Patent Application
20050043708
The present invention relates generally to the art of surgical instruments and methods and, in particular, to an improved apparatus and method for performing an anastomosis or surgical connection between tubular structures or vessels. The present invention finds particular application in the anastomotic joining of vascular tissue for the purpose of bypassing an occluded or diseased section of a blood vessel, such as a coronary artery, and will be described with particular reference thereto. However, it will be recognized that the present invention is amenable to anastomosis in general. The present invention further has broader applications in many different environments, such as securing patches for the noninvasive correction of intestinal perforations, deep hole wound closures, and others. The present invention has still further applications in the medical field, such as in affixing medical devices to tissues, attaching biological microelectromechanical systems (MEMS), drug delivery, sensor attachment and uses as a stent.
Commonly in coronary artery bypass graft (CABG) procedures, one or more graft vessels are hand sutured into place between a blood source, such as the aorta, and a target coronary artery, such as the left anterior descending artery. Most CABG procedures are accomplished by opening the chest wall to gain access to the coronary vessels. Through the use of heart-lung bypass machines and cardioplegia to protect the heart, the heart is stopped to enable the surgeon to perform the precise manipulations required to hand suture the tiny, delicate vessels.
Although bypass grafting has been highly successful, there exists a need for minimally invasive techniques for bypassing the coronary arteries and for performing the anastomosis on a beating heart. Minimally invasive procedures have been developed in which the bypass is performed through a small incision in the chest wall. A number of techniques are also known for reducing the effects of vessel movement when performing the suturing on a beating heart. However, techniques that dampen or isolate the translation of movement from the beating heart to the artery can damage the vessel or cause myocardial injury.
Additionally, techniques are also known which rely on cooling the patient to slow the rate of the beating heart. This allows the surgeon to place the sutures between heartbeats. However, such techniques can increase the time it takes to perform the procedure and do not eliminate the movement of the artery.
Consequently, there is a need for a catheter-based, mechanical method for automating an anastomosis, i.e. the surgical connection of tubular. structures. Such an apparatus and method do not require hand suturing and provides for a leak-free connection between vesicles.
Separate and apart from the above, left ventricular enlargement or “remodeling” is a pathologic, progressive process that can follow myocardial infarction and other cardiomyopathies. The infarcted region becomes noncontractile and akinetic or dyskinetic, thus reducing the volume output of the heart. As a result, left ventricular enlargement occurs to restore or maintain output of oxygenated blood to the body. This dilation has the deleterious effect, however, of imposing an extra workload on the remaining healthy heart tissue and increasing wall tension, which, in turn, stimulates hypertrophy. With damage to the myocardium, however, these increased requirements placed on the contracting myocardium may be of such an extent that cardiac output requirements are not met, and the heart continues to dilate progressively. This cycle can lead to congestive heart failure, which is a major cause of death and disability in the United States.
Additionally, postinfarction left ventricular aneurysm is an extreme example of adverse left ventricular remodeling. Such an aneurysm leads to deterioration of cardiac functions and symptoms of congestive heart failure.
In order to address these difficulties, it is known to place a patch within an enlarged left ventricle to reduce the volume, improve ejection fraction, reduce wall stress, and otherwise to restore the ventricle to a more physiologic morphology and function. Typically, these procedures have required incising and introducing the patch through the heart wall and hand suturing the patch in place. Thus, there also exists a need for an endoventricular patch plasty apparatus and method that is catheter-based and that does not require hand suturing.
The present invention contemplates new and improved catheter-based tissue attachment devices and non-invasive methods which overcome the above-referenced problems and others.
In a first aspect of the present invention, a catheter-based apparatus for treating a heart includes a housing member having a plurality of elongate channels defined therein and which is movable between a first collapsed position and a second expanded position. A tissue attachment member is positioned in each channel.
