The present invention relates to the field of surgery. More particularly, the present invention relates to devices, tools and methods for performing sutureless anastomoses.
There are many medical procedures which require the performance of one or more anastomoses in which a conduit such as a vessel, duct, graft or other tubular structure must be joined to another vessel, duct, or other hollow structure such as an organ to establish continuity between these structures. One of the more prevalent needs for improve anastomosis techniques lies with the treatment of coronary artery disease, where a stenosis of one or more coronary arteries prevents or seriously interferes with a normal blood supply to the heart tissue. In such situations, a total or partial blockage of a coronary artery is often treated by bypassing the obstruction in a heart bypass procedure, such as a coronary artery bypass graft (CABG) procedure, in which a graft is fluidly connected to the blood supply on opposite sides of the site of the stenosis to provide an alternate route for the blood to take on route to the heart.
The graft may be natural conduit, artificial conduit, or a combination of natural and artificial conduits. Typically, a natural conduit in the form of an autograft harvested from the patient is used. Common natural conduits include the saphenous vein from the leg, the radial artery from the arm, or the internal mammary artery rerouted to be anastomosed downstream of the site of the stenosis.
Conventional CABG procedures are currently performed while the beating of the heart has been stopped, with the circulation and oxygenation of the patient's blood being performed by a heart and lung bypass machine. This procedure requires significant manipulation and clamping of the aorta of the patient. Recently, it has been found that this procedure tends to increase the risk of dislodging plaque that may have accumulated on the internal wall of the aorta in the vicinity of the clamping. Dislodgment of plaque can cause emboli in various locations in the patient's body, cutting off the blood supply downstream of the locus of the embolus, which can cause a stroke or other serious medical complications. Further, the heart-lung bypass machine is thought to cause mechanical damage to the blood cells which furthers the risk of medical complications, due to potential clot formation.
Recently there has been an increase in the performance of beating heart CABG procedures, in which the bypass of one or more stenoses is performed while the patient's heart continues to beat, with the circulation and oxygenation of the patient's blood being performed naturally by the heart and lungs of the patient. While beating heart procedures reduce the associated risks of stroke and other post-operative complications associated with the clamping and manipulation of the aorta and the use of the heart-lung bypass machine, they also tend to increase the difficulty somewhat in performing what were already difficult and delicate anastomosis procedures that must be performed to connect the bypass graft or grafts during the CABG procedure.
The most conventional techniques for making anastomoses involves manually suturing the two tubular conduits together (e.g., manually suturing the graft to the target vessel) around an opening between them. Manual suturing is difficult, time-consuming and requires a great deal of skill and manual dexterity on the part of the surgeon performing the anastomosis. The difficulties in performing anastomoses by manual suturing are magnified when they are done during a beating heart CABG procedure as the beating of the heart introduces perturbations that make it even more difficult to suture in a reliable, consistent and efficient manner. These difficulties have largely limited CABG procedures to open surgical settings which provide sufficient surgical access and visualization to complete the delicate anastomoses.
Thus, there is a need for sutureless anastomosis devices, tools and techniques that offer a reliable alternative to suturing techniques, and which are relatively easier to implement while giving consistent results. It would further be desirable to provide such devices, tool and techniques that would facilitate the performance of higher quality anastomoses than those currently made and with less time required to make the anastomoses.
With continued interest and development toward CABG procedures which are even less invasive than the current techniques for beating heart CABG procedures, it will further be desirable to provide anastomosis techniques which can be performed endoscopically, with the surgeon working outside of the patient.
Devices for use in making an anastomosis between tubular fluid conduits in the body of a patient are described. The anastomotic device includes a unitary structure having a main body disposed annularly about a longitudinal axis and having first and second end portions; a plurality of members extending radially outwardly from the first end portion; and the second end portion having a plurality of spaced struts adapted to buckle in a radially outward direction upon axial compression of the device.
The device may further include a second set of spaced struts which are collapsible secondarily to the first set of struts, and over a variable range of distance to accommodate for varying wall thicknesses of the tubular conduits being joined by anastomosis.
The struts may be joined by a set of ring members to define the annular shape of the main body. A proximal end of the device includes members extending radially outwardly from the first end portion of the device. The radially extending members may extend from a proximal ring member. Where two sets of struts are provided, a third ring member may be provided to join the first and second sets of struts.
