Source: http://www.google.com/patents/US20040171906?dq=4316055
Timestamp: 2015-05-05 07:54:33
Document Index: 283044422

Matched Legal Cases: ['art 2', 'art 2', 'art 2', 'art 2', 'art 2', 'art 2', 'art 2', 'art 2', 'art 2', 'art 2', 'art 2', 'art 2', 'art 2', 'art 2', 'art 2', 'art 2', 'art 2', 'art 2', 'art 2', 'art 2', 'art 2', 'art 2', 'art 2', 'art 2', 'art 2', 'art 2', 'art 2', 'art 2', 'art 2', 'art 2', 'art 2', 'art 2', 'art 2', 'art 2', 'art 2', 'art 2', 'art 2', 'art 2']

Patent US20040171906 - Expandable cardiac harness for treating congestive heart failure - Google PatentsSearch Images Maps Play YouTube News Gmail Drive More »Sign inAdvanced Patent SearchPatentsA cardiac harness for treating congestive heart failure is disclosed. The harness applies elastic, compressive reinforcement on the left ventricle to reduce deleterious wall tension and to resist shape change of the ventricle during the mechanical cardiac cycle. Rather than imposing a dimension beyond...http://www.google.com/patents/US20040171906?utm_source=gb-gplus-sharePatent US20040171906 - Expandable cardiac harness for treating congestive heart failureAdvanced Patent SearchPublication numberUS20040171906 A1Publication typeApplicationApplication numberUS 10/788,791Publication dateSep 2, 2004Filing dateFeb 27, 2004Priority dateMar 10, 2000Also published asCA2402504A1, DE60124872D1, DE60124872T2, EP1261294A1, EP1261294B1, US6595912, US6602184, US6612979, US6663558, US6682474, US7077802, US7081086, US7097611, US7124493, US7189202, US7238152, US7276022, US7410461, US20020019580, US20020028981, US20020032364, US20020045798, US20020045800, US20020052538, US20030065248, US20040106848, US20040162463, US20040230091, US20050020874, US20050102016, US20050107661, WO2001067985A1Publication number10788791, 788791, US 2004/0171906 A1, US 2004/171906 A1, US 20040171906 A1, US 20040171906A1, US 2004171906 A1, US 2004171906A1, US-A1-20040171906, US-A1-2004171906, US2004/0171906A1, US2004/171906A1, US20040171906 A1, US20040171906A1, US2004171906 A1, US2004171906A1InventorsLilip Lau, Bill HartiganOriginal AssigneeLilip Lau, Bill HartiganExport CitationBiBTeX, EndNote, RefManReferenced by (2), Classifications (26), Legal Events (7) External Links: USPTO, USPTO Assignment, EspacenetExpandable cardiac harness for treating congestive heart failure
US 20040171906 A1Abstract
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS [0085] The preferred embodiment comprises an apparatus and method for treating established congestive heart failure (�CHF�), as well as for preventing its onset after acute myocardial infarction. Although reference is frequently made throughout this discussion to CHF caused by acute myocardial infarction, the cardiac harness of the disclosed embodiments can be used to treat CHF caused by forward-pump failure from any disease, such as idiopathic dilated cardiomyopathy, hypertrophic cardiomyopathy, and viral cardiomyopathy. The harness acts by the application of a elastic compressive reinforcement on the left ventricle to reduce deleterious and excessive wall tension and to resist shape change of the left ventricle during diastole. Use of this harness can attenuate and potentially reverse the remodeling process that occurs in the left and/or right ventricle following myocardial infarction. [0086] The harness applies compressive reinforcement around the left ventricle over a significant portion of the cardiac cycle while minimizing change to the shape of a ventricle and heart. Rather than imposing a dimension beyond which the heart cannot expand, the preferred embodiment attempts to set no distinct limit to end-diastolic volume. Instead, the apparatus of the preferred embodiment follows the contour of the epicardium and continuously applies a gentle resistance to wall stretch. This avoids the potential to create dangerous restrictive and constrictive conditions, similar to those seen in restrictive cardiomyopathy, constrictive pericarditis, and cardiac tamponade. [0087] A great advantage of the harness of the disclosed embodiments is its elasticity. Elasticity refers to the ability of a material or object to deform and recover its shape when a load is first applied and then removed from it. The greater the deformation from which it can recover, the greater is the elasticity of the material or object. Elasticity allows the cardiac harness to conform and apply pressure to the heart as it fills and empties. Elasticity of the harness is achieved by the use of hinges, which can be U-shaped, that bend elastically under load. These hinges can be arrayed or networked in various ways to impart a desired amount of support in a desired orientation, at a desired location. Another advantageous aspect of the cardiac harness is that the hinges are arranged so as to minimize or avoid foreshortening, especially in the longitudinal direction during circumferential expansion. This allows the device to reinforce the heart without necessarily altering the heart's sphericity to a great degree. [0088] In addition to providing passive elastic support of the heart, the device can also provide an interface to the heart that allows the application of noncardiac power to assist systolic ventricular function. [0089] A preferred embodiment comprises an array of connected hinge elements that are configured to be in compressive contact with the left