each of the proximal and distal portions  16 ,  18  of the sheath  10 . Shifting of the proximal and distal portions  16 ,  18  of the sheath  10  away from each other in the direction of arrows  26  exposes the stent  24  and balloon  30  of the balloon catheter. The sheath  10  may extend beyond an end of the balloon catheter  30  and may be tapered to a size which allows free passage and movement over the guide wire  12 . As illustrated in  FIG. 2   a,  inflation of balloon  30  expands the stent  24  to enlarge the lumen in the narrowed portion  22  of the aorta (AO). The balloon  30  may also be used in conjunction with a self-expandable stent to provide complete expansion of the stent.  FIG. 2   b  illustrates the state after the balloon  30  has been deflated leaving the expanded stent  24  in place in the aorta (AO). The sheath  10 , guide wire  12  and balloon catheter  28  are removed from the patient leaving the stent  24  in place.  
         [0067]     The insertion method may also be used to insert a valve  32 , such as a heart valve illustrated in  FIG. 3 . Valve  32  may include an anchor portion  34 , connectors  36  and a valve portion  38  spaced a distance away from anchor portion  34 .  
         [0068]     As illustrated in  FIG. 4   a,  the sheath  10  may be positioned such that contact point  20 , i.e., the location where the connecting ends of the proximal and distal portions  16 ,  18  of sheath  10  come together, is located in the patient at the desired deployment site for the valve  32 , for example, near the anatomical location of the native aortic valve. Further, X-ray supervision, injection of X-ray traceable liquids, intravascular or intracardiac ultrasound, ultrasonic measuring, etc., may also be used to assist in positioning the sheath  10 . An insertion device, such as balloon catheter  28 , as illustrated in  FIGS. 4   b  and  4   c,  may be advanced, for example, over the guidewire  12  through the sheath  10  such that distal balloon  44  is located on one side of the contact point  20  and proximal balloon  46  is positioned on an opposite side of the contact point  20 . The valve portion  38  of the valve  32  may be disposed over the proximal balloon  46  and the anchoring portion  12  may be disposed over the distal balloon  44 . Valve portion  38  may be disposed in the proximal portion  16  of the sheath  10  prior to deployment and is illustrated in dashed lines in  FIG. 4   b.  As an alternative to placement of the sheath  10  first and then advancing the balloon catheter  28  into position within the sheath  10 , the balloon catheter  28  may be disposed within the sheath  10  and advanced into position, for example, over guidewire  12  together with the already inserted sheath  10 .  
         [0069]     The proximal portion  16  of the sheath  10  may be at least partially withdrawn from the patient, for example, through the venous system, thus exposing the valve portion  38  of the valve  32 . The proximal balloon  46  may then be inflated so as to expand the valve portion  38 , as illustrated in  FIG. 4   b.  At this point, proximal balloon  46  may be shifted if the position of the valve portion  38  requires adjusting. The connectors  36  may be of sufficient length to allow the valve portion  38  to fully expand while the anchor portion  34  remains in a low profile state within sheath  10 . The proximal balloon  46  may be deflated, which provides for the valve portion  38  to be fully expanded and functional. The distal portion  18  of the sheath  10  may be shifted toward the femoral artery cannulation site, thus exposing the anchoring portion  34  of the valve  32 , as illustrated in  FIG. 4   c.  The distal balloon  44  may be inflated so as to fully expand the anchoring portion  34  in the aorta (AO). Anchoring portion  34  may also be self-expandable, in which case the distal balloon  44  may not be necessary but may still be used to provide complete expansion of the anchoring portion  34 . Thus, if a self-expandable anchoring portion  34  is used, the balloon catheter  28  may have a single balloon. The balloon catheter  28  may be removed from the patient, for example, through the venous system.  FIG. 4   d  illustrates the implanted valve  32  after the sheath  10 , balloon catheter  28  and guidewire  12  have been completely removed from the patient.  
         [0070]     Rather than entirely removing the proximal portion  16  of the sheath  10  to expose the valve portion  38 , the proximal portion  16  may be partially removed (enough to completely expose the valve portion  38 ) and then may be removed together with the balloon catheter  28  after valve  32  is fully implanted.  