Graft retaining members, such as tines may extend radially outwardly from the second end portion of the device. Upon loading a graft on the device, the graft is passed through an internal annular space defined by the main body of the device, and then everted over the second end of the device to be retained by the graft retaining members.
One or more locking members, such as locking tines, may be provided integrally with the second end portion of the device and slidably connecting with the first end portion. Upon buckling the struts of the device, the locking member or members slide with respect to the first end portion and extend beyond the first end portion. The locking member or member can then be bent over the first end portion to lock the relative positions of the first and second end portions in the buckled configuration.
The first end portion may include a plurality of eyelets axially aligned with the locking members for slidably receiving free ends of the locking members.
The struts of the second end portion of the device, upon buckling, are adapted to form a compression fit with the members extending radially outwardly from the first end portion to form a seal between the everted end of the graft vessel and an inner wall of a target vessel.
The distal end portion of the device may be adapted to further evert the conduit or graft retained thereon, upon buckling.
A deployment instrument for deploying an anastomosis device according to the present invention is provided to capture an anastomosis device adapted for making an anastomosis between tubular fluid conduits in the body of a patient and comprising a unitary structure having a main body disposed annularly about a longitudinal axis, having first and second end portions and configured to be loaded with a first of the two conduits to be joined by the anastomosis, wherein the conduit is loaded by passing a free end thereof through an internal space defined by the main body in a direction from the first end portion to the second end portion and everting an end of the first conduit over the second end portion. The deployment instrument includes first and second tubes concentrically arranged for axial sliding movement with respect to one another.
The first tube has a first outside diameter and further has a gradually increasing second outside diameter on a distal end portion thereof. The second tube has an inside diameter slightly greater than the first outside diameter of the first tube so that the second tube is free to slide with respect to first tube along the portions defined by the first outside diameter. The second tube further has radially expandable members defining a radially expandable distal end portion. Upon sliding the radially expandable distal end portion into contact with distal end portion of the first tube, or upon sliding the distal end portion of the first tube into contact with the radially expandable distal end portion, the gradually increasing outside diameter of the first tube distal end portion drives the radially expandable members radially outward to assume an expanded conformation. Upon sliding the distal end portion of the first tube out of contact with the radially expandable distal end portion or vice versa, the radially expandable members return to an unbiased, non-expanded configuration.
The first and second tubes of the deployment instrument are each provided with a longitudinal slot. The longitudinal slots align with one another and are configured to allow the first conduit or graft to pass therethrough. This feature allows side loading of the deployment device so that a graft or other conduit loaded on an anastomosis device need not have a second free end to be loaded into the deployment device.
The first and second tubes are configured to slide through the internal space defined by the main body of the device, in a direction from the first end portion to the second end portion, between an external wall of the first conduit or graft and an internal wall of the device, when the radially expandable members are in the unbiased, non-expanded configuration.
The first and second tubes can then be used to capture the device after sliding through the internal space. The capture is effected upon expanding the radially expandable members by moving the distal end portion of the first tube into contact with the radially expandable members. The radially expandable members, upon radially expanding, may contact and exert a force against the internal wall of the device. The distal ends of the radially expandable members may be provided with catch members that abut a distal end of the device upon radial expansion of the radially expandable members to capture the device.
The deployment instrument is further adapted to buckle the device for joining the first and second conduits. A stop member may be provided proximally of the distal end portions of the tubes. The first end portion of the device abuts against the stop member upon capture of the device. The first and second tubes are axially slidable in a proximal direction with respect to the stop member to exert a compressive force on the device to buckle it.
The first and second tubes are axially slid in a distal direction to release the compressive force after completion of the buckling of the device. The first tube is then slid still further distally with respect to the second tube, in order to take the distal end portion of the first tube out of contact with the radially expandable members. The radially expandable members accordingly return to the non-expanded configuration so that the buckled device may be slid off the distal ends of the first and second tubes.
The deployment instrument may be further provided with a third tube having an inside diameter slightly greater than an outside diameter of the second tube. The third tube may be linked with the first tube, so that when the first tube is axially slid within the second tube, the third tube axially slides over the outside of the second tube along with the sliding of the first tube. The third tube has an outside radius greater than a radial extent of the catch members of the second tube when they are in the non-expanded configuration. In this way, the third tube prevents the buckle device from catching on the catch members as it is released from the deployment instrument.
