US20020022880A1 - Device and method for restructuring heart chamber geometry - Google Patents

Abstract

A geometric reconfiguration assembly for the natural heart having a collar configured for surrounding the natural heart. The collar can include a plurality of bands, such as thin bands of about 0.2 mm in thickness, in a spaced relationship to each other, and a connector bar intersecting the plurality of bands and configured for maintaining the spaced relationship of the bands to each other. The collar may include a plurality of bands, such as from about 2 to about 10 bands, that are positioned parallel to each other. The bands can each be made of a biomedical material, such as polyacetal or a metal, such as titanium or steel.

The connector bar of the present invention can be positioned tangential to the plurality of bands, and may have a plurality of grooves configured to receive the thickness of each of the plurality of bands. The grooves also may be beveled to allow for the bands to flex as the heart beats. The connector bar's inner surface can have an outwardly convex curved configuration, and may even include a cushioned portion that can be made from a polymeric material. A pad may be positioned between the collar and the epicardial surface of the heart that may comprise a low durometer polymer, or either a gel-filled cushion or a fluid-filled cushion.

Description

REFERENCE TO COPENDING APPLICATION
• This is a continuation in part application of U.S. patent application Ser. no. 08/581,914, filed Dec. 23, 1997, entitled “Activation Device for the Natural Heart and Method of Doing the Same,” which is a continued prosection application of U.S. patent application Ser. No. 08/581,914 filed on Jan. 2, 1996.[0001]
TECHNICAL FIELD OF THE INVENTION
• The present invention relates to a device and method for treating cardiomyopathies and/or enlarged hearts and more specifically, a device and method for decreasing a heart chamber's wall tension.[0002]
BACKGROUND OF THE INVENTION
• The natural heart, and specifically, the cardiac muscle tissue of the natural heart (e.g., myocardium) can fail for various reasons to a point where the natural heart cannot provide sufficient circulation of blood for a body so that life can be maintained. More specifically, the heart and its chambers can become enlarged for a variety of causes and/or reasons, including viral disease, idiopathic disease, valvular disease (mitral, aortic and/or both), ischemic disease,[0003]
• Chagas' disease and so forth. As the heart and its chambers enlarge, tension of the walls of the heart's chambers increase and thus, the heart must develop more wall tensile stress to generate the needed pressure for pumping blood through the circulatory system. The process of ventricular dilation is generally the result of chronic volume overload or specific damage to the myocardium. In a normal heart that is exposed to long-term increased cardiac output requirements, for example, that for an athlete, there is an adaptive process of slight ventricular dilation and muscle myocyte hypertrophy. In this way, the heart may fully compensate for the increase cardiac output requirements of the body. With damage to myocardium or chronic volume overload, however, there are increased requirements put on the contracting myocardium to such a level that this compensated state is never achieved and the heart continues to dilate.[0004]
• A problem with an untreated dilated ventricle is that there is a significant increase in wall tension and/or stress, both during the diastolic filling, and during the systolic contraction. In a normal heart, the adaption of muscle hypertrophy (e.g. thickening) in the ventricular dilation maintain a fairly constant wall tension for systolic constriction. However, in a failing heart, the ongoing dilation is greater than the hypertrophy, and as a result, rising wall tension is required for systolic contraction. This is believed to result in further muscle damage.[0005]
• The increase in wall stress is also true for diastolic filling. Additionally, because of the lack of cardiac output, ventricular filling pressure tends to rise due to several physiologic mechanisms. Moreover, in diastole, both the diameter and wall pressure increase over normal levels, thus contributing to higher wall stress levels. As a solution for the enlarged natural heart, attempts have been made in the past to provide a treatment to maintain circulation. Prior treatment for heart failure generally fall into three categories, namely surgical treatments; mechanical support systems; or pharmacological.[0006]
• One such approach has been to replace the existing natural heart in a patient with an artificial heart or a ventricular assist device. In using artificial hearts and/or assist devices, a particular problem stems from the fact that the materials used for the interior lining of the chambers of an artificial heart are in direct contact with the circulating blood, which can enhance undesirable clotting of the blood, build up of calcium, or otherwise inhibit the blood's normal function. Hence, thromboembolism and hemolysis could occur with greater ease. Additionally, the lining of an artificial heart or a ventricular assist device can crack, which inhibits performance, even if the crack is at a microscopic level. Moreover, these devices must be powered by a source which can be cumbersome and/or external to the body. Drawbacks have limited use of these devices to applications having too brief a time period to provide a real lasting benefit.[0007]
• An alternative procedure is to transplant a heart from another human or animal into a patient. The transplant procedure requires removing an existing organ (i.e., the natural heart) for substitution with another organ (i.e., another natural heart) from another human, or potentially, from an animal. Before replacing an existing organ with another, the substitute organ must be “matched” to the recipient, which can be, at best, difficult and time consuming to accomplish. Furthermore, even if the transplanted organ matches the recipient, a risk exists that the recipient's body will reject the transplanted organ and attack it as a foreign object. Moreover, the number of potential donor hearts is far less than the number of patients in need of a transplant. Although use of animal hearts would lessen the problem with fewer donors than recipients, there is an enhanced concern with rejection of the animal heart.[0008]
