Abstract:
Methods and devices that treat the left atrial appendage by bringing the distal wall of the appendage to a position where the tissue of the wall blocks the ostium, thereby preventing blood from flowing into the appendage. The methods and devices are adapted to create a separation between the distal wall of the appendage and the adjacent pericardium such that the risk of rupturing the pericardium are minimized.

Description:
RELATED APPLICATIONS 
       [0001]    This application claims priority to U.S. Provisional Application Ser. No. 61/437,488 filed Jan. 28, 2011 entitled Methods And Devices For Treating The Left Atrial Appendage, and to U.S. Provisional Application Ser. No. 61/480,201 filed Apr. 28, 2011 entitled LAA Closure Device And Method, both of which are hereby incorporated herein by reference in their entireties. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    The left atrial appendage, or “LAA” as it will be referred to herein, is a structure that gives rise to stagnant blood flow and thrombus formation, especially in patients suffering from atrial fibrillation. It has been approximated that 90% of blood clots developed in atrial fibrillation cases are formed in the LAA. As the function of the LAA is thought to be mainly embryonic, one solution is to surgically remove the atrial appendage. However, surgery is always associated with risks due to infection, bleeding, incomplete ablation, etc. 
         [0003]    Efforts have been directed lately toward various devices and techniques to percutaneously ablate, close or occlude the LAA. Examples of such devices include the WATCHMAN device developed by Atritech Inc., of Plymouth, Minn. and the PLAATO device developed by Appriva Medical, Inc., of Sunnyvale, Calif. Many of the occlusive devices, however, have been relatively stiff, causing problems with pericardial effusion, embolization, incomplete LAA closure, device dislodgement, and a loss of device integrity. Moreover, all such devices leave a large, prosthetic surface at the ostium of the LAA, which can be thrombogenic, cause irritation, or inflammation. 
         [0004]    There is thus a need for a method and device useable to prevent blood from stagnating in the LAA, while having a compliance that does not interfere with normal blood flow through the left atrium, and does not result in pericardial effusion, embolization, and a loss of device integrity. There is also a need for a device that permits ostial ablation and presents an immediate and longterm tissue interface to the left atrial blood. 
       SUMMARY OF THE INVENTION 
       [0005]    Several embodiments are shown and described herein directed to percutaneously or surgically preventing the stagnation of blood in the LAA. The methods and devices are generally directed to accomplishing the steps of accessing the LAA, either surgically by endocardial or epicardial means or navigating percutaneously to the LAA; entering the LAA via the ostium of the LAA or externally accessing the LAA in an epicaridal surgical approach; creating separation between the outside wall of the LAA and the pericardium; deploying a distal retraction device between the LAA and the pericardium; and reducing or eliminating the LAA volume by pulling the wall of the LAA toward the LAA ostium and securing the LAA wall in place to block the ostium, leaving a tissue surface to ablate the LAA ostium both immediately and in the long term. 
         [0006]    For example, one embodiment of the method of the invention involves treating a left atrial appendage of a patient by navigating a catheter to the LAA via the left atrium of a patient; creating a space between the LAA and the pericardium of the patient adjacent the LAA; deploying an expandable device inside the space created; reducing an internal volume of the LAA by retracting the tissue of the LAA toward the ostium of the LAA; securing the expandable device such that said internal volume of the LAA remains reduced; and releasing the expandable device. 
         [0007]    Another embodiment of the method of the invention involves treating a left atrial appendage of a patient during an open heart procedure by accessing the LAA via the left atrium, deploying an anchor device on the epicardial surface of the LAA, and reducing an internal volume of the LAA by retracting the tissue of the LAA toward the ostium of the LAA; securing the expandable device such that said internal volume of the LAA remains reduced; and releasing the expandable device. 