The deployment instrument may be further adapted to lock the device after buckling the device, with the provision of a device lock. The device may be provided with at least one locking member which slides past a proximal end of the device upon compression of the device and which is connected with a distal end of the device. After buckling the device, the device lock of the instrument is slid distally with respect to the first and second tubes, wherein it abuts the at least one extending locking member and bends it over against the proximal end portion of the device, thereby locking the relative positions of the first and second end portions of the device.
A force limiter may be provided in the deployment device to interconnect the second tube with a relatively fixed portion of the instrument. The force limiter limits an amount of compressive force that the second tube can apply to the device during buckling.
A method of performing an anastomosis to join a first conduit to a second conduit is described to include: inserting a free end of the first conduit through an annular spaced defined by an anastomosis device comprising a unitary structure having a main body disposed annularly about a longitudinal axis and having first and second end portions; at least one first end member extending further radially outward than a radial extent of the annularly disposed main body; and graft retaining members extending from the second end portion, the graft being inserted in a direction from the first end portion to the second end portion so that the free end extends from a second end of the device; everting the extending free end of the graft over the second end of the device and retaining the everted free end with the graft retaining members; forming an opening through a wall of the second conduit, wherein the opening is dimensioned to allow the everted end and main body, but not the at least one first end member to pass therethrough; inserting the device and graft into the opening until the at least one first end member abuts the external wall of the second conduit; and compressing the device to buckle the second end portion, wherein the second end portion, upon buckling is no longer capable of passing back through the opening.
The compressing is performed only up until a pre-defined compression force has been reached. The compressing may further at least partially collapse the first end portion after buckling the second end portion.
The method may further include locking the relative positions of the first and second end portions after completion of compression.
A method of preparing a graft vessel and performing an anastomosis to join the graft to a target vessel is described to include: measuring an outside diameter and wall thickness of the graft vessel; selecting an appropriately sized anastomosis device, based on the outside diameter and wall thickness measurements; loading the graft vessel on the anastomosis device so that the graft vessel passes through a longitudinally extending annular space defined by a main body of the anastomosis device, extends beyond a distal end of the anastomosis device and is everted back over an external surface of the distal end of the anastomosis device; selecting a punch appropriately size matched to the outside diameter and wall thickness measurements and punching an opening through a wall of the target vessel; inserting the loaded graft into the opening, wherein the anastomosis device has an enlarged proximal end that is incapable of passing through the opening and abuts against the wall of the target vessel upon inserting the loaded graft; and buckling the anastomosis device so that a distal end portion thereof increases in diameter and compresses the everted end of the graft vessel against an internal wall surface of the target vessel.
The method of anastomosis may be performed either with a graft having two free ends or with a graft having only one free end.
These and other objects, advantages, and features of the invention will become apparent to those persons skilled in the art upon reading the details of the devices, tools and methods as more fully described below.
Before the present devices, tools and methods are described, it is to be understood that this invention is not limited to a particular device, method step or tool described, as such may, of course, vary. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to be limiting, since the scope of the present invention will be limited only by the appended claims.
Where a range of values is provided, it is understood that each intervening value, to the tenth of the unit of the lower limit unless the context clearly dictates otherwise, between the upper and lower limits of that range is also specifically disclosed. Each smaller range between any stated value or intervening value in a stated range and any other stated or intervening value in that stated range is encompassed within the invention. The upper and lower limits of these smaller ranges may independently be included or excluded in the range, and each range where either, neither or both limits are included in the smaller ranges is also encompassed within the invention, subject to any specifically excluded limit in the stated range. Where the stated range includes one or both of the limits, ranges excluding either or both of those included limits are also included in the invention.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention, the preferred methods and materials are now described. All publications mentioned herein are incorporated herein by reference to disclose and describe the methods and/or materials in connection with which the publications are cited.
It must be noted that as used herein and in the appended claims, the singular forms “a”, “and”, and “the” include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to “a tine” includes a plurality of such tines and reference to “the strut” includes reference to one or more struts and equivalents thereof known to those skilled in the art, and so forth.
The publications discussed herein are provided solely for their disclosure prior to the filing date of the present application. Nothing herein is to be construed as an admission that the present invention is not entitled to antedate such publication by virtue of prior invention. Further, the dates of publication provided may be different from the actual publication dates which may need to be independently confirmed.
