Patent Publication Number: US-7897086-B2

Title: Method of making a laminar ventricular partitioning device

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     None 
     INCORPORATION BY REFERENCE 
     All publications and patent applications mentioned in this specification are herein incorporated by reference to the same extent as if each individual publication or patent application was specifically and individually indicated to be incorporated by reference. 
     FIELD OF THE INVENTION 
     The present invention relates generally to the field of treating congestive heart failure and more specifically, to a device and method for partitioning a patient&#39;s heart chamber and a system for delivering the treatment device. 
     BACKGROUND OF THE INVENTION 
     Congestive heart failure (CHF), characterized by a progressive enlargement of the heart, particularly the left ventricle, is a major cause of death and disability in the United States and elsewhere. As a patient&#39;s heart enlarges, it pumps less efficiently and, in time, the heart becomes so enlarged that it cannot adequately supply blood to the body. The fraction of blood within the left ventricle that is pumped forward at each stroke, commonly referred to as the “ejection fraction”, is typically about sixty percent for a healthy heart. A congestive heart failure patient typically has an ejection fraction of 40% or less, and as a consequence, is chronically fatigued, physically disabled, and burdened with pain and discomfort. Further, as the heart enlarges, heart valves lose the ability to close adequately. An incompetent mitral valve allows regurgitation of blood from the left ventricle back into the left atrium, further reducing the heart&#39;s ability to pump blood. 
     Congestive heart failure can result from a variety of conditions, including viral infections, incompetent heart valves, ischemic conditions in the heart wall, or a combination of these conditions. Prolonged ischemia and occlusion of coronary arteries can result in myocardial tissue in the ventricular wall dying and becoming scar tissue. Once a portion of myocardial tissue dies, that portion no longer contributes to the pumping action of the heart. As the disease progresses, a local area of compromised myocardium can bulge during the heart contractions, further decreasing the heart&#39;s ability to pump blood, and further reducing the ejection fraction. 
     In the early stages of congestive heart failure, drug therapy is presently the most commonly prescribed treatment. Drug therapy typically treats the symptoms of the disease and may slow the progression of the disease, but it does not cure the disease. Presently, the only treatment considered curative for congestive heart disease is heart transplantation, but these procedures are high risk, invasive, and costly. Further, there is a shortage of hearts available for transplant, many patients fail to meet transplant-recipient qualifying criteria. 
     Much effort has been directed toward the development of surgical and device-based treatments for congestive heart disease. Surgical procedures have been developed to dissect and remove weakened portions of the ventricular wall in order to reduce heart volume. As is the case with heart transplant, these procedures are invasive, risky, and costly, and many patients do not qualify medically for the procedure. Other efforts to treat CHF include the use of an elastic support placed around the heart to prevent further deleterious remodeling, and mechanical assist devices and completely mechanical hearts have been developed. Recently, improvements have been made in treating patients with CHF by implanting pacing leads in both sides of the heart in order to coordinate the contraction of both ventricles of the heart. While these various procedures and devices have been found to be successful in providing some relief from CHF symptoms and in slowing disease progression, none has been able to stop the course of the disease. 
     SUMMARY OF THE INVENTION 
     The present invention relates to a ventricular partitioning device and a method of employing the device in the treatment of a patient with congestive heart failure (CHF). Embodiments of the device are adapted to span a chamber of the heart, typically the left ventricle, and partition the chamber into a main productive portion and a secondary non-productive portion. This partitioning reduces the total volume of the heart chamber, reduces the stress applied to the heart and, as a result, improves the blood ejection fraction thereof. 
     Embodiments of the device have a reinforced partitioning component with a concave, pressure-receiving surface which, in part, defines the main productive portion of the partitioned heart chamber when secured therein. The reinforced partitioning component preferably includes a hub and a membrane forming the pressure receiving surface. The partitioning component is reinforced by a radially expandable frame component formed of a plurality of ribs. 
     The ribs of the expandable frame have distal ends secured to the central hub and free proximal ends. The distal ends are preferably secured to the central hub to facilitate radial self expansion of the free proximal ends of the ribs away from a centerline axis. The distal ends of the ribs may be pivotally mounted to the hub and biased outwardly or fixed to the hub. The ribs may be formed of material such as superelastic NiTi alloy that permits compression if the free proximal ends of the ribs toward a centerline axis into a contracted configuration, and when released, allows for their self expansion to an expanded configuration. 
     The free proximal ends of the ribs are configured to engage and preferably penetrate the tissue lining a heart chamber, typically the left ventricle, to be partitioned so as to secure the peripheral edge of the partitioning component to the heart wall and to fix the partitioning component within the chamber so as to partition the chamber in a desired manner. The tissue-penetrating proximal tips are configured to penetrate the tissue lining at an angle approximately perpendicular to a center line axis of the partitioning device. The tissue penetrating proximal tips of the ribs may be provided with attachments such as barbs or hooks that prevent withdrawal of the tips from the heart wall. 
     The ribs in their expanded configuration angle outwardly from the hub and the free proximal ends curve outwardly so that the membrane secured to the ribs of the expanded frame forms a trumpet-shaped, pressure receiving surface. The partitioning membrane in the expanded configuration has radial dimensions from about 10 to about 160 mm, preferably about 50 to about 100 mm, as measured from the center line axis. 
     The partitioning device may be delivered percutaneously or intraoperatively. One particularly suitable delivery catheter has an elongated shaft, a releasable securing device on the distal end of the shaft for holding the partitioning device on the distal end, and an expandable member such as an inflatable balloon on a distal portion of the shaft proximal to the distal end to press the interior of the recess formed by the pressure-receiving surface to ensure that the tissue penetrating tips or elements on the periphery of the partitioning device penetrate sufficiently into the heart wall to hold the partitioning device in a desired position to effectively partition the heart chamber. 