ventricle. In another preferred arrangement, the connected hinge elements are in contact with the right ventricle or with both ventricles. The array of hinge elements provide selective elastic resistance to stretch during diastole and contractile augmentation during systole. Typically, elastic materials resist deformation with a force that increases with increasing deformation. This force is stored in the material and is released during the unloading of the material. Because wall stress in the left ventricle is thought to be greatest in the circumferential direction, the hinges are predominantly aligned to act in this direction, although it may be desirable to have some elastic support in the longitudinal direction, or some other direction, as well. [0090]FIG. 1 illustrates a mammalian heart 2 with the cardiac harness 4 applied to it. In this illustration, the cardiac harness surrounds both ventricles, from apex to base. Note that the hinges are relatively small in this illustrated embodiment, but in other preferred embodiments, the hinges can be larger. [0091] Each hinge 6 provides unidirectional elasticity, in that it acts in one direction and does not provide much elasticity in the direction perpendicular to that direction. FIGS. 2a-2 c illustrate a preferred embodiment of the elastic hinge. FIG. 2a illustrates how the hinge 6 can be generally U-shaped with a central portion 8 that has at least one inner and outer radius of curvature, and two arms 10 extending from the central portion 8. The two arms 10 are aligned to be roughly perpendicular to the primary direction of elasticity. The components of the hinge 6 lie flat in a plane parallel to the surface of the epicardium. Thus, when the ventricle dilates in congestive failure, the ends of the arms 10 are pulled away from each other, as illustrated in FIG. 2b. This imposes a bending moment on the central portion 8. Mechanically, this creates a state in which there is compression on the outside of the bend 12 and tension on the inside of the bend 14 in the central portion 8 of the hinge 6. These compressive 12 and tensile 14 regions are separated by a neutral axis. The stresses can be distributed differently by varying the shape of the central portion 8. For example, as illustrated in FIGS. 3-7, the hinges 6 can be V-shaped (FIG. 3), U-shaped (FIG. 4), square-wave-shaped (FIG. 5), teardrop-shaped (FIG. 6), or keyhole-shaped (FIG. 7). The deformation and bearing of the load in the hinge structure 6 is taken up primarily by the bending of the central portion 8 and the arms 10. Little load is carried in pure tension parallel to the wire direction. [0092] An advantageous feature is that the hinges 6 are designed such that the elastic limit or yield point of their material is not exceeded during use. In other words, the hinges 6 operate in their elastic range so that they can recover to their original, stress-free configuration when they are unloaded. In addition, an important aspect to the use of a harness 4 comprised of elastic hinges 6 is that the harness 4 is sized such that it remains in elastic, compressive contact with the heart 2. [0093] Another advantageous characteristic of the elastic bending hinges 6 is that they apply increasing resistive force with increasing bending. The more they are stretched, the greater force with which they resist. Overall, a harness 4 constructed of these hinges 6 will behave in a similar fashion. A goal of cardiac or left-ventricular harnessing according to the preferred embodiment is to apply a gentle compressive pressure against the surface of the epicardium of the heart 2. As the left ventricular wall distends locally or globally, it will be met with increasing pressure by the hinges 6, locally or globally. Increased pressure exerted by the harness 4 lowers wall stress within the left ventricle and thus may prevent further infarct expansion, global dilatation, and remodeling. The cardiac harness 4 according to the preferred embodiment mechanically resists size and shape changes that take place in the heart 2 after an acute myocardial infarction. In addition, the harness 4 may be capable of reversing the remodeling process that occurs post-infarction. If reverse remodeling occurs, and the left ventricular shape and size consequently decrease back toward normal, then resistive pressure from the harness 4 will commensurately decrease, as well. [0094] One of the most effective means of limiting infarct expansion and preventing the onset of the remodeling process after an acute myocardial infarction is revascularization of infarcted and jeopardized myocardium. Most often this is achieved by coronary artery bypass grafting. The application of a cardiac harness according to the preferred embodiment during bypass grafting can provide further benefit. The myocardial sparing effect of the harness, by decreasing wall tension, has been shown experimentally to reduce myocardial energy consumption and therefore reduce myocardial oxygen demand. If a bypass graft should become stenosed over time and cause the myocardium to become ischemic, the harness may attenuate any remodeling that might result. In addition to being an accompaniment to coronary artery bypass grafting, application of the cardiac harness might occur at the time of aortic or mitral valve repair or replacement surgeries. [0095] Hinges 6 can be disposed in