Abstract:
This invention is directed to a partitioning device for separating a patient&#39;s heart chamber into a productive portion and a non-productive portion. The device is particularly suitable for treating patients with congestive heart failure. The partitioning device has a reinforced, expandable membrane which separates the productive and non-productive portions of the heart chamber and a support or spacing member extending between the reinforced membrane and the wall of the patient&#39;s heart chamber. The support or spacing member has a non-traumatic distal end to engage the ventricular wall.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This is a divisional of pending U.S. patent application Ser. No. 10/754,182, filed on Jan. 9, 2004, which application is incorporated by reference as if fully set forth herein. 
     
    
     INCORPORATION BY REFERENCE 
       [0002]    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 
       [0003]    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 
       [0004]    Congestive heart failure (CHF) is characterized by a progressive enlargement of the heart, particularly the left ventricle and is a major cause of death and disability in the United States. Approximately 500,000 cases occur annually in the U.S. alone. As the patient&#39;s heart enlarges, it cannot efficiently pump blood forward with each heart beat. In time, the heart becomes so enlarged the heart cannot adequately supply blood to the body. Even in healthy hearts only a certain percentage of the blood in a patient&#39;s left ventricle is pumped out or ejected from the chamber during each stroke of the heart. The pumped percentage, commonly referred to as the “ejection fraction”, is typically about sixty percent for a healthy heart. A patient with congestive heart failure can have an ejection fraction of less than 40% and sometimes lower. As a result of the low ejection fraction, a patient with congestive heart failure is fatigued, unable to perform even simple tasks requiring exertion and experiences pain and discomfort. Further, as the heart enlarges, the internal heart valves such as the mitral valve, cannot adequately close. 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 forewardly. 
         [0005]    Congestive heart failure can result from a variety of conditions, including viral infections, incompetent heart valves (e.g. mitral valve), 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 the myocardial tissue dies, it is less contractile (sometimes non-contractile) and no longer contributes to the pumping action of the heart. It is referred to as hypokinetic. As the disease progresses, a local area of compromised myocardium may bulge out during the heart contractions, further decreasing the heart&#39;s ability to pump blood and further reducing the ejection fraction. In this instance, the heart wall is referred to as dyskinetic or akinetic. The dyskinetic region of the heart wall may stretch and eventually form an aneurysmic bulge. 
         [0006]    Patients suffering from congestive heart failure are commonly grouped into four classes, Classes I, II, III and IV. In the early stages, Classes I and II, 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 can not cure the disease. Presently, the only permanent treatment for congestive heart disease is heart transplantation, but heart transplant procedures are very risky, extremely invasive and expensive and are performed on a small percentage of patients. Many patient&#39;s do not qualify for heart transplant for failure to meet any one of a number of qualifying criteria, and, Furthermore, there are not enough hearts available for transplant to meet the needs of CHF patients who do qualify. 
         [0007]    Substantial effort has been made to find alternative treatments for congestive heart disease. For example, surgical procedures have been developed to dissect and remove weakened portions of the ventricular wall in order to reduce heart volume. This procedure is highly invasive, risky and expensive and is commonly only done in conjunction with other procedures (such as heart valve replacement or coronary artery by-pass graft). Additionally, the surgical treatment is usually limited to Class IV patients and, accordingly, is not an option for patients facing ineffective drug treatment prior to Class IV. Finally, if the procedure fails, emergency heart transplant is the only presently available option. 
         [0008]    Other efforts to treat CHF include the use of an elastic support, such as an artificial elastic sock placed around the heart to prevent further deleterious remodeling. 
         [0009]    Additionally, mechanical assist devices have been developed as intermediate procedures for treating congestive heart disease. Such devices include left ventricular assist devices and total artificial hearts. A left ventricular assist device includes a mechanical pump for increasing blood flow from the left ventricle into the aorta. Total artificial heart devices, such as the Jarvik heart, are usually used only as temporary measures while a patient awaits a donor heart for transplant. 
         [0010]    Recently, improvements have been made in treating patient&#39;s with CHF by implanting pacing leads in both sides of the heart in order to coordinate the contraction of both ventricles of the heart. This technique has been shown to improve hemodynamic performance and can result in increased ejection fraction from the right ventricle to the patient&#39;s lungs and the ejection fraction from the left ventricle to the patient&#39;s aorta. While this procedure has been found to be successful in providing some relief from CHF symptoms and slowed the progression of the disease, it has not been able to stop the disease. 