     More particularly, the invention relates to an intracorporeal partitioning component that includes a frame with a plurality of ribs that is integrated with one or more sheets of fabric to form a unified unilaminar, bilaminar, or multilaminar structure, as well as methods for making the. Embodiments of the invention thus include an intra partitioning component that includes a frame having a plurality of ribs with radially extending proximal ends and with distal ends secured to a hub; and a bilaminar sheet secured to the ribs of the frame by fused thermoplastic material within the bilaminar sheet of material. In some of these embodiments, the bilaminar sheet of material comprises ePTFE. In some embodiments, the bilaminar sheet includes a porous material; in other embodiments the bilaminar sheet includes a non-porous material. 
     Embodiments of the invention further include an intracorporeal partitioning component that includes a frame having a plurality of ribs with radially extending proximal ends and with distal ends secured to a hub; and a single sheet secured to the ribs of the frame by fused thermoplastic material on one side of the sheet of material to form a unilaminar structure. 
     Embodiments of the invention also include an intracorporeal product that includes a first component configured for intracorporeal deployment, the component encased in thermoplastic material; and at least two sheets of ePTFE material secured to the first component by fused thermoplastic material therebetween to form at least a bilaminar sheet of ePTFE material. 
     Embodiments of the invention include a method of securing a polymeric sheet material to rib components of a frame structure, including disposing a tube comprising thermoplastic material over each of one or more rib components of the frame to form a thermoplastic-material-encased rib; forming an assembly by applying the thermoplastic-encased rib above a first sheet and a second sheet above the thermoplastic-encased rib; and heating the assembly to fuse the first and second sheets to the thermoplastic material to form a bilaminar sheet, the fusion occurring by the melting and reforming of the thermoplastic material between the sheets, the rib remaining within the melted and reformed thermoplastic material. These embodiments include methods wherein the first sheet and second sheet of material include ePTFE. In other embodiments, the first sheet and second sheet of material include a porous material. And in still other embodiments, the first sheet and second sheets of material may include a porous material, and the other of the first sheet and second sheets may include a nonporous material. 
     In some of these method embodiments, the heating includes exposure to a temperature of about 500° F., and in some of these embodiments the heating occurs over a period of about 120 seconds. In some of these embodiments, the method further includes applying pressure to the assembly to fuse the thermoplastic material and the ePTFE sheets to the rib component, such applied pressure being between about 60 psi and about 90 psi. And in some of these embodiments wherein the pressure is applied for a period of about 120 seconds. 
     Some embodiments of the invention include a method of making an intracorporeal product, including: (a) providing two ePTFE sheets; (b) providing a rib component of a frame structure; (c) deploying a thermoplastic-material containing element over at least part of the rib component; (d) applying the ePTFE sheets to at least a portion of the rib component covered by the thermoplastic element, the rib component disposed between the sheets, to form an assembly; and (e) heating the assembly to fuse the thermoplastic material and the ePTFE sheets to the rib component, the ePTFE sheets thereby forming a bilaminar ePTFE sheet structure secured to the rib component. In various of these embodiments, the heating step includes exposure to a temperature ranging between about 260° F. and about 530° F. More particularly, the heating may include exposure to a temperature ranging between about 375° F. and about 520° F. Still more particularly, the heating may include exposure to a temperature ranging between about 490° F. and about 510° F. And in some embodiments, the heating may include exposure to a temperature of about 500° F. 
     Some embodiments of the method of making an intracorporeal product further include applying pressure to the assembly to fuse the thermoplastic material and the ePTFE sheets to the rib component. In some of these embodiments, the pressure applied is between about 10 psi and about 150 psi. In some particular embodiments, the pressure applied is between about 35 psi and about 120 psi. And in some particular embodiments, the pressure applied is between about 60 psi and about 90 psi. 
     Some embodiments of the method of making an intracorporeal product include applying heat and pressure to the assembly for a predetermined period of time that ranges between about 30 seconds and about 360 seconds. In some embodiments, the period of time ranges between about 75 seconds and about 240 seconds. And in some particular embodiments, the period of time is about 120 seconds. 
     Some embodiments of the method of making an intracorporeal product the fusion of polyethylene material and polytetra-fluoro-ethylene (PTFE) material occurs by the polyethylene melting and intercalating into the ePTFE fabric, cooling, and reforming to create interlocking zones of material continuity between polyethylene and polytetrafluoroethylene (PTFE). 
     Some embodiments of the method of making an intracorporeal product include (a) providing one ePTFE sheet; (b) providing a rib component of a frame structure; (c) deploying a thermoplastic-material containing element over at least part of the rib component; (d) applying the ePTFE sheet to at least a portion of the rib component covered by the thermoplastic element, the rib component disposed adjacent to the sheet, to form an assembly; and (e) heating the assembly to fuse the thermoplastic material and the ePTFE sheets to the rib component, the ePTFE sheet thereby forming a unilaminar ePTFE sheet structure secured to the rib component. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an elevational view of a partitioning device embodying features of the invention in an expanded configuration. 
         FIG. 2  is a plan view of the partitioning device shown in  FIG. 1 . 
         FIG. 3  is a partial longitudinal cross-sectional view of the hub of the partitioning device shown in  FIG. 1 . 
         FIG. 4  is a transverse cross sectional view of the hub shown in  FIG. 3  taken along the lines  4 - 4 . 
         FIG. 5  is a schematic elevational view of a delivery system for the partitioning device shown in  FIGS. 1 and 2 . 