• In an effort to use the existing natural heart of a patient, other attempts have been made to reduce wall tension of the heart by removing a portion of the heart wall, such as a portion of the left ventricle in a partial left ventriculectomy procedure (the Batista procedure). A wedge-shaped portion of the ventricular muscle has been removed, which extends from the apex to the base of the heart. By reducing the chamber's volume, and thus its radius, the tension of the chamber's wall is reduced as well. There are, however, several drawbacks with such a procedure. First, a valve (i.e., the mitral valve) may need to be repaired or replaced depending on the amount of cardiac muscle tissue to be removed. Second, the procedure is invasive and traumatic to the patient. As such, blood loss and bleeding can be substantial during and after the procedure. Moreover, as can be appreciated by those skilled in the industry, the procedure is not reversible.[0009]
• Another device developed for use with an existing heart for sustaining the circulatory function of a living being and the pumping action of the natural heart is an external bypass system, such as a cardiopulmonary (heart-lung) machine. Typically, bypass systems of this type are complex and large, and, as such, are limited to short term use in an operating room during surgery, or to maintaining the circulation of a patient while awaiting receipt of a transplant heart. The size and complexity effectively prohibit use of bypass systems as a long term solution, as they are rarely even portable devices. Furthermore, long term use of these systems can damage the blood cells and blood borne products, resulting in post surgical complications such as bleeding, thromboembolism function, and increased risk of infection.[0010]
• Medicines have been used to assist in treating cardiomyopathies. Some inotropic agents can stimulate cardiac work. For example, digoxin can increase the contractibility of the heart, and thereby enhances emptying of the chambers during systolic pumping. Medicines, such as diuretics or vasodilators attempt to reduce or decrease the heart's workload. For example, indirect vasodilators, such as angiotensin-converting enzyme inhibitors (e.g., enalopril), can help reduce the tendency of the heart to dilate under the increased diastolic pressure experienced when the contractibility of the heart muscle decreases. Many of these medicines have side effects, such as excessive lowering of blood pressure, which make them undesirable for long term therapy.[0011]
• As can be seen, currently available treatments, procedures, medicines, and devices for treating end-stage cardiomyopathies have a number of shortcomings that contribute to the complexity of the procedure or device. The current procedures and therapies can be extremely invasive, only provide a benefit for a brief period of time, or have undesirable side effects which can hamper the heart's effectiveness. There exists a need in the industry for a device and procedure that can use the existing heart to provide a practical, long-term therapy to reduce wall tension of the heart, and thus improve its pumping efficiency.[0012]
SUMMARY OF THE PRESENT INVENTION
• It is the object of the present invention to provide a device and method for treating cardiomyopathies that addresses and overcomes the above-mentioned problems and shortcomings in the thoracic medicine art.[0013]
• It is another object of the present invention to provide a device and method for treating cardiomyopathies that minimizes damage to the coronary circulatory and the endocardium.[0014]
• It is still a further another object of the present invention to provide a device and method for treating cardiomyopathies that maintains the stroke volume of the heart.[0015]
• Another object of the present invention is to provide a device and method for treating cardiomyopathies that supports and maintains the competence of the heart valves so that the heart valves can function as intended.[0016]
• Still another object of the present invention is to provide a device and method that increases the pumping effectiveness of the heart.[0017]
• Yet another object of the present invention is to provide a device and method for treating cardiomyopathies on a long term basis.[0018]
• It is yet still an object of the present invention to provide a device and method for treating cardiomyopathies that does not require removal of any portion of an existing natural heart.[0019]
• Still a further object of the present invention is to provide a device and method for treating dilated cardiomyopathies that directly reduce the effective radius of a chamber of a heart in systole as well as in diastole.[0020]
• Additional objects, advantages, and other features of the present invention will be set forth and will become apparent to those skilled in the art upon examination of the following, or may be learned with practice of the invention.[0021]
• To achieve the foregoing, a geometric reconfiguration assembly for the natural heart having a collar configured for surrounding the natural heart. The collar can include a plurality of bands, such as thin bands of about 0.2 mm in thickness, in a spaced relationship to each other, and a connector bar intersecting the plurality of bands and configured for maintaining the spaced relationship of the bands to each other. The collar may include a plurality of bands, such as from about 2 to about 10 bands, that are positioned parallel to each other. The bands can each be made of a biomedical material, such as polyacetal or a metal, such as titanium or steel.[0022]
• The connector bar of the present invention can be positioned tangential to the plurality of bands, and may have a plurality of grooves configured to receive the thickness of each of the plurality of bands. The grooves also may be beveled to allow for the bands to flex as the heart beats. The connector bar's inner surface can have an outwardly convex curved configuration, and may even include a cushioned portion that can be made from a polymeric material. A pad may be positioned between the collar and the epicardial surface of the heart that may comprise a low durometer polymer, or either a gel-filled cushion or a fluid-filled cushion.[0023]
• The assembly of the present invention may also comprise a closure device for enclosing at least one of the bands in the connector bar.[0024]
• In use, the present invention can reduce the wall tension on one of the chambers of the heart. A yoke or collar is surrounds the heart so as to provide the chamber of the heart as at least two contiguous communicating regions, such as sections of truncated ellipsoids, which have a lesser minimum radii than the chamber before restructuring. As such, the collar displaces at least two portions of the chamber wall inwardly from the unrestricted position.[0025]
BRIEF DESCRIPTION OF THE DRAWINGS
• While the specification concludes with claims particularly pointing out and distinctly claiming the present invention, it is believed the same will be better understood from the following description taken in conjunction with the accompanied drawings in which:[0026]