The term “tine” is used herein to denote an elongated structure forming a portion of an anastomosis device as described. A “tine” generally has a free end which can have any of a variety of tip configurations, including either a pointed or non-pointed tip.
A “strut” is defined herein to refer to a structural supporting or connecting element which joins at least two other components of an anastomosis device, such as two rings, for example.
A “ring” as used herein, refers to a body-shaping member of the anastomosis device which forms a general configuration over which a graft is mounted.
The present invention provides devices, tools and methods for joining two tubular conduits, such as vessels, organs or other tubular formations, particularly for forming anastomoses in cardiovascular applications, such as those required during the performance of a cardiopulmonary bypass. The present invention avoids the need by prior anastomosis techniques wherein the aorta is clamped to interrupt blood flow to the area of the aortic wall to which a vein or other conduit is to be anastomosed. Such clamping may result in liberation of plaques and tissue fragments which can lead to organ dysfunction, such as strokes, renal failure, or intestinal ischemia. The anastomosis techniques according to the present invention do not require any significant additional space surrounding the site of the anastomosis and inside the patient to connect the anastomotic device to the target vessel. According to the invention, a sutureless connection can be provided between a graft and a target vessel, while minimizing thrombosis or restenosis associated with the anastomosis. The devices allow the anastomosis to be performed very rapidly, with high reproducibility and reliability, without clamping, and with or without the use of cardiopulmonary bypass.
Device
The device 1 can be formed in various sizes to suit the dimensions of a graft or vessel to be joined to another site. For purposes of establishing a proximal anastomosis during performance of a coronary bypass procedure, devices 1 having outside diameters 2 varying within the range of about 3.0 mm to about 7.0 mm, a material thickness of about 0.007″±0.003″, and having an initial length 4 of about 0.2″ to about 0.7″, generally about 0.25″, so that they are adapted to accommodate anastomosis of a graft to aortas having wall thicknesses within the range of about 1 mm to about 5 mm.
Device 1 includes three rings 6, 8 and 10 which form a framework of a generally cylindrical structure as can be seen in
Support struts 16 join rings 8 and 10 and are generally equally spaced around the circumferences of the rings 8 and 10 to form a supporting portion of the device 1, which buckles only secondarily to the buckling portion. Support struts 16 are angled to enhance their buckling, but, in contrast to buckling struts 12, the bending angle of the support struts 16 is such that support struts 16 maintain conformity with the imaginary cylindrical surface defined by rings 8 and 10. Comparatively, when the buckling section collapses, buckling struts bend outwardly so as to effectively increase the outside diameter of that portion of the device 12, while, in contrast, struts 16 tend to bend or buckle in a direction substantially perpendicular to the direction that struts 12 bend in, so that the struts 16, even after bending, substantially conform to the imaginary cylindrical surface and do not substantially increase the outside diameter of the support portion of the device 1.
External tines 18 extend from ring 10 and are bent substantially perpendicularly to the longitudinal axis L of device 1 during forming. External tines 18 form the contact surface by which device 1 applies pressure to the external surface of a vessel (e.g., external wall of the aorta) to which a graft held by device 1 is being joined. Locking tines 20 extend from ring 6 at substantially evenly spaced locations about the circumference of ring 6. Locking tines 20 have a sufficient length to span the remaining length of device 1 when they are folded over by one hundred and eighty degrees during forming. The external tines 18 which are aligned with locking tines 20 contain locking receptacles 22 through which the respective locking tines 20 pass upon folding them back one hundred and eighty degrees during forming. The locking tines 20 are bent over to the external side of the general cylindrical shape of device 1, and threaded through the locking receptacles 22 on the external tines which extend radially away from the general cylindrical shape of the device 1, as shown in
Another significant difference in the device of
Locking tines 20 include weakened sections or cutouts 21 which assist in the preferential bending of the tines in the locations of the weakened sections during the locking phase of deployment of the device. This helps ensure that the locking tines bend into the configuration for which they have been designed, thereby providing the intended secure locking function. Weakened section 21 can be formed by elongated slots, as shown in
In this arrangement, only two rings 106, 110 are provided to form the basic cylindrical structure of device 100. Buckling struts 112 join rings 106 and 110 and are generally equally spaced around the circumferences of the rings 106 and 110 to form a buckling portion of the device 100. Buckling struts 112 are bent outwardly from an outer surface of an imaginary cylinder defined by rings 106 and 110, to make the buckling portion more susceptible to collapse upon exertion of compressive forces along the longitudinal axis of device 100 and to direct the buckling motion of struts 112 in an outward direction so as to effectively increase the outside diameter of the buckling portion upon buckling. Graft tines 114 extend from ring 106, and are bent to positions substantially perpendicular to the longitudinal axis of device 100 during forming, to position them for anchoring the end of a graft, as discussed further below.
