US20080027274A1 - Cardiac harness having interconnected strands - Google Patents

Abstract

A cardiac harness for treating a patient's heart includes elastic rows connected by a connector assembly. The connector assembly can have a specific pattern, or can be formed of elongated elastic material connecting all of the apices of adjacent rows. The connectors maintain proper spacing between rows or rings on the harness and provide longitudinal stability.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS
• This application depends for priority upon U.S. Provisional Application No. 60/535,888 filed Jan. 12, 2004, which is incorporated herein in its entirety by reference.
FIELD OF THE INVENTION
• The present invention relates to a device for treating heart failure. More specifically, the invention relates to a cardiac harness configured to be fit around at least a portion of a patient's heart. The cardiac harness includes multiple elastic rows or undulating strands extending circumferentially around the heart and connected together by a connector assembly.
BACKGROUND OF THE INVENTION
• Congestive heart failure (“CHF”) is characterized by the failure of the heart to pump blood at sufficient flow rates to meet the metabolic demand of tissues, especially the demand for oxygen. One characteristic of CHF is remodeling of at least portions of a patient's heart. Remodeling involves physical change to the size, shape and thickness of the heart wall. For example, a damaged left ventricle may have some localized thinning and stretching of a portion of the myocardium. The thinned portion of the myocardium often is functionally impaired, and other portions of the myocardium attempt to compensate. As a result, the other portions of the myocardium may expand so that the stroke volume of the ventricle is maintained notwithstanding the impaired zone of the myocardium. Such expansion may cause the left ventricle to assume a somewhat spherical shape.
• Cardiac remodeling often subjects the heart wall to increased wall tension or stress, which further impairs the heart's functional performance. Often, the heart wall will dilate further in order to compensate for the impairment caused by such increased stress. Thus, a cycle can result, in which dilation leads to further dilation and greater functional impairment.
• Historically, congestive heart failure has been managed with a variety of drugs. Devices have also been used to improve cardiac output. For example, left ventricular assist pumps help the heart to pump blood. Multi-chamber pacing has also been employed to optimally synchronize the beating of the heart chambers to improve cardiac output. Various skeletal muscles, such as the latissimus dorsi, have been used to assist ventricular pumping. Researchers and cardiac surgeons have also experimented with prosthetic “girdles” disposed around the heart. One such design is a prosthetic “sock” or “jacket” that is wrapped around the heart.
• What has been needed, and is currently unavailable, is a cardiac harness having multiple elastic strands or rows interconnected by a connector assembly that prevents the longitudinal migration of the rows after the cardiac harness is mounted on the patient's heart.
SUMMARY OF THE INVENTION
• The present invention relates generally to a cardiac harness that is configured to fit at least a portion of a patient's heart. The cardiac harness includes adjacent rows that are connected to one another by one or more connectors. The connectors help to maintain the position of the elastic rows relative to one another. In one embodiment, the connectors form a connector assembly between the adjacent rows of the cardiac harness. The connector assembly has a pattern that provides longitudinal stability between the adjacent rows so that the rows do not expand or shift longitudinally while mounting the harness on the heart or during use after the harness is mounted on the heart.
• In another embodiment, an elongated connector is woven through the apices of adjacent rows to again maintain the spacing between the rows during delivery and use of the cardiac harness. Typically, the connectors are formed from an elastomeric material, preferably silicone rubber.
• The connectors are formed by placing the undulating strands or rows in a mold and injecting the elastomeric material through the gates in the mold to form the connectors. Typically, the connectors extend between the apices of adjacent rows so that the elastomeric material formed in the mold flows around the apices of adjacent rows. Preferably, the elastomer is a silicone rubber or similar material.
BRIEF DESCRIPTION OF THE DRAWINGS
• FIG. 1 depicts a schematic view of the heart with a prior art cardiac harness placed thereon.
• FIGS. 2A-2B depict a spring hinge of a prior art cardiac harness in a relaxed position and under tension.
• FIG. 3 depicts an unattached elongated strand or row, or series of spring elements that are coated with a dielectric material.
• FIG. 4 depicts a perspective view of an embodiment of a cardiac harness having a plurality of rows connected by a connector assembly.
• FIG. 5 depicts a portion of a elastic row showing the ends of the row being connected by a connector.
• FIG. 5A depicts a portion of a row showing the ends of the row being connected by a connector.
• FIG. 6 depicts an enlarged partial plan view of a cardiac harness wherein the connectors provide uniform spacing between adjacent rows.
• FIG. 6A depicts an enlarged partial plan view of a cardiac harness wherein the connectors form a pattern that permits distended spacing between adjacent rows.
• FIG. 7 depicts an enlarge partial plan view of a cardiac harness wherein the connectors form a connector assembly.