• FIG. 1 partial frontal anterior view of an exemplar natural heart;[0027]
• FIG. 2 vertical cross sectional view of an exemplar natural heart and blood vessels leading to and from the natural heart;[0028]
• FIG. 3 is a horizontal cross sectional view of an unrestrained left ventricle of the natural heart;[0029]
• FIG. 4 is a horizontal cross sectional view of a heart restrained made in accordance with the present invention;[0030]
• FIG. 5 is a perspective view of a device made in accordance with the present invention;[0031]
• FIG. 6 is an enlarged exploded perspective view of a portion of the assembly made in accordance with the present invention;[0032]
• FIG. 7 is an enlarged perspective view of another portion of the assembly made in accordance with the present invention;[0033]
• FIG. 8 is a cross sectional view of a connector of the present invention taken along line[0034]8-8 in FIG. 7;
• FIG. 9A is a partial horizontal cross sectional view of an assembly made in accordance with the present invention while the heart is at rest;[0035]
• FIG. 9B is a partial horizontal cross sectional view of an assembly made in accordance with the present invention while the heart is contracting:[0036]
• FIG. 10 is a perspective view of the assembly made in accordance with the present invention and positioned in the left ventricle;[0037]
• FIG. 11 is an alternative embodiment of the assembly made in accordance with the present invention;[0038]
• FIG. 12 is a cross sectional view of one embodiment of the collar of the present invention taken along line[0039]12-12 in FIG. 11;
• FIG. 13 is another alternative embodiment of the assembly made in accordance with the present invention;[0040]
• FIG. 14 is yet another alternative embodiment of the assembly made in accordance with the invention;[0041]
• FIG. 15 is another alternative embodiment of the assembly made in accordance with the present invention;[0042]
• FIG. 16 is a vertical cross sectional view of one embodiment of an auxiliary fastener made in accordance with the present invention;[0043]
• FIG. 17 is another vertical cross sectional view of the auxiliary fastener of FIG. 16 inserted into the assembly;[0044]
• FIG. 18 the vertical cross sectional view of the embodiment of FIG. 16 illustrating the auxiliary connecter; and[0045]
• FIG. 19 is a vertical cross sectional view of the auxiliary fastener of FIG. 16 a period of time after being inserted into position.[0046]
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
• Referring now to the figures in detail wherein like numerals indicate the same elements throughout the views, an exemplary natural heart, generally indicated in FIGS. 1 and 2 as[0047]10, has a lower portion comprising two chambers, namely aleft ventricle12 and aright ventricle14, which function primarily to supply the main force that propels blood through the circulatory system, namely the pulmonary circulatory system, which propels blood to and from the lungs, and the peripheral circulatory system, which propels blood through the remainder of the body. anatural heart10 also includes an upper portion having two chambers, aleft atrium16 and aright atrium18, which primarily serve as an entryway to the left andright ventricles12 and14, respectively, and assist in moving blood into the left andright ventricles12 or14. Theinterventricular wall40 ofcardiac tissue32 separates the left andright ventricles12 and14, and theatrioventricular wall42 ofcardiac tissue32 separates the lower ventricular region from the upper atrium region.
• Generally, the left and[0048]right ventricles12 and14, respectively, each has acavity13 and15, respectively, that is in fluid communication withcavities17 and19, respectively, of the atria (e.g.,16 and18) through an atrioventricular valve50 (which are each illustrated as being in the closed position in FIG. 2). More specifically, theleft ventricle cavity13 is in fluid communication with theleft atrium cavity17 through themitral valve52, while theright ventricle cavity15 is in fluid communication with theright atrium cavity19 through thetricuspid valve54.
• Generally, the cavities of the ventricles (e.g.,[0049]13 and15) are each in fluid communication with the circulatory system (i.e., the pulmonary and peripheral circulatory systems) through a semilunar valve44 (which are each illustrated as being in the open position in FIG. 2). More specifically, theleft ventricle cavity13 is in fluid communication with theaorta26 of the peripheral circulatory system through theaortic valve46, while theright ventricle cavity15 is in fluid communication with thepulmonary artery28 of the pulmonary circulatory system through thepulmonic valve48.
• Blood is returned to the[0050]heart10 through the atria (e.g.,16 and18). More specifically, thesuperior vena cava22 andinferior vena cava24 are in fluid communication with and deliver blood, as it returns from the peripheral circulatory system, to theright atrium18 and itscavity19. Thepulmonary veins30 are in fluid communication with and delivers blood, as it returns from the pulmonary circulatory system, to theleft atrium16, and itscavity17.
• The[0051]heart10 is enclosed in the thoracic cavity within a double walled sac commonly referred to as the pericardium. Its inner layer is the visceral pericardium or epicardium, and its outer layer is the parietal pericardium. Theheart10 is generally made up of, among other materials, cardiac muscle ortissue32, which has an exterior surface commonly known as theepicardial surface34 and an interior surface, orendocardial surface38, that generally defines the cavities (e.g.,ventricular cavities13 and15, respectively, andatrial cavities17 and19, respectively).Coronary arteries36 on theepicardial surface34 of theheart10 provide blood and nourishment (e.g., oxygen) to theheart10 and itscardiac tissue32.
• By way of a non-limiting example, the present invention will be discussed in terms of embodiments that are used to primarily assist in the restructuring or reconfiguring, and/or operation of the left ventricle chamber (e.g.,[0052]12) of thenatural heart10. However. it is noted that the present invention can also be used to assist in the restructuring or reconfiguring, and/or operation of other portions of thenatural heart10, such as either atria (16 and/or18), or the right ventricle chamber (e.g.,14).
• Turning now to FIG. 3, the chambers of the[0053]heart10, including theleft ventricle chamber12, is generally shaped as a hollow truncated ellipsoid having, at any circular cross-section perpendicular to its long axis, a center point “C₁” and a radius “R₁” extending from center point C₁to theendocardial surface38. Thecardiac tissue32 of theheart10 has a thickness “w,” which is generally the distance between theepicardial surface34 and theendocardial surface38.