In a second aspect of the present invention, a device for performing an anastomosis between a first tubular structure and a second tubular structure includes a housing member having a plurality of elongate channels defined therein and which is movable between a first collapsed position and a second expanded position. A surgical clip is positioned in each channel. A clip deployment mechanism projects the clips from their respective housings and a registration member approximates and aligns the first and second tubular structures.
In a third aspect, an apparatus for altering the morphology of a heart includes a sheet of biocompatible material adapted for placement within a ventricle and having a plurality of generally rigid elongate sleeves attached thereto. The sleeves are spaced apart and extend radially. A surgical barb is movably secured within each sleeve. The barb moves between a first position in which the barb is constrained within its respective sleeve and a second position adapted for securing the sheet to an interior wall of the heart.
For example, this aspect of the present invention can be used for the treatment of the enlargement of the left ventricle that results from a variety of heart ailments. This condition leads to congestive heart failure with a median population mortality of 5 years. The present invention can be utilized to reduce the volume of the left ventricle in order to reduce stress in the myocardium and increase the ejection fraction of the heart. In utilizing this aspect, a diaphragm can be deployed by a catheter into the left ventricle of the heart, creating two separate chambers and reducing the overall volume.
In a fourth aspect, a method for treating a heart includes forming a first elongate incision in a vascular graft and a second elongate incision in a target coronary artery of the heart to define an anastomotic site. A catheter is inserted into the graft and the incisions in the graft and the target artery are aligned. A registration device is passed from the catheter through the first and second incisions, into the target artery, and a tissue-fastening device is passed from the catheter into graft. The tissue fastening apparatus includes a housing member having a plurality of elongate channels defined therein, the housing member being movable between a first collapsed position and a second expanded position, a surgical clip positioned in each channel, and a clip deployment mechanism for projecting the clips from their respective channels. The graft and target artery are approximated with the registration device and the clips are deployed from their respective channels. The housing member, clip deployment mechanism, registration device, and catheter are then removed from the anastomotic site.
In a fifth aspect of the present invention, a method for reducing the volume of a heart ventricle includes introducing a patch into the ventricle and securing the patch to an interior wall of the ventricle using barbs. The patch includes a sheet of biocompatible material adapted for placement within a ventricle, a plurality of generally rigid, elongate, and radially extending sleeves attached to the sheet, and a surgical barb movably secured within each sleeve.
The present invention is adapted to minimally invasive techniques, thus reducing the trauma, risks, recovery time, and pain that accompany current open-chest techniques.
Still further advantages and benefits of the present invention will become apparent to those of ordinary skill in the art upon reading and understanding the following detailed description of the preferred embodiments.
The invention may take form in various components and arrangements of components, and in various steps and arrangements of steps. The drawings, in which like reference numerals denote like components throughout the several views, are only for purposes of illustrating preferred embodiments and are not to be construed as limiting the invention.
Turning now to the drawings, wherein the showings are for purposes of illustrating the preferred embodiments of the invention only and not for limiting the same,
A longitudinal incision 18 is defined in the artery 12 at the intended anastomotic site 10, for example, by surgically exposing or accessing the artery and cutting. Alternatively, a blade or other means for forming the incision 18 can be advanced to the anastomotic site 10 intraluminally in a catheter via the artery 12 for forming the incision 18 percutaneously. A corresponding incision 22 is also defined in the graft 14.
The graft vessel 14 can be a harvested blood vessel segment such as the saphenous vein or interior mammary artery (IMA), or, a synthetic vascular graft material. Alternatively, the graft 14 can be a nearby vessel anastomosed to the artery 12 in situ. In still other embodiments, the graft 14 may be a vessel, such as the IMA, that is harvested at one end only and left attached at the end distal to the anastomotic site.
Referring now to
In operation, the graft 14 and artery 12 are placed in longitudinal alignment so that the respective incisions 22 and 18 are substantially in aligned, facing relation. The catheter is then advanced within the lumen of the graft 14 until the distal end 24 is aligned with the incision 22.