         [0008]    A third embodiment of the method of the invention involves treating a left atrial appendage of a patient during a closed-heart procedure such as CABG. In this embodiment, the ostium of the LAA would be accessed and an expandable anchor device depoloyed at the ostium and again retracting the LAA tissue against the ostium of the LAA, such that said internal volume of the LAA remains reduced; and releasing the expandable device 
         [0009]    Using the posterior LAA wall to block the ostium overcomes many of the problems with prior art attempts to occlude or close the LAA as the LAA wall is native tissue, which flexes with the contractions of the heart and presents no risk of fatigue over time. This tissue interface is immediately in place, obviating the need for anticoagulation measures after implant. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]    These and other aspects, features and advantages of which embodiments of the invention are capable of will be apparent and elucidated from the following description of embodiments of the present invention, reference being made to the accompanying drawings, in which 
           [0011]      FIG. 1  is a cutaway view of the left side of a heart with a component of the invention entering the left atrium through the foramen ovale; 
           [0012]      FIG. 2  is a perspective view of an embodiment of a component of the invention entering an LAA; 
           [0013]      FIG. 3  is a perspective view of an embodiment of a component of the invention entering an LAA; 
           [0014]      FIG. 4  is a partial perspective view of an embodiment of a component of the invention; 
           [0015]      FIG. 5  is a partial perspective view of an embodiment of a component of the invention; 
           [0016]      FIG. 6  is a partial perspective view of an embodiment of a component of the invention; 
           [0017]      FIG. 7  is a partial perspective view of an embodiment of a component of the invention; 
           [0018]      FIG. 8  is a partial side view of an embodiment of a component of the invention; 
           [0019]      FIG. 9  is a partial side view of an embodiment of a component of the invention; 
           [0020]      FIG. 10  is a partial side view of an embodiment of a component of the invention; 
           [0021]      FIG. 11  is a partial perspective view of an embodiment of a component of the invention; 
           [0022]      FIG. 12  is a partial side view of an embodiment of a component of the invention; 
           [0023]      FIG. 13  is a partial perspective view of an embodiment of a component of the invention; 
           [0024]      FIG. 14  is a partial perspective view of an embodiment of a component of the invention; 
           [0025]      FIG. 15  is a partial perspective view of an embodiment of a component of the invention; 
           [0026]      FIG. 16  is a partial perspective view of an embodiment of a component of the invention; 
           [0027]      FIG. 17  is a partial perspective view of an embodiment of a component of the invention; 
           [0028]      FIG. 18  is a partial perspective view of an embodiment of a component of the invention; 
           [0029]      FIG. 19  is an axial view of an embodiment of a component of the invention; 
           [0030]      FIG. 20  is a axial view of an embodiment of a component of the invention; 
           [0031]      FIG. 21  is a partial side view of an embodiment of a component of the invention; 
           [0032]      FIG. 22  is a partial side view of an embodiment of a component of the invention; 
           [0033]      FIG. 23  is a partial perspective view of an embodiment of a component of the invention; 
           [0034]      FIG. 24  is a partial perspective view of an embodiment of a component of the invention; 
           [0035]      FIG. 25  is a partial perspective view of an embodiment of a component of the invention; 
           [0036]      FIG. 26  is a partial perspective view of an embodiment of a component of the invention; 
           [0037]      FIG. 27  is a partial perspective view of an embodiment of a component of the invention; 
           [0038]      FIG. 28  is a partial perspective view of an embodiment of a component of the invention; and, 
           [0039]      FIG. 29  is a perspective view of a deployed configuration of the component of  FIG. 28 . 
       
    
    
     DESCRIPTION OF EMBODIMENTS 
       [0040]    Specific embodiments of the invention will now be described with reference to the accompanying drawings. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. The terminology used in the detailed description of the embodiments illustrated in the accompanying drawings is not intended to be limiting of the invention. In the drawings, like numbers refer to like elements. 
         [0041]    Referring now to the figures, and first to  FIG. 1 , there is shown a cut away view of the left side of the human heart  1 , including the left ventricle  2 , the left atrium  3 , the LAA  4 , the ostium  5  of the LAA, the mitral valve  6 , and the right pulmonary veins  7 . Below the right pulmonary veins  7 , there is shown the foramen ovale  8 , which in normally developed hearts is closed. It is merely presented to show a potential entry point to the left atrium  3 . The oval labeled as the foramen ovale  8  is not to be interpreted as an open defective septum between the left and right atria. 
         [0042]    Accessing the LAA 
         [0043]    Via Catheter Navigation 
         [0044]    The first step in the method of the present invention is to navigate to the left atrium  5 . In one embodiment, this is accomplished with a delivery catheter  20  of the present invention, discussed in more detail below. Navigation to the left atrium  3  is accomplished using any of a variety of known or unknown methods, including but not limited to, the use of guide wires and/or steerable catheters, or surgery, and using as an entry point the foramen ovale  8 , or the apex  9  of the heart. 