External tines 118 extend from ring 110 and are bent substantially perpendicularly to the longitudinal axis L of device 100 during forming. Locking tines 120 extend from ring 106 at substantially evenly spaced locations about the circumference of ring 106. Locking tines 120 have a sufficient length to span the remaining length of device 100 when they are folded over by one hundred and eighty degrees during forming. Locking receptacles 122 are formed adjacent external tines 118 and extend from ring 110 in alignment with locking tines 120, and are bent substantially perpendicularly to the longitudinal axis L of device 100 to allow locking tines 120 to pass therethrough during formation of the device. The locking tines 120 are bent over to the external side of the general cylindrical shape of device 100, and threaded through the locking receptacles 122. By passing locking tines 120 through receptacles 122, locking tines 120 effectively link rings 106 and 110 to provide an important locking feature upon deployment of the device, as will be discussed below. External tines 118, along with the locking tines, when they are bent over during the locking procedure, form contact surfaces by which device 100 applies pressure to the external surface of a vessel (e.g., external wall of the aorta) to which a graft held by device 100 is being joined. Although not shown, an alignment tab 124, such as shown in the device 1 may be included on device 100, either adjacent to, or in place of one of external tines 118, to control proper alignment of device 100 when loaded on a deployment instrument.
Deployment Instrument
Each of the concentric tubes is provided with a longitudinal slot so as to define a channel 66 in the top of the arrangement that allows a graft (attached to a device 1, 100) to extend externally of instrument 50, and to render the cross-sectional views of the tubes to appear somewhat “C-shaped”. Advantageously, this feature allows a graft to be side fed into instrument 50 and also does not require that both ends of the graft be free in order to perform an anastomosis according to the invention. For example,
Currently known procedures using mechanical anastomotic coupling typically require the proximal anastomosis to be performed before the distal anastomosis is performed. This is disadvantageous for at least two reasons. One reason is that surgeons are currently trained to perform the distal anastomosis prior to performing the proximal anastomosis. A second reason is that, depending upon the location of the coronary artery which is being bypassed, it is very frequently necessary to move the heart out of its natural position, such as by elevating it out of the chest cavity to provide access to the site where the anastomosis is to be performed. If the proximal anastomosis must be performed first, this makes it very difficult, if not impossible to accurately measure the length of graft that will be needed to properly perform the distal anastomosis. This is so, because in the displaced position, the heart is not fully perfused, and therefore any measurements made at this time are almost certain to be inaccurate, as the actual distance between proximal and distal anastomosis sites will change when the heart is returned to its natural position and becomes fully perfused, thereby enlarging somewhat. The current invention allows the distal anastomosis to be performed first, after which the heart can be properly positioned and an accurate assessment of the graft length needed can be made before performing the proximal anastomosis.
Therefore, it is often advantageous to perform the distal anastomosis prior to the proximal anastomosis in a cardiac bypass procedure as it is much easier to gauge the correct length to which the graft needs to be cut when the distal anastomosis is performed first since the heart will be normally loaded with blood and the surgeon can get a better approximation of where the locus of the proximal anastomosis will reside after completion of the procedure, which allows a more direct measurement of the length of the graft needed. As noted, the heart very often needs to be displaced to perform the distal anastomosis. By performing the distal anastomosis first, the heart can then be repositioned to its natural location and orientation, thereby making it much easier for the surgeon to visualize and directly measure or approximate the length of graft needed to reach the proximal anastomosis site. Since most surgeons traditionally perform the distal anastomosis first, even when using suturing methods, they will be more inclined to accept a procedure where distal anastomosis can be performed first.
