Abstract:
A cardiac support device and placement tool assembly. The cardiac support device has a flexible jacket with an open base end. The placement tool includes a cannula having an open end, a collapsible support on the end of the cannula releasably connected to the cardiac support device at a plurality of locations around the base end, and an acutuator. The collapsible support is movable between a collapsed state in a retracted position at which the collapsible support and cardiac support device are within the end of the cannula, and an open state in an extended position at which the collapsible support and cardiac support device are outside of the cannula with the collapsible support holding the base end of the cardiac support device in an open position for placement onto a patient&#39;s heart. The actuator moves the collapsible support between the collapsed and open states.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     The present application is a continuation of U.S. Ser. No. 10/810,099, filed Mar. 26, 2004, which is a continuation of U.S. Ser. No. 10/367,346, filed Feb. 13, 2003, now U.S. Pat. No. 6,893,392, which is a continuation of U.S. Ser. No. 10/084,806, filed Feb. 25, 2002, now U.S. Pat. No. 6,544,168, which is a continuation of U.S. Ser. No. 09/696,651, filed Oct. 25, 2000, now U.S. Pat. No. 6,375,608, which is a continuation of U.S. Ser. No. 09/483,466, filed Jan. 14, 2000, now U.S. Pat. No. 6,165,122, which is a continuation of U.S. Ser. No. 08/935,723, filed Sep. 23, 1997, now U.S. Pat. No. 6,077,218, which is a continuation of U.S. Ser. No. 08/720,556, filed Oct. 2, 1996, now U.S. Pat. No. 5,702,343, which applications and issued patents are incorporated herein by reference. 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]     The present invention is generally directed to a device and method for reinforcement of the cardiac wall. The invention is particularly suited for the treatment of cardiac disease which result in atrial or ventricular dilation. The invention provides reinforcement of the cardiac wall during diastolic chamber filling to prevent or reduce cardiac dilation in patients known to have experienced such dilation or who have a predisposition for such dilation occurring in the future. The cardiac reinforcement structure is typically applied to the epicardial surface of the heart.  
         [0003]     Cardiac dilation occurs with different forms of cardiac disease, including heart failure. In some cases, such as post-myocardial infarction, the dilation may be localized to only a portion of the heart. In other cases, such as hypertrophic cardiomyopathy, there is typically increased resistance to filling of the left ventricle with concomitant dilation of the left atria. In dilated cardiomyopathy, the dilation is typically of the left ventricle with resultant failure of the heart as a pump. In advanced cases, dilated cardiomyopathy involves the majority of the heart.  
         [0004]     With each type of cardiac dilation, there are associated problems ranging from arrhythmias which arise due to the stretch of myocardial cells, to leakage of the cardiac valves due to enlargement of the valvular annulus. Devices to prevent or reduce dilation and thereby reduce the consequences of dilation have not been described. Patches made from low porosity materials, for example Dacron™, have been used to repair cardiac ruptures and septal defects, but the use of patches to support the cardiac wall where no penetrating lesion is present has not been described.  
         [0005]     Drugs are sometimes employed to assist in treating problems associated with cardiac dilation. For example, digoxin increases the contractility of the cardiac muscle and thereby causes enhanced emptying of the dilated cardiac chambers. On the other hand, some drugs, for example, beta-blocking drugs, decrease the contractility of the heart and thus increase the likelihood of dilation. Other drugs including angiotensin-converting enzyme inhibitors such as enalopril help to reduce the tendency of the heart to dilate under the increased diastolic pressure experienced when the contractility of the heart muscle decreases. Many of these drugs, however, have side effects which make them undesirable for long-term use.  
         [0006]     Accordingly, there is a need for a device that can reduce or prevent cardiac dilation and reduce the problems associated with such dilation.  
       SUMMARY OF THE INVENTION  
       [0007]     The present invention is an improved placement tool and method for use with a cardiac support device having a flexible jacket with an open base end. A placement tool in accordance with one embodiment of the invention includes a body having an end and support on the end of the body for releasable connection to a cardiac support device. The support holds the base end of the cardiac support device in an open position for placement on a patient&#39;s heart. In another embodiment of the invention, the support is a collapsible support movable between a retracted position within the body and an extended position outside the body. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0008]      FIG. 1  is a frontal view of one embodiment of a cardiac reinforcement patch.  