         [0045]    An embodiment of a catheter  20  is shown in  FIG. 1 , entering the left atrium  3  through the foramen ovale  8 . Doing so creates a small puncture wound through the foramen ovale  8 , which will typically heal in a short time without complication. The catheter  20  is then navigated to the ostium  5  of the LAA  4 . 
         [0046]    Via Endocardial Surgery 
         [0047]    The first step in the alternative endocardial surgical approach is to access the ostium of the LAA via the left atrium. This could be performed concomitant to a separate surgical procedure such as mitral valve repair or surgical ablation. Since the pericardium is already retracted, puncturing the opposite surface of the LAA is straightforward and does not require a separate step to create pericardial separation (below). The rest of the procedure would be similar to the percutaneous approach described below but without the need to puncture the pericardium or separately engage the LAA tissue. 
         [0048]    Via Epicardial Surgery 
         [0049]    The first step in the alternative epicardial surgical approach is to access the LAA directly, and puncture the LAA to gain access to the ostium of the LAA. This could be performed concomitant to a separate surgical procedure such as Coronary Artery Bypass Surgery (CABG). Since the pericardium is already retracted, puncturing the surface of the LAA is straightforward and does not require a separate step to create pericardial separation. In this iteration an anchor is deployed first over the ostium of the LAA. What is the proximal anchor in the percutaneous or endocardial approach becomes the distal anchor and the distal retraction device becomes in effect a proximal retraction device. The rest of the procedure would be similar to the percutaneous or endocardial approach described below. 
         [0050]    Creating Pericardial Separation 
         [0051]    The next step of an embodiment of the method of the invention is creating a separation between the wall  10  of the LAA  4  and the pericardium  9  (shown in  FIG. 2 ). This separation is desired prior to deployment of a device in order to mitigate the risk of puncturing the pericardium, which may result in damage to the pericardium. A worse result of puncturing the pericardium may be accidental deployment of the device outside of the pericardium, resulting in a possible pericardial tear during the retraction step. 
         [0052]    The invention includes many embodiments of methods and devices useable to create a separation between the wall  10  of the LAA  4  and the pericardium  9 . Creating this separation is generally shown in  FIGS. 2 and 3 . As shown in  FIG. 2 , the catheter  20  has been navigated to the ostium  5  of the LAA  4 . A tissue engaging device  30  has been deployed into the LAA  4  and has engaged the tissue of the distal wall  10  of the LAA  4 . In  FIG. 3 , the tissue engaging device  30  is being retracted into the catheter  20 , thereby creating a separation between the pericardium  9  and the LAA wall  10 . 
         [0053]      FIGS. 4 and 5  show an embodiment of a tissue engaging device  30  in a retracted state ( FIG. 4 ) and a deployed state ( FIG. 5 ). The tissue engaging device  30  is slidably disposed within the catheter  20  and includes a sheath  32  and an engagement tool  34 .  FIG. 4  shows the sheath  32  axially cutaway so the engagement tool  34  is visible in its contained configuration. The engagement tool  34  is a wire-like device having an end that includes at least one hook  36 . The at least one hook  36  is predisposed to a deployed, curved configuration, as shown in  FIG. 5 , but is flexible enough to assume a straight configuration when contained inside the sheath  32 . The radius of the curve of the hook  36  is selected such that when the engagement tool  34  is extended relative to the sheath  32 , the axial advancement of the hook  36  is enough to engage tissue of the LAA wall  10  but flares outwardly prior to reaching the pericardium  9 . The number of hooks  36  is at least one but may be two, as shown, or even three or more. The sliding relationship between the sheath  32  and the engagement tool  34  may also be limited to prevent the tool  34  from being able to reach the pericardium  9 . 
         [0054]    Alternatively, as shown in  FIG. 6 , the engagement tool  34  may be constructed with a barbed distal end  38  including at least one barb  40 . In this embodiment, the engagement tool  34  is slidingly disposed within the sheath  32  such that the distance it may be extended is limited to prevent the engagement tool  34  from being able to puncture and/or engage the pericardium  9 . 
         [0055]      FIG. 7  shows another embodiment of the distal end  38  of the engagement tool  34  in which a helical screw tip  42  is usable to engage the wall  10  of the LAA  4 . The engagement tool  34  of this embodiment is both slidingly contained within the sheath  32  but also able to be rotated relative to either the sheath  32  or the catheter  20 . 