• The[0054]assembly60 of the present invention exemplified in FIGS.4 to7 preferably is configured and positioned relative to thenatural heart10 to displace at least two portions of thecardiac tissue32 inwardly (see, e.g., FIG. 4) from the unrestricted position, as exemplified in FIG. 3. By displacing portions of thecardiac tissue32 inwardly, the shape of the chamber (e.g., the left ventricle chamber12) of theheart10 is generally restructured or reconfigured from a generally hollow truncated ellipsoid (see, e.g., FIG. 3) to a chamber generally shaped as having at least two continuous communicating portions of truncated ellipsoids (see, e.g., FIG. 4). In generally reconfiguring or restructuring theheart10 as such, each of the truncated ellipsoids has an adjusted radius “R₂,” which is preferably shorter than radius “R₁.”
• The[0055]assembly60 can be static in that it does not actuate or pump theheart10, but rather, displaces and holds portions of thecardiac tissue32 in a generally predetermined fixed position as theheart10 continues to contract (e.g., beat) and pump blood through its chambers and through the body's circulatory system. Nevertheless, theassembly60 can be configured and constructed to permit torsional deformation as thenatural heart10 beats.
• The[0056]assembly60 can include a yoke orcollar62, as exemplified in FIGS.5-7, to assist in restraining or restructuring a ventricle, such as theleft ventricle chamber12.Collar62 can be any desired shape and preferably surrounds or encircles theheart10, and preferably one chamber (e.g., the left ventricle chamber12) as best exemplified in FIG. 10, so as to restructure or reconfigure theleft ventricle chamber12 as having a shape approximating at least two continuous communicating portions of truncated ellipsoids. Preferably, a portion orregion64 of thecollar62 can extend along the longitudinal plane or along the longer axis of the chamber. Suitable locations on theepicardial surface34 for theregion64 can include the basal portion near the atrioventricular groove43 (see, e.g., FIG. 1) andapical portion20 of theheart10, the anterolateral surface of theleft ventricle chamber12, or the posteromedial surface of theleft ventricle chamber12.
• The[0057]collar62 may include two or more bands (e.g.,76) configured for positioning around theheart10. Preferably,bands76 are circumferentially flat and may be oriented with thesurface78 being positioned generally tangent to theepicardial surface34 of theheart10, and having the smaller dimension, as compared withsurface80.Surface80 is generally oriented perpendicular to theepicardial surface34.Band76 should be sized so as to provide for low deformation in the direction perpendicular to theepicardial surface34 of theheart10, but only require a low strain energy for tortial deformation as the heart1O beats.Band76 can have a thickness “th” acrosssurface78 and a width “w” acrosssurface80, that each varies depending on the selected material and its particular deformation characteristics. When metallic material is used with the present invention, theband76 can have a thickness “h” acrosssurface78 of about 0.2 mm, and can have a width, “w” acrosssurface80 from about 5 mm to about 12 mm, and more preferably, about 7 mm. It should be noted that the particular dimensions of eachassembly60, and of its components (e.g. collar62 and its various portions,bands76, etc.) will depend, as will be discussed later, according to particular anatomy, the desired application, and upon the particular size and configuration of the individualnatural heart10.
• In constructing[0058]assembly60 usingbands76, from about 2 to about 10bands76 may be used, and preferably about 4bands76 are used in the present invention. Nevertheless, the number ofbands76 may be selected dependent upon the property of the material selected for each of thebands76, as well as the load stress required to appropriately restructure the heart chamber geometry.
• [0059]Bands76 are each preferably made of a light weight, generally rigid material that has a low bending strain under expected levels of stress so that the material has sufficient wear resistance in use while theheart10 beats, and maintains its desired shape in use adjacent theheart10. Illustrative examples of suitable materials which may be employed asbands76 include any biocompatible or biomedical materials, such as metals, including titanium or stainless steel, or a suitable polymer, including polyacetal or an ultra high molecular weight polyethylene, or a combination of the same.
• The[0060]collar62 may preferably include aconnector82, and preferably a plurality ofconnectors82 spaced along thecollar62, as exemplified best in FIG. 5. Theconnectors82 can assist in maintaining the space relationship of thebands76 relative to each other, and of theassembly60 to theheart10. Turning now to FIGS.6-8, theconnector82 preferably has a contact or aninner surface84, which is configured for placement adjacent or against theepicardial surface34 of thenatural heart10. Theinner surface84 may be configured so that theepicardial surface34 may slide alonginner surface84 during contraction and expansion of theheart10, and to minimize damage to theepicardial surface34, and the coronary arteries (e.g.,36). Preferably, theinner surface84 is curved convex outwardly in a longitudinal plane (see, e.g., FIGS. 4 and 8) and has a smooth surface, and/or preferably roundededges87 so thatcollar62 can be configured to be positioned adjacent or on theepicardial surface34 whereby intimate contact can be established and maintained, even during the contraction or beating of theheart10.
• FIGS.[0061]6-8 illustrate theconnectors82 as each including one ormore grooves92, which can extend inwardly from anopening98 in theouter wall86, and toward the contact orinner surface84. Eachgroove92 is preferably sized and configured to receive aband76 whereby itssurface78 would be positioned adjacent thebase wall94, and itssurfaces80 preferably would be positionedadjacent sidewalls96.
• In an preferred embodiment, groove[0062]92 should be configured to assist in allowing flexion movement of theband76 as theheart10 beats and moves. As best exemplified in FIGS.6-8,grooves92 may be tapered inwardly as thegrooves92 proceeds or extends from theouter surface86 inwardly toward thecontact surface84. In addition,grooves92 may also be tapered inwardly as the groove extends from each of the lateral surfaces88 inwardly (e.g., upwardly and/or downwardly), as best illustrated in FIG. 6.
• [0063]Connectors82 are each preferably made of a light weight, generally rigid material that has a low bending strain under expected levels of stress so that the material has sufficient wear resistance in use while theheart10 beats, and maintains its desired shape in use adjacent theheart10. Illustrative examples of suitable materials which may be employed asconnectors82 may include any biocompatible or biomedical materials, such as metals, including titanium or stainless steel, or a suitable polymer, including polyacetal or an ultra high molecular weight polyethylene, or a combination of the same.