• FIG. 8 depicts an enlarged partial plan view of a cardiac harness wherein the connectors form a connector assembly.
• FIG. 9 depicts an enlarged partial plan view of a cardiac harness wherein Y-shaped connectors connect adjacent rows of the cardiac harness.
• FIG. 10 depicts an enlarged partial plan view of a cardiac harness wherein a single elongated connector is woven between apices of adjacent rows.
• FIG. 11 depicts an enlarged partial plan view of a cardiac harness wherein a single connector is woven between all of the apices of adjacent rows.
• FIG. 12 depicts an enlarged partial plan view of a cardiac harness wherein a single connector is attached to the apices of adjacent rows.
• FIG. 12A depicts a cross-sectional view taken alonglines12A-12A showing attachment of the connector to an apex of one of the rows.
• FIG. 13A depicts a plan view of a sheet of material used to form a connector.
• FIG. 13B depicts a plan view of a sheet of material having cuts that form an elongated connector.
• FIG. 13C depicts a plan view of an elongated connector.
• FIG. 14 depicts a plan view of a mold for forming connectors between adjacent rows of a cardiac harness.
• FIG. 15 depicts a plan view of a mold for forming connectors between adjacent rows of a cardiac harness.
• FIG. 16 depicts an enlarged partial plan view of a cardiac harness wherein connectors extend longitudinally along the rows of the cardiac harness attaching distal apices.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
• The present invention relates to a method and apparatus for treating heart failure. As discussed in Applicants' co-pending application entitled “Expandable Cardiac Harness For Treating Congestive Heart Failure,” Ser. No. 09/634,043, which was filed on Aug. 8, 2000, now U.S. Pat. No. 6,702,732 issued Mar. 9, 2004, the entirety of which is hereby expressly incorporated by reference herein, it is anticipated that remodeling of a diseased heart can be resisted or even reversed by alleviating the wall stresses in such a heart. The present application discusses certain embodiments and methods for supporting the cardiac wall. Additional embodiments and aspects are also discussed in Applicants' co-pending applications entitled “Device for Treating Heart Failure,” Ser. No. 10/242,016, filed Sep. 10, 2002, now U.S. Pat. No. 6,723,041 issued Apr. 20, 2004; “Heart Failure Treatment Device and Method,” Ser. No. 10/287,723, filed Oct. 31, 2002; “Method and Apparatus for Supporting a Heart,” Ser. No. 10/338,934, filed Jan. 7, 2003; “Cardiac Harness,” Ser. No. 10/656,722, filed Sep. 5, 2003; “Cardiac Harness Delivery Device and Method,” Ser. No. 10/715,150, filed Nov. 17, 2003; “Multi-Panel Cardiac Harness,” Ser. No. 60/458,991, filed Mar. 28, 2003; “Self Anchoring Cardiac Harness,” Ser. No. 60/486,052, filed Jul. 10, 2003; and “Cardiac Harness,” Ser. No. 10/698,237, filed Oct. 31, 2003, the entirety of each of which is hereby expressly incorporate by reference.
• FIG. 1 illustrates amammalian heart30 having a cardiac wall stress reduction device in the form of aharness32 applied to it. Thecardiac harness32 includes rows of elastic members that circumscribe theheart30 and, collectively, apply a mild compressive force on the heart to alleviate wall stresses.
• The term “cardiac harness” as used herein is a broad term that refers to a device fit onto a patient's heart to apply a compressive force on the heart during at least a portion of the cardiac cycle. A device that is intended to be fit onto and reinforce a heart and which may be referred to in the art as a “girdle,” “sock,” “jacket,” “cardiac reinforcement device,” or the like is included within the meaning of “cardiac harness.”
• Thecardiac harness32, illustrated inFIG. 1, includes several rows orstrands36 of elastic members. Each row has a series ofspring elements34, also referred to as hinges or spring hinges, that are configured to deform as theheart30 expands during filling. For example,FIG. 2A shows one embodiment of ahinge member34 at rest. Thehinge member34 has acentral portion40 and a pair ofarms42. As the arms are pulled, as shown inFIG. 2B, a bendingmoment44 is imposed on thecentral portion40. The bendingmoment44 urges thehinge member34 back to its relaxed condition. Note that a typical row or strand has a series of such hinges, and that thehinges34 are adapted to elastically expand and retract in the direction of thestrand36.
• In the embodiment illustrated inFIG. 1, theelastic rows36 are constructed of pulled or extruded wire that is deformed to form the spring elements. AlthoughFIG. 1 shows adjacent rows interwoven one with another, it is to be understood that, in additional embodiments, adjacent rows may not overlay or touch one another.
• With next reference toFIG. 3, a close-up of a portion of one embodiment of anelastic row36 is shown. In the illustrated embodiment, the row comprises an undulating strand ofwire46 formed into a series ofsuccessive spring elements34. Adielectric coating48 is disposed over the spring elements. In the illustrated embodiment, the dielectric coating comprises silicone or more precisely silicone rubber. Other acceptable materials include urethanes as well as various polymers, elastomers and the like. In the illustrated embodiment, the silicone rubber coating comprisestubing50 that has been pulled over the wire. It is to be understood that other methods for applying a coating, such as dip coating and spraying, can also be used to apply a coating to the elastic row. Further, it should be understood that in other embodiments no coating is applied over the elastic row.