         [0056]      FIGS. 8 and 9  show yet another embodiment useable to retract the wall  10  in order to create space between the wall  10  and the pericardium  9 . In this embodiment the catheter  20  includes a distal balloon  22  sized and shaped to be able to create a seal over the ostium  5  of the LAA  4 . As shown in  FIG. 9 , once inflated, suction may be applied to remove the blood from inside the LAA  4 , creating a vacuum inside the LAA  4  strong enough to collapse the wall  10  and maintain the wall  10  in a collapsed state while penetrating the wall  10  with a distal retraction device, discussed below. 
         [0057]    It is also envisioned to use the catheter  20  as the engagement tool. This embodiment involves advancing the catheter  20  into the LAA  4  until the distal open end of the catheter  20  contacts the wall  10 . Suction is then applied to the wall  10  using a suction lumen in order to retract the wall  10  away from the pericardium  9 . It may be advantageous to employ a slightly flared distal catheter end in order to provide a better seal against the wall  10 . To this end, may also be advantageous to use a softer material at the distal tip of the catheter  20 . 
         [0058]      FIG. 11  shows another embodiment of the distal end  38  of the engagement tool  34  including a plurality of graspers  44  that curve outwardly when advanced from a sheath  32 . The graspers are capable of penetrating the tissue of the wall  10  but are not able to extend all the way through the wall  10 . When the sheath  32  is advanced back over the graspers  44 , the graspers close toward each other, thereby gripping the tissue and allowing the wall  10  to be retracted. 
         [0059]    Deploying the Distal Retraction Device 
         [0060]    The next step in the method of the present invention is to puncture the distal wall  10  of the LAA  4  and deploy a distal retraction device  50  between the LAA wall  10  and the pericardium  9 . This step is generally shown in  FIG. 12 . The distal retraction device  50  generally includes a shaft  52  and an expandable component  54 , various embodiments of which are described below. The distal wall  10  of the LAA  4  is preferably held away from the pericardium  9  with the engagement tool  34  (not shown in  FIG. 10 ), or the vacuum in the case of the embodiment of  FIGS. 8 and 9 , while the wall is being punctured by the device  50  to maintain the space between the wall  10  and the pericardium  9 , and to provide proximal resistance to the distal force exerted on the wall  10  while it is being punctured by the device  50 . A sharp distal tip  56  may be provided to effect puncturing the wall  10 . 
         [0061]      FIG. 13  provides an example of an embodiment of a distal retraction device  50  of the invention. In this embodiment, distal retraction device  50  includes a shaft  52  that includes a pusher sheath  64  slidably disposed over an inner element  62 . The inner element extends into the expandable component  54  and has a distal terminus  66  that is attached to the distal tip  56  of the expandable component  54 . The expandable component  54  includes an inner lumen containing the inner element  62  and a plurality of longitudinal slits  60 . 
         [0062]    As seen in  FIG. 14 , when the pusher sheath  64  is advanced distally, relative to the inner element  62 , the length of the expandable component  54  is shortened, causing the expandable component  54  to buckle, utilizing the slits  60  as relief. The result is a plurality of bent arms  68  radiating from the shortened expandable component  54 . The pusher sheath  64  is shown retracted slightly to show the inner element  62 . 
         [0063]      FIG. 15  shows another embodiment of a distal retraction device  50 . This device  50  includes a shaft  70  to which a plurality of self-radiating arms  72  extend, not unlike an umbrella. A deployment sheath  74  contains the shaft  70  and the arms  72  in a collapsed configuration until the distal tip  56  punctures through distal wall  10  of the LAA  4  and the device  50  can be deployed. At this time the sheath  74  is retracted relative to the shaft  70 , allowing the arms  72  to radiate outwardly. In one embodiment, the arms are stored in the sheath  74  such that the ends  76  of the arms  72  are at the distal end of the device  50 . This embodiment allows deployment almost immediately after the wall  10  has been penetrated. In another embodiment, the arms  72  are stored in the sheath  74  such that the ends  76  extend proximally in the sheath  74 . This embodiment requires more space behind the wall  10  before the arms are deployed, such that the arms do not get fouled by the tissue of the wall  10 . However, this embodiment may result in a greater retractive force being placed on the arms without the arms reassuming a folded configuration. 
         [0064]    It is also envisioned that the arms  72  may be contained in the sheath  74  in a spiral configuration, as shown in  FIG. 16 . This embodiment provides the additional strength of rearward-collapsing arms while minimizing the axial advancement past the distal wall  10  needed for deployment. 