• Turning back to FIG. 6, a[0064]structure100 can be provided so as to assist in maintaining thebands76 in thegroove92, in use. Anystructure100 contemplated for use withassembly60 should assist in restricting movement of theband76 out of thegroove92 throughopening98. In one embodiment, thestructure100 may take the form of aplate100 that can be secured or otherwise attached, and preferably releasably secured, to close off or restrict access through one ormore openings98. In addition to a plate-like structure, sutures (not shown) may also be threaded through theconnector82 to assist in restrictingbands76 movement throughopening98.Structure100 is preferably made of a biocompatible or biomedical material.
• Turning now to FIGS. 11 and 12, an alternative embodiment of the present invention may include a collar or[0065]yoke162 that provides an essentially continuous surface which contacts theepicardium surface34 of theheart10. In the present embodiment,collar162 may take the form of a generally continuous yoke-like structure that is essentially rigid.Collar162 preferably includes a contact or aninner surface184, which is configured for placement adjacent or against theepicardial surface34 of thenatural heart10. Theinner surface184 should be configured so that theepicardial surface34 may slide along theinner surface184 during contraction and expansion of thenatural heart10, and to minimize damage to theepicardial surface34 and the coronary arteries (e.g.,36). Preferably, theinner surface184 is curved convexly outwardly in a longitudinal plane and has a smooth surface, and/or preferably roundededges187 so that acollar162 can be configured to be positioned adjacent or on theepicardial surface34 whereby intimate contact can be established arid maintained, even during the contraction or expansion of thenatural heart10.
• The[0066]collar162 preferably is selected from a generally rigid biomedical or biocompatable material. Examples of such suitable materials may include a metal, such as titanium or steel, or a polymer, such as an ultra high molecular weight polyethylene, polyacetal, or a polymer composite material such as carbon fiber-epoxy or fiberglass-epoxy, or a combination of the same. Moreover, thecollar162 may be covered, either partially or entirely, with a material that promotes tissue ingrowth into thecollar162, such as a soft tissue polyester fabric sheeting or polyletrafluroethyhere (PTFE).
• In another alternative embodiments, exemplified in FIGS.[0067]13-14, it is contemplated that thecollar162 may include anattachment system163 that allows thecollar162 to be placed around theheart10, such as inbetween thepulmonary veins30 near the basal portion of theheart10 so as to reduce the possibility of lateral or medical displacement of theassembly60, or about the lateral atrium or the atrioventrialar groove region. In one embodiment, thecollar162 may include anattachment system163 that permits thecollar162 to be separated and then reattached at two or more sites or positions along thecollar162, preferably adjacent or near the region of thecollar162 configured for placement adjacent or on the basal portion and/orapical portion20 of thenatural heart10. While theattachment system163 is illustrated as an interlockingpin163B andreceptacle163A (e.g., a ball and socket-likejoint), it is contemplated, and as would be appreciated by those skilled in the art, other devices and assemblies for releaseably securing thecollar162 together can be used. Example of such devices and assemblies forattachment system163 could include sutures, a screw and bore holes through overlapping portions of thecollar162, clamps, a combination of these devices and assemblies.
• Alternatively, as illustrated in FIG. 14, the[0068]collar162 may include anattachment system163 at one site along thecollar162, preferably adjacent or at the portion of thecollar162 configured for placement adjacent on or the basal portion of theheart10. This embodiment ofcollar162 preferably would include aportion167 that can either include flexible material or apivotable section168 to provide movement of thecollar162 so that theattachment assembly163 can open, and thecollar162 can be slipped around in theheart10, and/or between thepulmonary veins30.
• In yet another embodiment illustrated in FIG. 15, the[0069]assembly260 may include acollar262 having aregion264 similar to the structure of thecollar62, exemplified above in FIGS.4-8, and connector portions orregions268, similar to the structure of thecollar162, discussed above, and exemplified in FIGS.12-14.
• To assist the[0070]epicardial surface34 in separating from each of thecollars62,162, or262 adjacent or at thelateral portions85 ofinner surface84 without creating substantial negative pressure, apad56 can be positioned and/or interposed between theepicardial surface34 and theinner surface84 of one or more of theconnectors82.Pad56 can be, as exemplified in FIGS. 9A and 9B, a fluid-filled or gel-filled pad or cushion, which generally will occupy space laterally beyond thecollar62 and thelateral portions85 ofinner surface84 while theheart10 is in as a relaxed state. However, as theheart10 contracts and the wall shortens (see, e.g., FIG. 9B), generally circumferentially (reducing cavity radius), theepicardial surface34 will “peel away” from thecollar62 and thelateral portions85 ofinner surface84 and thus, fluid or gel in thepads56 can fill this space so that theinner surface84 andepicardial surface34 remain in contact and effect focal restraint whereby thechamber12 is restructured, as detailed above.
• In one embodiment, the[0071]pad56 is a closed system. Alternatively, it is contemplated thatpad56 can be configured such that fluid and/or gel can be added or removed to enhance functionality of the device assembly of the present invention, as desired. For example, one ormore lines58 can be in fluid communication with a chamber inpad56.Line58 can extend frompad56 to aninjection port59, which can be positioned subcutaneous or elsewhere, as desired, for enhanced access. As will be appreciated by those skilled in the art, fluid or gel can be injected into theinjection port59 using a standard syringe and needle, or other device, to increase the size of thepad56 and/or the pressure within thepad56, as desired. Alternatively, fluid or gel can be withdrawn as desired.