         FIG. 6  is a transverse cross-sectional view of the delivery system shown in  FIG. 5  taken along the lines  6 - 6 . 
         FIG. 7  is an elevational view, partially in section, of the hub shown in  FIG. 3  secured to the helical coil of the delivery system shown in  FIG. 5 . 
         FIGS. 8A-8E  are schematic views of a patient&#39;s left ventricular chamber illustrating the deployment of the partitioning device shown in  FIGS. 1 and 2  with the delivery system shown in  FIG. 5  to partition the heart chamber into a primary productive portion and a secondary, non-productive portion. 
         FIG. 9  is a partial schematic view of the expandable frame of the partitioning device shown in  FIGS. 1 and 2  in an unrestricted configuration. 
         FIG. 10  is a top view of the expandable frame shown in  FIG. 9 . 
         FIGS. 11 and 12  are schematic illustrations of a method of forming the partitioning device shown in  FIGS. 1 and 2  from the expandable frame shown in  FIGS. 9 and 10 . 
         FIG. 13  is a schematic view of the assembled components shown in  FIG. 12 , as they are situated in a laminating press. 
         FIGS. 14A-14F  include views of a bilaminar assembly for the making of an intracorporeal partitioning device, as well as views of the assembled device.  FIG. 14A  shows an exploded and partially cutaway view of the components of the device assembled for lamination;  FIG. 14B  provides of cutaway view of the device within a press, the press in a closed position;  FIG. 14C  shows a perspective view of an exemplary device;  FIG. 14D  provides a frontal view of the device after assembly. 
         FIGS. 15A-15E  include views of a unilaminar assembly for the making of an intracorporeal partitioning device, as well as views of the assembled device.  FIG. 15A  shows an exploded and partially cutaway view of the components of the device assembled for lamination;  FIG. 15B  provides of cutaway view of the device within the press in a closed position;  FIG. 15C  shows a perspective view of an exemplary device; and  FIG. 15D  provides a frontal view of the device after assembly. 
         FIG. 16  provides cross-sectional views of an assembly from which a bilaminar partitioning device is formed.  FIG. 16A  shows a polyethylene-encased rib sandwiched between two sheets of ePTFE material as assembled prior to processing in a mold or press. In this embodiment, the rib is substantially cylindrical in form, or substantially circular in cross section.  FIG. 16B  shows the same materials after the application of heat and pressure, to form a bilaminar sheet, the sheets held together by melted and reformed polyethylene material to which they are both fused, a rib disposed within and adherent to the polyethylene. 
         FIG. 17  provides cross-sectional views of an assembly from which a bilaminar partitioning device is formed.  FIG. 17A  shows a polyethylene-encased rib sandwiched between two sheets of ePTFE material as assembled prior to processing in a mold or press. In this embodiment, the rib is substantially rectangular, but curved in cross section.  FIG. 17B  shows the same materials after the application of heat and pressure, to form a bilaminar sheet, the sheets held together by melted and reformed polyethylene material to which they are both fused, a rib disposed within and adherent to the polyethylene. 
         FIG. 18  provides cross-sectional views of an assembly from which a unilaminar partitioning device is formed.  FIG. 18A  shows a polyethylene-encased rib overlaying a sheet of ePTFE material as assembled prior to processing in a mold or press. In this embodiment, the rib is substantially circular in cross section.  FIG. 18B  shows the same materials after the application of heat and pressure, to form a unilaminar sheet fused to a rib by the melted and reformed polyethylene, the polyethylene interposed between the rib and the ePTFE sheet, adhering to both. 
         FIG. 19  provides cross-sectional views of an assembly from which a unilaminar partitioning device is formed.  FIG. 19A  shows a polyethylene-encased rib overlaying a sheet of ePTFE material as assembled prior to processing in a mold or press. In this embodiment, the rib is substantially rectangular but curved in cross section.  FIG. 19B  shows the same materials after the application of heat and pressure, to form a unilaminar sheet fused to a rib by the melted and reformed polyethylene, the polyethylene interposed between the rib and the ePTFE sheet, adhering to both. 
         FIGS. 20A and 20B  schematically depict the formation of a unilaminar integrated structure from the polyethylene-encased rib and ePTFE material by the melting and solidified reformed polythethylene to create interlocking continuities between the ePTFE and the polyethylene. This structure also depicts a portion of a larger bilaminar structure, such as a portion immediately overlaying a rib. 
         FIGS. 21A and 21B  schematically depict the formation of a bilaminar integrated structure from the polyethylene-encased rib and ePTFE material by the melting and solidified reformed polythethylene to create interlocking continuities between the ePTFE and the polyethylene. 
     
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION 
       FIGS. 1-4  illustrate a partitioning component  10  which embodies features of the invention and which includes a partitioning membrane  11 , a hub  12 , preferably centrally located on the partitioning device, and a radially expandable reinforcing frame  13  formed of a plurality of ribs  14 . Embodiments of the partitioning component  10  may be alternatively referred to as an intracorporeal partitioning component or an intracorporeal product, referring to its position within a ventricle of the heart, and to its function in partitioning the ventricle. Preferably, the partitioning membrane  11  is secured to the proximal or pressure side of the frame  13  as shown in  FIG. 1 . The ribs of the intracorporeal device  14  have distal ends  15  which are secured to the hub  12  and free proximal ends  16  which are configured to curve or flare away from a center line axis  17 . Radial expansion of the free proximal ends  16  unfurls the membrane  11  secured to the frame  13  so that the membrane presents a relatively smooth, pressure receiving surface  18  which defines in part the productive portion of the patient&#39;s partitioned heart chamber. 