The main housing 34 includes foldable or flexible walls 38 and hollow rigid or semirigid elongate clip housing members or stays 40, either defined therein or secured thereto, each defining a channel and retaining a clip 36. The flexible walls 38 are formed of a sheet material, such as Dacron polyester, polytetrafluoroethylene, and the like such as GORE-TEX polytetrafluoroethylene, or other FDA class 3 materials for implantation. The elongate clips 36 are formed from a shape memory alloy (SMA) or superelastic alloy that is FDA class 3 approved for implantation, such as NITINOL or TiNi, which are nickel-titanium based alloys, or alike materials.
The clips are formed of a shape memory or superelastic material, e.g., a nickel-titanium alloy, for example, in the form of a wire having a needle-like point 37 (see
The shape-memory or superelastic clips 36 are readily deformable and are placed in the elongate channels 40, which constrain the clips in temporary, straightened shape. In a particularly preferred embodiment, the elongate channels have a slightly elliptical or oval cross-sectional shape. Since the pre-shaped clips have a lower stress when the plane of the circle defined by the unrestrained clip is aligned with the long axis of the ellipse, the clip inherently maintains the desired alignment in the channel. Thus, the orientation of the channels is selected to control the direction and orientation of the clips 36 when they are deployed. The specific preset curvature of the clips is selected to control the bite of the clip as it is deployed. Also, the alloy composition and/or the heat-treatment conditions (temperature, time) can be adjusted to impart the desired shape-memory or superelastic characteristics.
In certain embodiments, a nickel-titanium alloy designed to take advantage of the superelastic effect, i.e., having an active Af temperature below the use temperature (e.g., body temperature), is employed as the clip 36 material. Such clips are extremely flexible and absorb the strain energy of being constrained in the clip housing channels 40. The strain energy is released as the applied strain is removed, i.e., when the clips are deployed from the channels 40, reverting to the helical shape. In this regard, the clip housings are elliptically shaped tubes that elastically constrain the previously shaped clips. The elliptical shape of the housing allows the direction of the deployed clip to be defined—the curvature of the clip will align itself with the major axis of the elliptical ID, which minimizes the strain in the clip. The clip may be deployed by mechanically ejection from the housing, for example, by pushing a wire (located behind the clip) into the housing. In applications where the clip remains attached to the housing (e.g., barbed attachment of patches) the clip and the pusher wire are preferably one piece (not separated) and only the helical end is exposed during deployment.
The preferred helical shape of the clips and barbs of the present invention is shown in
In other embodiments, a shape memory alloy, such as a thermally activated shape memory form of NITINOL, is employed. The clips are pliable when chilled and are readily maintained in a straightened shape in the housing channels 40. An alloy having a transformation temperature at or near body temperature is selected so that the clips will return to their circular shape when warmed to body temperature. The clip deployment is actuated by any mechanism that could exert an appropriate force on the pusher wife. For example, a toggle linkage, a pneumatic or hydraulic piston, or a shape memory spring can be used to actuate clip deployment.
Referring now to
Preferably, the registration member 32 is a pneumatic chamber that, when inflated, serves to approximate and register the vessels to be. joined. The registration member 32, which is a balloon in the depicted embodiment, extends through the incision 18 and into the artery 12. The balloon 32 is shown inflated, bringing the vessels 12 and 14 together in cooperation with the housing 34 storing the clips 36. A boundary 35 between the inflatable vessels 32 and 34 serves to register the clips, while the inflated chambers 32 and 34 push the tissues between the vessels together. The boundary 35 may be, for example, a constricted region formed therein, an annular band, or the like. By providing proper alignment of the incisions, healing is facilitated. When a nonliving graft material 14 is used, the opening 22 is preferably treated to allow limited tissue ingrowth.
In an alternative embodiment (not shown), the balloon 32 is replaced with a series of mechanical fingers located between the clips, that close to clasp the tissues between the vessels, thereby accomplishing both approximation and registration functions.