         [0009]      FIG. 2  is a perspective view of the cardiac reinforcement patch of  FIG. 1  in place on the epicardium of a heart.  
         [0010]      FIG. 3  is a perspective view of one embodiment of a cardiac reinforcement jacket according to the invention.  
         [0011]      FIG. 4  is a second embodiment of a cardiac reinforcement jacket according to the invention.  
         [0012]      FIG. 5  is a perspective view of the embodiment of the cardiac reinforcement jacket shown in  FIG. 3  in place around the heart.  
         [0013]      FIG. 6  is a schematic cross sectional view of one embodiment of a mechanism for selectively adjusting the predetermined size of a cardiac reinforcement jacket.  
         [0014]      FIG. 7  is a perspective view of a placement tool which can be used for applying a cardiac reinforcement jacket.  
         [0015]      FIG. 8  is a perspective view of a placement tool being employed to place a cardiac reinforcement jacket over the heart. 
     
    
     DETAILED DESCRIPTION  
       [0016]     The present invention is directed to reinforcement of the heart wall during diastolic filling of a chamber of the heart. The invention is particularly suited for use in cardiomyopathies where abnormal dilation of one or more chambers of the heart is a component of the disease.  
         [0017]     As used herein, “cardiac chamber” refers to the left or right atrium or the left or right ventricle. The term “myocardium” refers to the cardiac muscle comprising the contractile walls of the heart. The term “endocardial surface” refers to the inner walls of the heart. The term “epicardial surface” refers to the outer walls of the heart.  
         [0018]     The heart is enclosed within a double walled sac known as the pericardium. The inner layer of the pericardial sac is the visceral pericardium or epicardium. The outer layer of the pericardial sac is the parietal pericardium.  
         [0019]     According to the present invention, a cardiac reinforcement device (CRD) limits the outward expansion of the heart wall during diastolic chamber filling beyond a predetermined size. The expansion constraint applied to the heart by a CRD is predetermined by the physician based on, for example, cardiac output performance or cardiac volume. In contrast to known ventricular assist devices which provide cardiac assistance during systole, a CRD according to the present disclosure provides cardiac reinforcement during diastole.  
         [0020]     A CRD is made from a biomedical material which can be applied to the epicardial surface of the heart. As used herein, a “biomedical material” is a material which is physiologically inert to avoid rejection or other negative inflammatory response. A CRD can be prepared from an elastic or substantially non-elastic biomedical material. The biomedical material can be inflexible, but is preferably sufficiently flexible to move with the expansion and contraction of the heart without impairing systolic function. The biomedical material should, however, constrain cardiac expansion, during diastolic filling of the heart, to a predetermined size. Examples of suitable biomedical materials include perforate and non-perforate materials. Perforate materials include, for example, a mesh such as a polypropylene or polyester mesh. Non-perforate materials include, for example, silicone rubber.  
         [0021]     A biomedical material suitable for a device of the invention generally has a lower compliance than the heart wall. Even though the biomedical material is less compliant than the heart wall, some limited expansion of an elastic biomedical material can occur during cardiac filling.  
         [0022]     In an alternative embodiment, the biomedical material can be substantially non-elastic. According to this embodiment, the term “substantially non-elastic” refers to a material which constrains cardiac expansion during diastole at a predetermined size, but which has substantially no elastic properties.  
         [0023]     Regardless if the biomedical material is elastic or non-elastic, advantageous to a CRD according to the present disclosure is cardiac reinforcement which is provided during diastole. Moreover, a CRD as disclosed herein does not provide cardiac assistance through active pumping of the heart.  
         [0024]     I. CRD Patch  
         [0025]     In one embodiment, a cardiac reinforcement device (CRD) provides for local constraint of the heart wall during cardiac expansion. According to this embodiment, a CRD is a “patch” that provides reinforcement of the heart wall at a localized area, such as a cardiac aneurysm or at an area of the myocardium which has been damaged due to myocardial infarction. When discussing a “patch”, “predetermined size” of the patch means that the size of the patch is selected to cover an area of the epicardial surface of the heart in need of reinforcement without completely surrounding the circumference of the heart.  
         [0026]     A CRD patch can be prepared from the biomedical materials described above. In a preferred embodiment, the patch is an open mesh material.  