     As shown in more detail in  FIGS. 3 and 4 , the distal ends  15  of the ribs  14  are secured within the hub  12  and a transversely disposed connector bar  20  is secured within the hub which is configured to secure the hub  12  and thus the partitioning component  10  to a delivery system such as shown in  FIGS. 5 and 6 . The curved free proximal ends  16  of ribs  14  are provided with sharp tip elements  21  which are configured to hold the frame  13  and the membrane  11  secured thereto in a deployed position within the patient&#39;s heart chamber. Preferably, the sharp tip elements  21  of the frame  13  penetrate into tissue of the patient&#39;s heart wall in order to secure the partitioning component  10  within the heart chamber so as to partition the ventricular chamber into a productive portion and a non-productive portion. 
     The connector bar  20  of the hub  12 , as will be described later, allows the partitioning device  10  to be secured to a delivery system and to be released from the delivery system within the patient&#39;s heart chamber. The distal ends  15  of the reinforcing ribs  14  are secured within the hub  12  in a suitable manner or they may be secured to the surface defining the inner lumen or they may be disposed within channels or bores in the wall of the hub  12 . The ribs  14  are pre-shaped so that when not constrained other than by the membrane  11  secured thereto (as shown in  FIGS. 1 and 2 ), the free proximal ends  16  thereof expand to a desired angular displacement away from a center line axis  17  which is about 20 degrees to about 90 degrees, preferably about 50 degrees to about 80 degrees. 
       FIGS. 5-7  illustrate a suitable delivery system  30  delivering the partitioning component  10  shown in  FIGS. 1 and 2  into a patient&#39;s heart chamber and deploying the partitioning component  10  to partition the heart chamber as shown in  FIGS. 8A-8E . The delivery system  30  includes a guide catheter  31  and a delivery catheter  32 . 
     The guide catheter has an inner lumen  33  extending between the proximal end  34  and distal end  35 . A hemostatic valve (not shown) may be provided at the proximal end  34  of the guide catheter  31 . A flush port  36  on the proximal end  34  of guide catheter  31  is in fluid communication with the inner lumen  33 . 
     The delivery catheter  32  has an outer shaft  40  with an inner lumen  41  and a proximal injection port  42 , an inner shaft  43  disposed within the inner lumen  41  with a first lumen  44  and a second lumen  45 . Balloon inflation port  46  is in fluid communication with the first lumen  44  and flush port  47  is in fluid communication with the second lumen  45 . Torque shaft  48  is rotatably disposed within the second lumen  44  of the inner shaft  43  and has an injection port  49  provided at its proximal end  50  in fluid communication with the inner lumen  51  of the torque shaft. The torque shaft  48  is preferably formed at least in part of a hypotube formed of suitable material such as superelastic Nitinol or stainless steel. A torque knob  52  is secured to the proximal end  50  of torque shaft  48  distal to the injection port  49 . A helical coil screw  53  is secured to the distal end of the torque shaft  48  and rotation of the torque knob  52  on the proximal end  50  of the torque shaft  48  rotates the screw  53  on the distal end of torque shaft  48  to facilitate deployment of a partitioning device  10 . An inflatable balloon  55  is sealingly secured to the distal end of the inner shaft  43  and has an interior  56  in fluid communication with the first lumen  44 . Inflation fluid may be delivered to the interior  56  through port  44   a  in the portion of the inner shaft  43  extending through the balloon  55 . Inflation of the balloon  55  by inflation fluid through port  46  facilitates securing the partitioning component  10 . 
     To deliver the partitioning component  10 , it is secured to the distal end of the delivery catheter  32  by means of the helical coil screw  53 . The partitioning component  10  is collapsed to a first, delivery configuration which has small enough transverse dimensions to be slidably advanced through the inner lumen  33  of the guide catheter  31 . Preferably, the guide catheter  31  has been previously percutaneously introduced and advanced through the patient&#39;s vasculature, such as the femoral artery, in a conventional manner to the desired heart chamber. The delivery catheter  32  with the partitioning component  10  attached is advanced through the inner lumen  33  of the guide catheter  31  until the partitioning component  10  is ready for deployment from the distal end of the guide catheter  31  into the patient&#39;s heart chamber  58  to be partitioned. 
     The partitioning component  10  mounted on the screw  53  is urged partially out of the inner lumen  33  of the guide catheter  31  until the hub  12  engages the heart wall as shown in  FIG. 8B  with the free proximal ends  16  of the ribs  14  in a contracted configuration within the guide catheter. The guiding catheter  31  is withdrawn while the delivery catheter  32  is held in place until the proximal ends  16  of the ribs  14  exit the distal end of the guiding catheter. The free proximal ends  16  of ribs  14  expand outwardly to press the sharp proximal tips  21  of the ribs  14  against and preferably into the tissue lining the heart chamber, as shown in  FIG. 8C . 
     With the partitioning component deployed within the heart chamber and preferably partially secured therein, inflation fluid is introduced through the inflation port  46  into first lumen  44  of inner shaft  43  of the delivery catheter  32  where it is directed through port  44   a  into the balloon interior  56  to inflate the balloon. The inflated balloon presses against the pressure receiving surface  18  of the partitioning component  10  to ensure that the sharp proximal tips  21  are pressed well into the tissue lining the heart chamber. 
     With the partitioning device  10  properly positioned within the heart chamber, the knob  52  on the torque shaft  48  is rotated counter-clockwise to disengage the helical coil screw  53  of the delivery catheter  32  from the hub  12 . The counter-clockwise rotation of the torque shaft  48  rotates the helical coil screw  53  which rides on the connector bar  20  secured within the hub  12 . Once the helical coil screw  53  disengages the connector bar  20 , the delivery system  30 , including the guide catheter  31  and the delivery catheter  32 , may then be removed from the patient. 