• Alternatively, pad[0072]56 can be as a low durometer polymer such as a plastic or other material (e.g., rubber). In use, as detailed above, the-material accommodates and maintains the contact between thecollar62, and more specifically itsinner surface84, andepicardial surface34 and thus, the desired reconfiguration of theheart10 as theheart10 beats or deforms.
• To assist each of the[0073]assembly60 in remaining fixed in a spatial or spaced relationship to each other and adjacent or on theepicardial surface34, as desired, one or moreauxiliary connectors70 is provided.Auxiliary connector70 can take the form of various mechanical connectors used in the industry to attach and position prosthetic devices in the body.
• [0074]Auxiliary connector70 can take the form of a spike shaped object or pin75 that is configured to penetrate theepicardial surface34 into thecardiac tissue32. Also,auxiliary connector74 can take the form of abutton72 andcord73. One end of thecord73 can be attached or otherwise secured to thecollar62, and it can extend inwardly into and through thecardiac tissue32. Abutton72 can be attached to or adjacent the other end of thecord86 adjacent theendocardial surface38.Button72 can be made of any biocompatible material, and is preferably made of a material that enhances tissue growth around thebutton72 to minimize the possibility of the formation of blood clots. It is further contemplated that other surgical attachment articles and techniques can be used in accordance with the present invention, such as screws, surgical staples and the like, to assist in fastening and securing theassembly60 in position, as desired.
• Furthermore,[0075]auxiliary connector70 can take the form of apeg74, as exemplified in FIGS.16-19, that can configured to be lockably received in ahole67 positioned and/or aligned on theassembly60, and preferably on theconnectors82 or thecollar162.Peg74 generally comprises a generallypermanent potion74A configured preferably to be snugly received in thehole67, as discussed above. Theportion74A can be made of any suitable biomedical or biocompatible material. Suitable examples of materials forportion74A, can include the same materials that can be used with thecollar62, as exemplified above.
• At the end of the[0076]portion74A of thepeg74, a generally rigidabsorbable spike74B is provided, which preferably is a generally fustoconicall shaped and tapers inwardly as thespike74B extends away from theportion74A.Spike74B is sufficiently rigid so that it can pierce the tissue and then be inserted into the muscle tissue (e.g., the cardiac tissue32). The material used forspike74B should be a material that is absorbable by the body tissue over a period of time. Suitable materials can include a gelatin material, which can be partially denatured thermally or chemically to control solubility and the absorption rate in the tissue (e.g.,32), a polyglycol acid, or other materials, as will be appreciated by those skilled in the industry, used with absorbable surgical devices or sutures.
• Within the[0077]portion74A and spike74B is a generallyflexible extension74C configured, for example, as a strip, coil, tube, or loop which preferably may include exposed interstices (mesh), holes, loops or other surface enhancements to promote tissue in growth.Extension74C can be made from a material to enhance tissue integration therein. Suitable examples of materials for use asextension74C can include polyester, polypropylene, and other polymers used in as non-dissoluble implants.
• In accordance with the teachings of the present invention, the[0078]assembly60 should be so configured and positioned adjacent theheart10 whereby the wall tension is reduced in accordance with LaPlace's theory of a chamber, which is as follows:
• (Tension of wall)=K*(chamber pressure)*(radius of chamber)(wall thickness),[0079]
• wherein K is a proportionality constant.[0080]
• As an illustrative example of one embodiment in accordance with the teachings of the present invention, calculations will be performed based on the following model as exemplified in FIGS. 3 and 5. It is assumed that the long axis of the[0081]left ventricle12 of theheart10 is 100 mm, that the equatorial or short axis of thechamber12 is 70 mm, that the equatorial wall thickness “w” of the chamber is about 10 mm and the basal diameter of theheart10 is 60 mm. An arbitrary slice or plane of theleft ventricle12 will be analyzed to illustrate local dimensional computations for the present invention.
• Furthermore, this model will assume that the inner radius “R[0082]₁” (of the slice or plane) of the unrestricted heart10 (see, e.g., FIG. 3) is about 28.982 mm and that theheart10 has an outer radius of about 38.406 mm. As is known to those skilled in the industry, the width “w” and radius “R₁” can be directly obtained from high-resolution imaging, such as an echocardiogram, or preferably, by computation based on an assumed geometric model. The ratio of the restraint contract pressure of theleft ventricle12 of thedevice60 to the cavity pressure can vary from 1 to about 2. This example will further assume that the allowed ratio of the restraint contact pressure of theleft ventricle12 ofdevice60 to the cavity pressure is to be limited to a maximum of about 1.5, which is represented by symbol K in the mathematical formulas below. Also, it is desired to achieve an altered radius “R₂” of theleft ventricle12 to 80% of its original radius R₁, and as such:
• R₂=0.8*R₁
• R₂=0.8*28.982 mm
• R₂=23.186 mm
• In order to calculate the radius of curvature “g” of the[0083]inner surface64 ofmember62 in the transverse plane, the following formula can be used:
• g=(w+R₂)÷(k−1)
• g=(9.424 mm+23.186 mm)÷(1.5−1)
• g=(32.61 mm)÷0.5
• g=65.22 mm.
• Now that the value of radius of curvature of the[0084]inner surface84 “g” has been calculated, the angle “θ” between the line g₁(joining the center of curvature of themember62 with one margin, in this plane, of the contact area betweeninner surface84 and the epicardial surface34) and line g₂(joining the same center of curvature with the center of theinner surface84 in the same plane) can be calculated using the following formula:
• θ=(π/2)*[R₂−R₁]÷(R₂+w+g)
• θ=(π/2)*[28.982 mm −23.186 mm]÷(28.982 mm+9.424 mm+65.22 mm)
• θ=(π/2)*[5.796 mm]÷(103.636 mm)
• θ=0.09063 radius or 5.332 degrees
• Using the formula below, the distance inwardly that the[0085]heart10 should be displaced can be calculated so that the desired restructuring can be achieved. If “e” is the distance that the center of eithermember62 is to be separated from the absolute center of a remodeled ventricle in this plane, then:
• e=[(g+w+R₂)* cos θ]−g
• e=[(65.22 mm+9.424 mm+23.186 mm)* cos 5.332 degrees]−65.22 mm
• e=32.21 mm.
• As such, twice e or (2*e) is 64.42 mm, and this is the preferred distance separating the oppositely disposed[0086]inner surfaces64.