• With reference next toFIG. 4, an embodiment of acardiac harness32 having several adjacentelastic rows36 is illustrated. In this embodiment, adjacent rows preferably are connected to one another by one ormore connectors52. The connectors help maintain the position of the elastic rows relative to one another. Preferably, the connectors have a length oriented longitudinally relative to the elastic rows to create a space between adjacent rows. The illustrated harness is configured to circumferentially surround at least a portion of the heart between the heart apex and base portions. Preferably, the connectors allow some relative movement between adjacent rows.
• Theconnectors52 preferably are formed of a semi-compliant material such as silicone rubber. Most preferably the connectors are formed of the same material used for thedielectric coating48, if applicable. Some additional materials that can be used for the conductors include, for example, medical grade polymers such as, but not limited to, polyethylene, polypropylene, polyurethane and nylon.
• As discussed above, and as discussed in more detail in the applications that are incorporated herein by reference, theelastic rows36 exert a force in resistance to expansion of theheart30. Collectively, the force exerted by the elastic rows tends toward compressing the heart, thus alleviating wall stresses in the heart as the heart expands. Accordingly, the harness helps to decrease the workload of the heart, enabling the heart to more effectively pump blood through the patient's body and enabling the heart an opportunity to heal itself. It should be understood that several arrangements and configurations of elastic rows can be used to create a mildly compressive force on the heart to reduce wall stresses. For example, elastic members can be disposed over only a portion of the circumference of the heart or harness.
• In one embodiment, eachelastic row36 initially includes an undulatingelongate strand46. During manufacturing of thecardiac harness32, each elongate strand is cut to a length such that when opposite ends of the elongate strand are bonded together, the elongate strand assumes a ring-shaped configuration. The rings comprise the adjacent elastic rows. The lengths of the elongate strands are selected such that the resulting rings/rows are sized in conformity with the general anatomy of the patient's heart. More specifically, strands used to form theapex portion54 of the harness are not as long as strands used to form thebase portion56. As such, and as shown inFIG. 4, the harness generally tapers from the base56 toward the apex54 in order to generally follow the shape of the patient's heart.
• In another embodiment, the diameter of a base ring orrow58 at thebase56 of theharness32 is smaller than the diameter of the adjacent row. In this embodiment, the harness has a greatest diameter at apoint60 between the base and apex ends54, and tapers from that point to both the base and apex ends. Preferably, the point of greatest diameter is closer to the base end than to the apex end. It is contemplated that the lengths of the rows, as well as the sizes of thespring members34, may be selected according to the intended size of the cardiac harness and/or the amount of compressive force the harness is intended to impart to the patient's heart.
• With reference toFIG. 5, the opposite ends62,63 of each circumferentially extending row are attached to one another by aconnective junction64. In one embodiment, illustrated inFIG. 5, eachconnective junction64 includes asmall tube segment66 into which the opposite ends62,63 of the row are inserted. The tube segment serves to prevent the opposite ends of the row from tearing loose from one another after the harness is placed on the heart. Preferably, each tube segment is filled with adielectric material68 such as silicone rubber, or other similar material after the row ends are placed therein. It is to be understood that additional methods and structure can be used to form the connective junction. For example, in another embodiment, illustrated inFIG. 5A, eachconnective junction64 includes asmall tube segment66 into which thespring members34 at the opposite ends62,63 of therow36 are inserted. The connective junction is then back-filled with aliquid silicone rubber68 or other similar material. In still another embodiment, the ends of the strands can be welded together or intertwined. Also, in other embodiments, each ring can be unitarily formed without requiring cutting and joining of the ends.
• In a still further embodiment, acardiac harness32 is formed by arranging one or moreundulating strands46 in a helix (not shown). In such an embodiment, portions of the helically-arranged strand are disposed adjacent one another. As with the rows/rings36 shown inFIG. 4,connectors52 may connect the adjacent portions. In keeping with the invention, certain aspects and principles are discussed for connecting adjacent rows/rings of a harness. It is to be understood that the same principles can be applied to a helically-arranged harness embodiment, and that adjacent portions of such a harness may be treated like adjacent rows or rings.
• Due to the anatomy of the human heart, the right ventricle extends further from the apex of the heart than does the left ventricle. Thecardiac harness32 illustrated inFIG. 4 includes a rightventricle engagement portion70 configured to fit about the uppermost portion of the right ventricle where the ventricle begins to curve inwardly. With continued reference toFIG. 4, the right ventricle engagement portion of the harness haselastic rows36 that form only a partial row72. Preferably, the partial rows are connected to the adjacentfull row36 in a manner so that the partial rows are at least partially stretched when the rest of the harness is at rest. As such, the partial rows are biased inwardly. When placed on the heart, the partial rows “cup” the upper portion of the right ventricle. The harness fits better and is held more securely on the heart than if the right side of the harness were configured the same as the left side.