         [0065]    Another embodiment of a distal retraction device  50  is shown in  FIG. 17 . Like the embodiment of  FIG. 13 , this distal retraction device  50  includes a shaft  52  that includes a sheath  64  slidably disposed over an inner element  62 . The inner element extends into the expandable component  54  and has a distal terminus  66  that is attached to the distal tip  56  of the expandable component. The expandable component  54 , however, includes a plurality of wires  76  that extend between a proximal gathering cuff  78  and the distal tip  56 . These wires  76  may be a self-expanding material, such as Nitinol, or they may be actively expanded by shortening the distance between the distal tip  56  and the proximal gathering cuff  78 . Shortening this distance may be accomplished by applying a relative distal force on the sheath  64 . Alternatively, the proximal gathering cuff  78  may be constructed to act against a distal surface of the wall  10  when the distal retraction device  50  is retracted. 
         [0066]    For example,  FIG. 18  depicts a proximal gathering cuff  78  that includes a flexible skirt  80 . The flexible skirt  80  flares outwardly when acting against the wall  10  of the LAA. The skirt  80  thus provides the proximal resistance necessary to expand the expandable component  54 . The skirt  80  also serves to contain any potential bleeding through the small penetration made in the wall  10 . 
         [0067]    It is also envisioned that the proximal gathering cuff, with or without the skirt  80 , be treated with a compound, such as a medicament, fibrin, fibrinogen, polymer, or a hydrogel, for example, that further prevents bleeding and promotes healing of the penetration through the wall  10 . Alternatively or additionally, a membrane may be used to cover any of the expandable components of the invention in order to create a better seal. 
         [0068]    Additionally, the wires  76  of the embodiment shown in  FIG. 17  may be straight, braided, looped, or any configuration that would result in an expanded configuration when deployed. For example,  FIG. 19  shows an axial view of an expandable component  54 , in the expanded configuration that results from braided wires  76 .  FIG. 20  shows an axial view of an expandable component  54  in the expanded configuration that results from straight wires  76 . 
         [0069]    Reducing the LAA Volume 
         [0070]    The next step in the method of the present invention is to reduce or eliminate the volume of the LAA by retracting the wall  10  toward the ostium  5  and securing the wall  10  such that the wall  10  blocks the ostium  5 . As seen in  FIG. 21 , this is accomplished by pulling the distal retraction device  50 , thereby moving the wall  10  toward the atrium  3  until the ostium  5  is blocked. Preferably, the expandable component  54  of the distal retraction device  50  is sized such that it is greater than the diameter of the ostium  5 , thereby providing the physician a tactile indication that the expandable component  54  has contacted the outer surface of the left atrium and preventing the LAA from becoming inverted into the left atrium. 
         [0071]    Once the wall  10  has been retracted to the ostium  5 , it must be secured in place. One embodiment of the invention, shown in  FIG. 22 , deploys a proximal anchor  90  to accomplish this. The proximal anchor  90  may have a design similar to any of the designs of the expandable component  54  of the distal retraction device  50 . The proximal anchor  90  may even be an integral component of the distal retraction device  50 . For example, as shown in  FIG. 23 , there is shown a distal retraction device  50 , similar to that shown in  FIG. 13 , including a shaft  52  that includes a pusher sheath  64  slidably disposed over an inner element  62 . The inner element extends into the expandable component  54  and has a distal terminus  66  that is attached to the distal tip  56  of the expandable component  54 . The expandable component  54  includes an inner lumen containing the inner element  62  and a plurality of longitudinal slits  60 . A second set of slits  92  form the proximal anchor  90 . 
         [0072]    In this embodiment, the expandable component  54  and the proximal anchor  90  are both expanded by pushing the device  50  while pulling on the inner element  62 . In order to selectively expand the expandable component  54  first, a sheath is placed over the device. Preferably, in order to save space, the catheter  20  may be used as a containment sheath. As shown in phantom lines in  FIG. 23 , the catheter  20  is positioned to allow the expandable component  54  to buckle and expand, while preventing the proximal anchor  90  from expanding. Thus, once the distal wall  10  has been retracted to the ostium  5 , the proximal anchor may be deployed by retracting the catheter  20  in order expose the proximal anchor  90 . Once exposed, the proximal anchor may be expanded in the same way the expandable component  54  was expanded. 