• Based on the calculation, the wall of the[0087]heart10 needs to be displaced or moved inwardly about 6.20 mm from the unrestrained position to achieve the desired restructure or reconfiguration whereby wall tension is adjusted, as desired. Also, using the formula 2θg to calculate the desired contacting width of theinner surface84, which is about 11.68 mm in this example.
• To position the[0088]assembly60 into a body (e.g., the thoracic cavity) and around an existingnatural heart10, a high resolution image, such as a standard echocardiogram, or other analysis of theheart10 is preferred so that certain anatomical measurements can be electronically, preferably digitally, recorded and calculated, as detailed above. While the present application only includes one set of mathematic calculations to optimize the present invention, it is contemplated that measurements will need to be taken along several axes, planes, locations or positions along the longer axis of the chamber. Pre-surgical calculations are preferred so that theassembly60 can be constructed, as desired, before surgery to minimize surgical time, and preferably reduce or eliminate use of a heart/lung bypass machine.
• Thoracic surgery may be required to implant[0089]assembly60. Clinically sufficient anesthesia is administered and standard cardiac monitoring is employed to the patient and then, via a sternal or lateral wall incision, the pericardial sac where theheart10 is usually situated is opened using standard thoracic surgical procedures, which are known to those skilled in the art.
• Once the thoracic cavity and pericardium is opened, the[0090]heart10 must be narrowed or constricted so that theassembly60 can be placed around theheart10. In one embodiment, inflow to theheart10 may be occluded. This can be accomplished by placing a tourniquet around either the superior and/orinferior vena cava22 and24, respectively, as illustrated respectfully in FIGS. 1 and 2, for a brief period of time (e.g., about 3 to 4 heartbeats) whereby theheart10 shrinks and empties. Thereafter, thecollar62 may be slipped around theheart10. The tourniquets can be released from occlusion around the superior and/orinferior vena cavas22 and24, respectively, and theheart10 re-fills with blood.
• While for prolonged reduction of blood pressure by cardiac inflow occlusion, hypothennia techniques may be employed to lower body temperature to reduce the side effects that can be caused by reduced blood pressure in the circulatory system.[0091]
• If an open heart procedure employed in the present invention, circulation of blood to the[0092]natural heart10 may be bypassed so the present invention can be inserted on and/or into the patient. If so, referring back now to FIG. 2, thesuperior vena cava22, theinferior vena cava24, andaorta26 are cannulated. The circulatory system is connected to as a cardiopulmonary bypass machine so that circulation and oxidation of the blood are maintained during the surgical procedure. By way of example, the procedure discussed in detail will be for insertion of thepresent invention60 to restructure or reconfigure theleft ventricle chamber12.
• Turning now to FIGS.[0093]4-7 and10,assembly60, which may have been customized according to the anatomical measurements and calculations, is preferably positioned adjacent or against theepicardial surface34 in predetermined locations relative to each other and relative to the chamber (e.g., left ventricle chamber12).Assembly60 is positioned around theheart10 so that portions of theheart10 are displaced or urged inwardly, as desired.
• [0094]Auxiliary connectors70 can be used to further secure theassembly60 to theheart10. Turning now to FIGS.16-19, peg74 can be inserted in thehole67, whereby thespike74B is piercing theepicardial surface34 and is being inserted into the tissue (e.g., cardiac tissue32).Peg74 preferably locks into position once inserted (see FIG. 17), to further secure theassembly60 in place. Over time, it is preferred that spike74B, which has been inserted into the tissue, dissolve and be absorbed by the surrounding tissue. As thespike74B is being absorbed,extension74C becomes exposed to the tissue, and tissue thereby insinuates and grows into any exposed interstices, loops, holes, or other surface enhancements to promote tissue ingrowth. Thepeg74B can thereafter be held in place by the tissue insinuation and growth intoextension74C, which can assist in maintaining the position ofassembly60.
• Once the[0095]assembly60 is properly positioned and secured, termination of a cardiopulmonary bypass, if used, is attempted and, if successful, the thoracotomy is closed.
• Alternatively, once the thoracic cavity and pericardium is open, the[0096]collar162 exemplified in FIGS. 13 and 14, can be placed around theheart10, either between thepulmonary artery28 and the superior left atrial surface or between the aorta and thepulmonary artery28 and then across the posterior dorsal left atrial surface in between the left and rightpulmonary veins30. A portion of thecollar162, preferably the posterior portion, can be placed behind theheart10. An opening is sharply and/or bluntly developed in the leaves of the pericardium forming the anterolateral margin of the oblique sinus. Then, a hemostat can be used to place a portion of thecollar162 through the opening. Alternatively, a detachable cord, with one end attached to the portion of thecollar162, can be grasped and used to pull a portion of thecollar162 through the opening. Such placement of thecollar162 across theepicardial surface34 of the lateral atrium or atrioventricular junction should reduce the possibility of adverse medial or lateral displacement or movement of thecollar162.
• An alternative method for positioning the present invention includes removing the[0097]natural heart10 from the patient, positioning all the components of thepresent invention assembly60, as discussed above, and auto-transplanting thenatural heart10 back into the patient using standard cardiectomy and cardiac transplant techniques known in the industry.
• Having shown and described the preferred embodiments to the present invention, further adaptations of the activation device for the living heart as described herein can be accomplished by appropriate modifications by one of ordinary skill in the art without departing from the scope of the present invention. For example, the present invention can be used with any one or even as a plurality of the various chambers of a living heart, and also could be used with different structural embodiments to restructure he chamber. Several such potential modifications have been discussed and others will be apparent to those skilled in the art. Accordingly, the scope of the present invention should be considered in terms of the following claims and is understood not to be limited in the details, structure and operation shown and described in its specification and drawings.[0098]