         [0027]     A CRD patch can be applied to the epicardial surface of the heart over or under the parietal pericardium. A patch is typically applied to the epicardial surface by suturing around the periphery of the patch. The peripheral edge of the patch can include a thickened “ring” or other reinforcement to enhance the strength of the patch at the point of suture attachment to the epicardium. Generally, a patch is applied to the epicardium through a thoracotomy or other incision providing sufficient exposure of the heart.  
         [0028]     II. CRD Jacket  
         [0029]     In another embodiment, a CRD is a jacket that circumferentially surrounds the epicardial surface of the heart. When applied to the heart, a CRD jacket can be placed over or under the parietal pericardium.  
         [0030]     A CRD applied to the epicardium is fitted to a “predetermined size” for limitation of cardiac expansion. According to a jacket embodiment, “predetermined size” refers to the predetermined expansion limit of the jacket which circumferentially constrains cardiac expansion during diastolic filling of the heart. In practice, for example, a physician could measure cardiac output and adjust the jacket size to an optimal size for the desired effect. In this example, the optimal size is the “predetermined size”. In one embodiment, the predetermined size can be adjusted for size reduction as the cardiac size is reduced.  
         [0031]     In one embodiment, the CRD jacket is a cone-shaped tube, having a base broader than the apex, which generally conforms to the external geometry of the heart. When applied to the epicardial surface of the heart, the base of the jacket is oriented towards the base of the heart, and the apex of the jacket is oriented towards the apex of the heart. Typically, the base of the jacket includes an opening for applying the jacket by passing the jacket over the epicardial surface of the heart. The apical end of the jacket can be a continuous surface which covers the apex of the heart. Alternatively, the apex of the jacket can have an opening through which the apex of the heart protrudes.  
         [0032]     A cardiac reinforcement jacket, as disclosed herein, is not an inflatable device that surrounds the heart. Rather, the device is typically a single layer of biomedical material. In one embodiment discussed below, an inflatable member can be included with the device, but the inflatable member serves to reduce the volume within a localized region of the jacket and does not follow the entire jacket to surround the epicardial surface of the heart.  
         [0033]     In one embodiment, the CRD jacket can be secured to the epicardium by a securing arrangement mounted at the base of the jacket. A suitable securing arrangement includes, for example, a circumferential attachment device, such as a cord, suture, band, adhesive or shape memory element which passes around the circumference of the base of the jacket. The ends of the attachment device can be fastened together to secure the jacket in place. Alternatively, the base of the jacket can be reinforced for suturing the base of the jacket to the epicardium.  
         [0034]     Various sized CRD jackets can be prepared such that different sized jackets are used for different predetermined cardiac expansion sizes or expansion ranges. Alternatively, a CRD jacket can include a mechanism for selectively adjusting the size of the jacket. A mechanism for selectively adjusting the volumetric size of the jacket theoretically provides for a “one size fits all” device. More importantly, however, an adjustable jacket provides the ability to titrate (readjust) the amount of cardiac reinforcement by graded reduction in jacket size as therapeutic reduction of cardiac expansion occurs.  
         [0035]     A mechanism for selectively adjusting the size of the jacket can include a slot which opens at the base of the jacket and extends toward the apex end of the CRD. If the apex end of the CRD jacket is open, the apical extent of the slot can be continuous with the apex opening. The slot includes opposing lateral edges. By adjusting the proximity of the opposing lateral edges, the overall size of the jacket can be varied. Moving the opposing edges of the slot closer together narrows the slot and reduces the volumetric size of the jacket. The opposing edges of the slot can be fastened together at a predetermined proximity by, for example, one or more lateral attachment devices, such as a cord, suture, band, adhesive or shape memory element attached to each lateral edge.  
         [0036]     In another embodiment, a mechanism for selectively adjusting the size of the jacket can be an inflatable member. According to this embodiment, the inflatable member is mounted between the jacket and the epicardium. The volumetric size of the jacket can be reduced by inflating the inflatable member through an inflation port with, for example, a gas or liquid. As cardiac expansion volume responds to cardiac constraint by size reduction, the predetermined size of the jacket can then be reduced by inflating the inflatable member within the jacket. Once inflated, the size of the inflatable member is preferably maintained until therapeutic response causes a need for further inflation. According to the invention, the inflation of the inflatable member provides a reduction in the predetermined size of the jacket by a fixed increase in volume of the inflatable member. The inflatable member is not rhythmically inflated and deflated to provide assistance to cardiac contraction during systole.  