     The proximal end of the guide catheter  31  is provided with a flush port  36  to inject therapeutic or diagnostic fluids through the inner lumen  33 . Similarly, the proximal end of the delivery catheter  32  is provided with a flush port  42  in communication with inner lumen  41  for essentially the same purpose. An inflation port  46  is provided on the proximal portion of the delivery catheter for delivery of inflation fluid through the first inner lumen  44  to the interior  56  of the balloon  55 . Flush port  47  is provided in fluid communication with the second inner lumen  45  of the inner shaft  43 . An injection port  49  is provided on the proximal end of the torque shaft  48  in fluid communication with the inner lumen  51  of the torque shaft for delivery of a variety of fluids. 
     The partitioning component  10  partitions the patient&#39;s heart chamber  57  into a main productive or operational portion  58  and a secondary, essentially non-productive portion  59 . The operational portion  58  is much smaller than the original ventricular chamber  57  and provides for an improved ejection fraction. The partitioning increases the ejection fraction and provides an improvement in blood flow. Over time, the non-productive portion  59  fills first with thrombus and subsequently with cellular growth. Bio-resorbable fillers such as polylactic acid, polyglycolic acid, polycaprolactone, and copolymers and blends may be employed to initially fill the non-productive portion  59 . Fillers may be suitably supplied in a suitable solvent such as DMSO. Other materials which accelerate tissue growth or thrombus may be deployed in the non-productive portion  59 . 
       FIGS. 9 and 10  illustrate the reinforcing frame  13  in an unstressed configuration and include the ribs  14  and the hub  12 . The ribs  14  have a length L of about 1 to about 8 cm, preferably, about 1.5 to about 4 cm for most left ventricle deployments. The proximal ends  16  have a flared construction. To assist in properly locating the device during advancement and placement thereof into a patient&#39;s heart chamber, parts, e.g. the distal extremity, of one or more of the ribs and/or the hub may be provided with markers at desirable locations that provide enhanced visualization by eye, by ultrasound, by X-ray, or other imaging or visualization means. Radiopaque markers may be made with, for example, stainless steel, platinum, gold, iridium, tantalum, tungsten, silver, rhodium, nickel, bismuth, other radiopaque metals, and alloys and oxides of these metals. 
     Embodiments of the partitioning device  10 , both unilaminar and bilaminar embodiments, are conveniently formed by placing a thermoplastic tube  60 , e.g. polyethylene or high density polyethylene (HDPE), over the ribs  14  of the frame  13  as shown in  FIG. 11  until the proximal ends  16  of the ribs  14  extend out the ends of the thermoplastic tubes as shown in  FIG. 12 , to form thermoplastic-encased ribs. Further steps in the process of forming a unilaminar or bilaminar partitioning device make use of a press or lamination mold  63  that includes a female platen  62  and a male platen  65 , one or both of which can be heated and cooled according to process specifics. A first expanded polytetrafluoroethylene (ePTFE) sheet  61  of appropriate size is placed in the female platen  62  of the mold or press  63 . The frame  13 , with tubes  60  slidably disposed or deployed over the ribs  14 , is placed in platen  62  on top of the ePTFE sheet  61 . In some alternative embodiments, the ePTFE sheet may be placed over the ribs. The center portion of the sheet  61  may be provided with an opening through which the hub  12  extends. In the case of forming a bilaminar embodiment, a second ePTFE sheet  64  is placed on top of the ribs  14  of frame  13  as shown in  FIG. 13 . The melting point of the thermoplastic material is lower than that of the ePTFE, thus the application of heat and pressure, as detailed below, is sufficient to melt the thermoplastic material but does not cause melting of the ePTFE. 
     Embodiments of methods to form a partitioning device that joins ePTFE sheet material, polyethylene material, and ribs into an integral structure include the application of heat and pressure. Heat and pressure may be applied through a mold or press  63  for a period of predetermined period of time, such as from about 30 seconds to about 360 seconds, or more particularly from about 75 seconds to about 240 seconds, or still more particularly, for about 120 seconds. Either the male platen  65  or the female platen  62 , or both male and female platens may be heated so as to attain an operating temperature of between about 260° F. and 530° F., particularly to a temperature between about 375° F. and 520° F., and more particularly to temperature between about 490° F. and about 510° F., and still more particularly to a temperature of about 500° F. In some embodiments, the assembly may be pressed (i.e., pressured or pressurized), the applied pressure being in the range of about 10 psi to about 150 psi. In some particular embodiments, the pressure is between about 35 psi and about 120 psi, and in more particular embodiments, between about 60 psi and about 90 psi. In some embodiments, a single sheet of ePTFE is utilized to make a unilaminar device, the single sheet corresponding to the first sheet  61  of  FIG. 13 . 
     PTFE fabric is a woven material that varies with regard to the thickness of fibers and in the internodal distance between fibers. The presence of the space or volume between fibers provides the material with a foraminous quality which is advantageous for fusion or adhesion processes. Various forms of ePTFE have average internodal distances that vary from about one micron up to about 1,000 microns. Typical embodiments of ePTFE fabric appropriate for the manufacture of the herein described partitioning device may have internodal distances of between about 5 microns to about 200 microns, more particularly from about 10 microns to about 100 microns, and still more particularly from about 20 microns to about 50 microns. Aspects of the lamination process are described further below, and illustrated in  FIGS. 14-21 . Sheets may be formed of either porous or non-porous ePTFE, as well as other suitable biocompatible materials, as described further below. 