         [0073]    It is to be understood that any of the various embodiments of the expandable component  54  may also be used as the proximal anchor  90 . Additionally, any combination of components could be used. For example, the braided wire embodiment of the expandable component  54  shown in  FIG. 19  may be combined with the slit tube embodiment of the proximal anchor  90  shown in  FIG. 23 ; the proximal anchor  90  may have a straight wire construction like the one shown in  FIG. 20  while the expandable component  54  may have a braided wire design or vice versa, etc. It is also to be understood that the dimensions of the expandable component  54  and the proximal anchor  90  do not have to be related to each other. 
         [0074]    An embodiment utilizing braided wires on both the expandable component  54  and the proximal anchor  90  is shown in  FIGS. 28 and 29 . This embodiment also utilizes a connecting spring  96  between the expandable component  54  and the proximal anchor  90 . The connecting spring  96  may be included in any of the embodiments shown and described herein, and may be helpful in lessening stress on the tissue during contraction of the heart. In other words, the spring  96  acts as a shock absorber as the tissue flexes and the blood pressure in the atrium  3  fluctuates. 
         [0075]    Releasing the Device 
         [0076]    Once the proximal anchor  90  has been expanded, it is necessary to release the device  50  so that the catheter  20  may be removed. As shown in  FIG. 24 , one embodiment includes a threaded connection between the inner element  62  and the distal tip  56 . The threaded tip  56  would allow the inner element to be unscrewed from the device  50  once the device is in place. Risk of premature release is minimized because until the device is expanded, the device would rotate with the inner element  62 . Once the expandable component  54  and the proximal anchor  90  are expanded, the contact between these components and the tissue provided enough counter-rotating force that the threaded tip  56  can be unscrewed from the device  50 . 
         [0077]    In either of the surgical embodiments, releasing the device can be accomplished by cutting the connector mechanically under direct access, or by any of the described methods. 
         [0078]    Another embodiment, shown in  FIG. 25 , provides a small heating element  100  in the distal end of the inner element  62  and a lead  102  supplying power to the heating element  100 . The inner element  62  may be joined to the device  50  with an adhesive that breaks down when heated. When the physician is satisfied with the deployment of the device  50 , power is supplied to the heating element  100 , thereby degrading the adhesive and releasing the inner element  62  from the device  50 . 
         [0079]    Catheter Design 
         [0080]    The catheter  20  preferably houses and delivers all of the components discussed herein. One embodiment of the delivery catheter  20  is shown in  FIG. 26 . The catheter  20  includes a primary lumen  110 , a secondary lumen  112  and at least one steering wire  114 . The primary lumen  110  is sized to accommodate the device  50  while the secondary lumen is sized to accommodate the tissue engaging device  30 . Alternatively, if suction is used to engage the tissue, as discussed above, the secondary lumen may be utilized as a suction lumen. 
         [0081]      FIG. 27  shows another embodiment of a non-steerable delivery catheter  20  of the present invention. This embodiment includes a primary lumen  110  and a secondary lumen  112 , as described above, and a guidewire lumen  116  usable to advance the catheter  20  over a guidewire. It is also envisioned that the tissue engagement device  30  may be incorporated into the end of a guidewire, in which case the secondary lumen  112  may be used as a guidewire lumen. 
         [0082]    Although the invention has been described in terms of particular embodiments and applications, one of ordinary skill in the art, in light of this teaching, can generate additional embodiments and modifications without departing from the spirit of or exceeding the scope of the claimed invention. Accordingly, it is to be understood that the drawings and descriptions herein are proffered by way of example to facilitate comprehension of the invention and should not be construed to limit the scope thereof. 
         [0083]    For example, the devices and methods disclosed herein may be supplemented with features such as physiologic parameter monitoring. An example of this would be the incorporation of a pressure sensor mounted on the left atrial side of the device  50 . The pressure sensor is constructed and arranged to continuously or sporadically measure left atrial pressure. Additionally or alternatively, an electrocardiographic or electrical sensor could be placed on the left atrial side of the device  50  so that acute or chronic electrophysiology parameters can be obtained. Other parameters that may be monitored include, but are not limited to, left atrial size and function, left ventricular size and function, flow into and through the mitral valve, the occurrence of atrial fibrillation, the sensing of arrhythmias such as supraventricular arrhythmias or ventricular arrhythmias, to name just a few. These sensing device may be attached to or may become integral to the device  50 .