         [0071]     The proximal balloon  46  may be inflated before the distal balloon  44  to allow for positional adjustments of the valve  32  prior to anchoring. Alternatively, proximal balloon  46  and distal balloon  44  may be inflated simultaneously or distal balloon  44  may be inflated before proximal balloon  46 .  
         [0072]     Balloon catheter  28  may have only a single balloon. Valve portion  38  may not need to be expanded by a balloon because blood flow in the aorta (AO) may cause valve portion  38  to fully expand. Anchor portion  34  may be self-expandable and, therefore, may also not need to be expanded by a balloon.  
         [0073]     The valve portion  38  and anchor portion  34  maybe self- expandable and/or expandable using a retractable device. For example, the valve portion  38  and anchor portion  34  may be expanded using a balloon on, for example, a balloon catheter, or expanded using a retractable self expanding stent or any other suitable retractable expandable device capable of expanding the valve portion and/or anchor portion.  
         [0074]     Connectors  36  of valve  32  may extend along the commissural lines of the valve portion  38  a sufficient length to provide a strong connection with the valve portion  38 . The connectors  36  may also be connected to the valve portion  38  at different points along its circumference. Connectors  36  are connected on a distal end  40  to a proximal end of the anchor portion  34 . Connectors  36  may extend at least partially along the length of the anchor portion  34 . Connectors  36  may be connected to anchor portion  34 , for example, by welding, suturing, gluing, clipping, rivets, etc. Connectors  36  may also be integral with anchor portion  34 .  
         [0075]     The valve portion  38  may be covered by a cloth  48  made from, for example, DACRON®, but also may be used without any such covering. The portion of the connectors  36  connected to the valve portion  38  may be arranged between the cloth  48  and the valve portion  38 , as illustrated, or may be connected to an inner or outer surface of the anchor portion  34 . The valve portion  38  may be tapered toward the anchor portion  34 . The connectors  36  may include ribs, such as T-shaped ribs  54 , illustrated in dashed lines, to provide additional support to a proximal end  52  of the valve portion  38  and also to further secure connection of the connectors  36  to the valve portion  38 . Furthermore, the connectors  36  may include bores  56  for passage of sutures to connect to the valve portion  38 . The connectors  36  may be manufactured by injection molding, machining, using nano-synthesized metals, etc.  
         [0076]     The valve portion  38  may be supported solely via its connection to the connectors  16  and, in effect, may be suspended by the anchor portion  34 . Valve portion  38  may or may not have an additional stent disposed within or over it, which may adversely affect the performance of the valve  32 . That is, valve portion  38  may be stentless. Alternatively, valve portion  38  may include a stent to maintain its expanded position.  
         [0077]     Valve portion  38  may be made from biological materials, such as (i) small intestine sub-mucosa (SIS), (b) large tubular vascular structure, e.g., IVC, superior vena cava (SVC), aorta (AO), etc., (c) pericardial tissue, (d) fascia lata, (e) nano-synthesized material, such as Nitinol, (f) or other biocompatible materials such as urethane, polyurethane, polyethylene terephthalate (PET), polytetrafluoroethylene (PTFE), expanded PTFE, silk, Rayon, DACRON®, etc. The valve portion  38  may also be made from a suitable plastic, such as Elast-Eon™, a metal, metal alloy, etc.  
         [0078]     As illustrated in  FIGS. 5A  to  5 D, the valve portion  38 , illustrated without optional cloth  48 , includes a tubular portion  58  and flaps  60 .  FIGS. 5A  to  5 D illustrate the tubular portion  58  in open and closed states. A portion of the tubular portion  58  is removed in  FIGS. 5A and 5D  to expose the flaps  60 . The valve portion  38  is illustrated having a tricuspid configuration but may also have a bicuspid configuration. Furthermore, flaps  60  are illustrated having a rectangular shape but may have any suitable size and configuration, e.g., triangular, etc. The specific number of flaps and the size and configuration chosen for the flaps  60  will depend on the size, configuration, and/or nature of the vessel in which the valve  32  will be implanted. Flaps  60  move from an opened position in which they extend substantially parallel with the tubular portion  58  and, thus allow blood flow along arrow  62 A, as illustrated in  FIGS. 5C and 5D , and a closed position, as illustrated in  FIGS. 5A and 5B , in which the flaps  60  contact each other and, thus, prevent flow in one direction along arrow  62 B across the valve portion  38 . Valve portion  38  may be formed, for example, by invaginating a tubular structure, suturing the ends together at one or more suture points  62 , and incising an inner wall of the invaginated tubular structure in at least two locations to form leaflets or flaps  60 , which permit unidirectional blood flow.  