Claims (26)

I claim:

1. A geometric reconfiguration assembly for a natural heart, comprising:

a collar configured for surrounding the natural heart and having a plurality of bands in a spaced relationship; and

a connector bar intersecting the plurality of bands and configured for maintaining the spaced relationship of the bands to each other.

2. The assembly ofclaim 1, wherein the connector bar comprises an inner surface having an outwardly convex curved configuration.

3. The assembly ofclaim 1, wherein each of the plurality of bands are positioned parallel to each other.

4. The assembly ofclaim 1, wherein the assembly comprises from about 2 to about 10 bands.

5. The assembly ofclaim 1, wherein the bands comprise a high strength, high modulus polymer.

6. The assembly ofclaim 1, wherein the bands comprise a metal.

7. The assembly ofclaim 1, wherein the connector bar is positioned tangential to the plurality of bands.

8. The assembly ofclaim 1, wherein at least one of the bands has a thickness of about 0.2 mm.

9. The assembly ofclaim 1, wherein each of the bands includes a thickness, and the connector bar comprises a plurality of grooves configured to receive the thickness of each of the plurality of bands.

10. The assembly ofclaim 9, wherein the connector bar comprises at least one beveled groove.

11. The assembly ofclaim 1, wherein the connector bar comprises a cushioned portion.

12. The assembly ofclaim 1, comprises a closure device for enclosing at least one of the bands in the connector bar.

13. The assembly ofclaim 1, wherein the collar comprises a first restrictor region configured to be positioned adjacent the anterolateral surface of the heart and a second restrictor region configured to be positioned adjacent posteromedial surface of the heart.

14. The assembly ofclaim 11, wherein the cushion portion comprises a polymeric material.

15. The assembly ofclaim 1, wherein said assembly comprises a pad provided adjacent the inner surface of the connector bar.

16. The assembly ofclaim 15, wherein the pad comprises a low durometer polymer.

17. The assembly ofclaim 15, wherein the pad comprises a cushion.

18. The device ofclaim 17, wherein the cushion comprises a gel-filled cushion.

19. The assembly ofclaim 17, wherein the cushion comprises a fluid-filled cushion.

20. A geometric reconfiguration assembly for a natural heart, comprising;

a collar for surrounding a portion of the natural heart, said collar having a portion configured for placement on the basal portion of the natural heart in between the left and right pulmonary veins, said collar further comprising an attachment assembly configured for releasably connecting said collar together.

21. The assembly ofclaim 20, wherein the collar comprises an inner surface having a outwardly convex curve configuration.

22. The assembly ofclaim 20, wherein the attachment system comprises a pin and receptacle, said pin and receptacle being releasably detachable.

23. A geometric reconfiguration assembly for a natural heart, comprising

a collar configured for surrounding a natural heart, said collar having a first restrictor region for placement adjacent the anterolateral surface of the heart, and a second restrictor region configured for positioning adjacent the posteromedial surface of the heart; the first and second restrictor portions each comprising a plurality of bands in a space relationship and a connector bar intersecting the plurality of band and configured for maintaining the space relationship of the bands to each other.

24. The assembly ofclaim 23, wherein the collar comprises a first and second connector portion configured for placement adjacent the basal portion of the heart and a second connector portion configured for a position adjacent the apical portion of the epicardium of the heart.

25. A method for reducing wall tension on one of the chambers of the heart, comprising the steps of

providing a geometric reconfiguration assembly; and

surrounding one of the chambers of the heart with a geometric configuration assembly.

26. The method ofclaim 25, comprising the step of occluding blood inflow into the heart prior to placement of the assembly around the chamber of the heart.

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