Referring now to
In an alternative embodiment, the clips are not completely deployed from their respective housings, and one end of the clip remains attached to the housing. This barb attachment allows many different devices to be securely attached to various types of tissue. Although many other applications are appropriate, a particular application for the subject apparatus is endoventricular left ventricular (LV) volume reduction following physiologic LV remodeling (enlargement), e.g., following myocardial infarction and other heart ailments. Other applications include, for example, wound closure, attachment of biological microelectromechanical (MEMS). devices, and attaching patches for the noninvasive correction of intestinal perforations.
Referring now to
The stays 54 are hollow and each houses a barb 56. The device 50 assumes a folded or collapsed position by parallel alignment of the stays 54 and a corresponding folding of the patch material 52 for introduction into the ventricle via a catheter 60 defining a channel though which the device 50 is passed.
The patch 52 comprises a sheet material, which is circular, or, more preferably, oval or elliptical in shape. The patch may be formed from, for example, Dacron polyester, GORE-TEX polytetrafluoroethylene, or other FDA class 3 materials for implantation, which could be additionally treated with thromboses modulating agents or other prescriptions to allow controlled tissue ingrowth. Alternatively, the diaphragm can be formed of fixed mammalian tissue, such as bovine or porcine pericardium, autologous pericardium, etc.
The barbs 56 include a tissue-piercing pointed distal end 58 extending in a radially outward direction. The barbs are secured within the respective housings at an end opposite the pointed ends 58. Limited movement of the barb in the axial direction is optionally provided to extend the barbs for deployment.
The barbs 56 are formed of a nickel-titanium alloy having superelastic and/or thermally activated shape memory characteristics. When the clips are made of a superelastic alloy, the barbs are constrained in a straightened shape by the housings 54. When deployed, the barbs 56, e.g., by mechanically pushing the barbs outwardly a short distance from their respective housings, resume their helical shape, puncturing and curling into the adjacent tissue to form a strong mechanical connection. Similarly, a shape memory alloy which becomes activated at or below body-temperature can be used in similar fashion, in which case the thermally activated alloy is cooled to increase its flexibility and returns to the trained helical shape upon warming within the body. Each barb may be ejected as described above, for example, using a pusher wire urging, or more preferably, attached to the proximal end of the barb, and so forth.
In an especially preferred embodiment, the barbs are deployed sequentially to generate a torque that helps to assure contact of the diaphragm with the adjacent tissue 62, such as an inner ventricular surface. The sequential deployment is illustrated in
As may be further understood from the discussion above, the present invention has further, broader application to a wide variety of medical environments within the body to secure patches or to suture a site requiring closure, such as needed for wound repair, deep hole wound closures, intestinal perforations, incision sites and other needs where closure or suturing opposing tissues at a site are required.
The method for repairing tissue at a site requiring closure includes first introducing a patch into the body, preferably through a non-invasive catheter procedure. Such procedures may be initiated through vessels of various types, or initiated through the body cavity. The catheter would carry a patch or sheet of biologically compatible material, adapted for the specific tissue targeted for repair. Materials appropriate for closure of different sites in the body are known in the art for exposure to the environments in which they must function, and those discussed above are illustrative for the cardiovascular environment.
As with the illustrative device shown in
The patch is then secured over the portion requiring closure by extending said barbs to a helical position so that the barbs engage tissue surrounding the portion requiring closure. The barbs are made of materials as described above, such as superelastic, shape memory materials, or like materials, and are preferably extendable using a mechanical device to push them partially from the sleeves, in a manner similar to that described above, to deploy to a helical position. It is understood, however that the barbs may be activated assume a helical shape in other ways, including electrical heating, ultrasonic activation from a remote source, and timing devices. In accordance with the invention, the barbs are extended to a helical shape to provide for attachment of the patch without further suturing, and enable the patch to be attached from one side of the site, without further intrusion into the targeted site.