helical elements, also referred to in this discussion as rings 80, rows, or strips 20, around the circumference of the left ventricle or the heart. Strips 20 can contain one or more connected hinges 6. Hinges 6 in a strip 20 are oriented to have the same axis of elasticity as other hinges 6 in a strip 20. Strips 20 can be joined or they can be independent of one another. As shown in FIGS. 8a-8 e, strips 20 of hinges 6 can be joined by interconnecting elements 16 in a variety of ways. For example, an interconnecting element 16 can join the arm portion of one hinge 6 within a first strip 20 to a central portion 8 of a hinge 6 in a second strip 20. [0096] In FIG. 8b another configuration is illustrated. The central portion of a hinge 6 within a first strip 20 is joined to the central portion of another hinge 6 in a second strip 20, by an interconnecting element 16. As illustrated in FIG. 8c, the interconnecting element 16 can be angled to provide a spring-like mechanism between strips 20. FIG. 8d shows another configuration of the interconnecting element 16, providing firmer support between hinges 6 in different rows 20. [0097] Joined strips 20 can be linked by longitudinally oriented hinges 18 which act as interconnections between strips 20. These longitudinally oriented hinges 18 provide elastic recoil in the longitudinal direction, while the strips 20 of hinges 6 provide the usual elasticity in the transverse direction. This arrangement imparts a more isotropic elastic structure than the previously described embodiments. [0098] An advantageous feature of the preferred embodiment is the decoupling of the action of the harness in the circumferential or transverse dimension from the longitudinal direction. This decoupling is accomplished by allowing a hinge 6 to stretch or bend circumferentially, or transversely, without pulling much longitudinally on the adjacent hinges. This principal is illustrated in FIGS. 9a-9 c. The relaxed, or end-systolic, configuration of the rows or strips 20 of hinges 6 is shown in FIG. 9a. There is considerable longitudinal overlap between the hinges 6 from one strip to another. In FIG. 9b, one can see that by pulling the strips apart in the longitudinal direction (along the Y axis), there is a little or no foreshortening of the strips 20 of hinges 6 in the transverse direction (i.e., along the X axis). This lack of foreshortening in the X axis is due to the fact that pulling apart the strips 20 of hinges 6 in the Y direction produces very little compression of the hinges 6. [0099]FIG. 9c illustrates a corollary property of the hinges 6, most readily seen when the cardiac harness 4 is applied to a live heart 2: The stretching of the strips 20 of hinges 6 in the transverse (X-axis) direction produces very little or no foreshortening in the longitudinal (Y-axis) direction. In the region of the cardiac base, which is close to the outflow (aortic and pulmonic) valves, it is advantageous to have the rows 20 of hinges 6 expanding and contracting in the circumferential or transverse direction (i.e., along the X axis) while little or no foreshortening in the longitudinal direction (i.e., along the Y axis) occurs. This phenomenon is illustrated in FIG. 9c. Closer to the cardiac apex, it may be more advantageous to have the rows or strips 20 of hinges 6 move apart in the longitudinal direction (i.e., along the Y axis) while there is very little or no foreshortening in the circumferential or transverse direction (i.e., along the X axis). This phenomenon is illustrated in FIG. 9b. [0100] An additional way that the longitudinal expansion of the harness can be decoupled from the transverse expansion of the harness is through the use of elastically recoiling interconnecting elements 16, as illustrated in FIGS. 8a and 8 c. Additionally, having interconnecting hinges 18, as illustrated in FIG. 8e, is an additional way of decoupling the longitudinal from transverse expansion and contraction of the hinges 6 within the harness 4. [0101] Alternatively, as illustrated in FIGS. 10 and 11, the rows or strips 20 of hinges 6 can be interlocked (FIGS. 10a and 10 b) or interwoven (FIGS. 11a and 11 b). To interlock strips 20 of hinges 6, the central portion 8 of a hinge 6 from a first row, or strip 20, is placed between the arms 10 of a hinge from a second row. This placement of a �hinge within a hinge� occurs for one or more hinges 6 in a first strip 20, relative to the hinges in a second strip. To interweave strips 20 of hinges 6, as illustrated in FIGS. 11a and 11 b, the strips 20 are configured such that one arm 10 of a first hinge 6 from a first strip 20 lies under the central portion 8 of a second hinge from a second strip, while the other arm 10 of the first hinge 6 lies over the central portion 8 of the second hinge from the second strip. [0102] Another embodiment comprises a variable hinge network (not illustrated). In this network, hinges within a strip vary in height. Thus, a short hinge may be followed by a tall hinge, followed by a short hinge, and so on within a strip. This variable hinge network provides the capability to tailor the stiffness of the harness such that the stiffness varies with the degree of stretch. For example, at some first threshold of distension, the tall hinges deform, and at some higher threshold of distension, the shorter hinges, which are stiffer, begin