         [0037]     The biomedical material of the invention can be radioluscent or radiopaque. In one embodiment, the material of the jacket can be made radiopaque by inclusion of radiopaque markers for identification of the outside surface of the heart, the expansion slot or inflation port. As used herein, radiopaque means causing the CRD to be visible on x-ray or fluoroscopic viewing. Suitable radiopaque markers include, for example, platinum wires, titanium wires and stainless steel wires.  
         [0038]     A CRD according to the present disclosure provides a new method for the treatment of cardiac disease. As used herein, cardiac disease includes diseases in which dilation of one of the chambers of the heart is a component of the disease. Examples include heart failure or cardiomyopathy. Heart failure can occur as a result of cardiac dilation due to ventricular hypertrophy or secondary to, for example, valvular incompetency, valvular insufficiency or valvular stenosis. Cardiomyopathy, according to the invention, can be primary or secondary to infection, ischemia, metabolic disease, genetic disorders, etc.  
         [0039]     It is foreseen that constraint of cardiac expansion by a device of the invention can provide reduced cardiac dilation. Reduced cardiac dilation can cause reduction in the problems associated with cardiac dilation such as arrhythmias and valvular leakage. As reduction of cardiac dilation occurs, selective reduction of the predetermined size of the jacket also provides continued reinforcement for the size reduced heart.  
         [0040]     A CRD jacket can also be used to measure cardiac performance. According to this embodiment, the CRD jacket is rendered radiopaque by use of a radiographic marker. The radiographic markers are distributed throughout the jacket over the surface of the heart. By evaluation of the markers relative to one another with each heart beat, cardiac performance may be measured. As such, evaluation of cardiac performance may assist in adjusting the predetermined size of a CRD jacket.  
         [0041]     A CRD as described herein can be applied to the epicardium of a heart through a thoracotomy or through a minimally invasive procedure. For a minimally invasive procedure a CRD placement tool can be used to apply the CRD over the epicardium of the heart through a thorascopic incision. According to this embodiment, a CRD placement tool includes a cannula, a stiff rod or wire and a guide tube. For placement of a CRD, the wire is threaded through the guide tube which is passed around the circumference of the base of the jacket. The CRD with wire and guide tube passed through the base opening are then passed into the cannula. The cannula is of sufficient length and diameter to enclose the CRD, wire and guide tube during passage of the placement tool through a thorascopic incision. The placement tool is passed into the thoracic cavity and positioned at a point near the apex of the heart. When in position, the wire and guide tube are pushed out of the cannula away from the operator. Once outside the cannula, the wire and guide tube sufficiently expand the opening of the base of the CRD jacket to pass over the epicardial surface of the heart. When the CRD jacket is in position over the epicardial surface, the wire, guide tube and cannula can be removed. A second incision can then be made to provide access for suitable surgical instruments to secure or adjust the size of the CRD.  
         [0042]     The invention will now be further described by reference to the drawings.  
         [0043]      FIG. 1  is a frontal view of one embodiment of a cardiac reinforcement patch  1 . The CRD patch  1  shown here is a mesh biomedical material  2  having a thickened peripheral ring  3  which reinforces the peripheral edge  4  of the patch for attachment of the patch to the epicardial surface of the heart.  
         [0044]      FIG. 2 . is a perspective view of a CRD patch  10  in place on the epicardial surface of a heart  11 , for example, over a cardiac aneurysm (not shown) of the heart. In one preferred embodiment, the patch  10  is sized to cover the extent of the cardiac aneurysm and is placed on the epicardial surface of the heart  11 . In practice, the thorax is surgically opened and the region of the heart  11  with the aneurysm (not shown) is located and exposed. The patch  10  is placed over the aneurysm and sutured in place around the periphery  12  of the patch to provide sufficient constraint to prevent further dilation of the aneurysm.  
         [0045]      FIG. 3  is a perspective view of one embodiment of a CRD jacket  15  according to the invention. According to the embodiment shown, the jacket  15  is a mesh material  16 , and includes a circumferential attachment device  17  at the base end  18  of the CRD jacket. The apex end  24  of the jacket  15  is closed. The jacket  15  shown also includes a slot  19  having opposing lateral edges  20  and  21 , and fasteners (e.g. lateral attachment device  22  and  23 ) for selectively adjusting the volumetric size of the jacket  15 . The CRD jacket  15  shown also includes radiopaque markers  25  for visualizing the surface of the heart through radiographic study.  