The present invention further provides for the suturing of tissue at a site requiring closure using the helical barbs. The method again preferably involves the introduction of elongate sleeves, preferably through a catheter or other non-invasive tool. Surgical barbs are movably secured within each sleeve, and are spaced apart as desired for the suturing procedure desired. In the extended position, the surgical barbs will return to a helical shape, whether activated by temperature, electrical current, external power supply or a timer circuit to trigger conditions for shape change.
In the suturing application, the sleeves with barbs may be positioned at the site requiring closure one at a time, or in groups, or as a cluster attached to a sheet that deploys them to a desired spacing, whether such spacing is parallel, radial or in otherwise oriented. After positioning the sleeve or sleeves into the desired position, the barb is extended from the sleeve into a predefined helical position where the barb engages tissue on opposing tissues at the site requiring closure and serves as a suture. The helical barb is preferably then fully expelled from the sleeve, and the sleeve removed from the body or used to deliver consecutive barbs. When functioning as a remotely positioned suture, the helical barb of the present invention has the distinct advantage of providing secure connection from just one side of a tissue, without needing access to the opposing side of the tissue to achieve a secure attachment. It further serves both as the needle and the suture, and may be made of materials as discussed herein.
In a still further application in the medical field, the present invention encompasses a helical barb device that is suitable for affixing medical devices, generally, to tissues. While illustratively shown in the process of attaching a diagram in
Where the helical barb affixes medical devices within the body, it may be deployed in a manner similar to that described above from a sleeve attached to a larger implantable device, where a portion of the barb remains attached within the sleeve. Alternatively, the sleeve might also serve as the device to carry a device, whose inner and outer surface are exposed to the targeted tissues upon deployment of the helical barb.
Where micro and nanotechnologies are being inserted into the body, the helical barb itself may be the carrier for small devices attached to the surface of the barb. In this configuration, the micro or nano devices are appropriately positioned on the barb when it is in its first, non-deployed position, such as an elongated position in a sleeve, so that in its second position penetrating and attaching to tissue, the devices would be presented to the tissue without damage, and in a position where they function as desired. The devices so implanted are contemplated to monitor or measure biological conditions, manufacture or deliver medically efficacious materials, or perform other desired device functions. Where the helical barb serves as a carrier for devices, it is preferred that they be deployed in a manner similar to that described above for a sutures, separating from the delivery mechanism.
In its application to attach a device to tissue in a medical procedure, the helical barb functions to connect a man-made, preferably biologically compatible material to a biological material, in contrast to the suturing of two biological materials. By way of example and not limitation, devices which may be attached using the helical barb of the present invention include blood pressure transducers, glucose monitors, fluid flow sensors to detect bleeding at operative sites, leaking aneurysms, or local fluid build-up.
The provision of a simple helical barb means to deliver a MEMs device, or other nano or micro technology makes possible the dream of drug delivery at the site of need using a device which will remain in place where chosen. The potential to use such devices as small local drug factories, or as drug dispensing agents from which drugs can disperse over time is known in the art. The helical barb device of the present invention provides a secure means of attachment, whether serving as an attachment means for a larger device or as the carrier for very small drug delivery devices.
It is further contemplated in the drug delivery application of the present invention that the material of the helical barb may be hollow, and serve as a carrier for drugs. The hollow ends may be plugged with biodegradable material, or simply be plugged by the delivery mechanism so that once fully deployed and released at least one end of the helical barb becomes exposed to deliver treatment materials as the delivery device retracts. Alternatively, the helical barb may be coated with medicament, so that it is delivered directly to the tissue upon the penetration and attachment of the barb.
It is still further contemplated that the helical barb of the present invention may include biodegradable materials whose period of integrity is designed to last as long as the drug delivery device remains operable, or as long as timed release of drugs from a device lasts, after which time the helical barb device is designed to fail so that the device may be easily released and either expelled or retrieved from the body.