to deform. This arrangement can advantageously provide a pressure-versus-diameter curve for the harness that exhibits two distinct stiffness peaks at different diameters�with diameter corresponding to ventricular wall stretch or degree of distension. [0103] An important difference between the decoupled hinge harness construction of the preferred embodiment and a knitted fabric harness, or cardiac �sock,� is the hinge harness's ability to closely track changes in sphericity of the underlying heart, whether the heart is healthy or diseased. This has been demonstrated experimentally by using an inflated latex bladder, which simulates a heart in its expansion and contraction. First, relative changes in sphericity of the bladder were measured. Note that sphericity is defined as diameter (D) divided by length (L): sphericity = diameter length [0104] This relationship is illustrated in FIG. 12, which shows the diameter (D) of the heart in the transverse dimension and the length (L) of the heart in the longitudinal direction. The results of this experiment are illustrated in FIG. 13. When the bladder was inflated alone (i.e., without the presence of a harness), it generated a sphericity-versus-volume curve that is illustrated as the middle curve in FIG. 13. When a polyester knit �sock� was applied to the bladder, there was a great increase in sphericity as the volume of the bladder increased, as illustrated by the top curve of FIG. 13. In contrast, when the elastic hinge harness 4 of the preferred embodiment was applied to the bladder, the sphericity-versus-volume curve more closely matched that of the unencumbered bladder alone. The elastic hinge harness sphericity curve is illustrated as the bottom curve in FIG. 13. Thus, the elastic hinge harness of the preferred embodiment closely tracks changes in sphericity over a range of volumes of the underlying structure, in this case a latex bladder. The nonforeshortening elastic hinge harness 4 had little impact on the sphericity index as bladder volume increased. In fact, the sphericity index values were slightly lower than for the bladder alone. In contrast, the presence of the knitted sock significantly increased the sphericity of the bladder as its volume was increased. This demonstrates the potential importance of the nonforeshortening elastic feature of the harness with respect to its application to the human heart. The harness has the ability either (1) to �track� (i.e., minimally alter) changes in sphericity of one or both ventricles throughout systole and diastole; or (2) to progressively decrease the sphericity index of the heart, relative to an unencumbered heart (i.e., without the harness), as diastole proceeds, whether the heart is healthy or in congestive failure. [0105] The hinges 6 can be made of a variety of materials, including metals, polymers, composites, ceramics, and biologic tissue. Specific materials include stainless steel, Elgiloy, titanium, tantalum, Nitinol, ePTFE, collagen, nylon, polyester, and urethane. Advantageously, the hinges are made from a metal, particularly Nitinol, because metals have a higher Young's modulus or stiffness, than polymers or tissue. This allows less mass and volume of material to be used to achieve the same mechanical reinforcing strength. Prosthetic materials that are directly applied to the epicardium, especially if there is some relative movement between the epicardium and the material, can induce fibrosis, which is marked by collagen deposition leading to scarring. Consequently, an implant with less surface area in contact with the epicardium tends to generate less fibrosis on the surface of the heart. Excessive fibrosis can lead to a constrictive pericarditis and, ultimately, to elevated venous pressures with disastrous consequences. [0106] Nitinol is especially suitable for the construction of the harness 4. It has the advantageous capability of being able to remain elastic over a great range of strain, up to 4%, which is greater than other metals. It generates a relatively benign foreign body response from tissue, and it is relatively magnetic-resonance-imaging-compatible, as it is not highly ferromagnetic. Nitinol is also corrosion- and fatigue-resistant. In addition, metal such as Nitinol are more creep-resistant than polymeric or tissue based materials. In a passive elastic harness application, hinge 6 would be formed in an austenitic state at body temperature when no load is applied and the material is in a stress-free state. When the harness is placed on the heart, the contact pressure between the harness and the heart may stress-induce martensite within the otherwise austenitic structure. [0107] The hinge elements can be made from wire, or they may be machined from sheet or tubing material, or a combination of these. In order to make such a structure out of Nitinol wire, the wire is wound and constrained in the desired configuration. It is then annealed at approximately 470� C. for approximately 20 minutes to set the shape. Alternatively, Nitinol tubing can be machined with a laser to create the desired structure. Another alternative is the photochemical etching of sheets of Nitinol. In both of these latter methods, a subsequent annealing can be performed. [0108] In addition to varying the direction of elastic support, the extent of support or stiffness can be varied as well. Hinges