     As described further, below, the ePTFE fabric is typically stretched during the lamination process, under the conditions of heat and pressure that are applied by the press. Such stretching may not be uniform across the fabric surface, the maximal linear stretch in portions of the fabric may be of a magnitude of 2-fold to 4-fold. The stretching of fabric serves, in general terms, to reduce the thickness and overall collapsed profile of the device. 
       FIGS. 14A-14D  include further views of a bilaminar assembly for the making of an intracorporeal partitioning device (as also depicted variously in preceding  FIGS. 11-13 ) and views of the assembled device.  FIG. 14A  shows a perspective view of an exemplary device;  FIG. 14B  shows an exploded and partially cutaway view of the components of the device assembled for lamination;  FIG. 14C  provides of cutaway view of the device within the press in a closed position; and  FIG. 14D  provides a frontal view of the device after assembly. 
     In  FIG. 14A , the upper or male platen  65  of a press  63  and the lower or female platen  62  are seen above and below, respectively, an awaiting assembly that includes, from top to bottom, a sheet of ePTFE  64 , an assembly of polyethylene  60  covered ribs  14  that are formed into a cone-shaped configuration, and a bottom sheet of ePTFE  61 . Around the periphery of the upper platen  65  is a rim portion  66 A, and around the periphery of the lower platen  62  is a rim portion  66 B. These two rim portions ( 66 A and  66 B) form complementary planar surfaces which serve to hold edges of the sheets of ePTFE fabric as the central portion is being subjected to being pressed by the complementary surfaces of the central portion or shaping portion  67 A of the upper platen  65 , and the central portion  67 B of the lower platen  62 . The closure of the two halves of the platen is depicted in the cutaway view of  FIG. 14B . A perspective view of the device as it would emerge post-formation is seen in  FIG. 14C ; where the polyethylene encased ribs  14  may be seen. A frontal plane-flattening view of the device upon removal from the press is shown in  FIG. 14D , again showing the polyethylene encased ribs  60 A, the polyethylene now reformed from its native circular configuration. Details of this structure in a before-pressing form  60  and after-pressing pressing form  60 A are shown in  FIGS. 16 ,  17 , and  21 . 
       FIGS. 15A-15D  include various views of a unilaminar assembly for the making of an intracorporeal partitioning device, as well as views of the assembled device.  FIG. 15A  shows an exploded and partially cutaway view of the components of the device assembled for lamination;  FIG. 15B  provides of cutaway view of the device within a press, the press in a closed position;  FIG. 15C  shows a perspective view of an exemplary device;  FIG. 15D  provides a frontal view of the device after assembly. 
     In  FIG. 15A , the upper or male platen  65  of a press  63  and the lower or female platen  62  are seen above and below, respectively, an awaiting assembly that includes, from top to bottom, an assembly of polyethylene  60  covered ribs  14  that are formed into a cone-shaped configuration, and a bottom sheet of ePTFE  61  that will ultimately form a unilaminar device. Around the periphery of the upper platen  65  is a rim portion  66 A, and around the periphery of the lower platen  62  is a rim portion  66 B. These two rim portions ( 66 A and  66 B) form complementary planar surfaces which serve to hold edges of the sheets of ePTFE fabric as the central portion is being subjected to being pressed by the complementary surfaces of the central portion or shaping portion  67 A of the upper platen  65 , and the central portion  67 B of the lower platen  62 . The closure of the two halves of the platen is depicted in the cutaway view of  FIG. 15B . A perspective view of the device as it would emerge post-formation is seen in  FIG. 15C ; where the polyethylene encased ribs  14  may be seen. A frontal plane-flattening view of the device upon removal from the press is shown in  FIG. 15D , again showing the polyethylene encased ribs  60 A, the polyethylene now reformed from its native circular configuration. Details of this structure in a before-pressing form  60  and after-pressing pressing form  60 A are shown in  FIGS. 16 ,  17 , and  21 . 
     An aspect of ePTFE material that relates to the internodal distances within the fabric is that such distance is preferably sufficient to accommodate the flow of melted polyethylene from the thermoplastic tubes  60  during the heating and pressuring period of embodiments of the forming process. As melted polyethylene intercalates into the ePTFE fabric and then solidifies in a reformed configuration on cooling, intermingled and interlocking zones of material continuity having been created between polyethylene and polytetra-fluoroethylene (PTFE). These fusion zones of interlocking zones of material continuity provide a firm bonding matrix that (1) secures the still-polyethylene-encased rib  14  to the adjacent one ePTFE sheet (in a unilaminar embodiment) or two ePTFE sheets (in a bilaminar embodiment, and thereby within the bilaminar structure formed by the two sheets) and (2), in a bilaminar embodiment, the adheres the two ePTFE sheets together to form a bilaminar structure. 
       FIGS. 16 and 17  provide views of two embodiments of a metallic rib encased in a polyethylene tube  60 , prior to (A) and subsequent to (B) being fused within two ePTFE sheets ( 61  and  64 ), to form a bilaminar dPTFE sheet, the two sheets adhering to each other in the locale of the zone of fusion between the polyethylene and the ePTFE materials.  FIGS. 16A and 16B  depict a rib that is substantially circular in cross section. Similar embodiments (not shown) include those with cross sectional profiles that are somewhat flattened or elliptical. The cross sectional profile of ribs may vary, and various embodiments may provide advantages with regard, for example, to stiffness or to practical aspects of the assembly of the device. Other embodiments of ribs are more rectangular in cross section.  FIGS. 17A and 17B  depict a rib that is generally rectangular in cross section, though curved or arched as a whole in cross section in this particular embodiment, with a convex upper-facing surface and a concave lower-facing surface. 