       SUMMARY OF THE INVENTION 
       [0011]    The present invention is directed to a ventricular partitioning device and method of employing the device in the treatment of a patient with congestive heart failure. Specifically, the ventricular chamber of the CHF patient is partitioned by the device so as to reduce its total volume and to reduce the stress applied to the heart and, as a result, improve the ejection fraction thereof. 
         [0012]    A ventricular partitioning device embodying features of the invention has a reinforced membrane component, preferably self expanding, which is configured to partition the patient&#39;s ventricular heart chamber into a main productive portion and a secondary non-productive portion, and a support or spacing component extending from the distal side of the reinforced membrane for non-traumatically engaging a region of the patient&#39;s ventricular wall defining in part the secondary non-productive portion to space a central portion of the reinforced membrane from the heart wall. The partitioning device preferably includes a centrally located hub secured to the reinforced membrane. The partitioning membrane of the device may be reinforced by a radially expandable frame component formed of a plurality of ribs. 
         [0013]    The ribs of the expandable frame have distal ends secured to the central hub, preferably secured to facilitate abduction of the free proximal ends of the ribs away from a centerline axis. The distal ends of the ribs may be pivotally mounted or formed of material such as superelastic NiTi alloy which allow for compressing the ribs into a contracted configuration and when released allow for their self expansion. The ribs also have free proximal ends configured to engage and preferably penetrate the tissue of the heart wall so as to secure the peripheral edge of the membrane to the heart wall and fix the position of the membrane with respect thereto. The free proximal ends of the ribs may have tissue penetrating tips such as barbs or hooks. The partitioning membrane is secured to the ribs of the expandable frame, preferably on the proximal or pressure side of the expandable frame. 
         [0014]    The supporting component or stem of the device has a length configured to extend to the heart wall (typically about 5 mm to about 50 mm, preferably about 15 to about 35 mm), to support and space the membrane from the heart wall. While only one supporting component or stem is described herein, a plurality of such components may be utilized. The supporting component or stem may have at least one inner lumen extending therein for delivery of therapeutic or diagnostic agents through the ports provided along the length thereof. The stem is provided with one or more flexible bumper-type elements on its distal end to non-traumatically engage the weakened ventricular wall and maintain the reinforced membrane, preferably the central portion thereof, spaced a desired distance from the weakened ventricular wall. 
         [0015]    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. 
         [0016]    The partitioning device may be delivered percutaneously or intraoperatively. It is relatively easy to install and provides substantial improvement in the ejection fraction of the patient&#39;s heart chamber. These and other advantages of the invention will become more apparent from the following detailed description of the invention and the accompanying exemplary drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0017]      FIG. 1  is a schematic perspective view of a ventricular partitioning device embodying features of the invention. 
           [0018]      FIG. 2  is an elevational view of a delivery system for the partitioning device shown in  FIG. 1   
           [0019]      FIG. 3  is an enlarged view of the encircled region  3 - 3  shown in  FIG. 2 . 
           [0020]      FIG. 4  is a simplified view with parts removed similar to that shown in  FIG. 3  with the delivery catheter connected to the partitioning device. 
           [0021]      FIG. 5  is an end view of the hub which is secured in the proximal end of the stem of the partitioning device shown in  FIG. 1 . 
           [0022]      FIG. 6  is a schematic view of a patient&#39;s left ventricular chamber illustrating the partitioning device shown in  FIG. 1  disposed within the chamber separating a working portion of the chamber from a non-working portion of the chamber. 
           [0023]      FIG. 7  is a schematic perspective view of an alternative design embodying features of the invention with a pair of bumper elements on the distal end of the stem of the partitioning device. 
           [0024]      FIG. 8  is a schematic perspective view of another alternative design embodying features of the invention with three bumper elements on the distal end of the stem of the partitioning device. 
           [0025]      FIG. 9  is a schematic perspective view of another alternative design embodying features of the invention with four bumper elements on the distal end of the stem of the partitioning device. 
           [0026]      FIG. 10  is a schematic perspective view of a fourth alternative design embodying features of the invention with a plurality of bumper elements on the distal end of the stem of the device provided with hooks which fix the end to the interior surface of the patient&#39;s ventricular wall. 
           [0027]      FIG. 11  is a schematic perspective view of another alternative design embodying features of the invention with a membrane underlying a plurality of bumper elements on the distal end of the stem of the partitioning device. 