of different shape or of different material dimensions can accomplish this. Because of the difference in compliance between the left and right ventricles, it can be desirable to have the left side of the harness stiffer than the right side. This can be achieved in several ways. A harness structure can be constructed with stiffer hinges against the surface of the left ventricle than the right, as illustrated in FIG. 14. The hinges covering the left ventricle 22 are thicker, smaller, or otherwise stiffer than the hinges covering the right ventricle 24. Also shown in FIG. 14 are the individual strips 20 of hinges, as well as the interventricular septum 25, between left ventricle (LV) and right ventricle (RV). [0109] In a preferred arrangement, a wire or plastic frame comprising two struts (not illustrated) can be integrated with the harness 4. The frame acts similarly to a clothespin, in that it exerts a clamping pressure along vectors 180 degrees apart, limiting the amount the ventricle(s) are allowed to distend. The amount of pressure exerted by the frame can be adjusted by making the frame larger or smaller, or thicker or thinner. The harness can also feature more than one frame. The harness's hinges 6 positioned between the wire frames, or between struts of frames, can be of varying thickness or size to apply varying stiffness and to allow for more or less ventricular distension. [0110] In another embodiment, illustrated in FIG. 15, the cardiac harness may be selectively applied to only the left ventricle (or the right ventricle), depending on which side has failed. In this illustration, the cardiac harness is applied to the left ventricle because the left ventricle fails far more often than the right ventricle. The harness may be anchored to the left ventricle in a variety of ways, including having anchoring struts that extend into the interventricular septum 25, as shown in FIG. 15. [0111] Advantageously, most or all of the surface of the left ventricle is covered by the harness 4. This ensures maximum reinforcement both globally, to attenuate global shape change and dilatation, and locally, to prevent ventricular wall thinning and stretch in an infarcted area. Note that this not to say that the actual surface area of the harness in contact with the epicardium needs to be large. [0112]FIGS. 16a and 16 b illustrates a protection mechanism for minimizing compression of one or more coronary arteries 26. To minimize the risk of ischemia, the compression of the harness on an epicardial coronary artery 26 can be alleviated by placement of protecting strips 28 on either side of the coronary artery 26. This mechanism lifts the harness 4 off of the coronary artery 26. A suitable material for the protecting strip 26 can be expanded polytetrafluoroethylene ePTFE. [0113] Another approach to minimizing compression of the coronary artery 26 is illustrated in FIG. 17. A wire frame 30 that runs parallel to the coronary artery 26 can be integrated into the harness 4. The hinges 6 can be suspended from the wire frame 30 like curtains on a curtain rod. The hinges 6 extend from one arm of the wire frame 30 to the other over the surface of the myocardium, between coronary arteries. [0114] Advantageously, the compliance of the elastic harness 4 is in the range of compliance of native pericardium or latissimus dorsi muscle wraps. Preferably, the compliance of the harness 4 increases gradually as a function of stretch. Over the operational range of the harness, compliance should not fall so low that the harness 4 becomes constrictive. Therefore, the pressure exerted on the heart 2 by the harness 4 preferably does not exceed 10 mm Hg. However, if only the left ventricle is reinforced by the harness 4, then greater pressures are possible without causing constrictive conditions. [0115] Various designs incorporating decoupled hinges 6 are possible. The hinges 6 can wrap continuously around both ventricles or just around the left ventricle or right ventricle. The harness 4 can have a seam for size adjustment, or it can be of a one size fits-all design. A Nitinol harness can be provided presized to fit the dimensions of a patient's heart. Alternatively, the harness components can be provided in a kit that a surgeon can custom-assemble in the operating room, based on sizing information gained before or at the time of surgery. A kit can consist of modular components that can be assembled quickly. The use of hinge strips 20 that are ring-shaped and of varying diameters and stiffness is one possibility. The surgeon can interlock hinges 6 between adjacent hinge strips 20 in order to couple the strips 20, as illustrated in FIG. 10b. Precise sizing can be facilitated by using a belt buckle or adhesive fastener (e.g., a hook-and-loop fastener, such as Velcro�) type of design, as illustrated in FIGS. 18a and 18 b. FIGS. 18a and 18 b illustrate the harness 4 wrapped around the heart 2, with a leading flap 32 that integrates an adhesive strip, such as Velcro�, for securing the harness 4 onto the heart 2. Such a design is not readily achievable using the knitted sock of previous designs. [0116] Delivery of the harness 4 can be accomplished through conventional cardiothoracic surgical techniques through a median sternotomy. Alternatively, the harness 4 may be delivered through minimally invasive surgical access to the thoracic