• In yet another embodiment, a cardiac harness has a basal-most row (not shown) that is less compliant than rows elsewhere in the harness. In one embodiment, the basal-most row has a larger diameter wire (not shown) than the wire of the other rows of the harness. In another embodiment, the basal-most row has a shorter length of wire (not shown) than the other rows of the harness. As such, once the cardiac harness is appropriately positioned on the heart, the basal-most row tightly engages the heart and resists apical migration of the harness. The basal-most region of the ventricles adjacent to the AV groove undergoes less circumferential change during a cardiac cycle than does the remaining bulk of the ventricles. Accordingly, it is contemplated that the basal-most row will have minimal or no adverse impact on cardiac performance, or cardiac cycle dynamics. It is also to be understood that, in other embodiments, multiple rows, or a basal-most portion of the harness, may have the reduced compliance. Such reduced compliance may be obtained in any manner. For example, in one embodiment the basal-most portion is pre-stretched relative to the rest of the harness. In another embodiment, the basal-most portion is formed of a thicker or different material than other portions of the harness.
• It is to be understood that several embodiments of cardiac harnesses can he constructed and that such embodiments may have varying configurations, sizes, flexibilities, etc. As discussed in the above-referenced applications, such harnesses can be constructed from many suitable materials including various metals, woven or knitted fabrics, plastics and braided filaments, and may or may not include elastic rows. Suitable harness materials also include superelastic materials and materials that exhibit shape memory. For example, a preferred embodiment is constructed of Nitinol. Shape memory polymers can also be employed. Such shape memory polymers can include shape memory polyurethanes or other polymers such as those containing oligo(e-caprolactone) dimethacrylate and/or poly(e-caprolactone), which are available from mnemoScience. Further, harness materials can he elastic or substantially non-elastic.
• With reference toFIG. 6, a representative portion of a cardiac harness embodiment is illustrated. The illustrated portion presents a connector assembly having connectors as discussed in connection withFIG. 4. As discussed herein, the connectors interconnect adjacent rings of the cardiac harness and thus provide longitudinal structure to the harness. The connectors have a length oriented longitudinally relative to the rings so that adjacent rings are spaced apart a short distance.
• As shown inFIG. 6, each of therows36 includes an undulatingspring member74. For purposes of this discussion, each undulating spring member includes aproximal portion75 having aproximal apex76 and adistal portion78 having adistal apex80. Theconnectors52 connect adjacent rows by aligning the proximal apex of one row with the distal apex of an adjacent row, and a connector extends therebetween. The connectors define thespacing82 between the distal apex of one row and the proximal apex of an adjacent row. The connector assembly illustrated inFIG. 6 illustrates an arrangement of connectors that is used as a pattern generally through all or a portion of one cardiac harness embodiment. In connection with this embodiment, and at least the embodiments discussed below in connection withFIGS. 6-9, the term “connector assembly” refers to at least the pattern and spacing of connectors between rows.
• One way to describe the arrangement of connectors in aconnector52 in a connector assembly is by a transverse spacing T between connectors of adjacent rings orrows36. The transverse spacing T is measured as the number of apices between a connector disposed on aproximal apex76 of the row and the nearest connector that is disposed on thedistal apex80 of the row, when counting in a transverse direction (circumferentially). For example, in the embodiment illustrated inFIG. 6, the connectors have a transverse spacing T of 5. In other words, in the disclosed embodiment, there are three proximal apices and two distal apices, totaling five apices between the connectors. Of course, in other embodiments, the transverse spacing can be greater or less than 5. Further, the transverse spacing can vary through the harness. In the illustrated embodiment, however, the connector assembly is arranged such that there is a transverse spacing T of more than one apex between adjacent rows.
• With reference toFIG. 6A, it has been found that when a longitudinal force is applied to aharness32 with a connector assembly having a transverse spacing T of more than one apex betweenadjacent rows36, portions of the adjacent rows between theconnectors52 have a tendency to move longitudinally, while the distance between adjacent rows at the connector remains the same. As such,distended spaces84 are formed between adjacent rows. As shown inFIG. 6A, the result of such distended spaces is that the rows of spring hinges34 are somewhat deformed. In fact, the geometry of the undulatingrows46 can become significantly distorted and inconsistent. When mounting the cardiac harness onto the heart and during operation, the spring members are exposed to varying longitudinal and transverse stresses. Since the design of at least some embodiments of undulating rows are optimized for transverse stresses, distended spaces can result in inconsistent and irregular loading of the cardiac harness embodiment. This can reduce the efficacy of the harness and reduce the lifetime of the undulating rings.