           [0028]      FIG. 12  is a schematic perspective view of another alternative design embodying features of the invention with a helical coil bumper element on the distal end of the stem of the partitioning device. 
           [0029]      FIG. 13  is a schematic perspective view of yet another alternative design embodying features of the invention with an inflatable balloon secured to the underside of the partitioning device to space and support the partitioning device from the heart wall. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0030]      FIGS. 1-5  illustrate a partitioning device  10  which embodies features of the invention and which includes a partitioning membrane  11 , a stem  12  and a radially expandable reinforcing frame  13  formed of a plurality of ribs  14 . Preferably the membrane  11  is secured to the proximal or pressure side of the frame  13  as shown in  FIG. 1 . The distal ends  15  of the ribs  14  are secured to the central hub  16  and the proximal ends  17  of the ribs  14  are unsecured and are configured to radially extend away from a center line axis  18  which extends through the hub  16 . Radial expansion of the free proximal ends  17  unfurls the membrane  11  secured to the frame  13  so that the membrane presents a relatively smooth pressure side surface. Stem  12  extends distally from the hub  16  and has a distal end  19  which has a flexible, J-shape bumper element  20  to provide a yielding engagement with a heart wall when deployed within a patient&#39;s heart chamber. The frame  13  and attached membrane  11  are collapsible toward the centerline axis  18  for delivery through a catheter. 
         [0031]    The proximal or free ends  17  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 reinforced membrane  11  so as to partition the ventricular chamber in a desired manner. 
         [0032]    As shown in  FIG. 1 , the stem  12  is provided with an inner lumen  22  for delivery of fluid to the non-operative portion of the ventricular chamber and discharge ports  23  are provided in the stem. The hub  16  is secured within the inner lumen  22  in the proximal end of stem  12  suitable means such as a friction fit, an adhesive bond or a pin. The hub  16  has a deployment pin  24 , as shown in  FIG. 5 , which as will be described later allows the partitioning device  10  to be deployed within the patient&#39;s heart chamber and released from a delivery system used to place the device. The distal ends of the reinforcing ribs  14  are secured to the hub  16  in a suitable manner. They may be secured to the surface defining the inner lumen or the hub may be provided with channels or bores in the wall of the hub into which the distal ends of the ribs may be secured. The ribs  14  are preshaped so that when not constrained (as shown in  FIGS. 1 and 2 ), the free proximal ends  17  thereof expand to a desired angular displacement (.theta.) away from a center line axis  18  which is about 20.degree. to about 90.degree., preferably about 50.degree. to about 80.degree. 
         [0033]      FIGS. 2-4  illustrate a suitable delivery system  30  with a partitioning component device  10  as shown in  FIG. 1 . The delivery system  30  includes a control handle  31  with a delivery catheter  32  having a deploying coil screw  33  secured to the distal end  34  for releasing the partitioning device  10  from the delivery system  30 . The delivery catheter  32  has an inner lumen  35  through which therapeutic or diagnostic fluids may be delivered. The delivery catheter  32  extends through the handle  31  and the proximal end of the catheter  32  is secured to torquing knob  36  to allow rotation of the catheter by rotating knob  36 . An injection port  37  is provided in fluid communication with the delivery catheter  32  for injecting therapeutic or diagnostic fluids through the inner lumen  35 . 
         [0034]    The delivery system  30  may be introduced into a patient&#39;s body through guiding catheter or cannula  40  which has an inner lumen  41 . A radiopaque marker (not shown) may be provided on the distal end of the guiding catheter  40  to aid in fluoroscopically guiding the catheter to the desired location. The partitioning device  10  is slidably disposed within the inner lumen  41  with the free proximal ends  17  of the ribs  14  in a constricted configuration. The guiding catheter  40  is percutaneously introduced in a conventional fashion into the patient&#39;s vasculature and advanced therein until the distal end  42  of the guiding catheter  40  is position close to the desired location for the partitioning device  10  within the patient&#39;s heart chamber such as the left ventricle. The delivery system  30  is advanced distally within the inner lumen  41  until the J-shaped bumper  20  extends out the distal end  42  of the guiding catheter  40  and engages the ventricular wall. With the delivery system  30  held in place and the bumper  20  engaging the ventricular wall, the guide catheter  40  is pulled proximally until the free ends  17  of ribs  14  are released from the distal end  42  so that anchoring tip elements  21  on the free proximal ends  17  of ribs  14  penetrate into tissue of the patient&#39;s heart wall as shown in  FIG. 6  to secure the partitioning device  10  within the patient&#39;s heart chamber. With the partitioning device  10  properly positioned within the heart chamber, the delivery catheter  32  is rotated counter-clockwise to disengage the delivery system  30  from the hub  16 . Upon the counter-clockwise rotation of the delivery catheter  32 , the helical coil screw  33  attached to the distal end  34  of the delivery catheter  32  rides on the deployment pin  24  secured within the inner lumen  22  of the hub  16 . The delivery system  30  and the guide catheter  40  may then be removed from the patient. The proximal end of the guide catheter  40  is provided with an injection port  43  to inject therapeutic or diagnostic fluids through the inner lumen  41 . 