cavity, as illustrated in FIG. 19. A delivery device 36 may be inserted into the thoracic cavity 34 between the patient's ribs to gain direct access to the heart 2. Preferably, such a minimally invasive procedure is accomplished on a beating heart, without the use of cardiopulmonary bypass. Access to the heart can be created with conventional surgical approaches. The pericardium may be opened completely, or a small incision can be made in the pericardium (pericardiotomy) to allow the delivery system 36 access to the heart 2. The delivery system 36 of the disclosed embodiments comprises an integrated unit of several components, as illustrated in FIGS. 20a and 20 b. Preferably, there is a releasable suction device, such as a suction cup 38, at the distal tip of the delivery device 36. This negative pressure suction cup 38 is used to hold the apex of the heart 2. Negative pressure can be applied to the cup 38 using a syringe or other vacuum device. A negative pressure lock can be achieved through a one-way valve, stopcock, or a tubing clamp. The suction cup 38, advantageously formed of a biocompatible material, is preferably stiff to prevent any negative pressure loss through heart manipulation. this provides traction by which the harness 4 can be pushed forward onto the heart 2. In addition, the suction cup 38 can be used to lift the heart 2 to facilitate advancement of the harness 4 or allow visualization and surgical manipulation of the posterior side of the heart 2. After secure purchase of the apex of the heart 2 is achieved, the harness 4, which is collapsed within the body 46 of the delivery device 36, is advanced distally toward the heart 2 by actuating fingers 40. The harness 4 can be inverted (i.e., turned inside-out) ahead of time, to allow it to unroll, or evert as it advances over the surface of the heart 2. In this discussion, the term �evert� means turning right-side-in, i.e., reversing an inverting process. After the harness 4 is advanced into place, the suction is released and the delivery system 36 is released from the harness 4 and heart 2. [0117]FIGS. 21-25 illustrate the application of the cardiac harness 4 to the heart 2 in various stages. FIG. 21 shows the delivery device, which may be a catheter in one embodiment, comprising a body 46 and a handle 44. The catheter body 46 is advanced through the skin 48 of the patient. The suction 38 moves in proximity to the apex 42 of the heart 2. The harness 4 is inverted (i.e., turned inside out) and is collapsed within the body 46 of the delivery device. [0118]FIG. 22 illustrates engagement of the apex 42 of the heart 2 by the suction cup 38. Suction may be applied to the apex 42 of the heart 2 by moving the handle 44 in one or more directions, or by using a syringe or other suction device (not illustrated). [0119]FIG. 23 shows advancement of the harness 4 by the actuating fingers 40 within the body 46 of the delivery device. The harness 4 may be advanced over the heart 2 by moving the handle 44 toward the heart 2 relative to the body 46 of the delivery device. [0120]FIG. 24 shows further advancement and unrolling, or everting, of the harness 4 as the actuating fingers 40 move distally and outwardly relative to the delivery device body 46. The suction cup 38 remains engaged on the heart 2. [0121]FIG. 25 illustrates completion of the placement of the harness 4 on the heart 2. After the harness 4 is in position on the heart 2, the handle 44 may be withdrawn from the body 46 of the delivery device, pulling the actuating finger 40 back within the body 46 of the delivery device. The suction cup 38 is also released from the heart 2 and harness 4, and the delivery device is withdrawn from the patient though the skin 48. [0122]FIGS. 26a-26 d illustrate another embodiment of the delivery device, in which the actuating fingers 40 of the device form a loop or �flower petal� configuration. The actuating fingers 40 are withdrawn within the body 46 of the delivery device in FIG. 26a. FIGS. 26b and 26 c show a progressive advancement of the actuating fingers 40 distally from the body 46 of the delivery device. As the fingers 40 advance, they expand outwardly into a larger loop or flower petal configuration. FIG. 26d is an en face view of the delivery device body 46 and the flower-petal-shaped actuating fingers 40. [0123] The harness 4 can be secured in place on the heart 2, using sutures or staples to prevent it from migrating. Alternatively, the harness 4 can self-anchor to the epicardium to prevent it from migrating. This self-anchoring can be accomplished by incorporating inward-facing barbs or anchors 50 in the harness structure 4, as illustrated in FIGS. 27a and 27 b. The anchors 50 preferably extend from the hinges 6 into the wall of the heart 2. [0124]FIG. 28 shows an alternative embodiment of the delivery device. The body 46 of the delivery device is curved to facilitate placement and/or manipulation of the device by the surgeon. Also illustrated is a syringe 52 for injecting fluids or for generating suction on the distal suction cup 38 to secure the suction cup 38 to the apex 42 of the heart 2. Also illustrated is the harness 4 that is partially withdrawn within the body 46 of the delivery device. [0125]FIG. 29 shows an alternative embodiment of the delivery device. The body 46 of the delivery device is straight in this embodiment. [0126]FIG. 