• With reference toFIG. 7, a portion of another embodiment of acardiac harness32 is illustrated. The illustrated portion employs another embodiment of a connector assembly. In the illustrated embodiment, eachconnector52 extends between adistal apex80 of onerow36A and aproximal apex76 of aspring member34 on theadjacent row36B. As shown inFIG. 7, asecond row36B is connected to afirst row36A by aconnector52 extending from a proximal apex of the first row connected to a distal apex of the second row. The second row is then connected to athird row36C by a connector extending from a proximal apex of the second row to a distal apex of the third row. As shown, the connector between the second and third rows is arranged immediately adjacent the connector between the first and second rows so that the transverse spacing T between the connectors is only one apex. A similar disposition exists between thethird row36C andfourth row36D and, preferably through all or a portion of the harness. This arrangement is labeled and referred to as a “1-1-1” longitudinal structure. The transverse spacing T of- the “1-1-1” longitudinal structure minimizes the number of spring member apices between adjacent connectors, and thus minimizes distended stretching of spring members between adjacent connectors. Thus, the longitudinal stretching of the cardiac harness when the harness is installed on the heart is substantially reduced.
• In the embodiment illustrated inFIG. 7, two “1-1-1” connector assemblies (A, B) are shown. In one embodiment, several such connector assemblies extend from the apex54 to thebase56 of the harness. It is to be understood that such connector assemblies can also extend only part way from the base to the apex. It is also to be understood that a cardiac harness may have two or more connector assemblies having different patterns of connectors.
• FIG. 8 illustrates a portion of another embodiment of acardiac harness32 connector assembly. In the illustrated embodiment, the connector assemblies are arranged in a “1-2-1” longitudinal structure. More specifically, the connector assemble is comprised of asingle connector52 interconnecting aproximal apex76 of afirst row36A and adistal apex80 of asecond row36B, followed by twoconnectors52 connecting the adjacent proximal apices of the second row with two adjacent distal apices of athird row36C, followed by a single connector interconnecting a proximal apex of the third row and a distal apex of afourth row36D. As shown inFIG. 8, the two connectors interconnecting the second and third rows are disposed on the apices immediately adjacent the apices supporting the single connector between each of the first and second and the third and fourth rows. The transverse spacing T between adjacent connectors of the rows in this connector assembly embodiment is one apex.
• The illustrated arrangement lends further longitudinal rigidity to the cardiac harness, as longitudinal forces acting upon the harness are generally distributed through the connectors rather than the bending portions of the spring members. This is because there are no spring apices between connectors to allow the creation of distended spaces as illustrated inFIG. 6A. Additionally, the longitudinal stretching of the cardiac harness when the harness illustrated inFIG. 8 is installed on the heart is substantially reduced. Due to the longitudinal rigidity of the cardiac harness, it can be repositioned or moved on the heart by using forceps (or the physician's hand) to pull on the apex of the harness or to grasp and push on the base of the harness.
• It is to be noted that althoughFIGS. 6-8 illustrate connector assemblies comprised of specific numbers ofconnectors52, each connector assembly may advantageously be comprised of more than or less than the number of the connectors illustrated inFIGS. 6-8, depending on theparticular harness32 and/or utilization thereof contemplated. It is also to he understood that although just a few adjacent rows have been illustrated, the illustrated connector assembly arrangements are simply for illustration, and it is anticipated that such arrangements will extend longitudinally through all or at least a portion of the cardiac harness.
• FIG. 9 illustrates another embodiment of a connector assembly for interconnecting rows of a cardiac harness. The connector assembly is formed of several Y-shapedconnectors85, each of which includes afirst attachment portion86, asecond attachment portion87, and athird attachment portion88. The attachment portions give the connector a generally “Y-shaped” geometry. Preferably, the connector is formed of a semi-compliant material, such as silicone rubber or other similar material. In the embodiment illustrated inFIG. 9, the first and second attachment portions of each connector are attached toproximal apices76 of afirst row36A, while the third attachment portion of each connector is attached to thedistal apex80 of an adjacent second row. In another embodiment, the proximal/distal arrangement is reversed.
• As illustrated the transverse spacing T between thefirst attachment portion86 orsecond attachment portion87 and thethird attachment portion88 is one apex. As such, when the harness is subjected to longitudinal forces, most or all of the longitudinal forces will be communicated through the Y-shapedconnectors85 and the bending portions of the undulatingspring members34 will encounter little or none of the longitudinal force.