         [0035]      FIG. 6  illustrates the placement of partitioning device  10  within a patient&#39;s left ventricle  45 . The membrane  11  secured to the proximal side of ribs  14  partitions the patient&#39;s heart chamber  45  into a main productive or operational portion  46  and a secondary, essentially non-productive portion  47 . The operational portion  46  is much smaller than the original ventricular chamber  45  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  47  fills initially with thrombus and subsequently cellular growth. Bio-resorbable fillers such as polylactic acid, polyglycolic acid, polycaprolactone and copolymers and blends may be employed to fill the non-productive portion  47 . Fillers may be suitably supplied in a suitable solvent such as DMSO. Other materials which accelerate tissue growth may be deployed in the non-productive portion  47 . 
         [0036]      FIGS. 7-12  illustrate distal ends  19  of the partitioning devices having alternative bumper elements for providing non-traumatic contact with a weakened ventricular wall. In  FIG. 7  the distal end  19  of stem  12  has a pair of J-shaped bumpers  50  and  51 . In  FIG. 8  the distal end  19  has three J-shaped bumpers  52 ,  53  and  54 .  FIG. 9  illustrates a distal end  19  having three J-shaped bumpers  55 ,  56 ,  57  and  58 .  FIG. 10  depicts a slight change, where the distal end  19  has four wire J-shaped bumpers  59 - 62  (not shown in drawing) with sharp tips  63 - 66  (not shown) for securing the ends of the bumpers in heart tissue. A further alternative is illustrated in  FIG. 11  where a membrane  68  is applied to the J-shaped bumpers In  FIG. 12 , the distal end  19  of stem  12  is provided with a coiled bumper  70  for engaging a ventricular wall. 
         [0037]    Another modification is shown in  FIG. 13  wherein an inflatable balloon  80  is provided on the distal side of the frame  13  to support and space the partitioning device  10  from a patient&#39;s ventricular wall in lieu of the stem with flexible bumpers, as shown in the partitioning devices previously described. 
         [0038]    The ribs  14  of the partitioning device have a length of about 1 to about 8 cm, preferably, about 1.5 to about 4 cm for most left ventricle deployments. To assist in properly locating the device during advancement and placement thereof into a patient&#39;s heart chamber, the distal extremity of one or more of the ribs and/or the stem 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, alloys and oxides of these metals. 
         [0039]    The membrane  11  may be formed of suitable biocompatitble polymeric material which include ePTFE (expanded polytetrafluoroethylene), Nylon, PET (polyethylene terephthalate) and polyesters such as Hytrel. The membrane  11  is preferably foraminous in nature to facilitate tissue ingrowth after deployment within the patient&#39;s heart. The delivery catheter and the guiding catheter may be formed of suitable high strength polymeric material such as PEEK (polyetheretherketone), polycarbonate, PET, Nylon, and the like. Braided composite shafts may also be employed. To the extent not otherwise described herein, the various components of the partitioning device and delivery system may be formed of conventional materials and in a conventional manner as will be appreciated by those skilled in the art. 
         [0040]    While particular forms of the invention have been illustrated and described herein, it will be apparent that various modifications and improvements can be made to the invention. Moreover, individual features of embodiments of the invention may be shown in some drawings and not in others, but those skilled in the art will recognize that individual features of one embodiment of the invention can be combined with any or all the features of another embodiment. Accordingly, it is not intended that the invention be limited to the specific embodiments illustrated. It is intended that this invention to be defined by the scope of the appended claims as broadly as the prior art will permit. 
         [0041]    Terms such a “element”, “member”, “device”, “section”, “portion”, “steps”, “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. Accordingly, it is not intended that the invention be limited, except as by the appended claims.