       FIG. 16A  provides a cross sectional view of a metallic rib  14 , substantially circular in cross section, encased in a polyethylene tube  60 , the tube disposed between the two ePTFE sheets  61  and  64  prior to application of pressure and heat.  FIG. 16B  provides a view of the same materials after heat and pressure to form a bilaminar device. The thermoplastic material that originally comprised tube  60  disposed over the rib  14 , has reformed as polyethylene material  60 A, which is fused into the porous matrix of the ePTFE sheets  61  and  64 . (The polyethylene material represented by  60  in its native form and by  60 A in its post-melt and reformed form is substantially conserved in terms of total volume, but it is redistributed as schematically depicted in  FIGS. 16A-16B , as well as in  FIGS. 17-21 . In addition to the schematically depicted polyethylene  60  and  60 A, also depicted schematically and not necessarily to scale are the relative sizes of the ribs  14  and the PTFE fabric  64 .) The first and second ePTFE sheets thereby form a bilaminar ePTFE sheet, and at sites where the bilaminar sheet surrounds the thermoplastic material; the bilaminar ePTFE and the thermoplastic material solidify, thereby securing the sheets  61  and  64  to the ribs  14  and preventing their delamination during use of the partitioning device. The encircled detail within  FIG. 16A  that is labeled  21 A is a reference to  FIG. 21A  which provides a more detailed of the ePTFE and polyethelene materials prior to their fusion during the lamination process, as described below. The encircled detail within  FIG. 16B  that is labeled  21 B is a reference to  FIG. 21B  which provides a more detailed of the ePTFE and polyethelene materials after their fusion during the lamination process, as described below. 
       FIGS. 17A and 17B  provide a representation of an embodiment of the device wherein the rib  14  is substantially rectangular in cross section, but wherein the process of forming a device is otherwise substantially parallel to the sequence shown in  FIGS. 16A and 16B .  FIG. 17A  provides a cross sectional view of a metallic rib  14 , substantially rectangular in cross section, encased in a polyethylene tube  60 , the tube disposed between the two ePTFE sheets  61  and  64  prior to application of pressure and heat to form a bilaminar device.  FIG. 17B  provides a view of the same materials after heat and pressure. The thermoplastic material that originally comprised tube  60  disposed over the rib  14  has reformed as polyethylene material  60 A, which is fused into the porous matrix of the ePTFE sheets  61  and  64 . The first and second ePTFE sheets thereby form a bilaminar ePTFE sheet, and at sites where the bilaminar sheet surrounds the thermoplastic material; the bilaminar ePTFE and the thermoplastic material solidify, thereby securing the sheets  61  and  64  to the ribs  14  and preventing their delamination during use of the partitioning device. Sheets may be formed of either porous or non-porous ePTFE, as well as other suitable biocompatible materials, as described further below. 
     In embodiments where only a single sheet of ePTFE is used, a unilaminar structure is formed, with the ribs  14  adhering to the ePTFE sheet  61  by way of the melted and reformed polyethylene that originally comprised the thermoelastic tube  60  surrounding rib  14 . These unilaminar embodiments are described further below, and depicted in  FIGS. 18 and 19 . In both cases, i.e., the unilaminar and bilaminar embodiments, the reforming of the polyethylene which originally encases the rib  14  to a configuration that intercalates through the ePTFE weave, it is the reformation of the polyethylene that is substantially responsible for the integration of the ePTFE and the polyethylene-encased ribs(s) into an integrated structure. 
     In embodiments where only a single sheet of ePTFE is used, a unilaminar structure is formed, with the ribs  14  adhering to the single ePTFE sheet  61  by way of the melted and reformed polyethylene that originally comprised the thermoelastic tube  60  surrounding rib  14 , the polyethylene material still encasing the rib. Unilaminar embodiments of the invention are depicted in  FIGS. 18 and 19 .  FIG. 18A  shows a cross sectional view of a rib, substantially circular in cross section, encased in a polyethylene tube  60 , the tube disposed adjacent to ePTFE sheets  61  prior to application of pressure and heat.  FIG. 18B  provides a view of the same materials after application of heat and pressure. The thermoplastic material that originally comprised tube  60  disposed over the rib  14  has fused into the porous matrix of the ePTFE sheet  61 . 
     The encircled detail within  FIG. 18A  that is labeled  20 A is a reference to  FIG. 20A  which provides a more detailed of the ePTFE and polyethelene materials prior to their fusion during the lamination process, as described below. The encircled detail within  FIG. 18B  that is labeled  20 B is a reference to  FIG. 20B  which provides a more detailed view of the ePTFE and polyethelene materials after their fusion during the lamination process, as described below. 
     Similarly,  FIGS. 19A  shows a cross sectional view of a rib, generally rectangular in cross section, encased in a polyethylene tube  60 , the tube adjacent to ePTFE sheet  61  prior to application of pressure and heat.  FIG. 19B  provides a view of the same materials after heat and pressure. The thermoplastic material that originally comprised tube  60  disposed over the rib  14  has fused into the porous matrix of the ePTFE sheet  61 . 
     In some embodiments of the method, a cooling step is applied following the application of pressure and heat. A relatively passive cooling method is appropriate for some embodiments, and can be achieved by simply placing the mold on a cold surface (for example, a chilled block of copper) or by submerging it in any suitable cold medium such as chilled water. In other embodiments, more active, permeative, or quick cooling is preferred, and may be accomplished by circulating any suitable coolant (for example, chilled water, liquid nitrogen) through cooling channels built into the lamination mold body to bring the temperature into a range of about 0° F. to about 32° F. 