         [0079]     Each of the flaps  60  may be constructed to form a pouch cavity, which fills with blood when the valve  32  is closed. This construction may minimize paravalvular leaks by a mechanism similar to a hyrdrofoil.  
         [0080]     Anchor portion  34  may be a collapsible and radially re-expandable support, such as a stent, made from, for example, Nitinol, stainless steel, NP-35N alloy, etc. Anchor portion  34  may include markers, such as heavy metal markers, to facilitate placement within the body. Anchor portion  34  may include, for example, a gold, platinum, iridium tantalum or similar metal, etc., as a marker. The diameter of the anchor portion  34  may be, for example, between 4 mm and 50 mm. Anchor portion  34  may be cylindrical or may have a truncated conical form tapering toward the valve portion  38 .  
         [0081]     Anchor portion  12  is illustrated in  FIG. 3  as having a sinusoid configuration but may have any type of cell design including, for example, zig-zag elements, ring members, braided strands, helically wound strands, consecutively attached ring members, tube members, a frame cut from solid tubes, etc. Further, the anchor portion  34  may be larger in diameter than the inner diameter of the vessel in which it will be implanted so as to facilitate maintenance of the valve  32  in the vessel.  
         [0082]     Additional examples of suitable anchor portions for use with valve  32  include those described in U.S. Pat. No. 6,508,833 to Pavcnik et al., entitled “Multiple-sided Intraluminal Medical Device,” U.S. Pat. No. 6,464,720 to Boatman et al., entitled “Radially Expandable Stent,” U.S. Pat. No. 6,231,598 to Berry et al., entitled “Radially Expandable Stent,” U.S. Pat. No. 6,299,635 to Frantzen, entitled “Radially Expandable Non-Axially Contracting Surgical Stent,” U.S. Pat. No. 4,580,568 to Gianturco, entitled “Percutaneous Endovascular Stent and Method for Insertion Thereof,” and U.S. Patent Application Publication No. 2001/0039450 to Pavcnik et al., entitled “Implantable Vascular Device,” each of which is expressly incorporated herein in its entirety by reference thereto.  
         [0083]     A resorbable material may also be used for the anchor portion  34 . A number of resorbable materials are believed to be conventional, and any suitable resorbable material may be used. Examples of suitable types of resorbable materials include resorbable homopolymers, copolymers, blends of resorbable polymers, etc. Specific examples of suitable resorbable materials include poly-alpha hydroxy acids, such as polylactic acid, polylactide, polyglycolic acid (PGA), and polyglycolide, trimethylene carbonate, polycaprolactone, poly-beta hydroxy acids, such as polyhydroxybutyrate or polyhydroxyvalerate, and other polymers such as polyphosphazines, polyorganophosphazines, polyanhydrides, polyesteramides, polyorthoesters, polyethylene oxide, polyester-ethers (e.g., polydioxanone), polyamino acids (e.g., poly-L-glutamic acid or poly-L-lysine), etc. There are also a number of naturally derived resorbably polymers that may be suitable, including modified polysaccharides, such as cellulose, chitin, and dextran, and modified proteins, such as fibrin and casein, etc.  
         [0084]      FIG. 6  is a cross-sectional view of valve  32  taken along line  6 - 6  in  FIG. 3 . As illustrated in  FIG. 6 , connectors  36  have a roughly C-shaped cross section with a slot  64 .  