• It is to be understood that in other embodiments, the specific form and shape of a connector assembly may be different. Yet, the assembly may similarly be adapted to connect adjacent undulating rows so that a proximal portion of a first row is attached to a distal portion of an adjacent row in a manner that communicates longitudinal forces through the connectors and minimizes longitudinal distension of spring members due to such longitudinal forces.
• FIG. 10 illustrates another embodiment of a connector assembly which is utilized for interconnecting rings of a cardiac harness. The connector assembly is comprised of a long,thin connector90 which is interwoven between apices92 (reference number92 points to the apex region since the connector covers the apex) of adjacent undulatingrows36 of acardiac harness32. As shown inFIG. 11, the connector has a length sufficient to pass through every apex92 of the adjacent rows and thus interconnects all of the undulations forming the adjacent rows. The connector preferably is formed of a semi-compliant dielectric material, such as silicone rubber or other similar material. In the embodiment illustrated inFIG. 11, the connector is formed from silicone tubing substantially similar to the silicone tubing discussed with reference toFIG. 3.
• In another embodiment, illustrated inFIG. 12, a row connector is comprised of a long,thin strip94 of dielectric material which is formed into numerouselongate portions96 andattachment portions98. The attachment portions are disposed at opposite ends of each elongate portion. The elongate portions interconnect all of the apices of adjacent undulatingrows36 of the harness. The attachment portions facilitate fastening the elongate portions of the apices93. One embodiment of an attachment portion is illustrated inFIG. 12A, which is cross-sectional view ofFIG. 12, taken alongline12A-12A. As shown, theattachment portion98 is passed over the spring member apex92 (apex region) and adhered to the underside of theelongate portion96, thereby locking the spring member within the attachment portion. Thewire100 forming the cardiac harness has adielectric coating102, which is covered by the attachment portion in the area of the apex of the row. Preferably, an adhesive104 is used to adhere the attachment portion to the elongate portion.
• With continued reference toFIGS. 10 through 12A, because all of the apices participate in connecting the rows of the harness, distended spaces such as those shown inFIG. 6A are substantially eliminated. Additionally, the connectors shown inFIGS. 10 and 12 prevent the rows from becoming overturned, flipped over, or tangled with one another during installation of the harness on the heart.
• It has been found that cardiac harnesses comprised of connector assemblies of the forms shown inFIGS. 10 and 12 exhibit low compliance in longitudinal tension, yet provide relatively high compliance in longitudinal compression. This facilitates normal longitudinal strain of the heart during the cardiac cycle. It has also been found that the connector assemblies ofFIGS. 10 and 12 provide harnesses exhibiting relatively high compliance in shear. This allows adjacent rows to twist with respect to one another, and thereby allows for normal epicardial shear (i.e., torsion) during the cardiac cycle. Moreover, the connectors shown inFIGS. 10 and 12 generally uniformly distribute the compressive forces of the rows on the surface of the heart, thereby reducing the possibility that myocardial aneurysms may form between adjacent rows.
• With reference toFIGS. 13A through 13C, one embodiment of a method for making theconnector94 ofFIG. 12 is shown. Initially, the connector is formed from asheet106 of material having properties and/or characteristics desired for the connector. Preferably, the sheet material is a dielectric, semi-compliant material such as silicone rubber or other similar material. As shown inFIG. 13A, the sheet has a length which is generally longer than its width. As shown inFIG. 13B, a series ofcuts108 are applied to the sheet on opposite sides. The cuts preferably are generally linear along a direction transverse to the length of the sheet. The cuts alternate from one side of the sheet to the other side to form a series ofelongate portions96 which are endwise attached to one another. An undulatingconnector94 is thus provided upon stretching the sheet lengthwise, as shown inFIG. 13C.
• In another embodiment, a row connector includes an elongate tube or wire formed of an elastomeric material such as silicone rubber wound between adjacent apices of adjacent undulating rows. In still another embodiment, the connecting member is not wound between every single adjacent apex. In still another embodiment, a connecting member is formed by molding a row connection member substantially in the shape of the cut connector shown inFIG. 13C.
• With reference toFIG. 14, another example of a method and apparatus for interconnecting theelastic rows36 of aharness32 is provided.FIG. 14 discloses one embodiment of amold110 for making theconnectors52 shown and discussed in connection withFIG. 4, and for assembling a cardiac harness having adjacent undulating rows. The mold includes abase portion112 and aconnector portion114. The connector portion includes agate116 for injecting a liquid material into the connector portion. The connector portion has a shape and size optimal for allowing the liquid material to solidify into a connector. Preferably, the liquid material used for the connectors is silicone rubber or other material suitable for making the connectors. The shape and size of the connectors can vary and the connectors can be formed with ridges or protrusions on the side facing the heart to increase frictional engagement between the connectors and the heart to hold secure the harness on the heart. The base portion is configured to receive at least tworows36. The two rows are releaseably attached to the mold so that at least one apex118 from each row passes within the connector portion. In one embodiment, the rows are fastened to the mold in a stretched state. This facilitates adjusting the positions of the rows on the mold. The mold preferably is made of Teflon or other similar material.