     While porous ePTFE material is included in typical embodiments, non-porous ePTFE may be appropriate for some embodiments. The choice of using non-porous or porous ePTFE depends on the intended use or desired features when the partitioning device is placed in the heart. A porous membrane can advantageously function as a filter-like barrier that allows blood through-flow, but blocks transit of particles or emboli. On the other hand, in some medical applications it may be desirable to form a significant seal between two cardiac compartments with the intervention of the partitioning device, in which case a non-porous ePTFE may be preferred. 
     Further, the membrane  11  may also be formed of other suitable biocompatible polymeric materials such as, by way of example, may include Nylon, PET (polyethylene terephthalate), and polyesters such as Hytrel. The membrane  11  may advantageously be foraminous in nature to facilitate tissue ingrowth after deployment within the patient&#39;s heart, and further, to provide an advantageous matrix for bonding with melted polyethylene material, as for example, from a thermoplastic tube  60 . The delivery catheter  32  and the guiding catheter  31  may be formed of suitable high strength polymeric material such as, by way of example, polyetheretherketone (PEEK), polycarbonate, PET, and/or Nylon. Braided composite shafts may also be employed. 
       FIGS. 20 and 21  provide schematic views of the lamination zones of the device, at microscopic scale. Embodiments of the porous or foraminous ePTFE sheets may have internodal distances between woven fabric strands that range between about 5 and about 200 microns, as described above. The internodal areas delineated by the fibers also provide space into which polyethylene material from the thermoplastic tubes  60  intercalates as it melts and reforms during embodiments of the lamination process. As melted polyethylene material intercalates into the unmelted ePTFE material and then solidifies into a reformed configuration on cooling, intermingled and interlocking zones of respective material-material continuity are created between polyethylene and polytetra-fluoro-ethylene (PTFE). The continuity of the PTFE fibers remains substantially unchanged, even though the fibers may be stretched, and the polyethylene forms a continuous solid that includes the PTFE fibers within it. These interlocking zones of material continuity provide a firm bonding matrix that both (1) adheres the two sheets of the bilaminar structure together, and (2) secures the rib  14  to and within the bilaminar structure. The formation of integrated laminar structures that include one or two ePTFE sheets and thermoplastic material entrapping a rib is depicted in  FIGS. 20 and 21 ; these are schematic views, drawn such that the internodal distances appear at a scale that is larger than that of the device as a whole. 
       FIGS. 20A and 20B  schematically depict the formation of a unilaminar integrated structure from the polyethylene-encased rib and ePTFE material by the melting and solidified reformed polythethylene to create interlocking continuities between the ePTFE and the polyethylene. This structure also depicts a unilaminar or split-laminar portion of a larger bilaminar structure, such as a portion immediately overlaying a rib  14 .  FIG. 20A  depicts a woven sheet of ePTFE disposed over or adjacent to a portion of the wall of a polyethylene tube encasing a rib before being subjected to pressure and heat within a press.  FIG. 20B  depicts the unified structure after the application of heat and pressure, and after the polyethylene has melted and reformed within and around the weave of the ePTFE fabric. 
       FIGS. 21A and 21B  schematically depict the formation of a bilaminar integrated structure from the polyethylene-encased rib and ePTFE material by the melting and solidified reformed polythethylene to create interlocking continuities between the ePTFE and the polyethylene.  FIG. 21A  depicts two woven sheets of ePTFE disposed, respectively, over and under a portion of the wall of a polyethylene tube encasing a rib before being subjected to pressure and heat within a press.  FIG. 21B  depicts the unified structure after the application of heat and pressure, and after the polyethylene has melted and reformed within and around the weave of the ePTFE fabric. This bilaminar structure occurs in areas not immediately overlaying a rib  14 , but rather in the area that lies immediately adjacent to a rib  14 , and spreading out peripherally, thereby creating a substantial area of mutual connection between the two ePTFE sheets. 
     Unless defined otherwise, all technical terms used herein have the same meanings as commonly understood by one of ordinary skill in the art of interventional cardiology. Specific methods, devices, and materials are described in this application, but any methods and materials similar or equivalent to those described herein can be used in the practice of the present invention. While embodiments of the invention have been described in some detail and by way of exemplary illustrations, such illustration is for purposes of clarity of understanding only, and is not intended to be limiting. Various terms have been used in the description to convey an understanding of the invention; it will be understood that the meaning of these various terms extends to common linguistic or grammatical variations or forms thereof. It will also be understood that when terminology referring to devices ir equipment has used trade names, brand names, or common names, that these names are provided as contemporary examples, and the invention is not limited by such literal scope. Terminology that is introduced at a later date that may be reasonably understood as a derivative of a contemporary term or designating of a subset of objects embraced by a contemporary term will be understood as having been described by the now contemporary terminology. Further, any one or more features of any embodiment of the invention can be combined with any one or more other features of any other embodiment of the invention, without departing from the scope of the invention. Still further, it should be understood that the invention is not limited to the embodiments that have been set forth for purposes of exemplification, but is to be defined only by a fair reading of claims that are appended to the patent application, including the full range of equivalency to which each element thereof is entitled. 
     Terms such a “element”, “member”, “device”, “section”, “portion”, “step”, “means” and words of similar import, when used herein shall not be construed as invoking the provisions of 35 U.S.C. .sctn.112(6) unless the following claims expressly use the terms “means” followed by a particular function without specific structure or “step” followed by a particular function without specific action. All patents and patent applications referred to above are hereby incorporated by reference in their entirety.