         [0085]     The connectors  36  may be connected to the valve portion  38 , for example, by suturing, stapling, riveting and chemical adhesion, etc. Connectors  36  may also be connected to the valve portion  38  mechanically, as illustrated in  FIG. 7 .  FIG. 7  is a cross-sectional view taken along line  7 - 7  in  FIG. 3 . As illustrated in  FIG. 7 , a T-shaped member  66  is slid into slot  64  along with tubular portion  58  thereby securing connector  36  to valve portion  38  via tubular portion  58 . T-shaped member  66  may be sized and shaped to provide a snug fit within slot  64 . As indicated above, connector  36  may be connected to valve portion  38  using suturing, stapling, riveting, chemical adhesion, etc., in which case, the cross-section of the connector  36  may not need to have slot  64  and may have any other suitable shape.  
         [0086]     Valve  32  or stent  24  ( FIG. 1   c ) may be folded and radially compressed for insertion into sheath  10  using, for example, a crimping device including a plurality of adjustable plates resembling a typical single lens reflex (SLR) camera variable restrictor. Each plate moves along a line passing off an opening in the center, and all plates are equidistant from the center opening. The plates may be adapted to move simultaneously by a lever and transmission.  
         [0087]     The placement of the valve  32  in the aorta (AO) may need to be precise in order to avoid blocking the opening to the coronary arteries, which branch off the aorta (AO). Separation of the anchor portion  34  and the valve portion  38  may allow for the use of a shorter valve portion and may facilitate placement of the valve portion  38  in the aorta (AO) without blocking the coronary arteries by the valve portion  38  or the anchor portion  34 . In valves having stents disposed within or over the valve, the valves may need to be long enough to accommodate a stent of sufficient length to assure fixation and support of the valve. Separation of the valve and the stent may allow for the use of a shorter valve and, thus, may provide a surgeon more leeway in placement of the valve because the connectors  36  may be placed adjacent the opening of the coronary arteries without presenting any danger of blockage.  
         [0088]      FIG. 8A  illustrates a valve  32 ′ similar to that illustrated in  FIG. 3  except that the valve portion  38  is directly connected on its distal end  53  to the proximal end  42  of the anchor portion  34  via, for example, sutures, staples, rivets, chemical adhesion, etc. Valve portion  38  is supported solely via its connection on its distal end  53  to the anchor portion  34  and is, in effect suspended by the anchor portion  34 . As in the arrangement illustrated in  FIG. 3 , valve portion  38  does not have an additional stent disposed within or over tubular portion  58 , which, as indicated above, may adversely affect the performance of the valve  32 . That is, tubular portion  58  may be stentless. Alternatively, as indicated above, valve portion  38  may include a stent to maintain its expanded position. During insertion, the anchor portion  34  may be arranged within the distal portion  18  of the sheath  10 , and the valve portion  38  may be arranged within the proximal portion  16  of the sheath  10 .  
         [0089]     The insertion method may also be used to implant the valve  32 ″ illustrated in  FIG. 8B , which is similar to that illustrated in  FIG. 3  except that the anchor portion  34  has a horizontal sinusoidal configuration and the connectors  36  are integral with the anchor portion  34 . The anchor portion  34  has a main body portion  68  and connectors  36  that are integral with the anchor portion  34  and extend beyond a proximal end  42  of the main body portion  68 . The valve portion  38  may be connected to a proximal portion of the connectors  36  such that a gap exists between the body portion  68  and the valve portion  38 . The longer the gap, and the fewer the number of connectors  36 , the less the expansion of the body portion  68  may affect the functioning of the valve portion  38 . The above applies to the arrangements illustrated in  FIGS. 3 and 8 A as well. Further, with respect to the arrangement illustrated in  FIG. 8B , the larger the number of sinusoids in the main body portion  68 , the less the expansion of the body portion  68  may affect the functioning of the valve portion  38 . During insertion, the valve portion  38  may be arranged within the proximal portion  16  of the sheath  10 , and the anchor portion  38  may be arranged within the distal portion  18  of the sheath  10 .  