Medically efficacious materials that may be delivered include drugs, hormones, small molecules, proteins, genetic materials, radioactive materials, markers, biological agents and other treatment materials. By way of example and not limitation, human growth factor Veg-F might be delivered using the helical barb or in combination with a MEMs or other devices to treat coronary artery blockage, promote angiogenisis, or provide cardiac drug delivery without the need for repeated hearth catheterizations. Use in targeted high blood flow areas can also provide for enhanced treatment opportunities. Radioisotopes and chemotherapeutic agents may also be placed and positively attached with the helical barb of the present invention directly at the site of tumors, providing longer-term drug delivery.
In a further drug delivery application, the helical barb of the present invention (in a first elongated position), an implantable device, or a the sleeve may be initially implanted at a desired biological location by coating at least a portion thereof with a biological/protein attachment material targeting the desired site. Numerous targeting proteins are discussed in the art for different functional organs. In one configuration, the helical barb may be treated in its first elongate position, ingested or implanted, separately or in combination with a device, and once the device or barb adheres chemically to the targeted portion of the body, the attachment may then be made more permanent by delayed deployment of the helical barbs.
The helical barbs may be deployed in such an application, as with the other applications of the present invention discussed herein, through timed action or remote signal, such as an ultrasonic signal or other trigger, electrical current, temperature, or timed release of the barbs from a device.
In addition to serving as a helical barb for attachment, the helical device of the present invention may serve to lodge itself in a vessel or other generally tubular structure or opening by deployment from a first position, preferably by means of a catheter, to a second helical position where the helical device relies on its radius of curvature to expand to a size at which it lodges in the vessel, or other biological structure, opening, duct or orifice.
Such a vessel, structure, opening or duct would have an average radius less than that of the helical device. As shown in
When serving as a stent, the helical device may be configured to have many loops, as shown in
The helical barbs, fastening clips and helical devices of the present invention are preferably formed either of a shape memory alloy (SMA) or a superelastic alloy that is FDA class 3 approved for implantation, such as NITINOL or TiNi, which are nickel-titanium based alloys, or alike materials, and are formed as a wire with diameters down to 25 microns, and have a needle-like point on at least one end. Some polymers, including but not limited to starch-based polymers, are also known which exhibit superelastic properties desirable for application in accordance with the various aspects of the invention described herein. In addition, the ends of the barbs may include end treatments such as barbs and teeth that provide additional anchoring capability for the barbs, devices, sutures and attachments described herein.
Use of SMA materials is contemplated for the above applications. Among the opportunities provided by such materials is the design of the shape-memory transition temperature. so that the natural hysteresis between phases would advantageously be set to enable activation of the material to cause shape change by electrical means. Specifically, the high transition to austentite would be just above body temperature. An electric current provide or induced in an adjacent or attached device would provide heat for the shape memory triggering once the helical barb was in position at the desired site for attachment to tissue or deployment into a helical shape. As long as the lower transition back to martinsite is below body temperature, the helical barb will hold its shape, just as with a device prepared for deployment upon exposure to body temperature.
In addition, the hysteresis of shape memory materials provides the opportunity for removal of devices after placement. If the memory shape is triggered by a temperature slightly higher than the body temperatures, then a return to a temperature slightly lower than body temperature, by using catheter supplied cooling, such as cooled fluids, cryogenic probes, cooled heat sinks, heat pipes, thermoelectric or other cooling devices, may provide for easier device removal.
The invention has been described with reference to the preferred embodiment. Obviously, modifications and alterations will occur to others, upon reading and understanding the proceeding detailed description.
It is intended that the invention be construed as including all such modifications and alterations insofar as they come within the scope of the appended claims or the equivalents thereof.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/US03/02929 | 1/31/2003 | WO |
| Number | Date | Country | |
|---|---|---|---|
| 60353973 | Jan 2002 | US |