The concentric tube arrangement includes a wedge tube 62 concentrically surrounded by a catch cam tube 64, with these tubes arranged for relative sliding movement with respect to one another along their longitudinal axes. A release tube 65 is concentrically arranged over catch cam tube 64, and is relatively fixed to wedge tube 62 so that is slides relative to catch cam tube 64 when wedge tube 62 is slid relative to catch cam tube 64. The wedge tube 62, catch cam tube 64, and release tube 65 operate in conjunction with other features of the instrument 50 to perform the functions of capturing an anastomosis device 1,100; buckling the device; locking of the device; and finally releasing the device from the distal portion 60 of instrument 50. An anastomosis device is securely mounted or loaded onto the distal portion 60 of the instrument 50 by way of the capture function. The wedge tube 62 includes a flared or wedged end portion 62w that has a generally increasing outside diameter as shown in
Device 1,100 may include an alignment tab or tine 24 extending from ring 1,100 which is bent over, radially inward of the device into an orientation substantially perpendicular to the longitudinal axis of the device L during forming. Device 1,100 is aligned with instrument 50 by sliding alignment tab 24 in channel 66. This alignment ensures that each of the locking tines 20,120 will be properly aligned so as to be contacted by device lock 68 during the locking operation described below. The device 1, 100 is slid onto the distal portion until it makes contact with stop member 70. Stop member 70 is fixed with regard to handle 52 of device 50. Stop member 70 may include a beveled portion 70b, which provides a ramping surface against which device 1,100 comes to rest. In this way, stop member not only correctly positions device 1,100 in a longitudinal position along the distal portion 60, but also performs a centering function to keep device 1,100 properly centered on the distal portion 60 of deployment device 50.
Once device 1,100 is properly positioned and abutted against stop member 70, pin or button 58 is released, and wedge tube 62 is spring loaded so as to be drawn back with respect to catch cam tube 64, such that wedge portion 62w slides against and contacts catch cams 64c, radially expanding them to assume a larger outside diameter, as shown in
Device 1 is securely held by the abutment of ring 10 against stop member 70, and by contact of ring 6 by catch cams 64c.
Referring to the proximal end portion view of
Pin 77 can slide in the slot 91 on reverse motion to allow the catch cam catches 64c to retract as the wedge 62w extends distally of them, then the pin 77 contacts the distal (opposite) end of the slot 91 so that the catch cam tube 64 and wedge tube 62 again move together in any further distal sliding. That is, when the tension on spring 75 is relieved so that it no longer draws against compression slider 76, as catch cam tube returns to the reset position, the compression spring between pin 92 and compression slider 76 extends to release its compression, thereby sliding wedge tube 62 distally with respect to catch cam tube 64 until pin 77 contacts the distal end of slot 91. This biasing by the compression spring maintains the catch cams 64c in their retracted configuration in the reset position of device 50. During the compression motion, as the catch cam tube 64 and the wedge tube 62 are proximally slid in unison, the catch cams 64c and stop 70, a sa result, compress device 1,100 so that initially, the buckling section of the device buckles. Thus, in the case of device 1, the buckling section between rings 6 and 8 collapses or buckles first with struts 12 moving radially outwardly during buckling, as described above, to form a mushroom-shaped configuration.
As the trigger 54 continues further in its travel toward the body 52, the struts 16 of the strut section begin to collapse as the catch cam tube 64 and wedge tube 62 further advance toward stop 70. The collapse of the strut section is accomplished to draw a graft and vessel together during an anastomosis procedure with a sufficient force to form a successful seal between the two, while not compressing the anastomosis with too great a force to potentially cause damage to the living tissue. As such, the collapse of the strut 16 draws the rings 8 and 10 closer together, which effectively also draws the buckled struts 12 closer to ring 10, thereby compressing the tissues which are held there between during an anastomosis procedure.
Extension spring 74 interconnects rocker 72 with compression slider 76, which retracts the catch cam tube as described above. Extension spring 74 acts as a force limiter during the compression/buckling stage. Extension spring 74 has a preset load at which it begins to expand. F or example, extension spring may be designed so that the coils do not begin to expand or separate until a load of about 20 pounds has been reached. The effect achieved by this is that the catch cam tube will continue to be retracted, and therefore continue to compress/buckle device 1,100 until such time as a 20 pound load is exerted upon the extension spring 74, or until rocker 72 goes over center and reverses direction (via the 4 bar linkage. When an imaginary straight line connecting the two pivot points 71p1 and 72p2 becomes parallel with an imaginary straight line interconnecting trigger pivot 54p and rocker pivot 72p, the four bar linkage is considered to be at “center”. Further driving by the trigger 54 causes the linkage to go over or beyond center, which drives rocker 72 into a reverse rotation. The preset load on the extension spring may be reached or achieved when the buckled struts 12 (which carry an everted graft end) and external tines 18 compress the tissues there between sufficiently to form a leak tight seal.