30 illustrates advancement of the harness 4 and actuating fingers 40 onto the heart 2. [0127]FIG. 31 shows completed placement of the harness 4 onto the heart 2 by the delivery device. Note that the actuating fingers 40 form a loop, and, in some embodiments, the actuating fingers 40 are made of flexible material to form flexible straps or bands. [0128] The harness 4 not only has the capability of acting as a passive restraint around the heart, but may also be actively powered to provide contractile assistance during systole. This may be done by the application of electrical or mechanical power to the harness 4. [0129] If electrical current or heat is applied to the harness 4 in the stressed state, the resistive force generated by the bending deformation increases. In essence, the harness 4 generates a contractile force when current is applied to the harness 4. Hence, it is possible to actively power an otherwise passive elastic harness 4 in order to achieve systolic pumping assistance. This effect is additive in the myocardial sparing benefit that the harness 4 provides. [0130] During systole and perhaps at end-diastole, current can be applied to the harness 4 to make it contract and thus assist in left ventricular contraction. Such a mechanism is illustrated in FIG. 32. The harness 4 surrounds the heart 2. An electrical wire 60 extends from an internal power supply 54 to the harness 4. [0131] In this context, the internal power supply 54 is a device that supplies electrical energy to the harness 4. It may also comprise a battery and, in some embodiments, a radiofrequency transducer for receiving and/or transmitting radiofrequency signals to and from an external radiofrequency (�RF�) transducer 56 which may send and/or receive RF signals from the internal power supply 54. Thus, the external RF transducer 56 may recharge a battery within the internal power supply 54. Also, the external RF transducer 56 may be used to send program information from the external RF transducer 56 to the internal power supply 54, or vice versa, regarding electromechanical sensing and/or pacing information, cardiac rhythm, degree of ventricular or harness contractility, heart-rate information, or the like. Alternatively, the external RF transducer 56 may supply electrical power through inductive field coupling between the external RF transducer 56 and the internal power supply 54. [0132] In some embodiments, an external power supply 58 can be used, which may be a battery pack in various preferred arrangements. The external power supply 58 may supply current to the external RF transducer 56, which may in turn supply electrical energy to the internal power supply 54 through inductive field coupling. The technology for this inductive field coupling, including electronic programming and power transmission through RF inductive coupling, has been developed and is employed in, for example, cardiac pacemakers, automatic internal cardiac defibrillators, deep brain stimulators, and left ventricular assist devices. [0133] The power requirement of the device of the disclosed embodiments is significantly lower than that of conventional left ventricular assist device because the native heart in the present application continues to do some work. The powered harness 4 merely augments native cardiac contractions. [0134] Rather than a Nitinol harness 4 providing active systolic assistance, variable current can be applied to the Nitinol to simply vary the harness's 4 passive stiffness. As such, power is not used to actively �squeeze� the heart 2 during systole. The harness 4 is instead a passive elastic harness with adjustable compliance. A physician can adjust the power to a harness 4 to vary the amount of resistive pressure it exerts on the left ventricle during both systole and diastole. The passive stiffness of the harness 4 can be set to change throughout the cardiac cycle, or it can be adjusted to maintain constant levels. For example, when the cardiac harness 4 is placed on the heart 2, the physician can set the harness 4 to a certain degree of stiffness. Depending on how the patient responds, the physician can then increase or decrease stiffness by varying the electrical stimulating parameters to the harness 4. Adjustment and stimulation of the harness 4 can be accomplished through an implantable pacemaker-like box, the internal power supply 54, that is electrically connected to the harness 4 through at least one wire 60. This is one embodiment of the configuration illustrated in FIG. 32. [0135] The harness 4 may be integrated with an implantable pacemaker or a internal cardiac defibrillator, according to the needs of the patient. [0136] Mechanical power can be applied to the harness 4 through sliding cables 70 as illustrated in FIGS. 33 and 34. A cable 70 can extend over the surface of the harness 4 between two points. The cable 70 is actually an inner sliding element that resides partially within an outer housing 68. Mechanical actuation of the cable 70 by, for example, an actuation box 62 causes the two components, illustrated in FIGS. 33 and 34 as struts 72 within the harness 4, to slide or otherwise move relative to each other. If the end 74 of the housing 68 is attached to one strut 72, and the distal end of the cable 70 is attached to another strut 72, then actuation of the cable causes the two struts to move closer