         [0090]     When the valves are used as a cardiac valve prosthesis in the aorta or main pulmonary artery, it is possible to mount the valve proximal to the native valve, within the native cardiac valve (with or without stenting of the native valve) or distal to the native valve, e.g., in the ascending aorta (AO), descending aorta or distal the main pulmonary artery. The valve may be used in place of the tricuspid valve, mitral valve and in artificial or biological conduits that may connect different chamber in the cardiovascular system, e.g., right ventricle (RV) to pulmonary artery conduits, intracardiac or extracardiac Fontan connections, left ventricle (LV) to ascending aorta (AO), etc.  
         [0091]     As indicated above, prior to shifting the proximal and distal portions  16 ,  18  apart to expose the medical device, the proximal and distal portions  16 ,  18  may be disconnected. A distal end of the proximal portion  16  and a proximal end of the distal portion  18  may be releasably connectable. For example, the proximal and distal portions  16 ,  18  may be connected via a threaded connection  70 , as illustrated in  FIG. 9 . The sheath  10  may be separated into the proximal and distal portions  16 ,  18  by rotating these portions in opposite directions about a longitudinal axis  72  of the sheath  10 .  
         [0092]     A sheath  10  with a threaded connection  70 ′ is illustrated in  FIG. 10 . The sheath  10  may include a pocket  74  for delivery of a medical device or drug  76  into the body of the patient. Pocket  74  is opened upon disconnection of the proximal portion  16  and the distal portion  18  of the sheath  10 . Pocket  74  may be internally threaded to receive an end of the proximal portion  16 , which may also be threaded.  
         [0093]     The proximal and distal portions  16 ,  18  may be magnetically connected, as illustrated in  FIG. 11 . A coil  76  may be connected, for example, to an end of the proximal portion  16  and a magnetically-attractable member, such as a permanent magnet  78 , for example, in the form of a ring, may be connected, for example, to an end of the distal portion  18 . To secure the ends of the proximal and distal portions  16 ,  18  together, a current is passed through the coil  76  to generate a magnetic field which is attracted to the magnetic field produced by the permanent magnet  78 . A controller  80 , may be used to control the current supplied to coil  76  via line  82 . The permanent magnet  78  may be replaced by a second coil and controller, such that both portions of the sheath  10  include an electro-magnet. The coil  76  and line  82  are illustrated connected to an outer surface of the sheath  10 , but they may also be connected to an inner surface of the sheath  10 , embedded within the sheath  10 , or extended through a lumen in a wall of the sheath  10 .  
         [0094]     As illustrated in  FIG. 13 , line  84  may be connected to a motor or servo  86  used to control a latch  88 . Latch  88  may move in the direction of arrow  92  between a connected position illustrated in  FIG. 13 , in which the latch  88  sits in a slot  90 , and an unconnected position in which latch  88  is pivoted by motor or servo  86  out of slot  90 . A controller connected to line  84  may be used to power the motor or servo  86  and, thus, open and close latch  88 .  
         [0095]     Line  84  may also be used to manually pivot the latch  88  between a locked and unlocked position. As illustrated in  FIG. 12 , line  84  may be slidingly disposed within lumen  94  and may connect at one end to latch  88 . Pulling line  84  in a direction of arrow  96  may pivot latch  88  and disconnect the proximal and distal portions  16 ,  18  of sheath  10 .  
         [0096]     Although explained in connection with cardiac heart valves implanted in the aortic position, the insertion methods described herein may be used to implant medical devices in other non-cardiac vessels or in other channels in the body, for example, in the veins, esophagus, stomach, ureter, bladder, urethra, biliary passes, lymphatic system, intestines, in CNS shunts and in the Fallopian tubes or other portions of the reproductive system, etc. The valve prosthesis may be used to replace a natural valve or to establish a new valve function in one of the channels in the body that does not naturally include a valve. The valve may be arranged to provide that fluids, such as blood, flows in only one direction through the valve. In persons having varicose veins, the blood flows in the wrong direction. A valve hereof may, for example, be placed in the varicose vein to prevent flow of blood in the wrong direction.  
         [0097]     The foregoing description and example embodiments have been set forth for illustrative purposes only and are not intended to be limiting. Each of the disclosed aspects and example embodiments may be considered individually or in combination with other aspects, embodiments, and variations. Modifications of the described example embodiments may be made without departing from the spirit and scope hereof.