Once the predetermined force or load is reached, extension spring 74 begins to extend, so that no further driving/retraction of the catch cam tube 64 can occur and device 1,100 is therefore compressed no further. For example, accounting for about 8-9 pounds required to buckle a device, 1,100, and the force need to counteract a reset spring 85, which abuts against the handle 52 and the compression slider 76 to exert a return or resetting biasing force to reset the catch cam when no force is being applied to it by spring 74 of the deployment device, an extension spring 74 having a preset load of about 20 pounds translates to a compression force of about 3-4 pounds which is actually applied to the tissues compressed by device 1,100 when spring 74 begins to extend. Of course the present invention is not limited to a final compression force of about three to about four pounds, as slightly less force may be applied (e.g., about one to three pounds) or slightly greater force, so long as it is not so great as to cause tissue damage.
With the force-limiting feature, device 1, 100 is not collapsed to a predefined length. Rather, it is collapsed until a predefined buckling force is achieved. Because of this, device 1,100 can reliably seal an anastomosis of a graft to vessels of varying wall thickness, wherein the compressive force for connecting a graft to a thin walled target vessel (e.g., aorta) is substantially the same as the compressive force established when connecting a graft to a thick walled vessel (e.g., an aorta having a relatively thicker wall than the previous one). That is, instead of forcing the device 1,100 into a particular thickness, it is adjustable to various wall thicknesses, and is controlled to be collapsed only to a thickness that will achieve a predetermined amount of compressive force on the site of the anastomosis. Practically speaking, this means that the thickness of the gap in which device 1,100 compresses the graft and vessel will vary with the thickness of the vessel wall and graft wall, but will achieve substantially the same compressive force regardless of the thickness of the tissues being joined.
As the trigger 54 continues its motion toward the handle/body 52, after the buckling of device 1,100 has been accomplished, pin 73 reaches the end of slot 72s in rocker 72. Continued advancement of rocker 72 then drives lock driver 81, which is an integral portion of (or may be connected to) device lock tube 81 (upon which the device lock 68 is fixed) at its distal end As the device lock tube 81 is driven in a direction toward the distal end of deployment device 50, this motion drives device lock 68 toward device 1,100, while catch cam tube 64 and wedge tube 62 remain fixed with respect to device 1,100. Additionally, a lock spring 83 which abuts a ledge or shoulder 81L formed on device lock tube 81 at one end, and another ledge, abutment or shoulder 52L formed in handle 52, is compressed by the advancement of device lock tube 81 relative to handle 52. Stop member 70 is fixed with regard to handle 52, and therefore maintains its fixed position as device lock tube 81 and device lock 68 advance. The device lock 68 includes curved guide surfaces 68g which guide the ends of locking tines to be bent radially outward, with further advancement of device lock 68 bending the locking tines 20,120 over locking receptacles 22,122 and against external tines 18 or the wall of the graft (in the case of a design such as device 100). By bending the locking tines 20,120 over against locking receptacles 22,122, the locking tines secure the positions of rings 6 and 10 from being spread apart. This permanently sets the positions of the rings and the force applied thereby, preventing the device 1, 100 from expanding or unbuckling.
As the trigger 54 completes its travel toward handle 52, the reverse rotation of rocker 72 releases the force between rocker 72 and device lock tube 81, which allows the biasing force contained in lock spring 83 to reset the tool. The locking driver (device lock) 68 is retracted back to its neutral starting position, thereby breaking contact with the locking tines 20,120. At the same time, the reverse rotation of the rocker 72 takes the load off spring 74 so that the biasing force of spring 85 drives the compression slider 76 and catch cam tube distally to their neutral positions. The wedge tube 62 is driven distally along with the catch cam tube 64. The motion of the trigger 52 going forward (i.e., toward the body of the tool) also drives wedge link 89, so that an end of the slot 89s in wedge link 89 abuts pin 89p connected to button 58, and then drives button 58 distally to further drive the wedge tube 62 in the distal direction so that the wedge portion 62w breaks contact with catch cams 64c, which, as a result, return to their relaxed or retracted positions, to define an outside diameter that is smaller that the inside diameter of the device 1,100. This is the release position of the deployment tool, and allows the distal end portion 60 to be slid out from inside device 1,100, leaving device 1,100 undisturbed at the site of the anastomosis.