         [0046]      FIG. 4  is an alternative embodiment of a CRD jacket  30 . Similar to the embodiment shown in  FIG. 3 , the embodiment of  FIG. 4  includes a base end  31  and an apex  32  end. The base end includes a circumferential attachment device  33  for securing the CRD jacket  30  to the heart. The CRD jacket  30  of  FIG. 4  also includes a slot  34  having opposing lateral edges  35 ,  36 . The lateral edges  35 ,  36  are shown pulled together at  37  by a lateral attachment device  38 , for example, a suture. In contrast to the embodiment shown in  FIG. 3 , the embodiment shown in  FIG. 4  has an opening  39  at the apex end  32  of the CRD jacket  30 .  
         [0047]      FIG. 5 . is a perspective view of a CRD jacket  40  around a heart  41 . According to the embodiment shown, at the base  42  of the jacket  40 , there is a circumferential attachment device  43  which secures the CRD jacket  40  near the base of the heart  44 . A slot  45 , is shown with opposing lateral edges  46 ,  47  fastened together by a lateral attachment device  48 . In the embodiment shown, the CRD jacket  40  has an opening  49  at the apical end  50  of the jacket. The apex of the heart  51  protrudes through the opening  49  at the apical end  50  of the jacket  40 .  
         [0048]     Still referring to  FIG. 5 , in a preferred embodiment, if one or more of the lateral attachment device  48  are made of an elastic material, such as silicone rubber, the device can provide a way of applying a graded constraint around the outside of the heart  41  to reduce cardiac dilation over time. In practice, the jacket would be placed over the heart  41  as shown, either over or under the parietal pericardium (not shown). The circumferential attachment device  43  and lateral attachment device  48  would then be tightened to cause a constraining effect on the outside of the heart.  
         [0049]     In a preferred embodiment, if one or more of the lateral attachment cords  48  is made of an elastic material, such as silicone rubber, surface pressure exerted on the epicardial surface of the heart varies as a function of the amount of dilation of the heart. This variable pressure has the effect of reducing the cardiac dilation to a certain point and then stopping because the surface pressure drops to a negligible amount. The amount of constraint or reduction in dilation that is accomplished over time and the resultant cardiac performance may be monitored radiographically using techniques known in the art, for example fluoroscopy, by observing radiographic markers ( FIG. 4, 25 ), if present.  
         [0050]      FIG. 6  is a schematic cross sectional view of an alternative embodiment of an arrangement for selectively adjusting the predetermined size of a jacket  53 . According to this embodiment, an inflatable member  54  is inserted within the jacket  53  between the jacket  53  and the epicardial surface  55  of the heart  56 . The inflatable member  54  includes a filling apparatus  57  for entry of a fluid (liquid or gas) to inflate the inflatable member  54  and reduce the predetermined size of the jacket  53 .  
         [0051]      FIG. 7  is a perspective view of a placement tool  60  which can be used for placement of a CRD jacket  61  around the epicardium of the heart. As shown here, the base end of the jacket  62  is held open by guide tube  63  through which is passed a wire or stiffening rod  64 . The wire  64  can be removed from the guide tube  63  by pulling on the wire extraction grip  66 . The placement tool  60  includes a cannula  65  which encloses the jacket  61 , guide tube  63  and wire  64  during insertion of the tool into a thorascopic incision.  
         [0052]      FIG. 8  is a perspective view of a placement tool  70  being employed to place a jacket  71  over the heart  72  on the outside of the parietal pericardium  73 . The placement tool  70  is guided through a small incision in the thorax and the jacket  71  is maneuvered into position over the heart  72 . Once the jacket  71  is in proper position, the wire  74 , which is passed through the guide tube  75  around the base  76  of the jacket  71 , is extracted from the guide tube  75  by pulling on the wire extraction grip  77 . The guide tube  75  is then extracted by pulling on the guide tube extraction grip  78 . The cannula  79  is removed from the chest and the circumferential attachment cord (not shown in this view), and the lateral attachment cord  80  can be fastened to secure the jacket  71 .  
         [0053]     The above specification and drawings provide a description of a cardiac reinforcement device and method of using on the heart. Since many embodiments of the invention can be made without departing from the spirit and scope of the invention, the invention resides in the claims hereinafter appended.