• In operation, theconnector portion114 of themold110 is partially filled with liquid silicone rubber or another material selected for theconnector52. The liquid silicone rubber is injected into the connector portion through thegate116. As discussed above, the tworows36 are positioned on the mold so that oneapex member118 from each ring is positioned within the connector portion, as shown inFIG. 14. Once the apices are suitably positioned, the connector portion is filled to capacity with the liquid silicone rubber. The liquid silicone is then cured in the connector portion. In one embodiment, the liquid silicone rubber is baked in the connector portion at a temperature of about 150° C. for a period of about five minutes. The solidified connector is then removed from the mold along with the two rows.
• In other embodiments, theconnector portion114 can have shapes and sizes different than those shown inFIG. 14, depending on the type of connectors desired. For example, in another embodiment, the connector portion may have a “Y-shape” as illustrated and discussed above in connection withFIG. 9. Moreover, themold110 may include several connector portions to facilitate assembling most or all of a harness.
• FIG. 15 discloses one embodiment of amold110 for making a connector assembly comprisingmultiple connectors52. The mold shown inFIG. 15 is configured for making connector assemblies of the form illustrated and discussed in connection withFIG. 8.Several rows36 can be disposed in the mold shown inFIG. 15 and themultiple connector portions114 can be filled with the liquid material simultaneously. It will be appreciated that in other embodiments, the positions of the connector portions on the mold may be changed to facilitate making other connector assemblies, such as any of the connector assemblies illustrated inFIGS. 6-9.
• Molds of the type illustrated inFIG. 15 are particularly suitable for one method embodiment of making acardiac harness32, in which a totality of the elastic rows36 (FIG. 3) comprising the harness are positioned in amold110 havingmultiple connector portions114 positioned at locations suitable for formingconnectors52 between the elastic rows of theharness32. The elastic rows are positioned in the mold in an arrangement which facilitates simultaneously forming all of the connectors between all of the elastic rows of the harness. Operation of the mold is substantially identical in all respects to the operation of the mold illustrated and discussed in connection withFIG. 14. Once the connectors are formed, the elastic rows are folded so that the opposite ends of each strand meet one another, thereby forming the rows of the harness. The opposite ends are secured to one another as illustrated and discussed in connection withFIGS. 5-5A.
• With reference toFIG. 16, a portion of another embodiment of acardiac harness32 is illustrated. The illustrated portion employs another embodiment of a connector assembly, in which a singleelongate connector120 spansseveral rows36. More specifically, the elongate connector attaches to thedistal apices80 of several adjacent rows. In this embodiment, thespring elements34 are in phase in that all of thedistal apices80 are in line. In a preferred embodiment, one elongate connector extends from abase portion56 of the harness to anapex portion54 of the harness. As such, longitudinal expansion of the harness at or near the connector is substantially entirely controlled by the connector. In another embodiment, an elongate connector spans three or more adjacent rows, and extends at least a portion of the distance between the apex and the base.
• In the embodiment illustrated inFIG. 16, theelongate connectors120 connect to thedistal apices80 ofrows36 spanned by the connector. It is to be understood that other arrangements may also be acceptable. For example, an elongate connector may connect only toproximal apices76 ofadjacent rows36, or may connect to one or both of the proximal anddistal apices76,80 of adjacent rows.
• Although this invention has been disclosed in the context of certain preferred embodiments and examples, it will be understood by those skilled in the art that the present invention extends beyond the specifically disclosed embodiment to other alternative embodiments an/or uses of the invention and obvious modifications and equivalents thereof. In addition, while a number of variations of the invention have been shown and described in detail, other modifications, which are within the scope of the invention, will be readily apparent to those of skill in the art based upon this disclosure. It is also contemplated that various combinations or subcombinations of the specific features and aspects of the embodiments may be made and still fall within the scope of the invention. Accordingly, it should be understood that various features and aspects of the disclosed embodiments can be combined with or substituted for one another in order to form varying modes of the disclosed invention. Thus, it is intended that the scope of the present invention herein disclosed should not be limited by the particular disclosed embodiments described above, but should be determined only by a fair reading of the claims.