and/or farther apart relative to one another, causing the heart to contract and/or expand. If timed with systole, this mechanism provides contractile assistance. [0137] Also illustrated in FIGS. 33 and 34 are the actuation-box 62, which-converts electrical energy to mechanical energy to move the cable 70 within the housing 68; a power lead line 64, extending from the internal power supply 54 to the actuation box 62; and an electrical sensing lead 66, which can sense cardiac contractions or cardiac electrical activity, such as an electrocardiographic signal. This sensing is similar to the way in which pacemakers sense cardiac electrical activity, receiving information concerning the rate and rhythm of the heartbeat. Also illustrated in FIGS. 33 and 34 are the external RF transducer 56 and the external power supply 58, as previously described. [0138]FIG. 33 illustrates the struts 72 as unattached to one another, while FIG. 34 shows the struts 72 attached at a point 76 near the apex of the heart 2. These two different embodiments can confer different mechanical and hemodynamic advantages upon actuation of the cable 70 and consequent contraction and expansion of the heart 2. [0139]FIG. 35a-36 b illustrate a method of manufacturing the strips, or rows, of hinges 6. A sheet (or more than one sheet) of Nitinol or other suitable material is cut to form a single, continuous ring 80 of hinges 6. This ring 80 is initially flat after it has been cut from the sheet of material, as shown in FIG. 35a (top view) and 35 b (side view). The ring 80 is preferably parallel to the surface (e.g., a table or board) on which the ring 80 is formed. The ring is then manipulated to create a band-like configuration, which can be cylindrical or beveled, as illustrated in FIG. 36a (top view) and 36 b (side view). [0140] Compared to conventional left ventricular assist devices, the harness 4 of the disclosed embodiments has many advantages. It can be minimally invasively delivered, and it can be permanently implanted without need for subsequent removal. This allows it to provide incremental therapy as needed. If necessary, it can be powered to provide contractile assistance. If this is not necessary, the power can be shut off to allow it to act as a passive elastic reinforcement for the failing heart. [0141] In addition, such a system can provide circulatory assistance with a fraction of the power demands of a left ventricular assist device. Left ventricular assist devices are estimated to require nearly ten watts of power. The heart itself operates at only approximately one watt of power. Because a powered harness works with the existing heart, it should not need nearly the amount of power of a left ventricular assist device. In addition, because the harness 4 does not come in direct contact with blood, there is no need to anticoagulate the patient with, for example, warfarin (Coumadin) or heparin. There is also no independent reason to treat the patient with antiplatelet drugs. A harness system involves less machinery than a left ventricular assist device. This and other attributes impose less detriment to a patient's quality of life. Last, such a system is relatively simple and therefore less costly than a left ventricular assist device. [0142] Power to actuate the cable 70 can come from an internal or external source. An internal source can alternatively be skeletal muscle, such as in situ latissimus dorsi muscle or a mechanical motor. If power is needed, it can be delivered transcutaneously as described above, using existing technology developed by, for example, left-ventricular-assist device companies. [0143] Although the present invention has been described in terms of certain preferred embodiments, other embodiments that are apparent to those of ordinary skill in the art are also within the scope of the invention. Accordingly, the scope of the invention is intended to be defined only by reference to the appended claims. Referenced byCiting PatentFiling datePublication dateApplicantTitleUS7621866May 31, 2005Nov 24, 2009Ethicon, Inc.Method and device for deployment of a sub-pericardial sackUS7959555Oct 13, 2009Jun 14, 2011Ethicon, Inc.Method and device for deployment of a sub-pericardial sackClassifications U.S. Classification600/37International ClassificationA61N1/362, A61N1/375, A61F2/24, A61N1/05, A61F2/00, A61B17/00Cooperative ClassificationY10T29/49995, A61M1/1068, A61M2205/3523, A61M1/1048, A61M1/1003, A61N1/3627, A61M1/1056, A61F2/2481, A61M2205/0266, A61F2002/0072, A61N1/0587, A61M1/127, A61M1/122, A61M2205/8206, A61F2002/2484European ClassificationA61M1/10E50B, A61F2/24W2, A61N1/362C, A61N1/05PLegal EventsDateCodeEventDescriptionSep 16, 2014FPExpired due to failure to pay maintenance feeEffective date: 20140725Jul 25, 2014LAPSLapse for failure to pay maintenance feesMar 7, 2014REMIMaintenance fee reminder mailedJan 25, 2010FPAYFee paymentYear of fee payment: 4Nov 3, 2009ASAssignmentOwner name: PARACOR MEDICAL, INC., CALIFORNIAFree format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:EUGENIO, JOHN;REEL/FRAME:023456/0518Effective date: 20090907Dec 18, 2007CCCertificate of correctionNov 7, 2006CCCertificate of correctionRotateOriginal ImageGoogle Home - Sitemap - USPTO Bulk Downloads - Privacy Policy - Terms of Service - About Google Patents - Send FeedbackData provided by IFI CLAIMS Patent Services