Although the catch cams 64c retract to a conformation that may be slid out from inside the device 1,100, it was discovered that there was still some potential for one or more of the catch cams 64c to catch on a ring or strut of the device 1,100 as the deployment tool 50 was being withdrawn. For example, if the device 1,100 was allowed to drop down on the distal end portion 60, this would leave a large gap between the deployment device end portion 60 and the bottom of the device 1,100, while the top portion of device 1,100 would contact the catch cam tube 64 and then be trapped by the catch cam 64c during an attempt to remove the deployment tool. To ensure that the deployment tool 50, and particularly a catch cam 64c does not catch on the device 1,100 during removal of the tool 50, a release tube 65 is provided, as shown in
Release tube 65 concentrically surrounds catch cam tube 64 for sliding movement relative thereto, and also has a slot to match those of the catch cam tube 64 and wedge tube 62. Release tube 65 is linked to wedge tube 62, such as by a pinned interlink 92, so that it moves together with wedge tube 62 at all times. Thus, during the loading/capture of a device 1, 100, release tube 65 is retracted away from the catch cams 64c as wedge 62w is retracted into the catch cams 64c to expand them (as shown in
During the release procedure, as the wedge tube 62 is pushed out from the catch cam tube 64, release tube 65 slides with wedge tube 62, so as to approximate the catch cams 64c of catch cam tube 64, as shown in
Performing the Anastomosis
The present invention is applicable for performing a variety of anastomosis procedures, including coronary artery bypass grafting. One or more anastomoses are performed on a target vessel within a patient, by connecting one or both ends of a graft to the target vessel. The following description pertains to a specific, non-limiting application of the present invention in performing an end-to-side anastomosis of a proximal end of a graft to the wall of the aorta.
The description begins with the surgical site having already been prepared for performance of the anastomosis. The anastomosis can be performed with the heart stopped and the patient on cardiopulmonary bypass or during a beating heart bypass procedure. Examples of grafts appropriate for use in performing an anastomosis include an internal mammary artery having only one free end (the end on which the anastomosis is to be performed), a saphenous vein graft or radial artery graft having two free ends (in which case it is possible to perform the distal anastomosis first, if desired, as noted above) or some other suitable graft or conduit.
After selection and preparation of the graft to be used, the proximal end of the graft 3 is loaded and everted onto the device 1, by passing the proximal end 3 through the interior of the device 1,100 and then everted over the proximal end of the device 1,100, as shown in
Aortotomy punch 160 provides an initial blade stab with a retracting rotary punch that creates a circular aortotomy 162 having a specific diameter that is matched to the outside diameter of the graft 3 everted over the device 1,100, see
With a single continuous squeeze or depression of the trigger 54 toward the handle 52 of the deployment tool 50, the device 1,100 is compressed, compression fitted and locked to join the graft 3 to the aortic wall, and the deployment tool 50 then releases its capture of the device 1,100 so that the surgeon can remove the deployment tool from inside the device 1,100 with the graft 3 at the same time being slid out of the channel 66, thereby completing the anastomosis.
As the trigger 54 continues further in its travel toward the body 52, the struts 16 of the strut section begin to collapse, as shown in
As the trigger 54 continues its motion toward the handle/body 52, and the lock driver 81 is driven in a direction toward the distal end of deployment device 50, the device lock 68 bends over the locking tines 20, as shown in
Device 100 is deployed in the same manner as described above with regard to device 1. However, with only one set of struts 112, the struts expand outwardly by a greater distance and expand beyond the extent of the everted end of the graft 3. Additionally, since the graft tines are located on the ring 106, the graft 3 is not everted to as great an extent as what occurs when buckling the device 1. The result is still an intima to intima anastomosis, but the intima to intima contact is periodically interrupted by the radially extending collapsed struts 112 which extend therebetween. For this reason the device 1 is preferred.
While the present invention has been described with reference to the specific embodiments thereof, it should be understood by those skilled in the art that various changes may be made and equivalents may be substituted without departing from the true spirit and scope of the invention. In addition, many modifications may be made to adapt a particular situation, material, composition of matter, process, process step or steps, to the objective, spirit and scope of the present invention. All such modifications are intended to be within the scope of the claims appended hereto.