Claims (12)

1-26. (canceled)

27. A method of making a cardiac harness for mounting on a heart, comprising:

providing a first row and second row of elastic members;

providing a mold;

placing the rows of elastic members at least partially in the mold; and

injecting connector material into the mold so that the connector material extends between a portion of the first row and a portion of the second row.

28. The method ofclaim 27, wherein placing the first row into the mold comprises stretching the first row.

29. The method ofclaim 27, wherein the connector material comprises an elastomer.

30. The method ofclaim 29, wherein the elastomer is silicone rubber.

31. The method ofclaim 27, wherein the connector material is a polymer.

32. The method ofclaim 31, wherein the polymer is taken from the group of polymers consisting of medical grade polymers, polyethylene, polypropylene, polyurethane, and nylon.

33. The method ofclaim 27, wherein ridges are formed on a surface of the connectors during the molding process.

34. The method ofclaim 27, wherein protrusions are formed on a surface of the connectors during the molding process.

35. The method ofclaim 27, wherein the connectors are attached at an apex on the first row and the second row.

36. The method ofclaim 30, wherein the silicone rubber is baked in the mold at temperature of about 150° C. for a period of about five minutes.

37. The method ofclaim 27, wherein multiple connectors are formed simultaneously by injecting the connector material through multiple gates.

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